[论文解读] Numerical modeling of rocking of shallow foundations subjected to slow cyclic loading with consideration of soil-structure interaction

S. Mohsen Haeri, Aria Fathi|arXiv (Cornell University)|Aug 13, 2018

Seismic Performance and Analysis参考文献 9被引用 7

一句话总结

本研究采用基于ABAQUS的有限元建模方法，结合自定义FORTRAN子程序，模拟了在慢速循环荷载下浅基础的抗弯行为，同时考虑了线性和非线性土-结构相互作用（SSI）。结果表明，基础抗弯导致刚度退化并增加能量耗散，尤其在高层结构中表现明显；而线弹性-理想塑性土模型预测的上拔量大于非线性弹塑性模型，尤其在低层建筑中更为显著。

ABSTRACT

Strong Vibration of buildings during seismic or wind loading may result in an uplift or partial separation of the foundation from the underneath soil. To date, various researches have indicated that Soil-Structure Interaction (SSI) has many favorable features including a probable increase in natural period of the soil-structure system and also a decrease in shear base demand in structures. Furthermore, Rocking is one of the most important factors in describing the rotational behavior of a structure built on a shallow foundation especially on a soft soil which can affect the dynamic behavior of the structure noticeably. To study the effects of rocking of shallow foundations subjected to slow cyclic loading with consideration of soil-structure interaction, a Finite Element Method (FEM) using ABAQUS software has been deployed to simulate the rocking motion of shallow foundations. For a more efficient simulation of the soil, both linear and non-linear elasto-plastic behavior of the soil has been taken into account in the analysis using the sub-routine coded in FORTRAN. The results notably show that allowing the foundation to rock may result in stiffness degradation of the soil-structure system and an increase in energy dissipation of soil-structure, especially in high rise structures. Additionally, results describe that deploying the linear elastic-perfect plastic approach may result in higher uplift of the foundation in comparison to that using a non-linear elasto-plastic approach, particularly in structures with lower heights.

研究动机与目标

• 研究在慢速循环荷载下基础抗弯对土-结构相互作用（SSI）的影响。
• 评估不同土本构模型（线性与非线性弹塑性）对抗弯响应和上拔行为的影响。
• 量化软土地基上浅基础因抗弯引起的体系刚度变化与能量耗散。
• 比较线弹性-理想塑性与非线性弹塑性土模型在基础上拔和动力响应预测方面的差异。

提出的方法

• 在ABAQUS中采用有限元法（FEM）对浅基础在慢速循环荷载下的抗弯行为进行动力模拟。
• 使用自定义FORTRAN子程序在数值框架中模拟线性和非线性弹塑性土体行为。
• 显式模拟土-结构相互作用（SSI），以捕捉基础与下卧土体之间的动力耦合效应。
• 对比两种土模型：线弹性-理想塑性与非线性弹塑性，评估其对上拔和刚度的影响。
• 施加慢速循环荷载以模拟地震或风致动力激励对浅基础的影响。
• 分析重点包括基础上拔量、基底剪力减小量以及土-结构体系中的能量耗散。

实验结果

研究问题

• RQ1 在慢速循环荷载下，基础抗弯如何影响土-结构体系的刚度和能量耗散特性？
• RQ2 线弹性-理想塑性与非线性弹塑性土模型在预测上拔响应方面有何差异？
• RQ3 结构高度如何影响抗弯幅度及其对SSI的动力效应？
• RQ4 抗弯在多大程度上导致体系自振周期延长和基底剪力减小？
• RQ5 土本构模型的选择如何影响浅基础抗弯响应预测的准确性？

主要发现

• 基础抗弯导致土-结构体系显著刚度退化，尤其在高层建筑中更为明显。
• 抗弯增加了土-结构体系的能量耗散，且在更高层结构中效应更为显著。
• 线弹性-理想塑性土模型预测的上拔量高于非线性弹塑性模型，尤其在低层建筑中。
• 非线性弹塑性建模能更真实地预测循环荷载下的上拔和转动响应。
• 土-结构相互作用降低了基底剪力需求并延长了体系基本周期，其中抗弯在该行为中起关键作用。
• 在低层建筑中，动力响应对土模型非线性的敏感度更高，尽管上拔不明显，但更依赖于建模假设。