UC San Diego
Development of Low Seismic Damage Structural Systems
- Author(s): Nema, Arpit
- Advisor(s): Restrepo, José I
- et al.
Modern society requires enhanced seismic performance from its structures that is beyond simple life-safety requirements, which has been the main design objective in the 20th and early 21st centuries. Multiple approaches to low-damage seismic structures have been developed towards the end of the last century, one of which is the hybrid re-centering element approach studied experimentally and analytically in this work.
The first half of this dissertation focuses on the application of re-centering behavior to structural walls in multi-story structures. A four story, half scale structure with an eccentric arrangement of structural walls was tested dynamically at the UC San Diego Large High-Performance Outdoor Shake Table (LHPOST). The test also incorporated a new low damage gravity column concept. Results from the test provided valuable information about the two-dimensional seismic behavior of multi-story structures incorporating hybrid-re-centering structural walls.
An analytical model was developed for modeling the behavior of re-centering structural walls and calibrated as a part of a full three-dimensional model of the test specimen analyzed under a sequential application of the measured excitation history. An analytical model for a re-centering system applicable to moment frames was also developed and calibrated against experimental results from a previous study undertaken at UC San Diego. As a conclusion, the two models were incorporated into an analytical model of a thirteen-story structure with different lateral force resisting systems in orthogonal directions which was then studied using seven historic ground motions following the guidelines of ASCE/SEI 7-10 (2010).
The second half of the dissertation focuses on re-centering systems in bridge structures. A 35% scale, bridge bent with two hybrid re-centering columns was tested dynamically at the UC Berkeley PEER Shaking table. The specimen was constructed using a new socket connection based Accelerated Bridge Construction technique. Precast construction was utilized for the three major bent components: the columns, the bent-cap and the foundation, which were then assembled at the test facility. Results from the test were used to calibrate the dynamic behavior of a computational model developed for the analysis of re-centering bridge columns. The proposed model improves upon earlier models resulting in significantly faster analysis speeds, allowing for the modeling of complete bridge systems in reasonable time-frames. Finally, the multi-column bridge bent model was incorporated into a comprehensive three-dimensional model of an existing bridge and used for studying the bridge response under different configurations of prestress force capacities and energy dissipation capacities.