NEESR-II: Toward Rapid Return to Occupancy in Unbraced Steel Frames

Portland State University, Portland OR

Investigators

Abstract

This award is an outcome of the NSF 08-519 program solicitation George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES) Research (NEESR) competition and includes Portland State University (lead institution), University of Washington (subaward), and California State University, Los Angeles (subaward). The project will utilize the multiple shake table NEES equipment site at the University of Nevada, Reno. The basic seismic design philosophy for steel frame buildings has been to rely on the gravity load system in order to prevent loss of life. However, the expectations of building owners and society are no longer satisfied with merely providing life safety, so new structural systems are needed for achieving improved performance levels that limit damage. One of the design targets needs to include rapid return to occupancy, especially for earthquakes that are less severe than the maximum expected. The overall objective of this project is to develop a lateral load resisting system, the linked column frame system, for unbraced steel frames capable of achieving specific target performance levels. The proposed structural system includes configurations of novel and conventional structural components that together result in predictable and rapidly recoverable damage. NEES equipment sites offer a unique capability to experimentally evaluate system level response under dynamic loads, which is required to study the interaction of the structural components and evaluate the potential advantages of the proposed building frames. This NEES individual investigator project will transform seismic design approach in regions of moderate and high seismicity by developing a unique seismic load resisting system, thereby contributing to the intellectual merit of the project. The research will use advanced experimental and computational research methods to develop the necessary understanding of system and component behaviors. Data sets from large-scale dynamic experiments will be generated to ensure that analytical models capable of capturing both component and system behavior are developed. The depth of understanding achieved through such an experimental and analytical research program will enable the development of robust design methodologies. The outcomes of this research will not only impact seismic design, but also result in other broader impacts. Utilization of such new structural systems will reduce post-event downtime and building repair costs, and thus will have a significant impact on reducing earthquake losses and life-cycle costs. Further, the research will develop understanding of a novel composite construction that could be adapted to other structural components. This project will also impact engineering education and diversity through active collaboration with faculty and undergraduate students from a minority serving and predominantly undergraduate institution. The proposed activities are combined with an integrated educational component designed to emphasize the importance of capacity and performance design in undergraduate engineering education. These educational aspects will be reinforced through research participation using existing NEES web based telepresence tools. Data from this project will be made available through the NEES data repository (http://www.nees.org).