WHAT: Structural test of a new shear wall design for steel high-rise buildings that could improve seismic safety and bomb resistance. The concrete and steel composite shear wall, designed by a structural engineering professor at the University of California, Berkeley, will be slowly stressed to determine how it handles large earthquake motion.
WHEN: 11 a.m. Thursday, Oct. 18
WHERE: Structures Laboratory test bay, on the second floor of Davis Hall. Davis Hall is on Hearst Ave. near LeRoy Ave. Parking is easiest on surrounding streets.
WHO: Abolhassan Astaneh-Asl, UC Berkeley professor of civil and environmental engineering and an expert on steel buildings and their response to earthquakes and bomb blasts.
BACKGROUND: One of the newest techniques for improving the earthquake response of high-rise steel buildings is steel plate shear walls - 3/8-inch steel sheets bolted to columns and beams to increase stiffness and limit lateral motion that could bend or break the steel during an earthquake or bomb attack. Astaneh has tested such shear walls, an improvement over concrete shear walls and steel frames, and has come up with an innovative combination of steel and concrete that he thinks is better. He proposes bolting a 6-inch slab of pre-cast concrete to the 3/8-inch steel plate. The concrete would keep the steel from buckling under compression, while the steel would keeps the concrete from cracking under tension. The National Science Foundation is funding study of the design.
Preliminary tests show this system works well seismically, and Astaneh proposed it also could help protect the lower floors of buildings from truck bomb blasts. After several weeks inspecting steel from the collapsed World Trade Center as part of another NSF investigation, he says the design also could protect upper floors from airplane collisions.
Thursday's test will assess the response of the composite shear wall to lateral forces like those expected in a large earthquake or from the impact of a large plane. Astaneh and doctoral student Qiuhong Zhao built a half-scale two-dimensional model of a cross-section through a steel-frame building with composite shear walls. The model, 20 feet high and 9 feet wide, is laid on its side and the bottom bolted securely to a concrete block so that a hydraulic jack can push the top up to a foot forward or backward.
VISUALS: As the hydraulic jack slowly pushes the structure back and forth, the concrete will crack and the steel will start to buckle. There likely will be no dramatic failure. Astaneh also has on display examples of 3/16-inch buckled steel and three-inch shattered concrete from previous tests.