薄壁空心墩有效刚度试验研究

Study on Effective Stiffness of Thin-walled Hollow Pier Based on Semi-static Experiment

有效刚度是基于位移的抗震设计方法的重要参数,也是建立混凝土桥墩双折线模型和分析桥墩动力特性的物理基础,为快速评估混凝土桥墩的抗震性能提供了简化方法。鉴于圆端薄壁空心墩与矩形空心墩乃至实心墩的性能差异,现有文献和规范中存在大量基于实心墩试验的有效刚度计算公式,这些公式对圆端薄壁空心墩的适用性有待深入研究。通过5个圆端型薄壁空心墩拟静力试验,观测并分析轴压比、配箍率对圆端薄壁空心墩有效刚度的影响规律。基于国内外有效刚度计算公式与试验结果的对比分析,研究表明:圆端型薄壁空心墩有效刚度随轴压比、剪跨比增大而增大,配筋率、纵筋及混凝土强度等对其有一定影响;与现有成果相比,所提公式的计算效果更好,适于估算圆端型薄壁空心墩的有效刚度。

Effective stiffness is an important parameter of the displacement-based seismic design method as well as the physical basis for establishing a concrete pier double-fold-line model,and for analyzing the dynamic properties of a pier,which provides a simplified method for quick assessment of the seismic performance of a pier concerned.The formula for calculating the effective stiffness in the existing literature and codes are mostly obtained by the solid pier test.In view of the difference in the performance of the round-end thin-walled hollow piers,the rectangular hollow piers and the solid piers,the applicability of these formulas to the round-ended thin-walled hollow piers is to be studied in depth.The influence of axial compression ratio and stirrup ratio on the effective stiffness of round-end thin-walled hollow pier was observed and analyzed by the quasi-static tests of five large-scale thin-walled hollow piers.The comparative analysis was made on the calculation formula and test results of effective stiffness at home and abroad.The results show that the effective stiffness of the round-end thin-walled hollow pier increases with the increase of the axial compression ratio and the shear span ratio.The reinforcement ratio,longitudinal reinforcement and concrete strength have some influence on the effective stiffness.Compared with the existing results,the proposed formula is better in calculation effect and can be used to estimate the effective stiffness of the round-shaped thin-walled hollow pier.