不同锚栓布置的外露式柱脚弱轴方向力学性能研究

Analysis on mechanical properties of exposed column-base plate weak-axis connections with different anchor bolt layouts

为了研究弱轴方向不同锚固构造及锚栓布置的外露式柱脚受力性能,以锚栓直径、锚栓位置及底板厚度为参数,设计了7个足尺试件并进行水平低周往复加载试验,对不同外露式柱脚试件典型破坏模式、抗弯刚度、延性和耗能能力等进行研究。研究结果表明:外露式柱脚节点属于半刚性连接,具有良好的延性和耗能能力,设计时应对螺栓直径、底板厚度及柱脚焊缝高度进行匹配,避免脆性破坏;相较于内部布置锚栓方案,外部布置锚栓能有效提高柱脚的受弯承载能力,但延性会降低;增大锚栓直径能有效提高锚栓内部布置节点的受弯承载能力。基于有限元模型分析不同试件典型破坏部位的应力变化,并进行参数化分析,研究不同参数对外露式柱脚抗弯性能的影响。分析结果显示:锚栓外部布置和锚栓内部布置的柱脚节点均对轴压比、锚栓直径较为敏感,其受弯承载力变化幅度均在20%以上;相较于锚栓外部布置的柱脚节点,采用锚栓内部布置的节点对强轴及弱轴锚栓间距、底部钢板厚度更敏感,其受弯承载力变化幅度大于采用锚栓外部布置方式的。

To investigate the mechanical properties of exposed column-base plate weak-axis connections with different anchor bolt layouts,taking anchor bolt diameter,anchor bolt position and base plate thickness as parameters,seven full-scale exposed column-base plates were designed and tested under low-cycle lateral reversed cyclic loading.The typical failure modes of specimens were defined,as well as the flexural rigidity,ductility,and energy dissipation capacity of specimens were investigated.The test results show that the exposed column-base plate with anchor bolts can be considered as semi-rigid connections,and it has favorable ductility and energy dissipation capacity.Furthermore,the bolt diameter,the thickness of base plate and the height of the stud welding should be designed accordingly to prevent brittle failure.Compared with the internal layout of the anchor bolt,the external layout can increase the flexural bearing capacity of the exposed column-base plate connections,but the ductility will be reduced.In addition if the diameter of the anchor bolt are increased,the flexural bearing capacity of the exposed column-base plate connections with anchor bolt internal layout will be improved.The finite element model was used to analyze the stress in the typical failure parts of different specimens as well as the parametric analysis was carried out to investigate the influence of different parameters on the flexural behavior of exposed column-base plate connections.The simulation result shows that the column-base plate connections with different anchor bolt layouts are more sensitive to the axial compression ratio and anchor bolt diameter,and its flexural bearing capacity varies by more than 20%.Compared with the external ones,the internal layout is more sensitive to the three types of parameters:the anchor bolt distance in the strong axis,the anchor bolt distance in the weak axis,and the thickness of the base plate.The bearing capacity of internal layout varies more than the external layout ones.