柱头科斗栱偏心受压性能试验研究及有限元分析

Experimental study and finite element analysis on eccentric compressive performance of Dou-Gong brackets at column tops

为研究竖向偏心荷载对柱头科斗栱受力性能的影响,对3个柱头科斗栱足尺试件进行不同偏心率下的竖向加载试验,得到了斗栱的破坏形态、刚度退化和变形能力。轴心受压破坏模式主要是大斗的压溃和正心瓜栱与单翘的劈裂,偏心受压时大斗和平板枋出现明显的转动,造成斗栱的抗压刚度与承载力降低。采用ABAQUS有限元软件对3种偏心率的斗栱进行有限元分析,模拟结果与试验结果吻合较好。在此基础上,对斗栱进行了参数分析,研究了竖向荷载偏心率,木材的抗压强度、弹性模量和摩擦系数对其受力性能的影响。结果表明:竖向荷载的偏心率越大,则斗栱的转动角度越大,其承载力越低;当偏心率为0.3时,斗栱的承载力比轴心受压时降低了41.64%;进入塑性阶段后,偏心受压斗栱的刚度退化较显著;随木材顺纹抗压强度和顺纹弹性模量的增加,斗栱的竖向承载力提高;木材的摩擦系数越大,斗栱产生的竖向位移越小。

In order to study the effects of the vertical eccentric loading on the mechanical performance of Dou-Gong brackets, the vertical loading test on three full-size Dou-Gong brackets at column tops under different eccentricities was carried out, and the failure mode, stiffness degeneration and deformation capacity of Dou-Gong brackets were obtained. The failure mode of the Dou-Gong brackets under axial loading was mainly the collapse of Da-Dou and cracks of Zhengxingua-Gong and Dan-Qiao. The obvious rotation of Da-Dou and Pingban-fang was observed when the Dou-Gong brackets were subjected to eccentric loading, inducing the reduction of compressive stiffness and bearing capacity of Dou-Gong brackets. The finite element software ABAQUS was adopted to simulate and analyze three Dou-Gong brackets with different eccentricities and the calculation results were in good agreement with the test results. Based on the verified model, a parameter analysis considering the eccentricity of load as well as the compressive strength, elasticity modulus and friction coefficient of wood was performed. The results show that the rotation angle of the Dou-Gong brackets increase with the eccentricity of the vertical load, resulting in a decrease in the bearing capacity of the Dou-Gong brackets. When the eccentricity reaches 0.3, the bearing capacity of the Dou-Gong brackets is reduced by 41.64% compared to the model subjected to axial loading. The stiffness degeneration of eccentrically compressive Dou-Gong brackets is obvious during their plastic stage. The vertical bearing capacity of Dou-Gong brackets increases with the compressive strength and elastic modulus along the grain direction of the wood, but the vertical displacement of Dou-Gong brackets decreases with the friction coefficient of wood.