Abstract
The appropriate modeling of the soil-pile interaction (SPI) is critical to get the reasonable dynamic responses of bridge structure under impact loading. Of various SPI modeling approaches, utilizing p-y and t-z curves is a common method to represent the nonlinear lateral resistance and skin friction of pile-surrounding soil. This paper accomplished SPI modeling for the bridge pylon impact analysis with compression-only nonlinear springs and linear dashpots. The kinematic interaction and pile group effect were incorporated into the SPI. A variety of pylon impact analyses were conducted under energy-variation impact loads. The structure dynamic responses were compared and discussed considering the influences of pile group effect, soil damping, and axial t-z spring. An approximate approach was proposed to derive the linearized stiffness of soil for the purpose of engineering calculation. It was concluded from the extensive simulations that the impact load generated from higher initial energy induced more significant structural responses and larger soil inelastic deformation than smaller initial energy. The piles in the leading row possessed larger bending moments, whereas they exhibited smaller pile deformation than the responses of trailing row piles. Soil damping applied in SPI played positive roles on the reduction of structural responses. Replacing the t-z spring by fixing the degree-of-freedom (DOF) in the vertical direction was capable to yield satisfactory results of structural responses. The proposed linear soil stiffness was demonstrated to be applicable in the SPI modeling of structure impact analysis.
Highlights
Catastrophic accidents from the vessel-bridge collisions have raised concerns about the bridge safety under impact loading
Design methods and protective measures of bridge structures under vessel impact action get a lot of attention from engineers and researchers in recent years [1,2,3]. e static equivalent vessel impact forces were recommended in the design codes and specifications of many countries and communities [4,5,6,7]
Ere are several alternative methods to accomplish soil-pile interaction (SPI) in the bridge foundation modeling for structure dynamic analysis. e soil continuum assumption based on elastic mechanics is often employed to investigate the soil resistance to piles while sometimes it is difficult to consider the nonlinear soil properties in the analysis process [14, 15]
Summary
Catastrophic accidents from the vessel-bridge collisions have raised concerns about the bridge safety under impact loading. In the structure dynamic analysis under vessel impact load, the impact responses of the whole bridge structure, especially for the substructure, were strongly influenced by soil-pile interaction (SPI) [11, 12]. E SPI modeling approach based on Winkler foundation theory can be classified into two categories according to the features of soil stiffness. Since the constant stiffness assumption ignored the soil inelastic deformation behavior and may not be applicable under dramatic lateral loading such as earthquake and vessel impact, the p-y curve for soil lateral resistance and t-z curve for the soil-pile skin friction are more appropriate in the SPI simulation in this study [19]. The soil-pile interaction (SPI) was considered in the pile group foundation modeling of cablestayed bridge pylon. An equivalent linear soil stiffness approximation method is proposed and validated for the purpose of engineering application
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