桥梁高桩承台基础地震破坏机理试验研究

Experimental Study on Seismic Failure Mechanism of Elevated Pile-cap Foundation for Bridge Structures

摘要:

进行了平面布置2×3钢筋混凝土高桩承台基础模型试件在砂土中的往复荷载拟静力试验.基于推倒(Pushover)分析方法，对试验进行了数值分析，并揭示了试件的地震破坏机理.结果表明:试件的各桩在距桩顶1倍桩径、土面以下约3~8倍桩径范围内先后形成损伤区域；边桩最先屈服，边桩桩顶截面最先达到极限曲率，对抗震设计起控制作用；桩顶的损伤特征对于桩身自由段长度不敏感，而地面以下桩身的损伤特征对自由段长度敏感.

Abstract:

This paper focuses on the seismic failure mechanism of elevated pile-cap foundation in bridges. Pseudo-static testing were carried out on two 2×3 elevated reinforced concrete pile-cap foundation specimens in sand. Numerical pushover analysis based on Beam on Nonlinear Winkler Foundation (BNWF) model was conducted. Results indicate that side piles yielded earlier than middle piles. Each pile forms two plastic hinges at pile-top sections and under-ground pile sections with the depth of approximately 3~8 times of section width respectively, specimens suffer failure damage when the top section of the side pile attain to the theoretical ultimate curvature. The pile-top damage area is not sensitive to the above-ground height while the under-ground pile damage area is sensitive to the above-ground height.