弯剪受力下后锚固群锚承载力计算方法分析

DESIGN METHOD OF POST-INSTALLED ANCHORAGE GROUP SUBJECTED TO BENDING MOMENT AND SHEAR

在现有研究理论基础上,针对钢-混凝土后锚固连接钢材破坏时群锚弯剪承载力计算进行分析。采用椭圆型拉剪计算公式并假定所有锚栓均参与受剪,将群锚弯剪受力问题转化为受拉最大那排锚栓的拉剪承载力计算。进行了弯剪受力下的型钢-混凝土后锚固连接件静力和低周反复加载试验,锚固方式采用化学植筋。试验结果表明:受拉最大的钢筋首先达到屈服,且发生在整体锚固破坏前,仅钢筋周围局部混凝土在临近破坏时损坏,可以判断为钢材破坏,破坏前有明显的变形征兆,低周反复加载下后锚固连接承载力较相应的静力时低,建议抗震设计时取承载力折减系数0.8。通过对比分析,该文改进后的群锚弯剪受力方法的计算结果与试验数据吻合较好,可为工程设计提供参考。

Existing researches on the multiple-anchor steel-to-concrete connection, the strength of which is controlled by the strength of the anchor steel, are used to develop a revised method for the strength prediction of post-installed fastening connections subjected to bending moment and shear. Based on the assumption that all anchors take up shear load, the revised method considers that only the row of most stressed anchors in the tension zone are needed to meet the elliptical interaction of tension and shear capacity requirement during the design process of anchorage group under the action of shear and bending moment. The .static and dynamic behavior of the connection, in which steel members are attached to concrete by boned-in reinforcement, have been tested due to eccentric shear loadings. The experimental results show that the outermost row of tension reinforcements reach their yielding strength prior to failure of the connection and slight concrete cone failure occurs under ultimate load. The significant deformation guarantees ductile behavior of the connection. The yielding capacity of the connection under reversed cyclic loading is lower than that of static condition. Thusly, the predicted capacity in aseismic design is advised to multiply by a reduction factor of 0.8. Compared with experiment results, the revised method presents satisfactory accuracy to be used in practice.