考虑桩-土相互作用的不等高墩桥地震响应分析

Seismic response analysis for unequal height pier bridges considering soil-pile interaction

基于LS-DYNA有限元软件的二次开发功能,引入p-y桩土动力相互作用模型和钢材的BONORA损伤本构模型。以某大桥四跨引桥为研究对象,建立了包括考虑土-结构相互作用的WINKLER地基梁模型、有效桩长模型、全桩长模型,以及不考虑土-结构相互作用的无桩模型等四种桩基础分析模型和上部结构弹塑性损伤分析模型;通过场地自由场求解,在桩侧节点上施加相应位置的加速度时程,对基于四种桩基础模型的该大桥进行了自振特性以及在小震、中震和大震下的位移、加速度、内力、损伤分析,并探讨了WINKLER地基梁模型不同深度下桩-土p-y模型的应力-应变关系和桩身变形特性。结果表明,桩基础数值分析模型对结构整体响应影响显著,不等高墩桥顺桥向与横桥向响应差距大,所开发的p-y模型可用于桥梁结构精细化数值分析。

Based on the secondary development of LS-DYNA software,the nonlinear dynamic p -y model and Bonora damage constitutive model of steel were introduced into the soft ware.Taking a four-span approach bridge as study object,the plastic damage model of the upper structure and four simplified bridge pile-foundation models including Winkler foundation beam model,effective length pile model,whole length pile model considering soil-structure interaction and no pile model were built.The earthquake motions were exerted on positions with different depths of pile profile.The natural vibration characteristics,displacement,acceleration,internal force and damage of the bridge with 4 pile-foundation models under different levels of earthquake motions were analyzed.The stress-strain relations of p -y model and pile deflection of Winkler-foundation beam model with different depths were explored.The results indicated that the four pile-foundation models have obvious effects on the entire bridge structure;the seismic responses of the unequal height pier bridge in longitudinal and transverse directions are quite different;the p -y model developed can be used to simulate seismic responses of bridge structures precisely.