Parametric study on the effect of structural and geotechnical properties on the seismic performance of integral bridges

Abstract

In this paper practical techniques are introduced for detailed modeling of soilpile and soil-abutment interaction effects for integral bridges (IBs). Furthermore, a parametric study is conducted to determine appropriate structural configurations and geotechnical properties to enhance the seismic performance of IBs. For this purpose, numerous nonlinear structural models of a two-span IB including dynamic soil-bridge interaction effects are built. Nonlinear time history analyses (NTHA) of the IB models are then conducted using a set of ground motions with various intensities. In the analyses, the effect of various structural and geotechnical properties such as foundation soil stiffness, backfill compaction level, pile size and orientation, abutment height and thickness are considered. The results of NTHA are then used to assess the effects of these properties on the seismic performance of IBs in terms of member forces and deformations. It is found that while the proposed modeling techniques for IBs are easy to implement in commercially available structural analysis programs, they are also computationally efficient. However, the proposed structural model may not be used to study the soil deformations along the length of the embankment. For the IB and modeling approach under consideration, the bridge seismic response is found to be insensitive to the length of the embankment and damping of the embankment soil. Furthermore, IBs built with shorter and thinner abutments as well as large steel H-piles oriented to bend about their strong axis exhibit better seismic performance.

Integral abutment bridges: Investigation of seismic soil‐structure interaction effects by shaking table testing

“…While in the case without CI the peak acceleration atop the bridge (i.e., accelerometer 20) was 0.46 g, it dropped to 0.42 g and 0.43 g with one layer and two layers of PU foam, respectively. This trend is confirmed by observations from parametric studies on integral abutments 86 . When the intensity is lower, as in test S1 (Figure 8 left), and in the absence of EPS, the instruments located at 0.4 m depth recorded accelerations as high as those on the ground surface.…”

“…As can be seen from Figure 7, EPS1‐CP has the lowest natural frequency (about 9.5 Hz) in the third white noise test which was conducted immediately prior to S6 excitation. Displacements are also affected by the different natural frequencies of the test configurations 86 . The above observations can be used in a comparative way to estimate the potential benefits in terms of displacement decrease for IABs when such mitigation measures are employed.…”