腹板摩擦式自定心预应力混凝土框架梁柱节点的理论分析

为减少钢筋混凝土框架在地震作用下的残余变形和损伤,提出一种新型的腹板摩擦式自定心预应力混凝土梁柱节点。其中,预制的钢筋混凝土梁柱通过无黏结预应力钢绞线进行拼接。当梁端弯矩超过节点的临界张开弯矩,梁柱接触面张开;震后,接触面在预应力的作用下重新闭合。梁柱的接触部位分别预埋钢套和钢板,以避免梁柱相对转动时混凝土的压碎。在梁端钢套的腹板处设置摩擦耗能件,从而可以在梁柱相对转动时耗散地震能。介绍腹板摩擦式自定心预应力混凝土梁柱节点的基本构造和受力特点,对梁端轴力、剪力、弯矩以及梁柱接触面张开后转动刚度的表达式进行推导,建立起梁端弯矩-相对转角关系的理论分析模型,并得到节点耗能系数和等效黏滞阻尼比的计算公式。理论分析结果与试验值吻合较好,为腹板摩擦式自定心预应力混凝土框架的设计提供了依据和参考。

Theoretical analysis of beam-column connections of self-centering prestressed concrete frame with web friction device

To reduce the residual deformation and damage of beam-column connections of reinforced concrete frames,a novel self-centering prestressed concrete(SCPC) beam-column connection with web friction devices is developed.The precast concrete beams and columns are assembled in the field via unbonded prestressed tendons(PTs).When moments at beam ends exceed the imminent gap opening moment,gap opening occurs at beam-column interfaces;after the earthquake,the interfaces close again under the PT forces.Steel jackets and steel plates at the beam ends and columns,respectively,are fabricated in the shop,so that concrete crushing is avoided as the beam rotates against the column.In particular,friction devices are used at the beam webs for energy dissipation.This paper presents the configuration and mechanical behaviors of the SCPC connections.Formulas are given with regards to axial forces,shear forces,moments at beam ends and the bending stiffness after gap-opening occurs.A theoretical model for the moment-relative rotation relationship at beam ends is proposed,and equations of the relative energy dissipation ratio and the equivalent viscous damping ratio are derived.Good agreement is observed between analytical results and test results.The proposed analytical models can be used in the design of SCPC frames with web friction devices.