Jan. 21st, 2008
Edition - We're Back!!
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Table Tests Prove Structures Can Be Seismically Sound With Less Steel Than
Called for by Current California Code
- San Diego,
coverage of testing in Real Player University
of California, San Diego (UCSD) structural engineers have announced that a
violent simulated reproduction of the Northridge earthquake shook a
seven-story structure at the UCSD Jacobs School of Engineering's
Engineering Center, and resulted in only minor cosmetic damage to the
building. The experiment, (Click
to view Video 1 from angle in photo above) along with earlier shakes, was conducted to test a
revolutionary new theory that mid-rise concrete apartment, condominium and
hotel structures can be built to survive powerful earthquakes using less
steel reinforcement than currently required by California building codes.
"Many people don't realize that excessive building strength can actually
promote poor structural performance and non-structural damage during an
earthquake," said Robert Englekirk, founder of the
Englekirk Companies and a
co-principal investigator of the project. "The structural engineering
community wants to develop regional design procedures that allow for the
development of more suitable buildings in Southern California." UCSD
structural engineers said the building held up as well as the theory.
The test (click
to view Video 2 of the southeast corner of the structure, links to
more videos can be found at the bottom of the middle column) was conducted under tight safety
precautions with the powerful mechanical jolts delivered by a 25 ft. by 40
ft. shake table. The experiment duplicated ground motions from the Jan. 17,
1994, Northridge earthquake that were recorded at the Olive View Hospital in
Sylmar, CA. The 275-ton, 65-foot-tall building was also tested on Nov. 22,
2005, with ground motions that were recorded during the Northridge
earthquake farther from the epicenter, at a seven-story hotel in Van Nuys,
CA. The November, 2005 test produced horizontal accelerations that were 30
percent of the force of gravity, and the Jan. 14 test simulated the
earthquake closer to its epicenter, with horizontal accelerations of 82
percent of gravity.
"What we found is
fairly simple; if we use an intelligent design strategy that reduces the
demands required by the current California building standards, and use about
half the reinforcing steel that's required, mid-rise buildings will survive
powerful earthquakes with only minor damage," said
Jose Restrepo, professor of structural engineering at the UCSD
Jacobs School of Engineering
Department of Structural Engineering and co-principal investigator of the
project. Prof. Restrepo likened the design to that of a car, where upon
impact, a large amount of the force is dissipated at the bumper, prior to
spreading through the car to the passenger area. So to in this design, the
intent was to have the brunt of the impact absorbed in an energy absorbing
“plastic hinge” located at the ground floor, causing a dissipation of the
earthquake forces prior to their spreading throughout the building.
Restrepo said the performance of the seven-story building was even better
than the sponsors of the project had expected. "The professional engineers
we have talked to were thrilled," said Restrepo.
“I can’t tell you how
satisfying it is to see the BauGrid Welded Reinforcement Grids (WRG)
withstand such tremendous large tension and compression forces,” said Hanns
U. Baumann, S.E., president of BauTech,
Inc., which donated the WRG that were used as the confinement
reinforcement in the walls of the 7-story test structure. “This design is
one that Bob Englekirk has espoused for some time, and I’m glad to see that
Prof. Restrepo’s test program has done such an excellent job of showing that
he was absolutely right.” said Baumann. Baumann added that “Because of
public safety concerns, it is quite important that design engineers
understand that the WRG used in this structure is not the same as the much
weaker Welded Wire Reinforcement (WWR). WRG is manufactured with high
strength welds at every location where the steel rods intersect, which
provides the unique and valuable inter-cell confinement that was exhibited
during the test.”
Restrepo said the
seven-story building may be put through additional tests to provide further
scientific confirmation that less reinforcing steel than currently required
could improve the performance of mid-rise concrete buildings in densely
populated and seismically active regions in California.
Sixty people were
killed and 7,000 injured during the Northridge earthquake which left 20,000
homeless, and damaged more than 40,000 buildings in Los Angeles, Ventura,
Orange, and San Bernardino Counties. The death toll and roughly $40 billion
in property damage prompted professional structural engineers to call for
more scientific testing of mid-rise residential buildings.
When asked how soon
new design procedures such as this could be incorporated into Southern
California buildings, in that implementation of new ideas into building
codes is a process that is notoriously slow moving, Englekirk stated that
the current code already allows use of this “performance-based” design.
“The code allows engineers two ways to design structures. There are
prescriptive designs, as spelled out in the codes, and there are
performance-based designs, where through the use of testing and proven
scientific methods, it is shown that a design is safe.”
Continued next column
Yes, we're back, and we promise not to go
away for such a long time again. We will be updating on a
regular basis again, and we hope that you'll join us as we try to make
information about construction trends and innovation more available on
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Shake Table Test, Continued
Full-scale tests of
such large buildings have previously not been possible because of weight,
space, and technical limitations of smaller indoor shake tables. UCSD's
shake table can actually support a building roughly 10 times heavier than
the seven-story structure it currently holds.
The $9 million shake
table at the Jacobs School's Englekirk Center is one of 15 earthquake
testing facilities in the National Science Foundation's Network for
Earthquake Engineering Simulation. The UCSD-NEES shake table, the largest in
the U.S. and the only outdoor shake table in the world, is ideally suited
for testing tall, full-scale buildings.
Click here to take an animated
tour of the facility.
Construction of the
seven-story test building was led by Highrise Concrete Systems, Inc. of
Dallas, TX, a company which specializes in the construction of multi-story
concrete buildings using the latest formwork technology. Additional
financial support donated equipment and labor was provided by Tech, Inc.;
Dywidag Systems International, USA;, Inc. (DSI); HILTI; Associated Ready
Mix; California Field Ironworkers; Cemex: Concrete Steel Reinforcing
Institute (CRSI); Douglas E. Barnhart, Inc.; Englekirk & Sabol, Inc.;
Fontana, Grace, Hanson Aggregates; Morley Builders; Pacific Southwest
Structures; Schuff Steel-Pacific Inc.; Southern California Ready Mix
Concrete Association; the Portland Cement Association(PCA); and
Carpenters/Contractors Cooperation Committee, a nonprofit labor and
The Englekirk Structural Engineering Center, part of UCSD's renowned Powell
Structural Research Laboratories, is named in recognition of Robert and
Natalie Englekirk's support of structural engineering research and education
at UCSD Jacobs School of Engineering Department of Structural Engineering.
Construction of the Englekirk Center and the earthquake research program
there are supported by the Englekirk Center Industry Advisory Board, a group
of 43 structural engineering firms and associations in Southern California.
Patron members include Carpenters/Contractors Cooperation Committee,
Englekirk Systems Development, Inc., and Highrise Concrete Systems, Inc.
Other partners include: American Segmental Bridge Institute; Anderson
Drilling; Baumann Engineering; Brandow & Johnston Associates; Burkett and
Wong Engineers; Charles Pankow Builders, Ltd.; Clark Pacific; Douglas E.
Barnhart, Inc.; Dywidag Systems International, USA, Inc. (DSI); Englekirk
and Sabol Consulting Structural Engineers, Inc.; EsGil Corporation; GEOCON;
Gordon Forward; HILTI; Hope Engineering, Inc.; John A. Martin and
Associates; Josephson Werdowatz & Associates Incorporated; JVI, Inc.; KPFF
Consulting Engineers; Matt Construction Corporation; Morley Builders; Nabih
Youssef and Associates; Oak Creek Energy Systems; Occidental Petroleum
Corporation; Pacific Southwest Structures; PCL Construction Services, Inc.;
Portland Cement Association; Precast/Prestressed Concrete Manufacturers
Association of California (PCMAC); Saiful/Bouquet Consulting Structural
Engineers, Inc.; Schuff Steel-Pacific, Inc.; Structural Engineering
Association of Southern California (SEAOSC); Simon Wong Engineering, Simpson
Manufacturing Co., Inc.; Smith-Emery Company; Stedman & Dyson Structural
Engineers; The Eli & Edythe L. Broad Foundation; Twining Laboratories; UC
San Diego Design and Construction; Verco Manufacturing Co.; Weidlinger
Associates, Inc.; and the Structural Engineering Association of San Diego (SEAOSD).
coverage of testing in Real Player
Video of base cracking
Video of bottom cracking
Video of corner cracking
Video of first floor movement
Video of desk on first floor
Video of perpendicular view of
testing (Video 1, above left)
Video of southeast view of
testing (Video 2, above left)
World of Concrete Underway
by Bill Coburn
Jan. 21, 2008
The World of Concrete kicked off on
Sunday with a tour of the Hoover Dam bypass, and today dozens of seminars
were conducted with the intent of educating attendees on the latest news
in concrete construction and technology. The World of Concrete uses more
than 900,000 square feet to inform its attendees about 1600 exhibiting
companies or organizations from 22 nations. The World of Concrete is
being held in Las Vegas, at the Las Vegas Convention Center, and while
figures are not yet available on the number of people coming to this
year's event, I'm told that in excess of 91,000 people were registered for
last year's event. I am on-site in Vegas, and will be updating the
website with reports over the next few days. If you can fit it into your
schedule, drop what you're doing and head to Vegas, this is by far the
most comprehensive look at concrete anywhere in the world today. In
addition to the training seminars and trade exhibits, there are ACI
certification courses and trade demonstrations, including decorative
concrete contests, bricklaying contests, and trucking/equipment driving
skill demonstrations. If you can't make it this year, plan ahead. Next
year's event is scheduled for Feb. 2nd through 6, 2009.
Francisco’s 590-ft Skyscraper Lifts Seismic Design's Stature
job breaks per-floor speed record on West Coast
By Nadine M. Post for ENR in San
engineer Ron Klemencic had extra reasons for gratitude during the 2005
Thanksgiving season. After hitting his head against the wall on and off
for more than three years, he finally received stamps of approval for the
first two performance-based seismic design high-rises in earthquake prone
San Francisco. PSD can cost less, improve design and ease construction.
Word about the 38- and 43-story Infinity towers came the
last week of November, followed by news about the 64-story One Rincon Hill
(ORH) in early December. “I was elated both times,” says Klemencic,
president of Magnusson Klemencic Associates, Seattle. “It was two years of
blood sweat and tears on [the Infinity] before we even initiated Rincon
Hill.” That review took a year, twice the norm for San Francisco towers.
The city’s approval marked the beginning of the end of a
logjam in big California cities for performance seismic design (PSD) of
buildings taller than 240 ft. “People are going to be doing this
left-handed at 100 mph in five years thanks to Ron...,” predicts one
prominent San Francisco architect who declines to be identified...Read
the whole story
Former ACI Director Joins American Society of
Ward R. Malisch has joined the American
Society of Concrete Contractors (ASCC) as technical director. He was
senior managing director of the American Concrete Institute (ACI), a
position from which he recently retired.
Malisch previously was editor of
Concrete Construction magazine for nearly 15 years, the director of
construction information services for the Portland Cement Association, and
ACI's managing director of enginering. He taught at several
universities for nearly 20 years.
Malisch received his B.S., M.S., and
Ph.D. degrees in civil engineering from the University of Illinois.
In addition to his other duties at ACI,
Malisch answered concrete contractors' questions via the ASCC technical
hotline, and wrote the organization's Troubleshooting Newsletter.
He has been a member of the ASCC Board of Directors since 2001 and is a
former chair of the ASCC Education and Training Committee. He
assisted n producing ASCC's 26 Position Statements that offer practical
answers to situations commonly faced by concrete contractors.
As technical director, Malisch will
continue to answer the hotline and produce the Troubleshooting Newsletter.
His duties will also include reviewing construction related ACI documents,
writing technical articles and papers, coordinating research projects,
providing contractor input on technical matters to other organizations,
and developing programs for the technical education of contractors.
The ASCC is a non-profit organization
dedicated to enhancing the capabilities of those who build with concrete,
and to providing them a unified voice in the construction industry.
Members include concrete contracting firms, manufacturers, suppliers and
others interested in the concrete industry, such as architects, specifiers
and distributors. There are approximately 575 member companies in
the United States and five foreign countries. For more information
on the ASCC, visit the website at
www.ascconline.org or call (314) 962-0210.
Engineers' Association of California
American Bungalow Magazine
BauGrid Welded Reinforcement Grid System
Baumann Research and Development Corporation
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