装配式预应力桥墩地震损伤评估及影响参数分析

Seismic Damage Assessment and Influence Parameter Analysis of Precast Segmental Prestressed Piers

为明确装配式预应力桥墩的地震损伤性能,首先根据拟静力试验结果,对比分析装配式、整体式预应力桥墩以及钢筋混凝土桥墩在水平往复荷载作用下的损伤演化情况和破坏状态,然后应用6种混凝土损伤模型对桥墩试件进行损伤评估,分析各损伤模型的可靠性和适用性,最后基于OpenSees数值模拟,对恒载轴压比、纵筋配筋率、体积配箍率、耗能钢筋配筋率以及预应力筋配筋率等影响预应力桥墩损伤性能的参数进行分析。研究结果表明:在相同墩顶偏移比下,整体式预应力桥墩较钢筋混凝土桥墩的损伤更为严重,原因是承载力增大所致;而装配式预应力桥墩比整体式预应力桥墩损伤小是由于接缝张合导致耗能能力降低与接缝处耗能钢筋设置无黏结段造成的;与其他5种损伤模型相比,王东升修正的Park-Ang损伤模型对桥墩试件的损伤评估效果最符合实际情况,且离散性较小;塑性铰区域的体积配箍率是影响桥墩损伤性能的主要因素,且桥墩的损伤随着体积配箍率的增大而减小。

To study the seismic performance and influence parameters of precast segmental prestressed(PSP) piers, the damage evolutions of the PSP piers, monolithic prestressed concrete(MPC) piers, and reinforced concrete(RC) piers under cyclic loading were first analyzed and compared based on the results of the pseudo-static tests. The damage state of the pier specimens was then assessed using six types of damage models of concrete structures. The reliability and applicability of each damage model were analyzed. Finally, the parameters that affect the damage state of prestressed concrete piers, such as axial dead load ratio, longitudinal reinforcement ratio, hoop reinforcement volumetric ratio, energy-dissipating bar ratio, and prestressing steel ratio were analyzed based on numerical simulations using OpenSees. The results demonstrate that for the same drift ratio, the MPC piers sustain more damage than the RC piers due to the increase in bearing capacity. The reasons for the PSP piers being less damaged compared to the MPC piers is that the joint opening reduces energy dissipation and the unbonded length provided for the energy-dissipating steel bars at the joints. Compared to the other five damage models, the damage assessment of pier specimens using the modified Park-Ang model by Wang Dongsheng is the most realistic one, and the evaluation results are less different. The results demonstrate that the hoop reinforcement volumetric ratio in the plastic hinge zone is the main factor that affects the damage of piers, and the damage of piers decreases with an increase in the hoop reinforcement volumetric ratio.