Significance of SSI and nonuniform near-fault ground motions in bridge response I: Effect on response with conventional expansion joint

Abstract

This paper studies the influence of spatially varying near-source ground motions and soil-structure interaction (SSI) on the relative response of two bridge frames. The spatial ground motions are simulated according to a near-fault ground motion model with different wave apparent velocity and a coherency loss function. Numerical calculations of bridge structure responses including pounding and SSI effect to a number of simulated spatially varying ground motions are carried out. The study reveals that the assumption of uniform ground excitation and fixed base in the analysis and design might not provide a realistic estimation of the pounding responses of bridge frames. The consequence of adjusting bridge fundamental frequency ratio towards unity to minimize relative response and consequently girder pounding potential as recommended by current design regulations is also evaluated.

State-of-the-Art Review on Seismic Induced Pounding Response of Bridge Structures

“…Pounding is an extremely complex phenomenon involving damage due to plastic deformation, local cracking, and fracturing due to impact, and friction when adjacent components are in contact with each other. To simplify the analysis, many researchers model a bridge girder as a lumped mass [Saiidi et al, 1996;Jankowski et al, 1998;Malhotra, 1998;DesRoches and Fenves, 2000;Ruangrassamee and Kawashima, 2001;DesRoches and Muthukumar, 2002;Jankowski, 2006a;Chouw and Hao, 2005, 2008a, 2008bGuo et al, 2009] or beam-column elements [Jankowski et al, 2000;Kawashima and Shoji, 2000;Ruangrassamee and Kawashima, 2003;Chouw et al, 2006;Ruiz Julian et al, 2007;Abdel Raheem, 2009;Mitoulis and Tegos, 2010] as shown in Figs. 2(a) and 2(b), respectively.…”

Effect of Higher Modes on Structural Response With Nonlinear Soil-Foundation-Structure Interaction

“…Figure 2 shows the macro element model. The elastic stiffness of the 3DOF footing system can be calculated using the formulation described in Chouw and Hao [14]. …”

“…This equation was incorporated in a macro element model so that the response of structure with nonlinear SFSI can be calculated [13]. Chouw and Hao [14] also numerically studied and showed that SFSI can affect the pounding force between adjacent bridge structures.…”

Modelling of shear keys in bridge structures under seismic loads

“…[18,19]) revealed that soil-structure interaction (SSI) can further alter the bridge responses under earthquake loadings. Not to further complicate the problem, SSI is, however, not considered in the present study since the primary aim of this study is to investigate the influence of shear keys on the seismic induced pounding responses of bridge structures.…”