Special Topics in Structures

Single Abstract

342904 - Inelastic Displacement Ratios of SSI Systems under Repeated Earthquakes

Saturday, April 21
8:00 AM - 9:30 AM
Location: 204AB

In this research, the effect of soil-structure interaction (SSI) on seismic inelastic displacement ratios of SDOF systems is investigated for the case of single and repeated earthquakes. To account for the effect of SSI, a simplified equivalent fixed-base method is proposed based on FEMA guidelines. NEHRP soil types C and D were considered for different foundation aspect ratios and different structure strength reduction factors. Different models from the literature are adopted to account for the effect of repeated earthquakes.
A well-defined degrading model was used to conduct the dynamic analyses. A total of 100 earthquake records, including recent ones from Japan and New Zealand, with magnitudes greater than 5 and peak ground acceleration (PGA) values greater than 0.08g, were selected and scaled to the same hazard level. The effect of aftershock and pre-shock was included in the analysis. These earthquake records were applied on five RC columns that were chosen from the Pacific Earthquake Engineering Research Centre database. A large number of dynamic analyses were conducted to derive the required inelastic ratios. Different strength reduction factors, foundation aspect ratios, and repeated earthquake models were assumed for a range of NEHRP soil types C and D properties in the study. The results show that inelastic displacements are greatly affected by both the soil flexibility and the effect of repeated earthquakes.
The large collected data was used to derive mathematical expressions for inelastic displacement ratios, suitable for use in performance-based seismic evaluation in a design office. A simple expression was proposed to properly account for the different parameters influencing the behavior.

Ashraf Ayoub

Professor
City, University of London

Prof. Ayoub holds the Royal Academy of Engineering Pell Frischmann Chair of Nuclear Infrastructure at City, University of London, UK. He obtained his MSc and Ph.D. in Civil Engineering from the University of California-Berkeley and was a Post-Doctoral fellow at Stanford University. He is a Fellow of the American Concrete Institute; a past chair of Joint ACI-ASCE Committee 447, Finite Element Analysis of Reinforced Concrete Structures, and the ASCE committee on Emerging Computing Technologies; and a member of ACI committee 349, Concrete Nuclear Structures; committee 440, Fiber Reinforced Polymer Reinforcement, and the ASCE committee on Analysis and Computation. He currently serves as associate editor for the Journal of Structural Engineering, ASCE. His current research is in the field of design and analysis of nuclear infrastructure systems, nonlinear finite element analysis, constitutive modeling of materials through experimental and analytical techniques, earthquake engineering, and design of Fiber Reinforced Polymer composite systems. He was previously on the faculty at the University of Houston and the University of Missouri-Rolla, USA.

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Sinthujan Arulanantham

City, University of London

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Ertugrul Demirol

Section Engineer
Skanska

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