New building design withstands earthquake simulation
Ann Arbor, Mich.—Researchers at the University of Michigan simulated an off-the-charts earthquake in a laboratory to test their new technique for bracing high-rise concrete buildings. Their technique passed the test, withstanding more movement than an earthquake would typically demand.
|Engineers constructed a four-story, 40-percent replica of a building in a laboratory to test their new technique for bracing high rise buildings in earthquake zones. They simulated an earthquake by pushing and pulling the building with hydraulics.
Photo: Remy Lequesne
The engineers used steel fiber-reinforced concrete to develop a better kind of coupling beam that requires less reinforcement and is easier to construct. Coupling beams connect the walls of high rises around openings such as those for doorways, windows, and elevator shafts. These necessary openings can weaken walls.
"We simulated an earthquake that is beyond the range of the maximum credible earthquake and our test was very successful. Our fiber-reinforced concrete beams behaved as well as we expected they would, which is better than the beams in use today," said James Wight, the Frank E. Richart Jr. Collegiate Professor in the U-M Department of Civil and Environmental Engineering. Working with Wight on this project are Gustavo Parra-Montesinos, an associate professor in the Department of Civil and Environmental Engineering, and Remy Lequesne, a doctoral student in the same department.
Today, coupling beams are difficult to install and require intricate reinforcing bar skeletons. The U-M engineers created a simpler version made of a highly flowable, steel fiber-reinforced concrete. "We took quite a bit of the cumbersome reinforcement out of the design and replaced it with steel fibers that can be added to the concrete while it’s being mixed," Parra-Montesinos said. "Builders could use this fiber-reinforced concrete to build coupling beams that don’t require as much reinforcement."
The engineers envision that their brand of beam would be cast off the construction site and then delivered. Nowadays, builders construct the beams, steel skeletons and all, bit by bit as they’re building skyscrapers. Their fiber-reinforced concrete has other benefits as well. "The cracks that do occur are narrower because the fibers hold them together," Parra-Montesinos said.
The fibers are about one inch long and about the width of a needle. The engineers performed their test in December on a 40-percent replica of a 4-story building wall that they built in the Structures Laboratory. They applied a peak load of 300,000 pounds against the building, pushing and pulling it with hydraulic actuators.
To quantify the results, they measured the building’s drift, which is the motion at the top of the building compared with the motion at the base. In a large earthquake, a building might sustain a drift of 1 to 2 percent. The U-M structure easily withstood a drift of 3 percent.
The new beams could provide an easier, cheaper, stronger way to brace buildings in earthquake prone areas.
The researchers are now working with a structural design firm to install the beams in several high rises soon to be under construction on the west coast.
Watch and link to a video of the earthquake simulation at: https://www.ns.umich.edu/podcast/video.php?id=751. This research is funded by the National Science Foundation under the Network for Earthquake Engineering Simulation Program.
New design means cheaper, more sustainable construction
Raleigh, N.C.—People are always looking for ways to make something less expensive and more environmentally friendly and a team of researchers from North Carolina State University has figured out how to do both of those things at once when raising the large-scale buildings, such as parking garages, of the future.
More specifically, the researchers have figured out a way to use 30 percent less reinforcing steel in the manufacture of the concrete beams, or spandrels, used in the construction of parking garages—without sacrificing safety. Sami Rizkalla, Ph.D., one of the leaders of the research team, says they developed design guidelines that use less steel while maintaining safety and reliability. The new spandrel design "simplifies construction for precast concrete producers," Rizkalla says. In addition to using less steel, the new design cuts labor and manufacturing time in half—significantly decreasing costs.
Greg Lucier, a doctoral student at NC State who was also crucial to the research effort, says the new design guidelines include a significant margin for safety. For example, Lucier says the spandrels could handle two to three times the maximum weight they would be expected to bear. Lucier is also the lab manager of the Constructed Facilities Laboratory at NC State, which oversaw the testing of the new spandrel design.
The new design guidelines stem from a two-year project that was launched in January 2007, with support from the Precast/Prestressed Concrete Institute (PCI). PCI provided NC State with more than $400,000 in funding, materials and technical support over the life of the project.
The success of the project is already drawing interest from the concrete industry, with individual companies coming to NC State to get input on how to improve their products and manufacturing processes. For example, Rizkalla says, many companies want to collaborate with researchers at the Constructed Facilities Laboratory on research and development projects related to new materials, such as advanced composites, to be used in concrete products.
Researchers presented an overview of the entire project—including new testing data—for the first time at the spring convention of the American Concrete Institute in San Antonio last month.
Discover the latest tools and tactics at work in innovative firms
CHICAGO—AEC business leaders and technology professionals will convene at the 10th annual AEC Technology Strategies 2009 Conference on June 11-12 at the Green Valley Ranch & Resort in Henderson, Nev.
This year’s conference themes include: AEC Design and Business Systems, Corporate Strategy and the Role of AEC Technology, IT Infrastructure for the AEC Business, Leadership and the Role of the AEC IT Director, and Maximizing IT Resources in a Challenging Economy. Keynotes, concurrent, focus sessions, working group discussions, luncheon, and a networking cocktail reception will provide ample opportunity for listening, learning, and asking questions of leading IT professionals in the AEC industry.
Attendees will discover the latest tools and tactics at work in innovative firms today, and learn strategies for adapting and thriving in tomorrow’s AEC business.
Featured presentations include the following (as of 3/6/09):
Building a Cost Effective, Highly Performing Virtual AEC IT Team
Micki Nelson, Vice President & Chief Information Officer, MWH
Value Drivers: Information as a Blue Chip Asset
Bradley Horst, AIA NCARB, Principal & Chief Information Officer, Einhorn Yaffee Prescott Architecture & Engineering and Erin Rae Hoffer, AIA, LEED AP CSI, Architect & Industry Programs Manager, Autodesk Inc.
WAN Optimization: A Competitive Tool for Operating Locally and Leveraging Talent Globally
Brandt Karstens, Vice President & Director of Systems, HDR Incorporated’s Architecture Company
Communicating and Delivering IT Value in any Economy
Ty Kicklighter, Chief Financial Officer, Walter Schoel Engineering Company
Managing AEC Files Across Remote Sites and Project Teams
David Pluke, Principal, Vice President of Technology, Ericksen Roed & Associates
Aligning Technology and Core Business Strategy
Michael Tardif, Assoc. AIA, CSI, Hon. SDA, Director, Integrated Project Delivery Systems, Grunley Construction Company, Inc.
Presented by Stagnito Media, in association with Structural Engineer and CE News, and sponsored by Newforma. Attendees will also have the opportunity to attend a series of special software solution-oriented presentations offered through out the event.
For complete event details and confirmed sessions, please visit www.AECTechStrategies.com or call 1-800-466-6275.
EVENTS: – Add to calendar
May 3-5, 2009: PTI Technical Conference & Exhibition, Portland, OR
May 17-20: RECon The Global Retail Real Estate Convention, Las Vegas
May 19-21: Ecobuild America and AEC- Science and Technology Conference & Expo, Denver
AEC – Science & Technology, Ecobuild
June 11-12: AEC Technologies, Las Vegas
June 14-17: 26th International Bridge Conference, Pittsburgh
Engineers Society of Western Pennsylvania