土体约束对桩柱式桥墩塑性铰长度的影响

Confinement Effect of Soil on Plastic Hinge Length in Extended Pileshafts

摘要:

采用经过试验验证的建模方法，建立了常规桩柱式简支梁桥的单墩数值计算模型，系统分析了土体约束作用对桩柱式桥墩整体延性性能、不同延性水平下桩身的曲率分布规律以及等效塑性铰长度的影响.结果表明：土体约束作用会显著增大桩柱式桥墩的截面破坏曲率，提高桥墩的水平承载力和位移延性系数，并显著减小桩身塑性区域长度和等效塑性铰长度，同时，桩身等效塑性铰长度还会随着位移延性系数的增大而显著减小.

Abstract:

Based on the calibrated numerical modeling method, a finite element (FE) model of the extended pileshaft used in a simply supported bridge was developed. Then some FE models of extended pileshafts embedded in sands varying different relative densities were established to study the confinement effect of soil on ① the displacement ductile capacity; ② the curvature distribution along the shafts and ③ the equivalent plastic hinge length of piles. The study indicates that confinement effect of soil can enhance the maximum sectional curvature of extended pileshafts at failure significantly, increase both the lateral strength of piles and the displacement ductility factor, and lead to noticeable decrease of the plastic region length and the equivalent plastic hinge length of piles. The equivalent plastic hinge length of piles has a remarkable drop with the increase of the displacement ductility factor.