Structural Safety in High Rise Buildings

Transcription

Winston Churchill Memorial Trust
By
Lembit Kerks
2012
North America
September – October 2012
New York City
Chicago
Oklahoma City
Los Angeles
San Francisco
Toronto
Supported by
The Fire Service College
&
Passive Fire Protection
Federation
Lembit Kerks
Winston Churchill Fellows Report
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CONTENTS
Page
1
BACKGROUND
6
1.1
1.2
1.3
1.4
1.5
1.6
1.7
Acknowledgements
About the author
The start of my project
The Winston Churchill Memorial Trust
Aims and objectives of my visit
Selection of North American cities to visit
Structure of this report
6
7
7
8
8
9
9
2
BUILDING CONTROL
11
2.1
2.8
Building regulation controls in England and Wales
2.1.1 Internal fire spread (structure) B3
2.1.2 External fire spread B4
Building controls in the USA and Canada
USA building controls
2.3.1 Occupancy and construction
2.3.2 High Rise buildings
2.3.3 Surface linings
2.3.4 Fire resistance rated construction
2.3.5 Building heights and areas
2.3.6 Comparison of USA codes with UK building regulations
Canadian building controls
Enforcement of fire safety
2.5.1 Buildings under construction
2.5.2 Completion of building work and start of occupation
BTEA ‘Building Trades Employers Association’ in New York
Retrofitting of sprinklers to old buildings
2.7.1 New York City
2.7.2 Chicago
2.7.3 Los Angeles
2.7.4 San Francisco
2.7.5 Oklahoma City and Toronto
Fire engineered solutions
11
11
12
12
13
13
13
13
14
15
15
17
17
17
18
18
19
19
19
19
19
19
20
3
DESIGN OF STEEL FRAMED BUILDINGS
21
3.1
Background to steel framed buildings
3.1.1 Rigid frame
3.1.2 Framed shear truss
3.1.3 Framed tube
3.1.4 Wind loadings on High Rise buildings
21
21
22
22
22
2.2
2.3
2.4
2.5
2.6
2.7
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CONTENTS (continued)
Page
3.6
3.7
3.8
3.9
3.10
3.11
3.1.5 Braced tube
3.1.6 Bundled tube
Structural fire protection issues related to observed buildings
680 Folsom Street San Francisco, under construction
3.3.1 Outline of construction
3.3.2 Fire protection of steelwork
3.3.3 Other buildings with similar sprayed fire protection
Roosevelt University Chicago, under construction
AON Center Los Angeles, completed in 1973
3.5.1 Fire protection
3.5.2 Major fire incident at the building
One Maritime Plaza San Francisco, completed in 1967
John Hancock Tower Chicago, completed in 1970
Willis Tower Chicago, completed in 1973
Empire State Building New York, completed in 1931
Metropolitan Life Tower New York, completed in 1909
Summary of structural steel buildings
23
24
24
25
25
25
27
28
31
31
31
32
33
34
34
35
35
4
DESIGN OF REINFORCED CONCRETE FRAMED BUILDINGS
37
4.1
4.2
4.3
4.4
4.5
Background to reinforced concrete buildings
Trump International Tower Chicago, completed in 2009
Summary Trump International Tower
Devon Energy building Oklahoma City, completed in 2012
Summary Devon Energy Tower
37
37
39
41
43
5
EARTHQUAKE PROTECTION DESIGN
44
5.1
5.2
One Maritime Plaza San Francisco
680 Folsom Street San Francisco
44
46
6
OTHER BUILDING DESIGN FEATURES
47
6.1
6.2
6.3
Wall construction (non-loadbearing)
Large floor areas
Glazing systems
6.3.1 External glazing
6.3.2 Fire resistant glazing
6.3.3 Impact resistant glazing
Emergency lighting systems
Atrium design
Helicopter landing decks
47
48
49
49
50
51
52
52
53
3.2
3.3
3.4
3.5
6.4
6.5
6.6
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CONTENTS (continued)
Page
7
MISCELLANEOUS BUILDINGS
55
8
OKLAHOMA STATE UNIVERSITY
56
9
FINAL CONCLUSIONS
57
10
NEXT STEPS FOR THE PROJECT
60
APPENDICES
Appendix A
Appendix B
Appendix C
Appendix D
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References
List of buildings visited
WCMT Fellowship timetable – North America
Press report – Gloucestershire Echo
3 January 2013
Press report – Bolton News
22 January 2013
61
63
66
67
68
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1
BACKGROUND
1.1
Acknowledgements
My thanks to the following people who were extremely generous in giving me their time during my
research in North America.
• Richard S Tobin, Assistant Chief of Fire Prevention, Fire Department New York • O’Dell Horton,
Inspector, Fire Department New York • Andrew Dushynskiy, Inspector, Fire Department New York
• John Barrot, Senior Consultant, Arup New York • Jaewook Kwon, Fire Engineer, Arup New York
• Kurt Schebel, Fire Consultant, Arup New York • Steven Pirovolikos, Director of Safety, Structure
Tone Inc. New York • Matthew Ross, Superintendent Project Management & Construction, Lend
Lease New York • Thomas Connors, Executive Director Buildings New York City • Louis J Coletti, CEO
and President, Building Trades Employers Association New York • Carol J Karlin, Fire Safety Academy
New York • Richard C. Ford II, Deputy Fire Commissioner, Chicago Bureau of Fire Prevention • Steve
Johnson, Lieutenant, Chicago Fire Department • John Javorka, Chief Fire Prevention Engineer,
Chicago Fire Prevention Bureau • Chief Peter Van Dorpe, Chicago Fire Academy • Mike Norris,
Captain, Chicago Fire Department • Mark Prestigiacomo, Engineer, Chicago Fire Department • Eddie
Banks, Chicago Fire Department • Pat Mahoney, Assistant Chief Engineer, Trump International
Tower, Chicago • Kellie Sawyers, Deputy Chief/Fire Marshal, Oklahoma • Randy Williams, Captain,
Oklahoma Fire Department • Harold Thompson, Captain, Oklahoma Fire Department • William
McCaine, Captain, Oklahoma Fire Department • Martin Herman, Senior Manager Security, Devon
Energy Corporation, Oklahoma • Ronnie Roberts, Senior Manager, Business Continuity, Devon
Energy Corporation, Oklahoma • Bob Landram, Manager Hines Construction, Oklahoma • Mike Bjes,
Project Manager Holder-Flintco, Oklahoma • Todd Woodward, Senior Project Manager, City Maps
Project Office, Oklahoma • Mark S Beck, OCMAPS Project Office, Oklahoma • JJ Chambless, City
Subdivision & Zoning, Oklahoma • Randy Edwards, Buildings Department, Oklahoma • Craig L.
Hannan, Director, Fire Protection Publications, Oklahoma State University • Michael A Wieder,
Associate Director, Fire Protection Publications, Oklahoma State University • Anthony E Brown,
Associate Professor, Oklahoma State University • Donald l Frazeur, Deputy Chief, Los Angeles Fire
Department • Jaime Moore, Captain, Los Angeles Fire Department • Brian Jones, Captain, High Rise
Unit, Los Angeles Fire Department • Timothy N Kerbrat, Battalion Chief, Los Angeles Fire Department
• Brian McLaughlin, Associate, Arup, Los Angeles • Joseph Gentile, Fire Consultant Arup, Los Angeles
• Ted Moyles, Senior Fire Engineer, Arup, Los Angeles • John A Pattillo, Partner, Conquest Fire Spray,
Los Angeles • Janice Hayes, Captain, San Francisco Fire Department • Frederick E Stumpp, Fire
Protection Engineer, San Francisco Fire Department • Mary M Tse, Lieutenant, San Francisco Fire
Department • Armin Wolski, Associate Principal, Arup, San Francisco • Joe McBride, Chief Engineer,
One Maritime Plaza, San Francisco • Darwin Rodriguez, Superintendent of Construction, 680 Folsom
Street, San Francisco • Jim Fredrickson, Fireproofing Division, LVI Facility Services, San Francisco •
Frank Lamie, Deputy Fire Chief, Toronto Fire Services • Paul Catchpole, Captain, Toronto Fire Service
• Matthew Coombes, Superintendent, EllisDon Building Company, Toronto • Peter Mahut, Property
Manager Brookfield Services, The Palace Pier, Toronto • Darko Patekar, Maintenance Manager
Palace Pier, Toronto • Mike Fletcher, Facilities Manager Pinewood Studios, Toronto • Peter Frith,
General Manager Technical Services, Brookfield Place, Toronto • Philip Longton, Manager Security &
Life Safety Brookfield Place, Toronto • Roderick Blakey, Manager Security & Life Safety, First
Canadian Place, Toronto • William Roussy, Security Supervisor CN Tower, Toronto
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1.2
About the author
I am a mechanical engineering graduate of Aston University, and have had a career initially spent in
the process industries, and latterly in fire education and training.
During my time in the food and beverage industry I was a project manager of multi-disciplined
projects for the development of land, buildings and plant.
Over the last 25 years, I have been involved with fire training with the Fire and Rescue Services. I am
an Associate Tutor at the Fire Service College and am involved with fire training at the centralised UK
training establishment in Moreton-in-Marsh, Gloucestershire. Additionally, I have been involved with
university undergraduate education programmes through partnership arrangements between my
college and various UK universities.
My specialism is in building construction topics which are related to fire effects on buildings, building
regulations and general fire engineering subjects. The type of study courses with which I am involved
include fire safety training, fire service operational courses such as ‘Incident Command’ and Urban
Search and Rescue. The later courses have evolved since the ‘Twin Towers’ incident in 2001. I also
deliver similar courses for a wider international market. My personal development over the years
has included becoming a Chartered Member of the Institutions of Mechanical and Fire Engineers and
I have also undertaken a Masters in Building Services Engineering at Brunel University.
1.3
The start of my project
In the early part of 2011, I was asked to present a paper to an ‘International High Rise Symposium’ at
the Fire Service College. The main theme was to focus on fire fighting procedures in High Rise
buildings which was a subject area of great importance to Fire Services worldwide. To widen the
appeal of the symposium and enhance the expertise of presenters, senior fire service
representatives from New York and Toronto were invited to deliver papers.
Concurrently, the UK Fire Services are revising their emergency response procedures at High Rise
incidents and this is likely to continue for some years to come. It is also worthwhile noting the trend
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towards the development of ever increasing tall buildings in UK towns and cities. Knowledge and
experience related to their design and construction underpins the ultimate safety of people using
these buildings. This includes safe occupant evacuation and implications to Fire Service personnel
attending emergency incidents.
My particular paper for the symposium was to concentrate on building construction issues related to
High Rise buildings. It became clear to me whilst preparing materials for this presentation that
research of books, journal articles and the internet alone cannot portray a complete story. Although
I had visited two of the UK’s tallest buildings in London, the Canary Wharf and the Gherkin buildings,
I concluded I needed to visit a greater selection of High Rise buildings and much taller ones at that!
Because the development and history of High Rise building began in North America I started to
consider a possible visit there. As I deliberated over the preparation for the symposium I
remembered a conversation I had with a Churchill Fellow some two years before. I particularly
remember I liked the idea of undertaking a research project overseas but at the time could not
identify a suitable project warranting such sponsorship. It was at this point I linked together my need
to study High Rise buildings and the Winston Churchill Memorial Trust Fellowship.
In September of 2011 I duly submitted my application to the Trust and “the rest is history”
1.4
The Winston Churchill Memorial Trust
I would not have been able to undertake this project without the support of the Winston Churchill
Memorial Trust. The esteem in which Winston Churchill is regarded in North America is immense.
Because of this I was able to take advantage of many opportunities and meet people who might not
have otherwise availed themselves to me.
My thanks therefore to all staff at the trust, particularly those I have dealt with, Jamie Balfour, Julia
Weston and Sue Matthews.
1.5
Aims and objectives of my visit
This fellowship was awarded within the category of ‘Education and Vocational Training’ with the
project title ‘Structural Safety in High Rise Buildings’.
The aims and objectives of the project are;




Identify the significant differences in High Rise construction regulations between those of
North America and the UK
Investigate the design issues related to the protection of High Rise buildings against fire,
wind and earthquake
Specifically identify the protection provided to steel and reinforced concrete framed
buildings
Investigate and report on North American construction related to wall and floor
construction, and glazing systems
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


1.6
Develop a collection of photographs of High Rise buildings which would be suitable for
development of Fire Service training courses
Visit Oklahoma State University and view the educational facilities used for fire related
bachelor degree programmes
Improve my personal understanding of the issues related to High Rise buildings with respect
to their design, construction and building use.
Selection of North American cities to visit
I selected New York City and Chicago because they both have high densities of High Rise buildings.
They are also obvious choices because of the vast array of designs used for both commercial and
residential properties. Architecturally these cities were the foremost leaders in High Rise building
design. Chicago would also be particularly informative with respect to wind design because of its
location on the southern tip of Lake Michigan, a place known for high wind effects and hence known
as ‘The windy city’.
Toronto was included in the itinerary as it has some buildings similar to our own Canary Wharf
development in London albeit much taller.
The west coast including Los Angeles and San Francisco, offers more stringent building designs
against earthquake events due to their location close to the San Andreas Fault Line.
Finally, Oklahoma City offered two important attributes to the study project; the relationship and
impact of tornado events on building design (these are frequent events in this part of North
America); and secondly a visit to Oklahoma State University was considered desirable as it has
successfully run over many years, a ‘Fire Protection and Safety Technology’ Bachelor’s Degree
programme. The University also produces a well-respected ‘Fire Protection Publication’.
1.7
Structure of this report
From my visit to North American I was able to access a total of 22 buildings, as listed in Appendix B.
As expected, the structural forms of these buildings and their respective levels of fire protection
varied enormously. This report is structured as follows;
Section 2 sets the scene and discusses the building regulation controls for High Rise building in
England and Wales, USA and Canada. It concludes with a comparative analysis of the differences
found.
Section 3 discusses the methods used in North America for the protection of steel framed buildings.
Section 4 outlines the methods used for the protection of reinforced concrete framed buildings in
North America.
Section 5 discusses the methods employed to protect High Rise buildings from the effects of an
earthquake.
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Section 6 discusses some important building design features observed in High Rise buildings. These
include wall and floor construction, glazing systems, atria designs and the use of helicopter landing
decks.
Section 7 discusses some miscellaneous buildings, observed and photographed, which will be of
value for the development of Fire Service training courses.
Section 8 discusses the visit to Oklahoma State University.
Section 9 discusses the final conclusions from the project.
Section 10 discusses the next steps for this project.
Submitted in appendix C is a copy of the timetable of my visits whilst in North America.
Appendix D contains copies of published reports. They include reports published in the


Gloucestershire Echo on the 3 January 2013, and
Bolton News dated 22 January 2013.
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2
BUILDING CONTROL
This section reports on the building regulation controls for England and Wales, USA and Canada.
These include building design issues and enforcement procedures related to control of internal and
external structural requirements. This section concludes with a comparative analysis of the
differences found.
2.1
Building regulation controls in England and Wales
The Building Regulation requirements for fire safety in England and Wales are explained in, Building
Regulations (2000), Approved Document B. For this project High Rise buildings have been considered
as those with a greater height than 30m (98.4ft), and specifically with building uses (purpose groups)
of 2b Hotels, 1a Flats, and 3 Offices. Two particular parts of these regulations are relevant to this
project.
2.1.1
Internal fire spread (structure) B3
The regulations state “buildings shall be designed and constructed so that, in the event of a fire, the
stability will be maintained for a reasonable period.” To achieve this, building designs are centred on
either or both of the following;
(a) Sub-division of a building with fire-resisting construction;
(b) Installation of suitable automatic fire suppression systems.”
Further, the regulations indicate the safety requirements for High Rise buildings include the
following designs features;








All structural frame elements require protection of 2 hours fire resistance; reference BS 476parts 20-24:1987.
All floors need to be compartment floor of 2 hours fire resistance; however these can be
reduced to 90 minutes for elements not forming part of the structural frame.
All shaft openings i.e. staircases and service shafts, require wall enclosures of 2 hours fire
resistance; however these can be reduced to 90 minutes for elements not forming part of
the structural frame.
Fire resistance ratings for fire doors are selected from Table B1 of the regulations, resulting
in FD30S (30 min fire resisting), reference BS 476 part 22, or half the appropriate rating of
the wall it is fitted in, dependent upon application.
Floor plate areas can be unlimited.
Flats and Office use buildings require sprinkler protection throughout.
Hotel buildings have no requirements for sprinkler protection.
Fire fighting shafts will be required complete with fire fighting lifts, with lobby access on
each storey and with all walls of 2 hours fire resistance. A minimum of 2 such shafts will be
required, assuming large floor plate areas. Maximum hose lengths of 60m (197ft) to water
outlet connections for buildings with sprinklers, and 45m (148ft) for buildings without
sprinklers. Wet main raisers are required for buildings greater than 50m (164ft) in height.
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Note: The fire resistance ratings are referenced to BS 476 parts 20-24 fire tests on building materials
and structures.
Most importantly, all buildings within the scope of this project “Shall be designed and constructed so
that the unseen spread of fire and smoke within concealed spaces in its structure and fabric is
inhibited.” To satisfy this part of the regulations all raised floors and suspended ceiling void spaces,
greater than specific areas, require fire protection. Cavity barriers are typical forms of protection
which reduce the void space areas and therefore restrict the potential for fire spread.
2.1.2
External fire spread B4
This part of the regulations states “The external walls of a building shall adequately resist the spread
of fire over the walls and from one building to another, having regard to the height, use and position
of the building.”
For buildings with a boundary distance greater than 1m (3.3ft) the external walls require a nominal
surface control, fire propagation index I, reference BS 476 part 6, of not greater than 20, for walls up
to 18m (59ft). A higher control standard of Class O surface spread of flame, reference BS 476 parts 4,
6, 7, 11, is required on external wall heights greater than 18m (59ft). If boundary distances are less
than 1m (3.3ft) then the higher control standard of Class O is required.
To resist fire spread from one building to another controls are placed on unprotected openings, e.g.
windows and doors, in relation to the boundary distance from each external wall. In effect, because
High Rise buildings will be compartmented floor by floor, a high degree of unprotected openings are
allowed. Allowable unprotected areas in walls increases with boundary distance, providing a
minimum of 1m (3.3ft) boundary distance is available. This allows the designer to build external
walls in glazing materials without too many restrictions.
2.2
Building controls in the USA and Canada
Some time ago, both the USA and Canada consolidated a multiplicity of buildings codes used in their
countries through the International Code Council (ICC). This resulted in a common International
Building Code (IBC) being used throughout North America, which regulates the construction and
renovation of buildings. Additionally each city and town has a zoning ordinance which regulates
what can be built where, and how a building can be used. Both these regulated documents need to
be complied with, prior to approval of any building work.
The IBC building codes also make further references to ASTM (American Society for Testing and
Materials) and NFPA (National Fire Protection Association) standards. For example ASTM standards
are used for fire testing of materials and elements of construction, and NFPA standards are used for
automatic sprinkler installations.
The IBC code should be viewed as an equivalent status to UK regulations and should be treated as a
minimum standard. Each State in the US or Province in Canada, can amend the technical content in
the code as can the major cities. The amendments usually require additional technical requirements.
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For example New York City, with high density High Rise buildings, would have more demanding
requirements than New York State which is mainly rural.
2.3
USA building controls
With reference to structural safety related to High Rise Buildings, four chapters of the IBC codes
have particular relevance to structural design. They are;
2.3.1
Occupancy and Construction
As with many countries, the essence of regulatory safeguards from fire was to provide reasonable
levels of property protection. Thus, if property was adequately protected from fire, then the building
occupants would also be protected. The IBC codes have now evolved with the concept of equivalent
risk. This concept maintains an acceptable level of risk against the damages of fire, respective to a
particular occupancy type or group. It can be achieved by limiting the height and area of buildings
containing such occupancies according to the building’s construction type, (its fire endurance).
The whole built environment is therefore grouped into 10 occupancy uses classified by letter
designations, in comparison with the 7 UK purpose groups. High hazard, educational and
miscellaneous buildings are additionally designated in the US with appropriate design requirements.
To complicate matters the lettering systems vary across the cities of North America.
New York’s designation of relevant building groups is;
Table 1 IBC Occupancy groupings with designations for New York City
2.3.2
Building Occupancy
Designation
Residential Hotels
Residential Apartments
Business Offices
R1
R2
B
High Rise Buildings
Buildings with an occupied floor at a greater height than 23m (75ft) are classified as High Rise
buildings, compared with 30m (98.4ft) in the UK. An important safety design feature for all newly
built hotels, apartments, and office buildings is the compulsory requirement to fit automatic
sprinklers throughout the building. As would be expected, all such High Rise buildings also require
automatic fire alarm systems, emergency voice/alarm and communications systems, fire department
communication systems, a fire command centre and elevators complete with lobby approach.
2.3.3
Surface linings
Surface linings in buildings are controlled by ASTM E84 fire tests including smoke emission from
materials. These controls have been considered equivalent to UK provisions for the purposes of this
project.
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2.3.4
Fire resistance rated construction
The IBC code classifies buildings into 5 types of construction according to the proposed selection of
construction materials. This classification accounts for the response of a building in fire conditions as
a result of its occupancy or fire load. Each type of construction is then provided with a minimum
hourly fire resistance rating for the structural elements. However, this issue is simplified because
only non-combustible forms of construction are selected for elements of construction for High Rise
buildings throughout North America. Therefore the only relevant type of construction is Type 1A.
Fire resistance testing is undertaken according to ASTM E119, in which the test regime measures the
structural integrity of elements of construction and materials. Further the test takes into account
three important criteria; transmission of heat, transmission of hot gases through the element, and
the load carrying capacity for the duration of the test. Additionally, for walls and partitions, rated at
1hr or above, a hose stream test according to ASTM E2226 is applied to the element of construction.
This added test is used to monitor the cooling impact and to measure the resistance to
disintegration under adverse conditions. It is particularly relevant for the use of glass and glazing
systems in wall and partition elements. Further it can be concluded that wired glass is generally used
in North America because many alternative glasses fail the hose stream test. The hose stream test is
not used in the UK. The relevant fire-resistance requirements for structural elements are, reference
Table 2.
Table 2 IBC fire resistance requirements for elements of structure
Element of Structure
Fire Resistance Rating
Structural frame
Bearing walls external and internal
Floor construction including supporting beams and joists
Roof construction
3hrs
3hrs
2hrs
1.5hrs
Note: The IBC code does not specify requirements to protect void spaces above suspended ceilings
or below raised floors in High Rise buildings. Therefore the use of cavity barriers is limited. However,
fire stopping is specified which is very much in line with UK practice.
As in the UK the fire resistance ratings for external walls is based on fire separation distance of the
external wall from the boundary. The IBC code fire resistance ratings for external walls for hotels,
apartments, and office buildings are, reference Table 3.
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Table 3 IBC Space separation of buildings related to required fire resistance of external walls
Space Separation
Less than 9.1m (30ft)
9.1m (30ft) or greater
1hr
0
IBC code fire resistance requirements for openings including fire doors and shutters are, reference
Table 4.
Table 4 IBC code building openings related to fire resistance requirements
2.3.5
Opening assembly description
Walls and fire barriers of 3hrs
Walls and fire barriers of 2hrs
Walls and fire barriers of 1.5hrs
Shaft fire barriers requiring 1hr
Other fire barriers requiring 1hr
Fire partitions corridor walls 1hr
3hrs protection
1.5hrs
1.5hrs
1hrs
0.75hrs
0.75hrs
Building heights and areas
Floor area requirements are relatively simple to apply because unlimited floor areas are permitted
for High Rise buildings used for hotels, apartments, and office use, similar to the UK.
2.3.6
Comparison of USA codes with UK building regulations
Tables 5, 6 and 7 illustrate the comparative differences between the USA, IBC codes and UK
regulations for building use/occupancy, fire resistance ratings for elements of structure and
requirements for sprinkler protection.
Table 5 Occupancy classifications related to USA, IBC codes and the UK regulations
Occupancy classification
USA, IBC
UK
Residential Hotel
Business Offices
R1
R2
B
Purpose Group 2b
Purpose Group 1a
Purpose Group 3
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Table 6 Fire resistance ratings for building elements related to USA, IBC codes and UK regulations
Building Element/Fire resistance
USA, IBC
Fire resistance rating
UK
Structural Frame
Floors
Roof construction
Shaft barriers
Fire doors/shutters in fire walls
Fire doors/shutters in shafts
Fire doors in escape routes
Fire fighting shafts
3hrs fire resistance
1.5hrs fire resistance
1-3hrs fire resistance
1-3hrs fire resistance
N/A
0
0.5-0.75hrs fire resistance
0.33-0.5hrs fire resistance
Increased levels of fire resistance for elements of structure, reference Table 6, are required in the
USA in terms of;

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
Structural frames, increase of 1hr.
Floor construction, increase 0.5hr.
Shaft barriers have an increase of 0.5hr, and also are required to be impact resistant.
Fire doors and shutters built into fire walls are far more substantially constructed with up to
double the fire resistance requirements of the UK.
Fire doors and shutters built into escape routes are of 45min fire resistance compared with
20/30min fire doors in the UK.
Roof construction requires 1.5hrs with no controls in the UK
Fire fighting shafts in the USA are not designed as such. Fire resisting barriers to shafts are
provided and are likely to be of a higher rating than in the UK.
Table 7 Sprinkler requirements for occupancy classification related to USA, IBC codes and UK
regulations
Occupancy classification
/Sprinkler requirements
US, IBC
Sprinkler requirements
UK
Sprinkler requirements
Residential Hotel
Business Offices
Required
Required
Required
N/A
Required
Required
It is a compulsory requirement in the USA for new High Rise buildings to be fitted with sprinklers, as
it is in the UK. However it is noticeable that UK hotel buildings are an exception and do not require
sprinkler protection. Presumably the UK argument is centred on the fact that hotel construction is in
small cells (bedrooms) and therefore the fire resistance ratings of fire barriers are adequate to
prevent fire spread. From observations of hotel buildings in North America, design layouts do
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include commercial (restaurants) and assembly (spa facilities) areas positioned at high levels within
buildings. These areas with increased fire loads and larger floor areas would challenge the wisdom of
not regulating sprinkler protection for High Rise hotel buildings in the UK.
2.4
Canadian building controls
The relevant building codes for Toronto are;
‘Ontario Building Act 1992’ made effective through S.O. 1992 Chapter 23 of 1 June 2011. Specifically
part ‘Ontario Regulation 350/06’ (Division B – Acceptable Solutions) which is enforced by the
Building Control Department. The under-pinning background to the building code comes from the
IBC code with specific amendments adopted by Ontario and Toronto. The comparative differences
between this code and the UK are similar to those discussed for the USA, however with one notable
exception. The maximum fire resistance rating for elements of structure is 2hrs, which is similar to
the UK. Fire sprinkler requirements are the same as the USA.
‘Fire Protection and Prevention Act 1997’ made effective through ‘Ontario Regulation 213/07’,
specifies fire code requirements and is enforced by the Fire Services. These regulations are used for
on-going fire safety of buildings during occupation.
2.5
Enforcement of fire safety
2.5.1
Buildings under construction.
For the six North American cities visited, the fire safety enforcement requirements for buildings
under construction varied.
Fire safety enforcement with respect to compliance of building work to building codes is solely
undertaken by the buildings department in the cities of Los Angeles, San Francisco and Toronto.
Consultation processes do exist between departments, but the fire departments do not have any
enforcing powers.
Conversely, in the cities of New York, Chicago and Oklahoma the fire departments do have
enforcement powers, complete with violation penalty notice systems. Major fire safety issues are
controlled by the fire department. These are; storage of combustible building materials, hot working
permit systems, and provisions of water supplies to standpipes and wet mains in buildings whilst
under construction. For example fire water mains are required to be fitted up to the floor below the
construction working floor, complete with valves in readiness for fire fighting on the construction
site. In New York these water mains are required to be pressurised with air complete with an
inspection air gauge at a site entry point. Regular inspections are made to safeguard critical fire
protection systems and safe working practices.
In the UK, fire services do not have enforcement powers whilst a building is under construction. Fire
safety designs to meet building regulation requirements are enforced by the building control
authorities. Safe working practices during construction are enforceable by the Health and Safety
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Inspectorate. Fire Services may be asked to advise on fire safety matters during construction
however this is undertaken on a goodwill basis only.
2.5.2
Completion of building work and start of occupation.
When construction work on buildings is complete and occupation takes place, all six cities have fire
codes which authorises fire departments to inspect buildings with respect to fire safety matters. The
fire departments become the lead authority in implementing on-going fire safety. To assist the fire
departments in these duties enforcement powers are granted to them. Some of the US cities also
have violation penalty notice systems granted to them. For High Rise buildings the owner/occupier is
expected to have a ‘Fire Safety Plan’ and an ‘Emergency Action Plan’.
2.6
BTEA ‘Building Trades Employers Association’ in New York
Following several major incidents in New York City, Mayor Bloomberg instigated the setting up of
the BTEA organisation and supported by a Fire Safety Academy for the building trades in the city. As
the construction industry is a multi-billion dollar one and is critical to the development of economic
prosperity in New York, maximum support was given to the industry. The major incidents were:
On the 18 August 2007, the Deutsche Bank fire which occurred during the deconstruction phase of
the building. It suffered a fire caused by workers smoking carelessly, and in violation of the buildings
safety code. The building did not have a functioning water standpipe resulting in the fire spreading
over 10 floors. The fire killed two fire fighters and injured more than 100 fire fighters.
In March 2008 at East 51st Street, a crane jib snapped and fell off resulting in 7 people being killed,
and another crane collapse incident at Upper East Side in May 2008 resulted in 2 people being killed.
It was a great pleasure for me to meet with the President and CEO of the BTEA, Louis J Coletti
together with the Assistant Chief Fire Officer for Fire Prevention Richard Tobin. The progress made
by the BTEA in getting the general construction safety and particularly the fire safety messages over
to construction workers has been outstanding. Progress has been made by coordinating all the
agencies involved in construction, including buildings and fire departments of the city with
contractors. They are now in a position that all construction trades working in the city, fully
participate with safety training days and it is undertaken in a proactive manner by all. When
important information is published, such as dates for safety training or accident and violation
statistics, all trade organisations and individuals are notified accordingly. Meetings take place every
month and major decisions, made at the BTEA, are published widely.
To support the BTEA a Fire Safety Academy has been set up and is supported with finance to the
tune of $1m per year. The fire department of New York fully supports this activity and regularly gives
guidance and talks to construction workers. The support for this activity comes directly from the top
of the organisation via Richard Tobin the Assistant Chief Officer of Fire Prevention.
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2.7
Retrofitting of sprinklers to older buildings
Today, sprinklers are a requirement for High Rise buildings throughout North America. However this
has not always been the case. The building codes have developed over the years and fire sprinklers
have been added to the overall safety designs of buildings. The phasing-in of sprinklers and the time
given for owner/occupiers to fit them retrospectively varies across the continent. Much political
debate at city level takes place before implementing retrospective building requirements. Below is a
review of the status for the 6 cities visited.
2.7.1
New York City
All commercial buildings, including offices, not fitted with sprinklers require retrofit sprinklers.
Because these buildings are of a commercial nature the city expects companies to afford the
alteration works. Similar arrangements are required for residential buildings but there are many
exceptions. These exceptions are assessed on individual building safety merits. The use of asbestos
insulation is a significant one which might preclude a building from this conversion. A clean-up
operation would be difficult to achieve if the insulation was disturbed. Overall a completion period
of 10 years was granted for the retrofitting of sprinkler installations.
2.7.2
Chicago
Similar arrangements are in place with Chicago in that all High Rise commercial and residential
buildings without sprinklers require retrofit installations. This only affects some buildings built prior
to 1975. A period of time was granted to owner/occupiers of such buildings with completion
expected during 2013-2017. There are some 200 buildings in this category.
2.7.3
Los Angeles
All commercial buildings without sprinklers require retrofit sprinkler installations. This only affects
buildings pre-dating 1974 and again a 10 year completion period was granted to building owners.
Similarly residential buildings without sprinklers require retrofit sprinklers if building owners intend
undertaking structural building alterations. Under these conditions sprinklers are only required in
the communal areas of the building and not the main accommodation spaces. Asbestos insulation is
a significant feature affecting residential buildings.
2.7.4
San Francisco
All commercial buildings built without sprinklers require retrofit sprinkler installations. This affects
buildings built prior to 1994. 12 years were granted for the completion of these building works.
Hotel buildings had to comply with retrospective fitting of sprinklers whilst apartment buildings
were excluded. Historic buildings were also exempted from these requirements.
2.7.5 Oklahoma City and Toronto
The city authorities have not implemented any rules for the retrofitting of sprinklers to any type of
building.
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2.8
Fire engineered solutions
Fire engineered solutions are acceptable in North America. However, non-compliance with clauses in
city building codes is closely scrutinised. Sometimes fire engineering consulting companies carry out
third party evaluations of schemes on behalf of the authorities and paid for by the proposed
developer.
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3
DESIGN OF STEEL FRAMED BUILDINGS
This section reports on and discusses the styles of structural steel frames used in North America
including the effects of wind loadings on the structure. It continues with the methods used to
protect steelwork against fire complete with illustrative case studies. The section is concluded with a
summary of buildings visited related to their appropriate protection.
3.1
Background to steel framed buildings
Economics and the limitations of masonry construction dictated the early development of High Rise
buildings. The result was the emergence of iron/steel frame structures which minimised the depth
and width of structural members at building perimeters. Consequently, the larger openings were
filled with transparent glasses, while the iron/steel structures were clad with other solid materials
such as brick or terra cotta. These cladding materials did not carry any loads from the buildings
except their own weights and the lateral wind pressures. Later a new cladding concept “curtain
walling”, which allowed external glass panels to be hung from buildings, was developed with the
emergence of new structural systems, reference Mir M Ali and Kyoung Sun Moon (2007). Now-adays we classify steel framed buildings into the following generic structural systems as shown in
Figure 1.
Figure 1 Classification of High Rise (structural steel) systems related to storey heights,
reference, Mir M Ali and Kyoung Sun Moon (2007)
During my visit to North America the following five styles of steel frame structures were observed;
3.1.1
Rigid frame
These buildings consist of vertical columns and horizontal joist members rigidly connected together
in a grid form. The size of columns is controlled by gravity loads that increase towards the base of
the building giving rise to larger column sizes towards the base from the roof. The size of horizontal
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joists is controlled by the stiffness of the frame in order to ensure acceptable lateral sway of the
building.
Many High Rise buildings of this form of construction were observed, with most less than 30 stories
tall. Of particular note were the older buildings including, the Fuller Flatiron (22 floors) built in 1902,
and the Metropolitan Life Tower (45 floors) built in 1909, both located in New York. More modern
versions of this form of structure were observed at 680 Folsom Street in San Francisco (14 floors)
which is currently under construction.
3.1.2
Framed shear truss
These buildings are similar to rigid frame structures, with additional shear truss frame interacting
systems. Lateral loads are resisted mainly through axial stiffness of the frame members. The position
of the bracing in the building varies and because of this internal planning space may be limited due
to the shear trusses.
New York’s Empire State building (102 floors) completed in 1931 is a good example of this form of
structure.
3.1.3
Framed tube
When buildings are designed taller, the perimeter becomes structurally more significant. They
become more vulnerable to lateral forces, especially wind loads. Framed tubes are used to
counteract these forces by stiffening the external perimeter and rigidly connecting the external
frame. This comprises closely spaced columns with deep spandrel beams. A major disadvantage with
this form of design is the obstruction of views from the building, due to the close spacing of external
column members.
The Aon building in Los Angeles (62 floors) built in 1973 typifies this form of structure.
3.1.4
Wind loadings on High Rise buildings
Figure 2 shows the major forces exerted on a High Rise building caused by wind conditions, including
forces from the wind direction, cross-wind and resulting torsional twisting. Cross winds are
significant because they can be greater than the forces applied directly from the wind direction.
Wind flow patterns generated around buildings is complicated by distortion of the mean flow,
separation flow, formation of vortices and the development of the wake. Wind pressure fluctuations
on the building façade results in vibrating forces which further complicates the structural analysis.
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Figure 2 Diagram showing the forces acting
Figure 3 Computer model of wind effects on
on a building caused by wind effects reference, buildings reference,
Mendis P, Ngo T, Haritos N, Hira A (2007)
Mendis P, Ngo T, Haritos N, Hira A (2007)
Figure 3 shows computer simulated wind effects on High Rise buildings, complete with eddy current
flow paths. These create negative pressure areas around the building thus setting up the three main
component forces acting on the building. Vortex shedding causes cross wind forces and if the
structure is flexible, these forces cause oscillation. Further, if the vortex shedding frequency
coincides with the natural frequency of the building, failure can occur.
3.1.5
Braced tube
Braced tubes are a variation of the framed tube. Wider columns are used with further diagonal cross
bracing which stiffens the columns to create wall-like characteristics, thus eliminating the use of
closely spaced vertical columns. The diagonal bracing carries gravity loads and acts as inclined
columns.
Figure 4 One Maritime Plaza San Francisco,
with external cross bracing
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Figure 5 John Hancock building Chicago,
with external cross bracing
- 23 -
One Maritime Plaza in San Francisco (27 floors) built in 1967, and the John Hancock building in
Chicago (100 floors) built in 1970, see Figures 4 and 5 respectively, are good examples of this form of
structure.
3.1.6
Bundled tube
A bundled tube is a cluster of individual tubes connected together to act as a single unit. I was able
to visit the world’s first bundled tube building, the Willis Tower in Chicago (110 floors) built in 1973.
This building has nine steel framed tubes bundled together at the base, some of which terminate at
various levels along the building height with two tubes continuing between the 90th floor and the
roof, as illustrated in Figure 6 and 7.
Figures 6 Structural steel ‘Bundled tube’
Willis Tower building Chicago
reference, Mir M Ali and Kyoung Sun Moon (2007)
3.2
Figures 7 Structural steel ‘Bundled tube’
Willis Tower building Chicago
Structural fire protection issues related to observed buildings
Structural steel offers many advantages to the building designer including controlled manufacture of
component parts fabricated in the factory followed by site erection. However, steel does have a
major weakness from a fire perspective. Steel strength is dramatically reduced at relatively low
temperatures e.g. it loses half its strength at approximately 5500C. It is therefore important to fire
protect structural steel from fire.
In North America the majority of fire protection applied to steel framed buildings is by cement
sprays. Programmed installation schedules allow for preparation time to seal a floor, spraying time
to protect the steelwork, and time for clean-up operations. During this time other trades do not
undertake any building work within the vicinity of spraying. In the UK, cladding systems as well as
cement spray protection is used. Cladding systems alleviate safety and environmental issues
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associated with dusty cement spraying operations. Cladding systems are however used in North
American but only when high quality smooth surface finishes are required.
The design process for steelwork protection includes the architect selecting the cement spraying
process and specifying the fire resistance ratings for elements of structure, with the developers and
fire protection contracting companies marking up drawings and identifying spray coating thicknesses
to specific elements of structure. A good example to illustrate this is the construction works
witnessed at 680 Folsom Street, San Francisco.
3.3
680 Folsom Street San Francisco, under construction
3.3.1
Outline of construction
Alterations to this 14 storey building included, stripping the building back to a bare shell, adding 2
extra floors and extending the floor areas, reference Figure 8. The building is a rigid steel frame with
some exterior vertical supports with composite steel deck floors. Figure 9, illustrates the top side
view of a typical floor section prior to concrete pouring. The floor comprises; a profiled steel deck,
shear studs (right hand side of the photograph), and steel reinforcement bars.
Figure 8 14 storey building with 2 added
Floors and extended floor areas
3.3.2
Figure 9 Typical floor construction
Fire protection of steelwork
The architect specified the construction as a type 1A building and identified the fire resistance
ratings for the elements of structure as shown in Table 8. The ratings are in-line with IBC code
requirements as discussed in section 2.3 of this report.
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Table 8 Architect specified fire resistance ratings for elements of structure.
Element of structure
Column protection
Floor primary beams
Floor secondary beams
Floor deck
2hrs
2hrs
2hrs
The method of achieving the required fire resistance by cement spraying was drawn up by the
specialist fire protection contractor. The material used was CAFCO 300, fire tested for use in North
America to ASTM E119 (also suitable in the UK to meet BS 476 part 21 requirements). The specialist
fire protection company supplied drawings indicating material thicknesses for specified elements.
Figure 10 illustrates a typical floor plan with spray coating thicknesses for specified elements.
Differing colours are used to represent material spray thicknesses of; yellow 15/16in (24mm),
orange 1 1/16in (27mm), green 1 1/8in (29mm), purple 1 5/16in (33mm), blue 1 1/2in (38mm), and
chain dot purple 1 11/16in (43mm).
Figure 10 Typical floor plan identifying spray protection thicknesses to elements of structure
With respect to the extent of fire protection of the structural steelwork, the architect specified all
columns and beams to be cement spray protected. The composite floor structures throughout the
building are inherently of 2hrs fire resistance, therefore spraying of the underside of the floor deck
was not required. Factors which influence the fire resistance of the composite floors is; the
composite nature of the structure including the deck profile, the concrete mix used, and the
thickness of floor.
The preparation undertaken prior to spray protection is illustrated in; Figure 11, spray cleaning of
the existing and new steelwork, and Figure 12, fixing metal laths to improve fire protection spray
adhesion to the structure.
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Figure 11 Cleaning the structure prior to
fire protection spraying
Figure 12 Fixing of metal laths to improve
adhesion of fire protection spray
Finally, application of fire protection spraying is shown in Figure 13. The extent of fire protection
includes spray application to all columns and beams and with the underside of the floor left
unprotected, as can be seen in Figure 14.
Figure 13 Application of fire protection sprays
Figure 14 Extent of spray application
including all columns and beams and with
the underside of the floor unprotected
3.3.3 Other buildings with similar sprayed fire protection
The following buildings are further examples were cement spray protection was used for the
structural frame with all columns and beams protected, and with the underside of the composite
floor unprotected.
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


The Bank of Montreal Offices, Toronto completed in 1975
Brookfied Place, Toronto completed in 1992
Constellation Place, Los Angeles completed in 2003
Figures 15, 16 and 17 illustrate the extent of applied fire protection.
Figure 15 Bank of Montreal Office, Toronto
Figure 16 Brookfield Place, Toronto
Figure 17 Constellation Place, Los Angeles
3.4
Roosevelt University Chicago, under construction
Figure 18 All columns and beams fire protected
Figure 19 Underside of decking unprotected
I visited a new development for an indoor athletics facility at Roosevelt University. This three storey
building with a large foot print area is classified as assembly occupancy. The structural steel frame
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was fire protected with cement spray applied to all columns and beams, reference Figure 18. The
underside of the composite deck floor was left unprotected, reference Figure 19.
From the architects drawings I was able to cross reference the fire protection designs for elements
of structure to the UL (Underwriters Laboratories) specifications presented in the “Fire Protection
Schedule” for the building, reference Table 9. The specifications related to elements of structure
shown in Figures 18 and 19 are;
Columns – 3hrs fire resistance to UL X764, reference item 1 in Table 9. The approved companies
referred to in the UL listings included, Isolatek International, Newkem Products Corp, Luck Core
Insulating Materials and Manufacturing LLC. Materials and spray thicknesses are quoted in the
specifications. UL X752 specifies the requirements for box section columns.
Beams supporting composite floors – 2hrs fire resistance to UL D739. A comprehensive UL list of
approved companies is quoted for all component parts of the beam and floor structure. Composite
floors, constructed as per item 4 in Table 9, provide 2hrs fire resistance without fire protection to
the underside of the floor reference, UL D739.
Of great interest in the design of this building was the fire protection of a hidden structural column
which could not be sprayed with cement materials as location access was prohibitive. The fire
resistance rating was to be 3hrs. To overcome this difficulty the column was coated with
intumescent materials at the factory and fitted on site. The fire protection schedule specifies the use
of UL X650 specifications with Isolatex International as the approved UL listed company.
Throughout my visits I did not come across any other applications using intumescent coatings, which
surprised me as we frequently use them in the UK. Construction professionals in North America
were well aware of intumescent coating products and have occasionally used them but only as
special applications when cement spray or fire board cladding is difficult.
Whilst studying the UL listings for this building, I did come across specification UL XR622. The only
approved company for this specification is Leigh’s Paints, a UK manufacturer. The specified product
was Firetex M90 or M90TH, rated up to 2 1/2hrs fire resistance.
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Table 9 Architects specified fire resistance ratings for elements of structure with design specifications
for UL (Underwriters Laboratories) designations
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3.5
AON Center Los Angeles, completed in 1973
3.5.1
Fire protection
The process of fire design for this building was undertaken in a similar way to that previously
discussed. However the conclusions reached were somewhat different. The steel framed structure is
of a framed truss comprising composite floors. All columns and beams are spray protected including
the underside of the floor, reference Figures 20 and 21. The cement spray protection used was
supplied by Monokote.
Figure 20 Fire protection spray to
all columns and beams
Figure 21 Fire protection to
underside of all floors
The reason for fire protecting all steelwork including the underside of the floor, in what appears to
be over engineered fire protection, can probably be explained by three factors. These are, higher fire
resistance requirement in the USA, shallower profile of the steel decking, and the custom and
practices in the USA at the time of building. More recent USA buildings appear to be designed more
in-line with UK building practices.
Interestingly in Los Angeles, it is a building code requirement that all staircases are pressurised and
all have lobby approach to accommodation floors.
3.5.2
Major fire incident at the building
However it is important to note that this particular building suffered a serious fire on the 4 May
1988, in which one maintenance worker died and 40 others were injured. The building at the time
was owned by the First Interstate Bank. Fire started on the 12th floor and spread to the 16th floor
eventually destroying 4 floors and partially affecting another. It burned for 3 ¾ hours before it was
brought under control. Sprinklers were being installed in the building (installation 90% complete) at
the time of the fire however they had not been connected to water supplies. Perhaps it can be
argued that fire protection of the steel frame and the underside of floors is an appropriate form of
protection, albeit providing a further degree of property protection over and above UK regulated life
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safety provisions. Lack of fire sprinklers was obviously an important omission from the overall safety
components of the building’s safety systems. Figure 22 shows the building during the fire incident.
Figure 22 First Interstate building on 4 May 1988
Photograph by Boris Yaro of the Los Angeles Times
3.6
One Maritime Plaza San Francisco, completed in 1967
This building is of structural braced tube design. The external frame with diagonal members carries
gravity loads of the building, reference Figure 23. The structural steel external frame is fire protected
with encased concrete surrounding the frame members and is finished with decorative aluminium
sheeting see Figure 24.
Figure 23 Structural steel braced tube design
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Figure 24 External frame members
encased in concrete
- 32 -
The structural steel fire protection employed in this building includes cement spray protection
(supplied by Monokote) of all columns, beams and the underside of the composite floor, reference
Figures 25 and 26.
Figure 25 Cement spray protection of the
underside of the composite floor deck
3.7
Figure 26 Cement spray protection of beams
connecting through to the external frame
which is encased in concrete
John Hancock Tower Chicago, completed in 1970
This building is of structural braced tube design similar to One Maritime Plaza. Again the external
frame with diagonal members carries gravity loads of the building. The structural steel external
frame is fire protected with encased concrete surrounding the frame members and is finished with
decorative aluminium sheeting, reference Figures 27 and 28. The internal structural fire protection
includes spray protection of all columns, beams and underside of floors, reference Figures 29 and 30.
Figure 27 John Hancock building Chicago
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Figure 28 External columns, beams and
diagonal bracing encased in concrete
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Figure 29 Cement spray protection of columns
3.8
Figure 30 Cement spray protection of beams
And underside of floor
Willis Tower Chicago, completed in 1973
This building is of a bundled tube design. The structural fire protection comprises spray protection
applied to all steel elements including columns, beams and floor components similar to the buildings
discussed in sections 3.5, 3.6 and 3.7.
3.9
Empire State Building New York, completed in 1931
The building is of 102 floors and the structure comprises steel shear trusses and hinged frames. At
the time it was the tallest building in the world and remained so for forty years. The fire protection
of the structure is of concrete encased columns, beams and reinforced poured concrete floors,
reference Figures 31 and 32. It is interesting to note the concrete cover to columns is 8in (203mm)
thick.
Figure 31 Empire State building, New York
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Figure 32 Concrete encased beams with reinforced
concrete floors
- 34 -
The building is in the process of being completely up dated. The external facades have recently been
renovated, leaving a multi-million dollar project for the upgrade of the internal parts of the building.
Currently, there is no sprinkler protection in the building but it is scheduled to have them fitted
during the next stage of building works.
3.10
Metropolitan Life Tower New York, completed in 1909
This listed historic building has 45 storeys. It was built for offices and has been used as such up until
recent years, reference Figure 33. It is currently unoccupied awaiting alterations for a change of use
to an up market, five star hotel. The building is of a rigid steel frame structure with concrete encased
columns and beams, which provides the required level of fire resistance, reference Figure 34. Barrel
arched floors complete the structure. The fire protection to the floors is achieved from the ash
concrete materials used in construction, reference Figure 35.
Figure 33 Metropolitan Life building
New York
Figure 34 Concrete encased columns and beams
Figure 35 Barrel arched floors with concrete ash providing fire protection
3.11
Summary of structural steel buildings
Table 10 lists the structural steel buildings visited and highlights their type of building structure with
forms of fire protection used.
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Table 10 Structural steel buildings related to type of structure, form of fire protection, together with
occupancy use, number of floors, and date of completion of building.
Building
Type of
Structure
Metropolitan
Life Tower
New York
Rigid Frame
680 Folsom
San Francisco
Rigid frame
Empire State
Building
New York
Framed
shear truss
AON Center
Los Angeles
Framed tube
BMO
Toronto
Framed tube
Brookfield
Place
Toronto
Framed tube
Constellation
Place
Los Angeles
Framed tube
1 Maritime
Plaza
San Francisco
Braced tube
John Hancock
Building
Braced tube
Chicago
Willis Tower
Chicago
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Bundled tube
Fire Protection
Use
Floors Completion
Concrete encased columns and
beams. Barrel arched floors with
ash and concrete fire protection.
Retrofit sprinklers.
Composite deck floors with
cement spray protection to
columns and beams. Underside of
floor decking not protected.
Sprinklers throughout
Concrete encased columns and
beams. Reinforced concrete
floors (poured).
No sprinkler protection
columns, beams and underside of
floor decking.
Sprinklers throughout.
Sprinklers throughout
External steel frame concrete
encased. Internal columns, beams
and underside of composite floor
decking cement sprayed.
External steel frame concrete
encased. Internal columns, beams
and underside of floors cement
sprayed.
Office
45
1909
To be
altered
Office
14
Under
construction
Office
102
1931
Office
62
1973
Office
72
1975
Office
49
1992
Office
35
2003
Office
27
1967
Office
100
1970
columns, beams and underside of
floor decking.
Office
108
1973
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4
DESIGN OF REINFORCED CONCRETE FRAMED BUILDINGS
This section reports and discusses reinforced concrete framed buildings. Two case studies of
buildings visited are discussed to illustrate building construction and fire protection methods used
for these types of buildings in North America.
4.1
Background to reinforced concrete framed buildings
Reinforced concrete is an excellent building material. Concrete possesses high compressive strength
whilst steel has high tensile strength. An important advantage with reinforced concrete construction
is its excellent fire resisting properties, providing sufficient concrete cover is used to protect the
steel reinforcement. Tall buildings are designed to withstand massive building loads and resist
extreme imposed loads such as wind. Because of this the structural elements tend to be large which
enhances the buildings fire resisting properties. Additionally most of the buildings visited were of
residential occupancy with small cellular units, thus restricting the potential for fire spread.
There are many structural systems used for reinforced concrete buildings, including a basic rigid
frame for buildings up to 20 storeys. Shear walls and framed tubes are utilised to further strengthen
building structures allowing taller building heights. At the other extreme end of structural design are
‘Tube-in-tube’, and ‘Modular tube’ forms of construction which are used to build the super tall High
Rise buildings. Some buildings use a combination of these forms of structural design. All reinforced
concrete buildings visited were provided with sprinkler protection throughout.
The following is a review of 2 buildings visited, typical of this form of construction;


4.2
Trump International Tower in Chicago, and
Devon Energy building in Oklahoma City.
Trump International Tower Chicago, completed in 2009
This building is built alongside the Chicago River in the downtown area, reference Figure 36. The
lower part of the building up to floor 29 is designed for hotel use, with apartments above. Below
grade there are 4 basements, and interspaced within the building, are car parking, restaurants, and
health spa floors.
Overall the building has 3 distinctive setbacks designed to harmonise with neighbouring buildings.
These are at;



Level 16 which corresponds with the height of the neighbouring Wrigley building
Level 29 relates to the Marina City Towers
Level 51 aligns with the IBM building
The building then towers up to level 96 and the roof, a height of 1170ft (357m). These setbacks
together with external rounded surfaces assists the breaking up of wind patterns thus minimising
imposed building forces on the structure.
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Figure 36 Trump International Tower Chicago
The building design centres on a central core with outrigger systems which eliminates the need for
building dampers. The stiffness and weight of the building, combined with setbacks, support and
stabilise the tower resulting in minimum building movement. Reinforced concrete provides for a stiff
frame and enables flat-slab construction making it cost effective. Ground breaking high performance
concrete was used rated up to 16,000 psi and pumped and placed to an elevation of 650ft (198m)
above grade. Residential floor thicknesses are 9in (230mm) spanning up to 30ft (9.1m) without
further perimeter spandrel elements. The central concrete core is composed of six walls at the base
of the building, all heavily reinforced with steel bar, reference Figure 37, which decrease to two walls
at level 51.
Figure 37 Construction of central core wall, heavily reinforce with steel rebar reference,
http://www.cement.org/buildings/buildings_mixed_trump.asp
Massive reinforced concrete out-riggers at each setback level and the roof, tie the concrete core to
perimeter columns, thus increasing the buildings stiffness and resistance to wind effects. Large
diameter reinforced concrete columns of 6ft (1830mm) are used around the perimeter of the
building, and at the lower levels of the internal parts of the building, reference Figures 38 and 39
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respectively. By using fewer and larger diameter columns at the perimeter views over the Chicago
River area are improved.
Figure 38 Large Perimeter columns
Figure 39 Large internal columns
The foundations of the building are piled to a depth of 110ft (36m) through stiff clay and limestone
bedrock. Each pile has a steel sheath filled with concrete, and the piles are tied together with a 10ft
(3m) thick reinforced concrete slab. This slab is heavily reinforced with steel rebar, reference Figure
40.
Figure 40 Foundation slab preparation prior to concrete pouring, heavily reinforced with steel rebar,
reference http://www.structuremag.org/article.aspx?articleID=935
4.3
Summary Trump International Tower
The fire safety provisions, in this substantially constructed building, comprise reinforced concrete
frame, compartment floors throughout with a high degree of compartment subdivision, and
protected shaft enclosures for lifts and staircases, are all in excess of Chicago’s building code.
Likewise fire resistance ratings for all the elements of structure adequately meet building code
requirements.
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Additionally, water supplies are drawn from Lake Michigan and distributed throughout the building
by high pressure positive displacement pumps giving a system pressure of 350psi (24bar). Fire water
requirements are pumped to large holding tanks staged at various levels in the building which
service the automatic sprinkler system and wet main risers, reference Figure 41 and 42.
Figure 41 Inspection of fire pump systems
by the author
Figure 42 Fire water holding tank
The high design specification for this building is partly achieved by the type of construction used and
partly by the policy requirements of the Trump Hotels organisation. It can be concluded that this
building is well and truly protected in the case of a fire incident.
Interestingly, other systems such as lightning protection rods are also an essential part of the overall
safety package. Figure 43 shows the Trump and Willis Towers being struck simultaneously on the
evening of 23 June 2010.
Figure 43 Lightning striking the Trump and Willis Tower reference,
http://www.dailymail.co.uk/news/worldnews/article-1289162/Lightning-strike-Willis
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4.4
Devon Energy building Oklahoma City, completed in 2012
This building complex is built in the down town area of Oklahoma City, reference Figure 44. The
occupancy use of the building is that of offices with a single occupier which is the head-quarters of
Devon Energy Corporation. The company employs approximately 3,000 staff at the site. The complex
comprises a 51 storey tower block with a 6 storey entrance atrium, below grade a basement, and
restaurants on floors 48 and 49. The tower block is adjoined by other buildings including a 10 storey
car park, a further 6 storey office building, single storey fitness centre and a 285 seat auditorium.
Figure 44 Devon Tower Oklahoma
The tower building at a height of 844ft (256m) is the tallest building in the State of Oklahoma. The
cross sectional area of the tower is a modified reuleaux triangle, with each curved side formed by 2
flat surfaces. Inlets are also designed into the points on the triangle, and the top section contains
additional tapering flat surfaces. The cross sectional area tapers from large foot print areas at grade
level and gradually reduces with building height, reference Figures 45 and 46.
Figure 45 Sectional inlets with
tapering flat surfaces at the top
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Figure 46 Floor plan of modified
reuleaux triangle
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The shape of the building has been carefully designed in order to break up wind flow patterns, thus
reducing imposed wind forces on the structure of the building. It is important to note Oklahoma
suffers frequent tornados which can generate wind speeds up to 300 mph (482 km/h).
The building design centres on a tube-in-tube design with a strong central core connected through
floors to the equally strong external parts of the structure. The stiffness and weight of the building
combined with the carefully designed exterior, support and stabilise the tower resulting in minimum
building movement.
Large diameter reinforced concrete columns are used around the perimeter of the building, and at
the lower levels of the internal parts, reference Figures 47 and 48 respectively.
Figure 47 Large diameter external columns
Figure 48 Large diameter internal columns
In addition the substantial construction of the building is illustrated with large reinforce concrete
beams, reference Figure 49 and thick wall construction, reference Figure 50.
Figure 49 Large reinforced concrete beams
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Figure 50 Thick reinforced concrete walls
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The foundations of the building are piled and tied together with a 10ft (3m) thick reinforced
concrete slab. This slab is heavily reinforced with steel rebar, reference Figure 51.
Figure 51 Foundation slab preparation prior to concrete pouring, heavily reinforced with steel rebar
The Devon Energy Tower has a comprehensive control room which is capable of dealing with a fire
incident on its head-quarters site and any other incident at its numerous gas and oil installations
around North and South America, reference Figure 52.
Figure 52 Control room at the Devon Energy Tower
4.5
Summary Devon Energy Tower
It can be concluded this building adequately meets the fire protection requirements (similar to the
Trump Tower building previously reported) because of the following provisions;




Compartment floors throughout with protected shaft enclosures for all lifts and stairways
High levels of fire resisting construction prevail for structural elements
Good fire water supplies with adequate buffer capacity within the building
Sprinkler installations are provided throughout the building
Note: From observations it was noticeable that extremely limited use is made of pre-cast concrete in
the construction of High Rise buildings in the USA.
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5
EARTHQUAKE PROTECTION DESIGN
Making buildings heavier and stronger means they are less likely to fail in an earthquake, however
this is very expensive. Sometimes a very heavy pendulum called a “Tuned mass damper” is installed
high up in High Rise buildings. An earthquake event swings the damper which absorbs the
earthquake forces away from the buildings structure. The mass of these dampers can be as high as
600 tons.
From my visit to San Francisco I came across two buildings designed with earthquake systems;


5.1
One Maritime Plaza and,
680 Folsom Street
One Maritime Plaza San Francisco
On the 17 October 1989 a major earthquake struck the San Francisco Bay area. Caused by a slip
along the San Andreas Fault, the quake lasted 15 seconds, and measured 6.9 on the Richter scale. It
killed 63 people, injured 3,700 and made up to 12,000 people homeless.
I was fortunate to meet Joe McBride the chief engineer of this building who was at work on the 17th
floor at the time of the earthquake. It was good to hear first-hand experience of such a dramatic
event. His vivid recollection was of the to and fro response of the building, and most importantly,
the twisting effect throwing office chairs and people around the floor area. This eye witness account
will last in my memory. The building withstood the earthquake with only minor damage. Since this
event, the building owners initiated a seismic study and implemented a project to further strengthen
the building against future earthquakes. The project work was carried out by a specialist seismic
engineering company, Rivera Consulting Group Inc.
The project included the following alterations to the building and its structure;

Installation of steel diagonal braces around the base of the tower at the Plaza level,
reference Figures 53 and 54. These “W” frames strengthen the structure particularly from
twisting action.
Figure 53 Ground level diagonal bracing
frames.
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Figure 54 “W” frames in perspective
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
Installation of new horizontal beams at floors 8, 14 and 20 of the external frame. These
beams strengthen the corners of the building, spanning between the corner and first
column. A total of 6 additional beams were fitted to the elevation, reference Figures 55 and
56.
Figure 55 Additional 6 horizontal beams
to this elevation



Figure 56 Close up view of one additional
beam
Structural strengthening was also carried out on the “X” braces at the building core, and at
selected connection points.
Reinforcement works for stubs connecting floor framing to exterior braces at selected
points.
On plant room floors, additional anti-vibration dampers were installed to machine plinths to
complement existing springs, reference Figure 57.
Figure 57 Plant room plinths fitted with additional dampers (green boxes), to act together with
existing springs.
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5.2
680 Folsom Street San Francisco
This 1960’s building, previously discussed in section 3.3 of this report, is currently under construction
alterations and when completed will have 2 additional floors making it a 14 storey building. Floor
areas have also been greatly increased. Within the design of the new building seismic protection has
been included which will meet current San Francisco building code requirements.
A new central concrete elevator core will pivot on top of a single friction pendulum bearing at the
basement level, reference Figures 58 and 59. This new stiff core allows all floors of the steel frame to
lean uniformly and spread any earthquake movement evenly throughout the entire steel frame. This
prevents the possibility of a storey collapse. Earthquake action will also spread the strength of the
existing frame uniformly over the height of the building. Another desirable feature includes the
frame acting as a spring that returns the building to plumb after an earthquake.
Figure 58 Friction pendulum bearing fitted to the
base of the elevator core reference,
Tipping Mar – Project: 680 Folsom Street
Figure 59 Elevator core pivoted on friction
pendulum bearings reference,
Tipping Mar – Project: 680 Folsom Street
Earthquake protection measures which are designed into High Rise buildings not only safeguard the
occupants of the building during extreme events but also assist fire fighters during any subsequent
fire or rescue operations. Further protection is also afforded in terms of reducing property damage
and assisting business continuity after an event.
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6
OTHER BUILDING DESIGN FEATURES
Throughout my visits I came across a range of building design features which will have an implication
on the safety of buildings during fire, rescue or extreme events such as earthquake or blast effects.
My findings include the following designs;






6.1
Large floor areas
Glazing systems
Atrium design
Once the main structures of a storey are completed and prior to the start of any building services
work, steel studs are fixed to the underside of the floor. These are then aligned with final wall
positions, reference Figures 60 and 61. The alignment of building services follows the guidance of
fixed steel stud channels. Steel frame studs were used throughout for all new construction work.
Figure 60 Steel stud channels fixed to the
underside of floor to pre-determined
wall alignments
Figure 61 Steel stud wall complete with
wall boards
Further, non-loadbearing wall structures requiring fire resistance levels up to 3hrs comprised the
following component parts, reference Table 11;
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Table 11 Construction components related to fire resistance rating levels for non-loadbearing walls.
Fire
Resistance
Rating
Inner facing
Steel stud channel
1hr
2hrs
3hrs
5/8in gypsum panel
3 5/8in 25 gauge
2x 5/8in gypsum panel 3 5/8in 25 gauge
2x 5/8in gypsum panel 3 5/8in 20 gauge
Outer facing
5/8in gypsum panel
2x5/8in gypsum panel
3x5/8in gypsum panel
Note: further heat and acoustic insulation materials are fitted within steel stud channel sections.
6.2
Large floor areas
Many High Rise buildings in North America have large floor areas, much bigger than in the UK. From
my observations I found several examples. The largest floor areas found were in the Bank of
Montreal Offices building in Toronto, a tower building of 72 floors, reference Figure 62. The
dimensions of the floor are 190ft (57.9m) by 180ft (54.9m) with a central core location for the lifts
and staircases. Some of these floors are used as open plan offices. This is significant because it is
known fire could spread throughout the floor, known as travelling fires, resulting in a serious fire
attack on the structure. Further, under these conditions the fire could also spread out of the external
windows and affect the storey above, in what is known as conflagration. Although we know about
the resulting behaviour of such fires we do not fully understand them. This is intended to be the next
stage of future fire research.
Figure 62 Large floor areas in the Bank of Montreal Offices Toronto
Another general observation from my visits was the ease in which designers are allowed to open up
floors within High Rise buildings without any additional fire protection. A good example illustrating
this point is the 75 storey building at 157 West 57th Street New York. This building, under
construction, is designed to be a hotel up to the 22nd floor with apartments above. Some floors
contain duplex apartments spanning two floors such as the 71st and 72nd floors, reference Figure 63.
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It can be seen that a large open space spans the two floors. Presumably the safety justification is
achieved with the 3hrs fire resistance rating for the elements of structure (greater than the UK)
complemented with sprinkler protection throughout the building. This is all in accordance with the
New York City building code. Stunning views are to be had out of the duplex apartment, overlook
Central Park, reference Figure 64. Price of the apartment a cool $98,000,000!
Figure 63 Open floors in the duplex apartment
6.3
Figure 64 Views overlooking Central Park
Glazing systems
Three types of glazing systems were observed including, external, fire resistant and impact resistant.
6.3.1
External glazing
External curtain wall glazing comprised, factory made glazed panels mostly of a storey height in
length, fixing brackets and seals, reference Figure 65. Top sides of glazed panels are fixed via
brackets to the floor slab, reference Figure 66. The bottom side of the next glazing panel above rests
within the channel section of the lower panel complete with a seal. Glazing panels are designed with
multiple layers of glass providing heat and sound insulation. They are not fire resistant.
Figure 65 Curtain wall glazing
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Figure 66 Floor slab bracket fixed to the slab
glazing panel.
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Planar glazing systems were observed in several buildings used as external glazing and perimeter
glazing for atria, reference Figures 67 and 68. Some of these systems were fixed to space frames.
Figure 67 External planar glazing system
Figure 68 Atria perimeter planar
glazing system
Lessons were learnt following the fire at the AON building in Los Angeles, in which the fire
department had difficulties in safely breaking external glass to ventilate the fire during the incident.
Every fifth glazing panel throughout the building was replaced with panels of tempered glass which
breaks into small fragments compared with the original float glass breaking into dangerous large
shards.
6.3.2
Fire resistant glazing
Fire resisting glazing appears not to play any significant role in North America. It is only used in
limited applications and architects generally do not appear to select this design feature to any great
extent. Cost parameters are the major set-back. However, from discussions with fire engineering
consultancies, the trend appears to be changing with more fire resistant glazing being specified on
future building developments.
Wired glass is used internally in buildings for separating high hazard areas from accommodation
spaces. It is also used on external walls for separation of internal high hazard areas from public
access externally. Wired glass is probably selected because all fire resisting walls are required to pass
the fire resistance test and an additional hose stream test, see section 2.3.3 of this report.
Additionally, because High Rise buildings are fitted with sprinklers throughout, there is a tendency to
extend the system and protect glazing with sprinkler heads fitted to both sides of the glass,
reference Figure 69. Sprinkler heads for this application have special deflector plates fitted to
achieve the required water distribution over the glazing. This application of sprinklers is not specified
in the IBC codes but it has become acceptable practice.
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Figure 69 Sprinkler heads fitted on both sides of glass
During my visit I was able to witness one application of fire resisting glazing at the Russ building in
San Francisco. The glass was fitted to a protected shaft wall providing stairway access to an office
floor, reference Figure 70. The required fire resistance rating for the shaft walls was 2hrs. The
laminated glass markings revealed the following information;
Classified UL:
9FX5 – Pilkington Pyrostop:
120 minutes-54mm:
120–104, cat II:
North America
W-OH-T-120:
Figure 70 Fire resistant glazing rated at 120 minutes
Because wired glass does not provide 2hrs fire resistance the preferred selection was laminated fire
resisting glass. This design feature obviously maintains desirable day light for the office.
6.3.3
Impact resistant glazing
At the AON building in Los Angeles the control room on the ground floor adjoins a goods delivery
bay. This dock area was used many years ago for off-loading money to the then ‘First Interstate
Bank’. To maintain high security systems the glazed screens in the control room are designed to
resist bullet impact, reference Figure 71.
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Figure 71 Control room with high impact bullet resistant glazing
6.4
From my observations, most buildings in North America appeared to use somewhat dated signage
for the emergency lighting systems. Signs were displayed with instructions in words and illuminated
in red, compared with UK pictograms and green illuminations. However the latest codes in New York
and Chicago do appear to be following UK and European designs.
6.5
Atrium design
A large internal space in a building which breaches structural floors is called an atrium. This form of
building design is popular with architects and building occupants alike. It allows designers to use
building spaces more adventurously by improving internal communication and utilising more natural
light, reference Figures 72 and 73.
Figure 72 16 storey atrium
R Thompson Center Chicago
Administration centre for the State if Illinois
Figure 73 6 storey office atrium
Devon Energy building Oklahoma
Atrium designs are permitted in North America so long as IBC code requirements are met. The
building must be in compliance with the High Rise section of the code, and must have a smoke
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control system designed to technical guidance in “BOCA 1990”. The need for this is in lieu of full
compartmentation of the building because accommodation floors are open to the atrium. The bulk
of design requirements are in the supplementary guidance document with little mention in the
building codes.
However, a few details are specified in the IBC code including; smoke control minimum exhaust
volumes of 6 air changes per hour for atrium volumes of less than 660,000ft3, and 4 air changes per
hour when the volume of the atrium is greater than 600,000ft3. The absolute minimum exhaust flow
rate allowable is 40,000 ft3 per minute. Figure 74 shows the mechanical exhaust fans used for the
Devon Energy atrium, and Figure 75 shows the exhaust grilles on the top level of the atrium,
aesthetically designed and located. In addition to this, the code specifies the following information
to be submitted on plans for city approval, including;






Total area and volume of the atrium
Opening sizes with volume flow rates, complete with direction of flow (exhaust/supply)
Supply openings to be sized for 50% of exhaust capacity
Exhaust to be at the top of the atrium with intake at the bottom
Smoke detectors to be located at the top of the atrium and around the perimeter
Activation of the smoke control system to be from either of the following; a sprinkler
system, or smoke detectors in the atrium, or by manual switch at the fire alarm panel
Figure 74 Mechanical smoke exhaust fans
Devon Energy building Oklahoma City
Figure 75 Smoke exhaust grilles on the top
storey of the atrium.
Devon Energy building Oklahoma City
When construction of a large atrium is completed and before occupation takes place, it is common
practice to test the performance of the smoke extraction system. To simulate smoke from a fire,
special candles are used. Both the fire and building departments would be in attendance during this
test.
6.6
In Los Angeles the building code requires a helicopter landing deck to be installed on the roof of new
buildings greater than 150ft (45.7m) in height. The AON building in Los Angeles has such a helideck
installed on the roof, reference Figure 76.
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Figure 76 Helicopter landing deck
AON building in Los Angeles
This facility is for use by the fire department for fire emergency purposes. The fire department has a
fleet of 5 helicopters available 24/7 with capabilities of night time flying. None of the other cities
visited in North America has this requirement. The cost of building a helideck is approximately
$0.5m. Views from the top of this building clearly shows helidecks fitted to five neighbouring High
Rise buildings, reference Figure 77.
Figure 77 Los Angeles High Rise buildings with helicopter landing decks
An interesting safety point arises related to occupant escape procedures with the use of helicopters
at fire emergencies. The general escape concept is to always travel downwards and out of a burning
building. Safety plans for High Rise buildings with helidecks in Los Angeles will need to specify
occupant evacuation procedures and identify when escape should be upwards towards the roof
area. I would assume upward escape is only viable under the supervision of the fire department.
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7
MISCELLANEOUS BUILDINGS
From my visits I was able to photograph the following buildings externally. These are some of the
first High Rise buildings constructed in the USA some 100 years ago. They all have historical interest
to the enthusiast, and will prove useful for future development of High Rise training courses.








Fuller Flatiron building, New York
Monadnock building, Chicago
Phelan building, San Francisco
De Young building, San Francisco
The Palace building, San Francisco
Hobart building, San Francisco
Flatiron building, San Francisco
Matson building, San Francisco
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8
OKLAHOMA STATE UNIVERSITY
Whilst visiting Oklahoma, I was able to spend a day at the Oklahoma State University. The morning
was spent with IFSTA “International Fire Service Training Association” and FPP “Fire Protection
Publications”. The second part of the day was spent with the technology school of the university.
I met with the director of IFSTA, Dr Craig Hannan, and had useful discussions concerning the
structure of NFPA standards and how they are linked to FPP publications. Interestingly, the
organisation has been in existence since 1933 co-ordinating safe fire fighting practices for the fire
services, and publishing the outcomes in the form of manuals. Fire departments from all areas of
North America are invited to participate in this activity. I was particularly interested in the last
publication of “Building Construction Related to the Fire Service” and the very new publication for
“High Rise Fire Fighting”. Additionally, I met with Dr Mike Wieder, an associate director, and had
discussions related to Federal standards of qualifications, including those at associate, bachelors and
masters levels. To complete my meetings with IFSTA I met with Professor Tony Brown who deals
with disaster management and co-ordinates the annual conference for IFSTA.
The afternoon was spent with Dr Michael Larranaga, the course director for the bachelor’s degree
programme ‘Fire Protection and Safety Technology’. Besides discussing the building construction
parts of the programme I was given a guided tour of the laboratory facilities. These included the
laboratories for;

Fire detection and alarms, designed for hands on fault finding of electrical circuits

Fire burn unit capable of burning fires up to 1MW

Water pumping facilities, complete with set up valves and monitoring equipment

20 water main control valves complete with mains supply to range pipes and sprinkler
heads, including facilities for students to strip down and re-build valves

The largest cabinet display of sprinkler heads I have ever seen. These included heads from
the 1800’s through to latest versions, complete with performance data sheets.
This visit was extremely worthwhile and one which fuelled many ideas for the future.
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9
FINAL CONCLUSIONS
1
Building controls
A comparative review of High Rise building controls is reported in section 2 resulting in the
following significant findings;
a) Higher levels of fire resisting construction prevail in the USA compared to the UK, reference
section 2.3.6. These include elements of structure and fire doors. Canada has similar ratings
to the UK, reference section 2.4.
b) The quality of wall construction in North America is of a higher standard than the UK. An
additional hose stream test needs to be satisfied as well as a fire resistance test, reference
section 2.3.4. This is particularly relevant to walls fitted with glazed screens.
c) Compartment designs are treated differently in North America. It is possible to breach
structural fire floors without additional fire protection, reference section 6.2.
d) In North America building controls for void spaces such as suspended ceilings and raised
floor sections is not as stringent as the UK, reference section 2.3.4. Little use is made of
cavity barriers. However, fire stopping is specified which is in line with UK practice.
e) Sprinkler protection is widely adopted in North America and in some cities, retrospective
regulation is in place to up grade older buildings, reference sections 2.3.6 and 2.7. UK hotel
buildings do not require sprinkler protection were as they do in North America.
f) Fire departments in some cities in the USA have enforcement powers for fire safety matters
during construction of buildings, reference section 2.5.1.
2
Steel framed buildings
a) The favoured method of protecting structural steelwork in North America is cement
spraying, reference section 3.2. There are several reasons for this;
 It is considered easy to programme appropriate work schedules
 Costs are economical because of a competative market
 There does not appear to be any environmental constraints with using cement sprays
b) The extent of cement spray application was reviewed with two interesting conclusions;
 Some buildings had spray protection applied to all columns and beams, without the
underside of the floor sprayed, reference sections 3.3 and 3.4.
 Other buildings were fully protected with cement spray applied to all column, beams
and underside of floors, reference sections 3.5, 3.6, 3.7 and 3.8.
The probable reasons for more fire protection are;
 Higher levels of required fire resisting construction in the USA
 Shallower profiles of steel decking
 Regulators desire to have more property protection
 Custom and practice in the USA at the time of building
 Possible building insurance requirements.
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c) Cladding fire board protection and use of intumescent paints are not favoured in North
America. They are only used for special application, reference sections 3.2 and 3.4.
d) Older forms of fire protecting steelwork were also reviewed; reference sections 3.9 (Empire
State Building), and 3.10 (Metropolitan Life Tower). These used concrete encased structural
elements and floors of ash concrete respectively.
3
Reinforced concrete buildings
Most reinforced concrete buildings in North America are built for residential use. They are
substantially built making them relatively safe in emergency situations, reference section 4. They are
safe because;
a) Structural fire floors are designed throughout the building with a high degree of sub-division,
thus reducing potential fire spread.
b) Required fire resistance ratings for the structure are easily met.
c) All new buildings are sprinkler protected. Retrospective sprinkler installations have been
fitted to some older buildings.
d) Fire water supplies to sprinkler installations and wet main risers are plentiful with adequate
buffer tank capacities.
It was interesting to observe the limited use of pre-cast concrete in High Rise buildings.
4
Wind and earthquake protection
a) Wind loadings are a design requirement relevant to all High Rise buildings, reference section
3.1.4. In many cases it influences the construction style of buildings particularly with taller
ones. This design aspect is important to fire officers as a consideration for fire safety of
occupants. However, it also becomes critically relevant to incident commanders when
dealing with fire emergencies involving possible localised building collapse.
b) Earthquake protection is only relevant to buildings in areas which suffer these events. The
UK does not have such problems. However some fire officers in the UK work in specially
trained teams which undertake urban search and rescue work. These teams are frequently
sent overseas when major disasters occur. Some understanding of the principles of
earthquake design is valuable knowledge to these officers, reference section 5.
5
Fire resisting glazing
a) Fire resisting glass does not play a significant role in North America because of cost.
However, fire engineering consultancies reported a changing trend towards the use of these
systems on new building developments.
b) For limited applications wired glass is used because it satisfies both the fire resistance test as
well as a required hose stream test. The later test is not used in the UK.
c) There is a tendency to protect glazing with special sprinkler heads mounted on both sides of
the glass.
These conclusions are referenced to section 6.3.2
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6
General
By undertaking this project, my personal understanding of High Rise buildings has improved
immensely. I have been able to see and photograph over twenty relevant buildings which can be
developed into useful case studies for future fire safety training.
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10
NEXT STEPS FOR THE PROJECT
To date, the following presentations including an introduction to the ‘Winston Churchill Memorial
Trust’ have been made;
Date
Presentation details
Location
3 August 2012
Merseyside Fire and Rescue Srevice
Presentation (In-house training) for
High Rise building in the UK
Merseyside Training School
Liverpool
17 August 2012
GMC – Institution of Fire Engineers
High Rise Seminar
GMC Training School
Manchester
Oct and Sept 2012 - Project visit to North America
9 November 2012
London Tall Buildings Fire Safety Meeting
Presentation of interim project findings
The Shard
London
3 December 2012
North West Regional Meeting
Institution of Fire Engineers
Presentation of interim project findings
GMC Headquarters
Manchester
Following the submission of this Fellowship Report, the next steps for the project is to present the
findings to my two supporting organisations;


Fire Service College, the central fire officer training establishment in the UK
PFPF Passive Fire Protection Federation, industry sector
Additionally, three regional groups of the Institution of Fire Engineers have expressed an interest for
a project presentation including;



North West area to be held in Manchester
Mid Western area to be held in Bristol
Northern Ireland area to be held in Belfast
Alongside the above activities, the Merseyside Fire and Rescue Service have requested an in-house
professional development presentation based on my North American findings.
I also hope to write a journal article to be published in a construction/fire engineering arena.
Lembit Kerks
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Appendix A - References
ASTM, E84, Standard test methods for Surface Burning Characteristics of Burning Materials, , ASTM
International, 100 Bar Harbor Drive, PO Box C700, West Conshohocken, Pennsylvania, 19428-2959,
USA
ASTM, E119, Standard test methods for fire test of building construction and material, ASTM
International, 100 Bar Harbor Drive, PO Box C700, West Conshohocken, Pennsylvania, 19428-2959,
USA
ASTM, E2226, Standard practice for application of hose stream, ASTM International, 100 Bar Harbor
Drive, PO Box C700, West Conshohocken, Pennsylvania, 19428-2959, USA
BOCA 1990, National Building Code, 11 Edition, Building Officials and Code Administrators
International, 4051 West Flossmoor Road, Country Club, IL 60478, USA
BS 476, part 4, 1970, Fire test on materials and structures. Non-combustibility test for materials.
BS 476, part 6, 1989, Fire test on materials and structures. Method of test for fire propagation for
products.
BS 476, part 7, 1997, Fire test on materials and structures. Method of test to determine the
classification of the surface spread of flame of products.
BS 476, part 11, 1982, Fire test on materials and structures. Method for assessing the heat emission
from building materials.
BS 476, part 20, 1987, Method for determination of the fire resistance of elements of construction
(general principles).
BS 476, part 21, 1987, Method for determination of the fire resistance of loadbearing elements of
construction.
BS 476, part 22, 1987, Method for determination of the fire resistance of non-loadbearing elements
of construction.
BS 476, part 23, 1987, Method for determination of the contribution of components to the fire
resistance of a structure.
BS 476, part 24, 1987, Method for determination of the fire resistance of ventilation ducts.
Building Regulations (2000) “Approved Document B, Fire Safety, Volume 2 – Buildings other than
dwellinghouses, (2007 edition)”, Department for Communities and Local Government, RIBA, London,
2007.
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Appendix A – References (continued)
IBC, International Building Code (2009), 4051 West Flossmoor Road, Country Club, IL 60478, USA
Mendis P, Ngo T, Haritos N, Hira A, (2007) “Wind loadings on tall buildings”, EJSE international
journal special issue: Loading on structures, pages 41-54
Mir M Ali, Kyoung Sun Moon, (2007), “Structural development in tall buildings: Current trends and
future prospects”, Architectural science review, Volume 50.3, pp205-223
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Appendix B - List of Buildings Visited
Location and Address
Height and Construction
Use and History
1 New York - 157 West 57 Street
1004ft (306m)
75 floors + 2 Basements
Reinforced concrete
Fully sprinklered
Hotel + Apartments
Under construction
2 New York - Mony Building
1740 Broadway
375ft (114m)
26 floors
Steel frame
Fully sprinklered
Office
Completed 1950
3 New York - Metropolitan Life Tower
5 Madison Avenue
700ft (213m)
45 floors
Steel frame
Fully sprinklered
Future Hotel
Under construction
4 New York - Empire State Building
350 Fifth Avenue
1,250ft (381m)
102 floors
Steel frame
Office
Completed 1931
5 Chicago - 515 North Clark Street
240ft (73m)
18 Floors
Reinforced concrete
Fully sprinklered
Hotel
Under construction
6 Chicago - 516 North Lake Shore Drive 465ft (142m)
46 Floors
Reinforced concrete
Fully Sprinklered
Apartments
Under construction
7 Chicago - Trump Tower
401 North Wabash Avenue
1,170ft (357m)
96 floors
Reinforced concrete
Fully sprinklered
Hotel/Apartments
Completed 2009
8 Chicago - Field House Wabash Ave
Roosevelt University
3 floors
Steel frame
Sprinklered
Assembly
Under construction
Lembit Kerks
- 63 -
Appendix B - List of Buildings Visited (Continued)
Use and History
9 Chicago - Willis Tower
233 South Wacker Drive
1,450ft (442m)
108 floors
Steel frame (bundled tube)
Fully sprinklered
Office
Completed 1973
10 Chicago - John Hancock Tower
875 North Michigan Avenue
1,054ft (321m)
100 floors
Steel frame
Retrofit sprinklers to
commercial floors
Mixed use
Completed 1970
11 Chicago - James R Thompson Center 308ft (94m)
100 West Randolph Street
17 floors
Steel frame
Fully Sprinklered
Mixed use
Completed 1985
12 Oklahoma - Devon Energy Building
280 West Sheridan Avenue
844ft (257m)
52 floors
Reinforced concrete
Fully sprinklered
Office
Completed 2012
13 Los Angeles - Constellation Place
10250 Constellation Boulevard
491ft (150m)
35 floors
Steel frame
Fully sprinklered
Office
Completed 2003
14 Los Angeles - AON Center
707 Wilsher Boulevard
858ft (262m)
62 floors + 5 basements
Steel frame
Retrofit sprinklers
Office
Completed 1973
15 San Francisco – One Maritime Plaza 398ft (121m)
27 floors
Steel frame/ seismic retrofit
Sprinklers retrofitted
Office
Completed 1967
16 San Francisco – 680 Folsom Street
Office
Under construction
Lembit Kerks
210ft (64m)
14 Floors
Steel frame
Fully sprinklered
- 64 -
Appendix B - List of Buildings Visited (Continued)
Use and History
17 San Francisco – Russ Building
235 Montgomery Street
435ft (133m)
31 floors
Steel frame
Fully sprinklered
Office
Completed 1927
18 Toronto – Palace Pier
2045 Lake Shore Boulevard West
453ft (138m)
Reinforced concrete
Sprinklered
Apartments
Completed 1978
191 Toronto – Crescent Place
Crescent Town Road
250ft (76m)
25 floors
Reinforced concrete
Apartments
Completed 1971
20 Toronto – Ritz Carlton
181 Wellington Street West
688ft (210m)
Reinforced concrete
Fully sprinklered
Hotel
+ Apartments
Completed 2011
21 Toronto – Bay Wellington Tower
181 Bay Street
682ft (208m)
49 floors + basement
Steel frame
Fully sprinklered
Office
Completed 1992
22 Toronto – BMO Building
100 King Street West
978ft (298m)
72 floors
Steel frame
Fully sprinklered
Office
Completed 1975
Lembit Kerks
- 65 -
Appendix C – WCMT Fellowship Timetable – North America
August 30 Thur
To New York
NYC
August 31 Fri
Research Day 1
NYC
September
1
Sat
NYC
September
2
Sun
NYC
September
3
Mon
NYC
October
1
Mon Research Day 16 OKC
September
4
Tue
NYC
October
2
Tue
September
5
Wed Research Day 3 NYC
October
3
Wed Research Day 18 OKC
September
6
Thur
Research Day 4
NYC
October
4
Thur
To Los Angeles
LA
September
7
Fri
To Toronto
TOR
October
5
Fri
Research Day 19
LA
September
8
Sat
TOR
October
6
Sat
LA
September
9
Sun
TOR
October
7
Sun
LA
September 10 Mon Research Day 5 TOR
October
8
Mon
LA
September 11 Tue
October
9
Tue
Research Day 2
Research Day 6
Research Day 20
LA
September 12 Wed Research Day 7 TOR
October 10 Wed Research Day 21
LA
September 13 Thur
Research Day 8
October 11 Thur
Grand Canyon
September 14 Fri
Niagara Falls
October 12 Fri
Grand Canyon
September 15 Sat
Niagara Falls
October 13 Sat
Grand Canyon
September 16 Sun
Niagara Falls
October 14 Sun
To San Francisco
September 17 Mon To Chicago
September 18 Tue
TOR
Research Day 17 OKC
TOR
CHIC
Research Day 9 CHIC
October 15 Mon
October 16 Tue
SF
SF
Research Day 22
SF
September 19 Wed Research Day 10 CHIC
October 17 Wed Research Day 23
SF
September 20 Thur
Research Day 11 CHIC
October 18 Thur
Research Day 24
SF
September 21 Fri
October 19 Fri
Research Day 25
SF
September 22 Sat
CHIC
October 20 Sat
SF
September 23 Sun
CHIC
October 21 Sun
SF
September 24 Mon Research Day 13 CHIC
October 22 Mon Research Day 26 SF
September 25 Tue
October 23 Tue
SF
September 26 Wed
CHIC
October 24 Wed To New York
September 27 Thur
CHIC
October 25 Thur
September 28 Fri
CHIC
October 26 Fri
NYC
September 29 Sat
October 27 Sat
Research Day 28 NYC
September 30 Sun
To Oklahoma
October 28 Sun
NYC
OKC
NYC
Research Day 27 NYC
October 29 Mon To Birmingham
Lembit Kerks
- 66 -
Appendix D - Press Reports Gloucestershire Echo
Lembit Kerks
- 67 -
Appendix D - Press Reports Bolton News
Lembit Kerks
- 68 -

Structural Safety in High Rise Buildings

Transcription

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