Winter 2010

GINEERS
EN
CIATION
STRUCTUR
AL
O
ASS
PRST STD
US Postage
PAID
Houston TX
Permit No 6270
THE STRUCTURAL ENGINEER
TEXAS
A PUBLICATION OF THE STRUCTURAL ENGINEERS ASSOCIATION OF TEXAS
STRUCTURAL ENGINEERS ASSOCIATION OF TEXAS
President’s Message
6913 Poncha Pass
Austin, TX 78749
512 301 2744
http://www.seaot.org
A PUBLICATION OF THE STRUCTURAL ENGINEERS ASSOCIATION OF TEXAS
President: Ismael Legarreta, P.E
President-Elect: Jon Jelinek, P.E.;
(713) 821-0250 [email protected]
Past President: Eric Christiansen, P.E.;
(214) 346-6284 [email protected]
Secretary: Jon Jelinek, P.E.;
(713) 821-0250 [email protected]
Treasurer: Stan Agee; (817) 277-8566
[email protected]
Corpus Christi -Ramiro Munoz III, P.E.;
(361) 866-2141 lnvinc.com
El Paso - Armando Garcia, P.E.;
(915) 525-6825
[email protected]
Committee Chairs
Professional Activities and Legislative
Liaison - Dennis Paul, P.E.;
(281) 280-9972 [email protected]
Activities - John Schwab, P.E.;
(830) 624-2225 [email protected]
Communications - Joseph (Joe) Luke, P.E.;
(512) 445-2090 [email protected]
Community Impact - Dennis Paul, P.E.;
(281) 280-9972; [email protected]
Financial Health - Victor (Vic) Winter, P.E.;
(512) 372-8216; [email protected]
Membership - Ismael Legarreta, P.E.;
(915) 533-7483 [email protected]
State Conference - Luke Nelson, P.E.;
(512) 469-9490 [email protected]
Treasurer: Stan Agee
Past President: Eric Chrstiansen, P.E.
Executive Director: Liz Stansfeld
Email: [email protected]
GINEERS
EN
SE Emergency Response - Matt Carlton, P.E.;
(512) 835-0940 [email protected]
Technical & Code - Joe Kallaby, P.E.;
(281) 584-9300 [email protected]
For a complete list of SEAoT Officers, Board
Directors, Committees and Delegates, visit the
web site at: http://www.seaot.org
CIATION
Austin - Kris Swanson, P.E.;
(512) 472-9797
[email protected]
Information Technology - Will Ikerd, P.E. ,
(972) 699-8000 [email protected]
Secretary: Jon D. Jelinek, P.E.
O
ASS
Executive Director: Liz Stansfeld;
(512) 301-2744 [email protected]
Chapter Presidents
San Antonio - Roger Martinez P.E.;
(210) 355-5250, [email protected]
President Elect: Jon D. Jelinek, P.E.
AL
President: Ismael Legarreta, P.E.;
(915) 533-7483 [email protected]
Fort Worth - Robert Nicholas, P.E.
Sub-Committees
(817) 656-3200 [email protected]
Awards and Recognition - William Kelm, P.E.,
Houston/Gulf Coast - Rowdy Westbrook, P.E.;
(512) 345-5538 [email protected]
(713) 630-7316 [email protected]
Hall of Honor Committee - Britt Gardner, P.E.,
North Central Texas - David Parkin P.E.;
(713) 780-3345
(214) 221-2220 dparkin@ppoinc.
[email protected]
STRUCTUR
SEAoT State Corporation Board
TEXAS
6913 Poncha Pass
Austin, TX 78749
512 301 2744
http://www.SEAoT.org
As we come to this year's closure and look forward
to the holiday cheer, I would like to congratulate the
state board members for a job well done. The board
this year tackled issues that ranged from the
licensure initiative to restructuring the way state
conferences will be run in the future. I believe we as
a board have improved the organization greatly by
restructuring internal procedures and allowing our
Executive Director Liz Stansfeld more direct
responsibilities. The new year brings in a new slate
of officers for our board. Jon Jelinek will be our next
President and will be supported by Justice Edge as
President - Elect, Whit Smith as Secretary and Stan
Agee as Treasurer. I fully expect next year to be the
best ever for SEAoT as we eagerly anticipate next
years state conference in Dallas.
This year's state conference was a complete success.
John Schwab deserves praise for a very highly
complimented conference that included great
accommodations and great technical sessions.
Corpus Christi is a great city and proved it again. The
NCSEA “Diamond Review Program” added value
to an already great conference. The attendance by
NCSEA President James Malley this year was icing
on the cake.
The individual chapters continue to grow and by the
state reports we receive are doing an amazing job
keeping our members informed and allowing great
opportunities for continuing education. Looking
towards the future and assuring our successors a
solid foundation on which to build on, can only be
achieved when the local chapter and the state board
share a common vision and then proceed to work
towards that vision together. My hats off to our local
chapter presidents
Last year, our President Eric Christiansen reminded
us that possible changes to structural engineering
licensure would dominate this year's SEAoT
agenda. This prediction came true. Eric also
reminded us that Bob Navarro stated at one point,
“There are no part time structural engineers.” With
this in mind, our board voted to support SE licensure
in spite of TBPE continuing to oppose SE
legislation. SEAoT's Licensure Committee (SELC)
with Jon Jelinek as our presenter went before the
TBPE and presented our resolution (see page 3).
NCSEA, ASCE, The Texas Section of ASCE, SEI,
and CASE have issued position statements in
support of SE Licensure. We, as the SEAoT board,
By Ismael Legarreta - State President
voted to take the lead in filing a Bill in the State
Legislature to add the SE license to the Texas
Engineering Practice Act. (We are not
proposing that a new separate Engineering act
be enacted). The SEAoT board understands that
this change may not occur during this
legislation, but is committed to changing the
Texas Engineering Practice Act to add the SE
license. The board felt the SE designation
doesn’t dilute or diminish in any way the PE
title. To the contrary, it will enhance it. Under
the board’s view, this still allows civil engineers
to continue designing typical civil
infrastructures. The SE licensure requirements
would apply to more complex structures. Our
intent is to allow for responsible transitioning
and grandfathering. As the complexity of our
codes increases, especially in regards to seismic
and wind requirements, structural engineers
require more specialized training and therefore
a need for the SE designation.
In order to expedite the filing of our bill, the
SEAoT SE Licensure Committee (SELC) met
immediately after presenting TBPE our
resolution. This committee and its
subcommittees are armed with the fact that our
board is fully behind this initiative and have
committed substantial financial support. It may
take us years to complete this task but this issue
will not go away.
The SELC has created four subcommittees:
1. Preparation of Draft Bill (chair – Pete
Larson)
2. Selection of Bill sponsors (chair – Adam
Johnson)
3. Establishing/contact support organizations
(chair - Todd Speck)
4. Identify/obtain local legislators
(chair – Brian Caudle)
This committee needs direct help in contacting
and gaining support from your local state
representatives and state senators. Please call
Robert Navarro or Joe Luke if possible.
It may be the close of my year as SEAoT
president, but it starts a commitment required
from all of us to get “all others” to understand
that structural engineers are at the forefront of
“protecting the public health, safety and
welfare” of all Texas citizens.
Wiinter 2010
AL
STRUCTUR
CIATION
FOR DURABILITY, VERSATILITY AND EFFICIENCY, NOTHING BEATS GATE-CORE
GINEERS
EN
O
ASS
THE STRUCTURAL ENGINEER
When you are looking for an economical and efficient
solution for the construction of floors and roofs in
multi-story and high-rise buildings, hotels, motels,
apartment buildings, condominiums, schools,
churches, marinas, prisons and warehouses, nothing
beats Gate-Core.
As a “PCI” Certified Producer-Erector of precast
prestressed hollowcore planking across the South,
ADVERTISERS
Gate is the preferred Precast Manufacturer and the
STRUCTURAL ENGINEERING AT UTSA
recognized specialists in the erecting of Gate-Core
Continued from page 18
prestressed concrete hollowcore slabs.
IV. Student Concrete Canoe and Steel Bridge Competition
Students at UTSA have many opportunities to participate in
research projects and join in regional and national competitions. In
the structural area, three events where students at UTSA always
participate are the Concrete Canoe, the Timber Bridge
Competition and Steel Bridge Competition.
Thanks to our students, UTSA also has a good standing in these
national competitions in the last couple of years. Especially this
year, the ASCE-UTSA Steel Bridge Team ranks second among
eleven universities from Texas and Mexico and has advanced to
the National finals to be held at Purdue University. UTSA has also
received first place, second place and most aesthetical timber
bridge awards from 2006 to 2008.
UTSA is a growing university and has expanded its teaching and
research in structural engineering recently. With all the effort from
our faculty and students, we believe the Structural Engineering
division at UTSA will continue to grow strong. We maintain close
ties with structural companies in San Antonio. Some of the
professionals working at several structural companies assist in
evaluating structural projects as part of the Civil Engineering
Design capstone courses.
Little wonder that in 2009, Gate-Core was specified
and erected in new constructions across Texas,
Louisiana, Mississippi, New Mexico, and Oklahoma.
With eight manufacturing facilities, Gate
can deliver any type of precast imagined.
A special thanks to all the companies who support the Structural
Engineers Association of Texas with their advertising dollars.
With the current economic downturn, one of the first things to get
cut is advertising. So we are particularly grateful to the
companies whose advertising messages appear in this
publication. Their contributions help pay for the publishing and
printing of this newsletter, as well as theAnnual Directory.
Please take a moment to view these companies messages and
please visit their web sites:
American Institute of Steel Construction (AISC)
Azazz Galvanizing Services
Delta Structural Technology
Fugro Consultants
Gate Concrete
Lindapter
Mobile Enterprises
Pieresearch
Post-Tensioning Institute (PTI)
Raba-Kistner Consultants
Radarview
Terracon
Tolunay-Wong Engineers, Inc.
Unified Building Science and Engineering
Wiss, Janney, ElstnerAssociates
Ad Opportunities
Advertising is cost efficient and affordable. For under $90 an
issue your advertising message will reach over 700 structural
engineers and structural professionals across Texas. For rates and
specifications, please visit the SEAoT web site at
http://www.seaot.org/ad_rates.cfm
Gate Concrete Products Co.
MEMBER DUES
3201 Veterans Drive
Pearland, TX 77584
PH: (281) 485-3273 F: (281) 485-7644
www.gateprecast.com
Page 2
Figure 18.ASCE Steel team of UTSA2009
If you have not already paid your 2011 dues, please do so now
through the website. No login is necessary and it only takes
about 30 seconds to complete. http://www.seaot.org
Page 19
AL
AL
GINEERS
EN
CIATION
CIATION
STRUCTUR
THE STRUCTURAL ENGINEER
O
ASS
O
ASS
THE STRUCTURAL ENGINEER
STRUCTUR
GINEERS
EN
TEXAS
STRUCTURAL
ENGINEERING AT UTSA
RESOLUTION IN SUPPORT OF STRUCTURAL ENGINEERING LICENSING
Continued from page 17
(8) Blasting engineering and
classical civil engineering
Design
“Explosion Safety of Deck
Coverings for Shipboard Use”,
in which experimental tests are
conducted on the effects of
Figure 12. Interrogation signals in the structural component
Figure 11. A typical structural health monitoring system
explosives in rigid and flexible
ship deck coverings. Analytical
modeling of the effects of the explosives is performed and
recommendations on the most promising ship deck coverings are
suggested. It is worthy to note that this work was a result of
collaboration withABS Consulting.
“Development of
AASHTO Distribution
Factors for Exclusionary
Ve h i c u l a r L o a d s f o r
Prestressed Concrete Open
Box Beam (U-Beam)
Bridges”, in which an
analysis method for
Fig. 16. CMU Walls after construction
TxDOT U-beams is
suggested, and distribution
“Response and Modeling of CMU Walls under Blast Loading”, in
factors for typical U-beam
which analytical predictions of masonry walls to blast loading is
designs are determined.
performed. Several masonry walls subjected to shock tube
Fig. 13. Typical feature pattern of the EGlass polyurethane specimens
explosions are tested and used to verify analytical models.
Recommendations for the design of future masonry walls subjected
to blast loads are suggested. This work was in collaboration with
Baker Risk Engineering
WHEREAS the National Council of Structural Engineers Associations (NCSEA) Strategic Plan lists as one of the primary
objectives, to promote and work toward Structural Engineering licensure, and,
WHEREAS the ASCE Structural Engineering Institute adopted Policy Statement 101 in 2010 which states: “The Structural
Engineering Institute (SEI) of the American Society of Civil Engineers (ASCE) supports Structural Engineering licensure”;
and,
WHEREAS the Council of American Structural Engineers (CASE), a coalition of the American Council of Engineering
Companies (CEC) adopted “Position Statement on Separate Structural Engineering Licensure”, which supports Structural
Engineering licensures, and,
WHEREAS NCEES determined that “the role of the design and analysis of structures for lateral loading has increased
significantly in the design process, regardless of where in the country the structure is located” and that “Sixteen hours is
the appropriate number of examination hours for structural engineering licensure”; and,
WHEREAS NCEES will replace two 8-hour exams (the Structures I and II Exams) with a 16-hour exam (the PE Structural
Exam) in April 2011; and,
WHEREAS the Texas Board of Professional Engineers (TBPE) currently licenses those who pass a single 8-hour exam as
PE's and now must determine the appropriate license for those who pass the new 16-hour exam; and,
WHEREAS at the request of TBPE, the Structural Engineering Task Force (SETF) was established to provide advice, with
representatives from the Structural Engineers Association of Texas (SEAoT), ASCE Structural Engineering Institute (SEI),
Texas Section-ASCE, TSPE, and Texas CEC; and,
WHEREAS the SETF has proposed changes in the Texas Engineering Practice Act, supplemented with new TBPE Rules, in
order to establish SE Licensure in Texas for those who select and pass the new PE Structural Exam, as well as for all
Texas PEs who currently practice in the field of Structural Engineering; and,
WHEREAS the SEAoT will work with the SETF in the next few months to define possible modifications and additions to the
nd
Texas Engineering Practice Act prior to the 82 Session of the Texas Legislature and will continue to solicit input from
member societies; and,
WHEREAS the Board of Directors of the Structural Engineers Association of Texas voted unanimously to support Structural
Engineering Licensure, THEREFORE,
BE IT RESOLVED that the Structural Engineers Association of Texas supports modifications and additions to the Texas
Engineering Practice Act as well as corresponding modifications and additions to the TBPE Board Rules which will allow
SE Licensure in the form of a Practice Act which will restrict anyone from representing themselves as a Licensed Structural
Engineer unless they hold a Texas SE License, AND which will restrict anyone from designing certain types of structures,
unless they hold a Texas SE License, and,
BE IT FURTHER RESOLVED that the Structural Engineers Association of Texas will undertake the necessary efforts to enact
SE legislation.
Fig. 14. Modified Goodman curve through the suggested S-N model
Signed this day
Fig. 17. Measured pressures, average pressure and average impulse of the test
walls
November 17, 2010
By:
(Signed by Ismael Legarreta),
President, SEAoT
By:
(Signed by Jon D. Jelinek),
President-Elect, SEAoT
Continued on page 19
Fig. 15. Shock Tube Lateral View
Page 18
Page 3
AL
AL
GINEERS
EN
CIATION
CIATION
STRUCTUR
THE STRUCTURAL ENGINEER
O
ASS
O
ASS
THE STRUCTURAL ENGINEER
STRUCTUR
GINEERS
EN
TEXAS
STRUCTURAL ENGINEERING AT UTSA
By Mijia Yang,AlbertoArroyo, and Manuel Diaz
The University of Texas at San Antonio (UTSA) Structural
Engineering Program is part of the Department of Civil and
Environmental Engineering (CEE Department). The department
includes four areas of concentration: Environmental Engineering,
Geotechnical and Transportation, Hydraulic Engineering, and
Structural Engineering. The Department of Civil Engineering
graduated thirty-one students this past December. Currently, there
are 441 undergraduates and 55 graduate students enrolled in the
program. This is summarized in the table below.
Fall 2005
Fall 2006
Fall 2007
327
Full-Time
Students
275
Part-Time
Students
103
109
108
111
Full-time
equivalent
309.3
363.3
366
393
Graduates
46
60
330
Fall 2008
40
356
62
Table 1 Enrollment Trends; Civil Engineering
I. Structural Engineering Faculty and Courses
The structural engineering program at the University of Texas at
San Antonio is widely known in southern Texas for its quality
teaching and its leadership in innovative research. The structural
engineering faculty at UTSA consists of three full-time faculty
members, Drs. Alberto Arroyo (Professor), Manuel Diaz
(Associate Professor) and Mijia Yang (assistant Professor) and two
adjunct professors Dr. Asadul Chowdhury and Mr. Diego
Gorgazzi. All the faculty are registered professional engineers.
Their experience includes building and bridge design, evaluation
of existing structures, load rating of bridges, earthquake
engineering, structural dynamics, composite materials and blast
engineering. They bring to the CEE Department a combined
practical experience in structural engineering of more than 75
years. In addition to their practical experience the structural
engineering faculty has worked on research projects on earthquake
engineering, impact/blast loading and mitigation strategies, health
monitoring and condition assessment, structural stability including
bridge inspection, bridge load rating, and bridge management, as
well as light-weight structural systems, and masonry structural
design. Teaching for undergraduate level includes courses on
Statics, Dynamics, Mechanics of Materials, Properties/Behavior
of Engineering Materials, Structural Analysis, Structural
Dynamics, Steel Design, Reinforced Concrete Design, Prestressed
Concrete (Elective), Advanced Reinforced Concrete (Elective),
Page 4
Masonry and Timber Structures (Elective), and Advanced Steel
Design (Elective) and Foundations (Elective). The undergraduate
students and some full-time graduate students are involved in
extra-curricular activities such as the steel bridge competition, the
concrete canoe competition and the timber bridge competition.
UTSAstudents have won national recognition at these events.
The graduate courses in structural engineering have been renamed
in the 2009 – 2011 Graduate Catalog (http://www.utsa.edu/gcat/)
from topics in structures to courses with unique call numbers. The
courses that are scheduled for teaching within the next two years
are:
CE 5023 – Finite Element Methods
Fall 2009
CE 5103 – Advanced Steel Design
CE 5123 – Bridge Engineering
CE 5133 – Advanced Reinforced Concrete
345
CE 5153 – Prestressed Concrete
CE 5463 – Foundation Engineering
CE 6153 – Advanced Mechanics and Modeling of
96
Structural Materials
Other courses under Special Topics in Structures that
have been taught in the past and can be implemented as
377
the need arises are: Masonry Design of Structures,
Structural Dynamics, Earthquake Engineering, and
Advanced StructuralAnalysis.
55
All graduate courses can be audited to satisfy PDH units
needed for licensing requirements. In Fall 2010 the
Department of Civil Engineering started offering a
Master in Engineering which does not require a thesis or
special project for graduation (http://engineering.utsa.edu/
CE/NewMCE.html). This program has been developed with
practitioners in mind rather than focusing on research and
specializes in advanced professional training and new design
developments.
By providing students with sought-after skills and experience, they
stand poised to thrive in the competitive and increasingly
international work force.
Continued on page 14
STRUCTURAL ENGINEERING AT UTSA
Continued from page 14
Fig 7. Dynamic compact scenario Fig 8. Dynamic crashing simulation
Figure 4. Peanut-shape damage area of the laminate (symbol “*” in the figure
indicates the damage)
Figure 9. Composite automobile bumper design
Figure 5. Finite element modeling of ballistic impact of 0/+/- 60o braided
composite panel
(2)Progressive cracking and branching of concrete materials
The progressive damage of concrete was studied by Yang and
Bobaru (2008), and can be used to capture the progressive damage
process and branching of inhomogeneous materials. The damage
area predicted using adaptive meshless peridynamics methods is
shown in Figure 6.
(5) Effect of intermediate diaphragms on bridge stability
Using intermediate diaphragms for increasing bridge stability and
mitigating dynamic effects of abnormal loading on bridges is
always under debate. The structural group at UTSA systematically
studied the effects of intermediate diaphragms on bridge stability
under static and dynamic loading and suggested a guideline for the
optimized parameters of intermediate diaphragms (Figure 10).
Failure in intermediate
diaphragm near the
loading location
Figure 10. Effect of intermediate diaphragms
on bridge stability
Fig 6. Progressive cracking of concrete materials using adaptive peridynamics
(3) Forensic engineering consulting through two cases: Dynamic
compaction and Crash worthiness
The progressive damage due to dynamic compaction has also been
studied by Dr. Yang and his collaborators. An engineering
consulting report is completed under the PI's supervision. Crash
accidents on highway-rail grade crossing have also been analyzed
by the Structural Group, which can be used to assist in judging the
responsibility from two sides.
(4) Impact bumper design for Chevrolet at Creative Pultrusion
New advanced materials have been used in automobile structures.
The possibility of using GFRP composite for impact bumpers on
Chevrolet vehicles has been studied by the structural group and its
possibility of replacing aluminum alloy has been summarized in
the final report to Creative Pultrusion, Inc.
(6) Structure health monitoring and condition assessment
Structural health monitoring and in-situ condition assessment is
always a top priority for any structure, including typical civil
structures such as bridges and buildings. The structural group at
UTSA has conducted researches into structural monitoring on
composite materials used as stand alone structural components as
well as strength retrofitting for other structural components, such
as concrete beams, girders or columns.
(7) Fatigue characterization and strain rate effect of composite
materials
Fatigue and strain rate effect is prominent for composite materials.
The structural group has conducted an experimental fatigue
characterization of E-glass polyurethane polymer composites,
suggested an innovative fatigue life model, and greatly reduced the
required total test arrangements suggested by ASTM.
(Continued on page 18)
Page 17
AL
AL
GINEERS
EN
CIATION
CIATION
STRUCTUR
THE STRUCTURAL ENGINEER
O
ASS
O
ASS
THE STRUCTURAL ENGINEER
STRUCTUR
GINEERS
EN
TEXAS
NCSEA 2011 Winter Institute
The Amelia Island Plantation, Florida - February 25-26, 2011
Below are excerpts from the program. For complete details, and
registration, please go to http://www.ncsea.com
Friday February 25 - PDHs - 8
8:00 a.m. - 8:30 a.m. - Deferred Submittals Gone Wrong –
Ben Belson, Martin/Martin, Inc.
Tom DiBlasi, DiBlasiAssociates, P.C.
Tom Grogan, Haskell
8:30 a.m. - 9:45 a.m. - Building Officials Have Their Say
The complexity of deferred submittals is not often appreciated by
the structural engineer, nor fully comprehended by the contractor.
There will be a case study and the pros and cons of deferred
submissions, and concerns building departments encounter during
the permitting process when deferred submissions are used.
Ron Lynn, president of the International Code Council, Nevada, is
a certified building official and the Clark County, NE, Department
of Development Services-Building Division since 1981.
Jim Schock, deputy building official for Jacksonville, FL, is a P.E.
and certified building official, an appointed member of the Florida
Building Commission, and chairman of the Structural Technical
Advisory Committee to the Building Commission.
10:00 a.m. - 11:15 a.m. - Non-Standard Steel Joists
The communication between, and the responsibilities of, the
project registered design professional and the joist manufacturer
for non-standard steel joists will be reviewed. IBC section 2206
will be discussed, along with types and formats for steel joist
calculation submittals.
Tim Holtermann, based in Washington, MO, is the corporate
engineering manager for the Canam Steel Corporation.
11:15 a.m. - 12:30 p.m. - Design Responsibility for Engineered
Precast Systems
Discussion will include how best to convey necessary design
information in the contract documents and how to deal with issues
related to precast concrete lateral load resisting systems, as well as
approaches to avoid RFIs and design omissions.
Tim Salmons, is a precast design engineer who worked 10 years
for various precast concrete manufacturers before co-founding
Salmons P.C. in Albuquerque, NM, in 1997. He is a licensed P.E. or
S.E. in 31 states.
1:00 p.m. - 1:30 p.m. - Moderated Discussions En Route to the
Steel Joist and Concrete Products Facility Tours
1:30 p.m. - 2:30 p.m. - Tour of Canam Steel Joist Facility
See and learn about joist fabrication and metal decking; then view a
film on standard load testing and BIM. Tim Holtermann, chief
engineer, Canam Steel Corporation
3:00 p.m. - 4:30 p.m. - Tour of Gate Concrete Products Facility
Tour the facility and lab to see pretest of design mixes, production
of hollow core slabs and load testing. Tom Newton, vice president
operations, Gate Concrete Products
Saturday February 26 - PDHs - 7.5
8:00 a.m. - 9:30 a.m. - Specifying Wood & Cold-Formed Steel
Page 16
Trusses - Avoiding Pitfalls and Unnecessary Liability
Some of the pitfalls of specifying premanufactured trusses,
including the very different expectations of “who is responsible for
what” on the parts of the SER, the truss industry, contractors, and
the building department.
Ed Huston, principal in the firm of Smith and Huston, Inc.,
Seattle, WA, is a licensed civil and structural engineer in
Washington, with nearly 40 years of experience in structural
design, evaluation, investigation and code and standards
development.
9:45 a.m. - 11:00 a.m. - Cold-Formed Steel Submittals —
Expectations and Performance of Structural and Specialty
Engineers
The responsibilities of all members of the construction team with
respect to the use of cold-formed steel products, and with particular
emphasis on the roles of the SER and the specialty structural
engineer and the liability for design assumed with each of these
arrangements, will be discussed, along with recent case histories.
Steve Walker, is the principal engineer of the Light Gauge Steel
Engineering Group, Inc. (LGSEG). Mr. Walker, a P.E. from
Central Florida with more than thirty years experience in the
design of structural framing systems, is also a member of the
subcommittee that developed and periodically updates the AISI
Code of Standard Practice for the Cold-Formed Steel Structural
Framing Industry.
11:00 a.m. - 12:30 p.m. - Current Trends in Professional
Liability & Risk Management
Presentation will cover professional liability loss prevention
topics. The focus will be on duties and limitations when providing
construction phase services, important contract provisions that are
frequently the subject of difficult negotiations, and how poorly
worded provisions may impact a design professional.
Brian Hader, Suncoast Insurance, has 19 years of experience as a
specialist in professional liability insurance and loss prevention
education for architects and engineers.
Colleen Palmer, Beazley Insurance, has been an industry
professional since 2002 and, before that, was a practicing attorney,
specializing in providing risk management services to design
professionals.
1:30 p.m. - 2:45 p.m. - Deferred Submittal Documentation —
What You Really Need to Show Regarding Deferred
Submittals
Why is it important to clearly identify, in the contract documents,
what scope is covered by the EOR and what scope requires design
by a specialty engineer? Review of IBC requirements for deferred
submittal documentation, with common problems and avoidance
of unnecessary risks with various deferred submittal items.
C. Ben Nelson, iMartin/Martin, Inc., has 27 years of structural
engineering experience with a variety of materials and building
types, many with some aspect of deferred submittals, and has
taught continuing education seminars on deferred submittals.
3:00 p.m. - 4:30 p.m. - Deferred Submittals - Lessons Learned
Panel Discussion.
Page 5
AL
AL
GINEERS
EN
CIATION
CIATION
STRUCTUR
THE STRUCTURAL ENGINEER
O
ASS
O
ASS
THE STRUCTURAL ENGINEER
STRUCTUR
GINEERS
EN
TEXAS
NCSEA WEBINARS
NEW 16-HOUR STRUCTURAL EXAM
January 25, 2011: Heavy Timber Connections: Mistakes and
Lessons Learned
Ben Brungraber
NCEES has introduced a new 16-hour Structural exam, to be
administered for the first time in April 2011. The new exam will
replace the current Structural I and Structural II exams. Answers
to frequently asked questions are shown here. There is also more
information at http://www.ncees.org/Exams/PE_exam.php.
What is the Name of the Exam
The new exam is called the Structural exam. It is divided into two
8-hour components. The Vertical Forces Component is offered
only on Friday. The Lateral Forces Component is offered only on
Saturday. NCEES discourages using letters or numerals such as A
and B, 1 and 2, or I and II to prevent confusing the new exam
components with the Structural I and II exam
How much does the exam cost?
If a candidate sits for both Structural components and the
board/testing service submits both components for scoring, the
minimum cost would be $820 (two exams ordered, two exams
scored). Most boards/testing services have administration and
application fees as well determined solely by the board/testing
service. For example, when NCEES is the testing service for a
board, NCEES applies a $100 administration fee to each day a
candidate is testing to cover the space and proctoring services
needed. In the case of the new Structural exam, then, NCEES
would require a $200 administration fee for an examinee taking
both components in a single administration. The board/testing
service determines whether NCEES will collect fees from the
board or directly from a candidate.
What will the score report contain?
NCEES will send a component results notice to the board each
administration that a candidate takes a component. The notice will
show the history of the candidate's performance on each
component attempted. The results for each component will be
listed as acceptable or unacceptable. After a candidate has
received an acceptable result on both components within a 5-year
period, an exam pass notice will be sent to the board to indicate the
candidate has passed the Structural exam.
Will the Examinee Management System allow candidates to register
for both components in a single administration?
Yes, candidates can currently register on EMS for more than one
exam at a time if their state allows it.
Will there be different exam scripts for the FE and Structural exams
given on Saturday?
The Saturday exam script will accommodate sites that give the
Structural exam on Saturday along with the FE exam. A different
exam script will not be necessary. NCEES recommends
segregating the Structural candidates from the FE and FS
candidates, but a separate room is not required. This setup would
be similar to the way many states currently test PS and PE
examinees in the same room.
When will study materials for the Structural exam be available?
The Structural Sample Questions and Solutions was made
available in November 2010.
February 10, 2011: Detailing of Unbonded Post-Tensioned
Structures to Minimize the Effects of Restraint to Shortening
Bryan Allred
March 1, 2011: Building Information Modeling in Structural
Engineering Practice Today
David J. Odeh
March 10, 2011: Post-Tensioned Slabs on Ground Design
Bryan Allred
May 17, 2011: AISC T.R. Higgins Lecture - The AISC Seismic
Design Provisions: Past, Present and Future
James O. Malley
NEW FLEX -PLAN
NCSEA offers a flex plan that allows webinar participants to buy
groups of ten webinars for just $1950 (or five for $1100), and then
participate in the webinars when you have the time available to do
so.
NCSEA has access to over 20 recorded webinars (each includes a
CD and Notes) plus at least ten new ones added over the course of a
year. Buying in bulk offers a significant savings over the regular
price of $250 per webinar.
Sample topics and speakers include:
Designing Buildings for Wind Load by ASCE 7-05, Larry Griffis
Components of a Model QA Program, Cliff Schwinger
Tactics for Performance QA Review, Cliff Schwinger
AISC Seismic Provisions for Structural Steel Buildings, Jim
Malley
Foundation Design in a Three-Story Wood Light-Frame
Structure, Doug Thompson
Wind Load Examples, Steve Kerr and Dan Werdowatz
Code Requirements for Structural Integrity, Ron Hamburger
Seismic Design of Concrete Wall Buildings - Current Code and
Beyond, Joe Maffei
Tilt-up Wall Panel with Openings, John Lawson
As a special bonus for SECB certificants, when you first receive
certification or when you renew, you receive the option of
purchasing ten webinars for only $1495. This is a discount of over
$1000 when you consider that the individual pricing is $250 per
webinar.
All live webinars are 1.5 PDH Diamond-Reviewed, meaning these
hours are accepted as continued education in all 50 states by SECB.
For more information, visit
http://www.ncsea.com
Page 6
the NCSEA website at
Experienced personnel
State of the art
Our specialty is “volumetric” as-built surveys of concrete and masonry structures.
How was the key reinforcement
placed in your structure?
Dallas/Ft Worth
972.432.6666
Austin/Waco
512.551.0336
Houston/SE Texas
281.446.7363
San Antonio/
210.775.1637
CONCRETE SCANNING
Radarview is the largest and
most experienced in Texas
Corpus Christi
www.radarviewllc.com
800.557.3134
Page 15
AL
AL
GINEERS
EN
CIATION
CIATION
STRUCTUR
THE STRUCTURAL ENGINEER
O
ASS
O
ASS
THE STRUCTURAL ENGINEER
STRUCTUR
GINEERS
EN
TEXAS
STRUCTURAL ENGINEERING AT UTSA
Continued from page 4
SEAoT STATE CONFERENCE AWARDS
Several outstanding professionals were recently recognized and
honored at a banquet held at the SEAoT Annual State Conference
in Corpus Christi in October.
All of our structural engineering students have been able to secure
jobs not only in San Antonio, but also all over the State of Texas and
other States in the USA. A few of our graduates even have secured
jobs abroad (Mexico, Colombia).
Figure 1a: Dr. Diaz at work
Schoeller Award - Professor Richard Klingner
Award: SEAoT Service Award; Recipient: Ruben Ponce,
Jr., P.E. L – R in photo: Ismael Legarreta & Ruben Ponce
(Ismael Legaretta made the award presentation)
Figure 1b:Dr. Arroyo with students
Figure 3: The concrete lab
II Structural Engineering Facilities
The Structural Engineering Program at UTSA is equipped with
standard laboratory facilities, including a concrete lab and a MTS
and Structural Dynamics Lab.
The Structural Dynamics includes the following major testing
capabilities:
! Materials Testing System (MTS) with a capacity of 244 kN in
2
The Structural Dynamics lab has an area of 900 ft , and has a strong
floor and a strong wall to perform standard and specific structural
testing.
To date, a total of about $427k has been invested in equipment for
this lab.
The Concrete lab (above) includes the following testing
capabilities:
axial and torsional loading
! Axial loading rig with a capability of 244 kN
! Shaker table with 2 degrees of freedom.
! Instron loading machine with a capability of 600 kN
! Three hydraulic compression/indirect tension machines
! One electric saw for portioning concrete samples
! One drill for drilling asphalt concrete cores from 150 mm to 100
mm diameter
! Mixers and curing baths.
Figure 2a: 55 Kips uniaxial tension and torsional
Figure 2c: 22 Kips 0.01-10 Hz shake table
Page 14
Figure 2b: 55 Kips steel loading frame
Figure 2d: MTS controller and data acquisition
This lab is used as part of the testing facilities for
CE3242 (Properties/Behavior of Engineering
Materials). This lab was recently renovated and refurnished. New compression testing machines and
attachments were purchased at a cost of about $40k.
III. Previous projects conducted and consulted
The faculty of structural engineering at UTSA has
conducted various projects on different topics. A
summary of the research projects is listed below:
(1) Impact damage of composite materials
The damage of composite laminates induced by
impact was studied by Dr. Yang and his collaborators
(2004). The damage area was predicted using
Hashin's failure criteria, and the common accepted
peanut-shape damage pattern of a composite plate
under central impact was observed by the modeling
(Figures 4-5 - page 17). Dynamic modal analysis has
also been used to analyze the vibration and impact
behavior of sandwich materials by the PIs
(International Journal of Solids and Structures,
2005).
Continued on page 17
Award: Wilbur C. Schoeller Award; Recipient: Dr. Richard
Klingner. L – R in photo: Bill Kelm & Richard Klingner (Bill
Kelm made the award presentation)
Professor Klingner received his academic degrees (BS, MS and
PhD) from the University of California at Berkeley. His field of
specialization is structural engineering, with emphasis on the
analytical and experimental investigation of the dynamic response
of structures, earthquake-resistant design of masonry and concrete
structures, and anchorage to concrete.
Since 1977, he has been a faculty member in the Department of
Structural Engineering at the University of Texas in Austin, where
he teaches undergraduate and graduate classes on structural
analysis, dynamics, and the behavior and design of masonry and
reinforced concrete structures. He conducts investigation in those
areas, and has authored or co-authored more than 80 refereed
journal articles, 25 books or book chapters, and 400 other technical
publications. Currently, he conducts investigations of the seismic
behavior of new masonry and masonry veneer, and of autoclaved
aerated concrete masonry. Since 2004, he has been Associate
Department Chair, in charge of the Architectural Engineering
program.
He takes a leading role in the activities of many technical
committees of the US and other countries, including the American
Concrete Institute, The Masonry Society, and the American
Society for Testing and Materials. For the period 2002-2008, he
was Chair of the Masonry Standards Joint Committee, sponsored
by the American Concrete Institute, The Masonry Society, and the
American Society of Civil Engineers.
SEAoT Service Award - Ruben Ponce
Ruben Ponce, Jr., P.E., SECB, is President of Ponce Engineering,
Inc. He obtained his Bachelor of Science in Civil Engineering
(with a Structural Option) from the University of Texas at El Paso,
December 1979. He was encouraged by his engineering
supervisor, while working at Hunt Building Corporation, to attend
college and obtain his engineering degree. He enrolled at UTEP,
ten years after graduating from high school and while still working
full-time completed his BSCE degree in 6½ years. He is licensed
under the structural designation and has been practicing structural
engineering in both Texas and New Mexico since 1984.
The consulting structural engineering company at which he
worked was started in 1973. Ruben’s involvement began in
November 1978. In October 1980, he became a partner and in July
1993, the name of the company was changed to Ponce
Engineering, Inc.
Ruben is a member of the American Concrete Institute, the
American Institute of Steel Construction, the American Society of
Civil Engineers and the Structural Engineers Association of Texas.
He has served as a SEAoT officer at both the local and state levels
and is currently State Director for SEAoT for the El Paso Chapter.
His community involvement has included the City Planning
Commission; El Paso, (Oct. 2000-Oct. 2005), El Paso Vista Hills
Lions Club (June 1988-2002), Member - Zoning Board of
Adjustment; El Paso (Nov. 1997-Oct. 2000), Member - Building
Board of Appeals; El Paso, (Nov. 1989-Nov. 1997) and a member
of the School Improvement Team Committee for Slider Middle
School (1993-2002).
Ruben has been awarded the Partnership Volunteer of the Year
Nominee - Socorro ISD - 1993-1994, the Engineer of the Year Texas Society of Professional Engineers - El Paso Chapter,
February 1995 and the Service to People Award - Texas Section,
American Society of Civil Engineers in October 1995.
Ruben has been married to Emma since May 1971 (working on 40
years & more) and has two children, Edenia Yvette, a second grade
teacher, and R. Daniel, a foundation repair & general contractor.
Ruben and Emma have five grandchildren.
Continued on page 8
Page 7
AL
AL
GINEERS
EN
CIATION
CIATION
STRUCTUR
THE STRUCTURAL ENGINEER
O
ASS
O
ASS
THE STRUCTURAL ENGINEER
STRUCTUR
GINEERS
EN
TEXAS
SEAoT STATE CONFERENCE AWARDS
Letter from Ray A. Pinnell
STATE CONFERENCE 2011
Continued from page 7
October 26, 2010
Bob Tieman - Fifty Years of Service
Mr. Britt Gardner
Chairman SEAoT Hall of Honor
3200 Wilcrest Dr., Suite 305
Houston, Texas 77042
The 2011 SEAoT State Conference will be held at the Double Tree
Campbell Center in Dallas October 27- 29, 2011.
Planning for the Conference is underway. We would particularly
like to thank attendees of the 2010 conference who completed the
post conference survey. A number of valuable comments and
suggestions were made and are being carefully considered in the
planning and structuring of next year’s event.
More information about the Conference will follow in a
subsequent newsletter.
Dear Mr. Gardner:
I wish to sincerely thank you and all my structural
engineering colleagues for the honor that was bestowed on
me at the SEAoT annual conference in Corpus Christi on
October 22, 2010.
Award: Hall of Honor Award; Recipient: Ray Pinnell, P.E. L
– R in photo: Britt Gardner, Ray Pinnell & Davy Beicker
(Davy Beicker made the award presentation)
Award: 50 years of service as a Professional Engineer in
the State of Texas; Recipient: Bob Tieman; L – R in photo:
Bob Tieman & Joe Luke (Joe Luke made the award
presentation)
Hall of Honor - Ray Pinnell
Ray Pinnell was born on July 5, 1925 in Wichita Falls, Texas. With
his family, he moved to San Antonio when he was four years old.
Ray graduated from Thomas Jefferson High School and served on a
PT boat for the U.S. Navy during World War II. Thanks to the GI
bill, Ray pursued a degree after the war, first taking classes at San
Antonio Junior College and then at Trinity University. He
transferred to The University of Texas at Austin and earned a
Bachelor of Science degree inArchitectural Engineering in 1950.
Ray started working for R. Marvin Shipman Consulting Engineers
in 1950. He received his Professional Engineer registration #11160
in 1954 and went to work for Lift Slab, Inc. that same year,
eventually becoming Chief Engineer. In 1961, he partnered with
Dennis Feigenspan, P.E. and began the firm Feigenspan and Pinnell
Consulting Engineers. The company grew to 26 people at its peak
Offices statewide
• Engineering
• Environmental
• Facilities/Forensics
• Geotechnical
• Infrastructure
• Program
Management
• Testing
866.722.2547
rkci.com
Page 8
making it one of the largest engineering firms in San Antonio. Ray
worked with Dennis until Dennis’s retirement in 1988, then formed
his own firm which he named Ray Pinnell Jr. Consulting Engineers.
Ray was involved in the creation of several San Antonio landmarks
most notably the Tower of Americas and the Palacio Del Rio Hotel,
many projects along the Riverwalk and a majority of the stadiums
and exhibit buildings at Sea World of Texas. His work also extended
outside San Antonio and outside Texas, and included buildings in
Fort Worth, Kerrville, Galveston, College Station and San Marcos,
as well as Colorado, Nevada, Michigan and New York. His
international work included projects in Bedford, England, Jedda,
SaudiaArabia, and Bejing, China.
Mr. Pinnell was involved in many cutting-edge building
technologies and building methods and his engineering ingenuity
helped to solve a number of construction challenges. His work as a
structural engineer helped increase tourism to SanAntonio, which in
turn helped vitalize the city, creating new work opportunities and
securing San Antonio’s reputation as a major Texas tourist center.
He has found time to mentor and educate young people and authored
a book about his life experiences - “Engineering a Life: From Here
to China and Back.”
The Hall of Honor has now inducted nine “pioneers” of structural
engineering in Texas. Our charge as we go forward is to continue to
grow the Hall of Honor in stature and prestige, by recognizing and
adding more outstanding engineers, engineering educators and
those who have contributed to the engineering community.
2009 - Elmer W. Ellisor, 1924 - 1976
2008 - Wyatt C. Hedrick, 1888 - 1964
2008 - Walter Parker Moore Sr., 1903 -1983
2007- Phil Ferguson, 1899 - 1986
2006 - Otto H. Lang, 1864 -1947
2006 - Adophus Trost, 1876 -1957
2005 - Robert James Cummins, 1881 - 1960
2005 -William E. Simpson, 1883 - 1967
My induction into the State of Texas Structural Engineering
Hall of Honor by the Association is considered to be the most
rewarding recognition that I could receive. To be thusly
honored by those in your professional practice division is
one for which I am especially grateful and proud.
Also another item of personal pride is the distinguished
company of the prior eight inductees. Of these I am
privileged to personally know five.
Again I want to thank you and SEAoT for this special tribute.
Yours very truly
Ray A. Pinnell, Jr., P.E.
SEAoT DUES
Dues notices have been sent out to all current SEAoT members.
If you have not already paid your dues, please pay on line
through the website (www.seaot.org), or mail a check to:
Structural Engineers Association of Texas
9300 Sandstone Street
Austin TX 78737
Dues are $125 for Structural Engineer Members, Affiliates and
Associates; $100 for Graduate Engineers and $30 for Student
members. Membership runs from January through December.
You do NOT need to log in to the members’section to pay your dues
online.
MOBILE
Enterprises, Inc.
Specialty Commercial Contractor
Received ICRI 2006 Project of the Year Award
NCTRCA, DBE, HUB, WBE Certified
Architectural & Structural Restoration,
Waterproofing, Composite Strengthening,
Epoxy/Urethane Injection, Polymer Floors
(800) 375-6136 TX, LA, AR, OK
E-mail: [email protected]
Web: www.mobileenterprises.com
Page 13
AL
AL
GINEERS
EN
CIATION
CIATION
STRUCTUR
THE STRUCTURAL ENGINEER
O
ASS
O
ASS
THE STRUCTURAL ENGINEER
STRUCTUR
GINEERS
EN
TEXAS
PEDESTRIAN BRIDGE FAILURE CASE STUDY
Continued from page 11
The extent of design code violations evident from the plans leads to
a conclusion that the engineer of record did not refer, in a
meaningful way, to the design codes during the design process.
This apparent neglect of the design codes during the design process
is more than a bit disturbing. In view of the necessarily
conservative nature of engineering, a design engineer is expected,
first and foremost, to become familiar with the conventional and
customary practices relevant to the design. This familiarity can be
achieved by various methods such as review of previous similar
designs, discussion with experienced practitioners and industry
experts, and continuing education activities. Perhaps the most
important method is the study of relevant design codes, since
engineers, as a profession, commit considerable resources to the
development of design codes, which they tend to regard as the
embodiment of received wisdom. So, while a slavish adherence to
design code provisions is not a guarantee of design success, a close
study of relevant code provisions should be a significant part of the
design process.
The Use or Misuse of Computer Programs
The second point to be made regarding design procedures concerns
the use of computer programs for structural analysis and design.
The engineering profession is still grappling with the so-called
“black box” problem. A computer program is like a black box.
You can't see what goes on inside. How do you know the answers
produced by the program are good answers? Engineers have
evolved several strategies to deal with the problem.
In this case, the engineer of record made the error of using a plane
frame design program without appreciating that the program
assumes the frame is braced out-of-plane. Thus, although the
program's internally generated design checks indicated sufficiency
of individual truss members, the lack of out-of-plane bracing
resulted in buckling of the entire truss top chord at less than the
design dead load alone. Obviously, one important strategy is to
study the program documentation to understand the implications
of program assumptions and limitations.
Other strategies include techniques such as checking intermediate
and final results using other programs or manual methods;
studying intermediate results, such as displacements, to verify
correct structural behavior; changing variables to verify expected
responses; and re-analyzing previous designs to compare results.
These and other strategies for dealing with the black box problem
become all the more important as program complexity increases
and direct design methods become more widely used.
The Importance of Failure Case Studies
Although it's important to learn from your mistakes, it's much
easier and faster to learn from the mistakes of others. That's why
failure case studies are just as important as case studies of
successful projects. Learning about a successful project can build
confidence and show us how to do a good job.
But learning about a failure can warn about
misplaced confidence and show us where
improvements in our own practices are
needed.
References:
1. See AASHTO Standard Specifications for
Highway Bridge, Articles 10.16.4.1,
10.16.12.1, and 10.16.12.2 relating to the
design of vertical members, floorbeams,
and their connections on part-through truss
bridges.
2. See also AASHTO LRFD Guide
Specifications for the Design of Pedestrian
Bridges, 2009, which provides a detailed
explanation and guidelines for designing
the U-frame made of the vertical members
and floorbeams of part-through truss
bridges.
Composite Strengthening
Since 1991 Delta Structural Technology has been
committed to delivering turnkey solutions for
structural repairs and enhancements using
composite Fiberwrap technology.
Delta’s
partnership with universities and testing labs and
our hundreds of completed projects have
enabled structural composite technology to
become the accepted industry standard for
structural enhancements worldwide.
Composite technology is a proven technique in
structural strengthening, capacity upgrading,
corrosion repair, comprehensive flood proofing,
and blast protection of new and existing
structures.
As industry leaders in the application of advanced
composites, we have executed state-of-the-art
repairs to many facilities in the following
industries:
Presently, composite technology is used in a
broad range of applications to strengthen, repair,
and reinforce all types of structures from
columns, beams, joist, slabs, and shear walls.
Composites can be used to reinforce a wide
variety of materials including concrete, wood,
masonry, glulam, steel, and may even be applied
underwater! Combined with specific epoxies,
composites can be used for specialized
applications including:
High temperatures (up to 500 degrees F)
Underwater (fresh or saltwater)
Chemical resistant
Potable water approved
UV resistant coating
UL Rated Fire Coating
Hospital Grade Epoxy
Medical
Industrial
Petrochemical
Commercial
Military
Food Processing
Coastal
Architectural
Educational &
Research
Water & Waste
Water plants
As a pioneer in the field of composite
construction & strengthening Delta is ready to
assist you in your future projects. Contact us for
more information on how we might offer you a
composite solution to your strengthening needs.
Delta Structural Technology
Lightweight by Design
In comparison to traditional A36 steel, the EGlass Fiberwrap systems weigh one third the
weight of steel and have two times the tensile
strength.
3601 N Loop 336 W
Conroe, TX 77304
Phone (281) 821-3006
Fax (936) 539-2118
Visit our website:
www.fiberwrap.com
Figure 4. Truss Floorbeam Connection Detail
Page 12
Page 9
AL
AL
STRUCTUR
GINEERS
EN
CIATION
CIATION
THE STRUCTURAL ENGINEER
O
ASS
O
ASS
THE STRUCTURAL ENGINEER
STRUCTUR
GINEERS
EN
TEXAS
PEDESTRIAN BRIDGE FAILURE CASE STUDY
By Linwood E. Howell, P.E.
This case study looks at a beautiful pedestrian bridge
designed, built, and about to be opened when a
vigilant subcontractor's observations revealed
serious design flaws that made the bridge unstable
and near the point of collapse. After the flaws were
corrected by adding a midspan support and overhead
bracing as shown in Figure 2, the was bridge opened
without incident.
The pedestrian bridge consisted of a part-through
steel truss with eight, 20-ft panels for a total length
of 160 ft. The truss was supported at the first interior
panel points such that each end panel cantilevered to
a retaining wall at the embankment. Secondary
supports in front of the retaining walls controlled
possible downward deflection of the cantilever
ends. Decorative concrete panels enclosed the main
and secondary supports to give the appearance of
uniquely shaped abutments.
Figure 3. Truss Top Chord Buckled Shape.
Figure 1. Original Design of Part-Through Truss Pedestrian Bridge.
Discovery and Investigation
Soon after placing the bridge concrete deck, the
contractor noticed 1 to 2 inches of upward vertical
offset of the cantilever ends at the embankment
retaining walls. An initial evaluation suggested that
the embankments had settled, a common problem in
construction. Fortunately, before the embankments
could be rebuilt, a subcontractor installing
decorative lighting along the truss top chords raised
an alarm after noticing that the top chords swayed
several inches laterally during the installation. The
owner immediately ordered an investigation to
determine what was actually wrong with the bridge
and what could be done to fix it.
Two structural engineering consultants were hired to
carry out independent investigations. The result of
their investigations revealed a bridge near collapse
due to buckling of the truss top chords. Figure 3 Figure 2. Pedestrian Bridge withAdded Support and Overhead Bracing.
shows measurements of the top chord buckled
shape. Analysis indicated collapse was averted by
redundancy from the bending capacity of the truss
Tolunay-Wong
Engineers, Inc.
bottom chords, which consisted of W27x178 steel beams. This
bending capacity enabled the owner to fix the bridge inexpensively
Geotechnical Engineering and Testing · Engineering Consulting
Construction Materials Testing · Deep Foundations Testing
by installing columns at the under passing roadway median, in
effect rendering the truss mere decoration.
Houston Office (Headquarters)
Analyzing the Design Process
The averted collapse was a non-event that did not receive mention
in the local press, despite the high profile of the project. Looking at
the bridge today, unless you happen to be a structural engineer, you
might not suspect there had been any problem with the design.
Page 10
10710 S. Sam Houston Parkway W., Suite 100 Houston, TX 77031
Phone: 713-722-7064 Fax: 713-722-0319
Other Offices
Beaumont, TX ! Corpus Christi, TX ! Dallas, TX
Gonzales, LA ! Gainesville, FL
Visit us at: www.tweinc.com
But as a practicing structural engineer, you would have to ask an
important question: How could the design of this bridge have
gone so wrong?
Three aspects of the design process for this bridge stand out as
contributing factors in the resulting failure.
1.An architect's vision for the bridge involving a unique structural
concept.
2.An inexperienced engineer assigned to work out the structural
details.
3.No independent review of the design by an experienced bridge
engineer.
The point here is not to suggest that architects and unique
structural concepts are to be avoided in bridge design, but rather
that the firm engaged in such a project should expect that a greater
level of structural engineering expertise will be required than for
routine bridge design projects. While it may be true for routine
bridge designs that a thorough and independent review is seldom
carried out, such a review should be considered essential for a
design that goes beyond the familiar and customary parameters of
the practice.
The Role of Design Codes
Two important points can be made regarding design procedures
followed by the engineer of record. The first concerns the role of
design specifications or codes in the design process. Examination
of the design drawings for the pedestrian bridge revealed details at
odds with specific recommendations of relevant code provisions.
For example, the truss vertical member connection detail at the
lower chord, shown in Figure 4, does not provide a rigid
connection that can effectively resist lateral load applied at the
1,2
truss top chord as required by relevant code provisions. The
poor ability of this connection to resist top chord lateral load is one
of several significant design code violations that caused instability
of the bridge.
Continued on page 12
Page 11