采用预应力筋进行RC桥墩地震损伤控制的试验研究

Experimental research on the seismic damage control techniques for RC bridge piers by using prestressing tendons

为评价采用预应力筋进行钢筋混凝土桥墩地震损伤控制的有效性,设计6个竖向配置无粘结预应力筋和1个无预应力筋的钢筋混凝土桥墩试件,并分别进行了固定轴力下的拟静力加载试验。详细对比各试件的抗震性能并重点关注试件混凝土开裂和残余位移等地震损伤情况。结果表明,在桥墩试件中配置竖向预应力筋可有效减少其裂缝宽度和残余位移,提高试件的承载力和抗弯刚度,但在一定程度上降低了试件的耗能能力;确保预应力筋不拉断或松弛是桥墩地震损伤控制设计的关键;增加预应力筋初始应力,可减少桥墩的裂缝宽度,减少试件的延性和耗能能力,但对试件的残余位移和刚度退化影响不明显;改变预应力筋的位置对桥墩裂缝宽度、残余位移、延性及耗能能力、刚度退化等均未产生明显影响。

The objective of this research is to evaluate the effectiveness of the proposed technique to reduce the seismic damages to Reinforced Concrete （RC） bridge piers by using prestressing tendons. Six RC bridge piers with vertical unbonded prestressing tendons and one without tendon were designed and tested under constant axial load and reversed cyclic lateral loads. The seismic behavior of the piers were presented and compared with each other, with special attention to the seismic damages to the piers including concrete crack width and residual displacement. It is found that employing prestressing tendons in the bridge piers could result in obvious reductions of concrete crack width and residual displacement, and enhanced strength and lateral stiffness of the piers, but the energy dissipation capacity of the piers would be decreased. Avoiding tendon rupture or relaxation are the key measures for the seismic damage control design of the piers. Increasing the initial stress of the tendons would result in reduction of the concrete crack width, ductility and energy dissipation capacity of the piers, but has little influence on the residual displacement and stiffness degradation of the piers. And the seismic behavior of the piers, including the concrete crack width, residual displacement, ductility and energy dissipation capacity and stiffness degradation, would not be affected by the location of the prestressing tendons.