端板连接高强度螺栓群中和轴位置研究

为研究端板连接中高强度螺栓群的中和轴位置变化,对门式刚架外伸式端板连接进行了试验研究与理论计算.试验采用4种梁截面尺寸,选择端板厚度和端板加劲肋作为研究参数,对12个试件进行了单调加载试验,通过在螺栓杆无螺纹区开槽粘贴应变片测量了端板螺栓力的变化情况.理论计算系建立带弹性支座的连续梁模型模拟端板连接,将模型计算结果与试验结果比较分析,结果表明：加载过程中,螺栓群中和轴逐渐从其形心轴向受压区移动,但不超过受压翼缘内侧螺栓中心线;极限状态下,受拉翼缘和端板可简化为等效T型件.根据理论模型,进行了简单的参数分析,研究了撬力、端板厚度和螺栓排列等对连接性能的影响.最后结合试验结果及理论计算,对现有计算方法进行了评价.

Research on neutral axis location of high-strength bolts of end-plate connections

In order to study the neutral axis location of high-strength bolts in extended end-plate connections,a series of joint tests from portal frame and theoretical analysis were executed.There were altogether twelve connection specimens,which including four kinds of beam sections,were tested under monotone loading.Bolt force was measured by the strain gauges affixed to notched bolt shanks.Such parameters as end-plate thickness and end-plate stiffener were introduced.Continuous beam models with spring supports were set up to model end-plate connections.By comparing the results from tests with those from model analysis,the following conclusions can be drawn: during loading process,the neutral axis moves from the centroid axis to compression zone,not exceeding the center line of bolts inside the compression flange;ultimately,the tension flange and end-plate can be simplified as T-stub on the assumption that the axial forces of bolts in tension zone are equal to each other.Simple parameter analysis by theoretical model was done to study the influence of prying force,end-plate thickness and bolt arrangement on connection behavior.Finally,available calculation methods for bolts in end-plate connections were evaluated by the analysis of test data and theoretical calculation.