Kaloyana Kostova MEng CEng MICE Department of Architecture

Kaloyana Kostova MEng CEng MICE
Department of Architecture and Civil Engineering
University of Bath
10 July 2013
PhD Research Project:
A New Form of Architecture for Concrete Structures
Professor Tim Ibell
Head of Department
Associate Dean (Graduate Studies)
CEng BSc(Eng) PhD FIStructE MICE FHEA
Dr Antony Darby
BSc(Hons) PhD CEng MIStructE
Dr Mark Evernden
MEng PhD FHEA
Reinforced Concrete
Buildings
Bridges
University of Bath
Piles
Dams
Mauvoisin Dam, Switzerland
Second Severn Crossing
Reinforced Concrete Construction
 Formwork systems
 Compaction of concrete
 Protection of steel reinforcement
Concrete Production
Concrete - produced by the process of hydration (reaction
with water) of Portland cement mixed with sand, gravel or
crushed stone and water.
(Coarse)
(Fine)
Aggregates
Cement - typically made from
limestone and clay or shale. heated
in a rotary kiln where it reaches a
temperature of about 1400 C° to
1500 C°.
Cement
Fresh Concrete
Rigid moulds needed to
retain the fresh concrete
during construction
Formwork Systems
Formwork Systems
Most concrete elements
have prismatic shapes.
Building variable shapes
is related to higher:
• Cost
• Time consumption
• Waste
Compaction of Concrete
• Expels entrapped air from freshly
placed concrete and packs the
aggregate particles together to
increase the density of concrete
• Increases concrete strength
• Improves bond with reinforcement
• Decreases the permeability
Compaction of Concrete
• Immersion vibrators
• Surface vibrators
• Form “external” vibrators
Proper compaction ensures that
the formwork is completely filled
no pockets of honeycombed
material.
Typical Concrete Surface
Role of the Concrete Cover
Corrosion of Steel Reinforcement
Corrosion of Steel Reinforcement
Concrete
• very high alkalinity (pH
of 12 to 13)
• keeps the steel passive
and protected from
corrosion
Corrosion
• Carbonation (chemical reaction
of carbon dioxide in the air with
calcium hydroxide and hydrated
calcium silicate in the concrete
leads to reduction of the
alkalinity to pH as low as 8.5.
• Chlorides ingression
(chloride ions from deicing
salts or seawater) destroys
protective film of steel
Control of the Concrete Cover
Cover formers
CO2 emissions of typical commercially
produced concretes
Flower, D. J. M., and Sanjayan, J. G. 2007. Green house gas emissions due to concrete manufacture. The International
Journal of Life Cycle Assessment, 12, 5(Jul. 2007), 282-288.
Flexible Formwork
Fabric formwork
polyester, polyamide, polypropylene
and polyethylene textiles
Permeable
Lightweight
Low cost
Reusable
Courtesy
Courtesy
of Centre
of Centre
for Architectural
for Architectural
Structures
Structures
and Technology
and Technology
(C.A.S.T.)
(C.A.S.T.)
at theat
University
the University
of Manitoba,
of Manitoba,
Canada
Canada
Fabric Formwork in Industry
Applications in marine construction
– Concrete mattresses
Hawkswood, M., 2012. Fabric Formwork Systems used in Marine Construction.
2nd International Conference on Flexible Formwork (icff2012), Bath, 27-29 June 2012.
– Pile repairs
– Foundations to precast structures
Historical Development
• LILIENTHAL, L. W. G. 1899. Fireproof Ceiling. United States Patent
Office patent application 619769.
Historical Development
• WALLER, W. 1934. Method of building with cementitious material
applied to vegetable fabrics. United States Patent Office patent
application 1955716.
Timeline
VEENENDAL, D. 2011.
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Hanil Company Guesthouse
Byoung Soo Cho Architects, Seoul, Korea
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
Techology (C.A.S.T.)
(C.A.S.T.)
at
the University
at the University
of Manitoba,
of Manitoba,
Canada Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Belton S., 2012.The Application of Mechanically Prestressed Fabric Membranes as
Formwork for Complex Curved Concrete Structures Using Digital
Methods of Form-Finding, Structural Analysis, and Fabrication.. 2nd International Conference on
Flexible Formwork (icff2012), Bath, 27-29 June 2012.
Bhooshan S. and El Sayed M., 2012. Sub-division Surfaces in Architectural
Form Finding and Fabric Forming. 2nd International Conference on Flexible
Formwork (icff2012), Bath, 27-29 June 2012.
Kenzo Unno
“Zero-waste”
wall formwork
Manelius, A., 2012.Fabric Formwork: Investigations into Formwork Tec
Stereogeneity in Architectural Constructions. PhD Thesis
Manelius, A., 2012.Fabric Formwork: Investigations into Formwork
Tectonics and Stereogeneity in Architectural Constructions. PhD Thesis
Fabric-formed concrete
 Foundations
 Beams/ Slabs/ Panels
 Columns/ Walls/ Sculptures
 Vaults/ Shells/ Thin-walled panels
 Long-span structures using fabric formwork
supported on temporary cable nets
Landshape Wildlife Crossing
Large-scale mixed fabric and cable net formed structures
Torsing R., Bakker J., Jansma R., Veenendaal D., 2012. Large-scale designs for mixed fabric
cable net formed structures. 2nd International Conference on Flexible Formwork (icff2012),
Bath, 27-29 June 2012.
Torsing R., Bakker J., Jansma R., Veenendaal D., 2012. Large-scale designs for mixed fabric and cable net formed
nd
Advantages of Fabric Formwork
 Aesthetics
 Structurally efficient forms
 Improved surface and durability of
concrete
 Low-cost and accessible
ICFF 2012
Second international conference on flexible formwork
27th - 29th June 2012, University of Bath
• architectural applications of flexible formwork
• design of membrane formwork systems
• reinforcement for flexibly formed structures
• concrete durability enhancements using flexible formwork
• computational analysis of flexible formwork
• optimisation of formwork and design systems and
• sustainable design using flexible formwork systems
ICFF 2012 Panel construction
workshop
ICFF 2012 Beam construction workshop
Design
Reinforced Concrete Design
compression
tension
Hardened concrete strength
Uniform depth sections easier to
construct but structurally inefficient
Design of Fabric-formed Concrete
Form-finding
Boundary
conditions
Structural
optimisation
Concrete
element design
Computational design tool
Form-finding
Improved material use efficiency by formwork ties
String or
metal tie
Metal tie connecting
side plates
Optimised Design
Construction
Formwork Tables/Frames
Concrete Cover
Conventional construction
Fabric formwork construction
High risk of reinforcement being
displaced during construction
Fibre Reinforced Polymer (FRP) Bars
Pultrusion manufacturing process
constant cross-section composed of high performance fibres (glass,
carbon, aramid) embedded in a polymer matrix
•
high tensile strengths
•
high corrosion resistance
•
light weight
•
low maintenance requirements
Carbon FRP
1 - Continuous roll
of reinforced fibres
2 - Tension roller
3 - Resin
Impregnator
4 - Resin soaked
fibre
5 - Die and heat
source
6 - Pull mechanism
7 - Finished
hardened fibre
reinforced polymer
Glass FRP
Innovative fabric formwork construction
methods using FRP bars
 Straight glass FRP bars attached to the fabric
 Concrete shape formed by the hydrostatic
pressure
 FRP bar pulled to its design position by the
weight of fresh concrete
Novel Anchorage System
• Provides adequate anchorage to
the reinforcing bars
• Requires short embedment
length
• Suitable for FRP bars
• Can be applied on site
Test Beams
The Future…
Future Work
The research into fabric formwork, to date, has been
focused mainly on studying its advantages, improving the
construction techniques and demonstrating the feasibility
of fabric-formed structures design.
The future developments may involve:
• participating fabric as external shear reinforcement
• fabric formwork precast construction
• pre-stressed concrete to improve the stiffness of
optimised fabric-formed elements reinforced with FRP
composites.
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada
Courtesy of Centre for Architectural Structures and Technology
(C.A.S.T.) at the University of Manitoba, Canada