CAEE Seminar: Seismic Performance Reliability of Reinforced Concrete Shear Walls in Tall Core Wall Buildings

The Civil, Architectural and Environmental Engineering department will be hosting a seminar featuring Sunai Kim, S.E., Ph.D Candidate at the University of California Los Angeles and Candidate for the position of Assistant Professor of CAEE with a specialty in structures. The topic of the lecture will be Seismic Performance Reliability of Reinforced Concrete Shear Walls in Tall Core Wall Buildings.

Abstract

Since 2008, reinforced concrete core wall systems have been most widely used for the seismic design of tall buildings in the western United States. During high seismic events, core wall systems are intended to dissipate energy by the yielding of coupling beams, followed by the flexural yielding at the base of core walls. Although the behavior of core walls is governed by flexure, the design of core walls is often governed by shear as core walls experience high shear demands, usually up to the ACI318 code limit. This is because there is a general lack of redundancy in the number of shear walls in tall buildings and the lengths of shear walls are limited to the perimeter of the elevator core.

The design of tall buildings is typically conducted using performance-based design approaches recommended per Los Angeles Tall Buildings Structural Design Council (LATBSDC) and Pacific Earthquake Engineering Research Center Tall Buildings Initiative (PEER TBI). Both LATBSDC and PEER TBI guidelines recommend shear design using empirical factors for β (dispersion in mean shear demand) and φ (uncertainties in nominal expected capacity) that are based on engineering judgment. Despite the fact that the shear failure can be fatal due to its sudden and brittle nature, there has not been enough research to study reliability of the current design criterion. Thus, this research utilizes cutting-edge modeling and reliability methods for tall buildings, to assess reliability of shear walls, to create a robust shear design acceptance criterion, and to develop a framework to examine reliability of other structural components.

This presentation will highlight the major contributions of this research. This includes (1) modeling procedures for nonlinear response history analysis of tall buildings, (2) sensitivity of modeling and design parameters on structural responses, (3) quantification and treatment of uncertainties in demand and capacity, (4) Monte Carlo simulations to measure reliability of shear walls, and (5) post-earthquake safety assessment of tall buildings under performance based earthquake engineering. The benefits of this research are two-fold, on a structural component level and community level. On the component level, the reliability methods developed in this research are not only applicable for the shear design criterion but can also be utilized to assess reliability of other structural components under performance-based design. Adopting performance-based design is both important and necessary for a more efficient design and accurate analysis of structures. On a community level, the performance-based earthquake engineering framework can be utilized to measure post-earthquake safety of structures. This information will not only guide owners and designers in understanding the post-earthquake economic and damage risks but also better prepare communities for seismic events.