改进螺旋线型组合销剪力连接件承载力试验研究

为研究新型剪力连接件——改进螺旋线型(MCL)组合销剪力连接件的受力性能,考虑粘结摩擦力、椭圆开孔等因素,设计3组MCL组合销剪力连接件试件与3组开孔板(PBL)剪力连接件试件共同进行推出试验,对比分析2类剪力连接件的破环形态、极限承载力、抗剪刚度、延性及结构应变,并根据试验结果得到MCL组合销剪力连接件承载力计算公式。结果表明:2类剪力连接件试件破坏形态均为混凝土剪切破坏,且为延性破坏;MCL组合销剪力连接件的极限承载力高于PBL剪力连接件,在MCL组合销剪力连接件上开椭圆孔会明显提高其极限承载力,但会降低其刚度;MCL组合销剪力连接件的抗剪刚度和延性均优于PBL剪力连接件;钢销下部应变变化幅度较大,为MCL组合销剪力连接件应力集中区域。文中提出的MCL组合销剪力连接件承载力公式计算方法考虑了组合销、粘结摩擦力和椭圆孔承载力,工程适用性较好。

Experimental Study of Load Bearing Performance of Modified Clothoid Shape Composite Dowels

To study the mechanical behavior of a new type of shear connector,namely the modified clothoid shape(MCL)composite dowels,three groups of specimens with MCL composite dowels and three groups of specimens with PBL shear connectors were prepared for push-out test,considering the adhesive friction forces and effect of elliptic holes.The failure mode,ultimate load bearing capacity,anti-shearing stiffness,ductility and structural strain of the two types of shear connectors were compared and analyzed.Based on the results of the test,the calculation formula for the MCL composite dowels was figured out.The results show that the failure modes of the two types of shear connectors all reveal shear failures of concrete that all belong to the ductile failure.The ultimate load bearing capacity of the MCL composite dowel exceeds that of the PBL shear connector,and elliptic holes can remarkably improve the load bearing capacity of the MCL composite dowel,but compromises the stiffness.The anti-shear stiffness and ductility of MCL composite dowel are superior to those of the PBL shear connector.The fluctuation of strain in the lower part of the steel dowel is significant,where is considered the stress-concentrated area of MCL composite dowel connection.The calculation formula for the load bearing capacity of MCL composite dowel proposed in this paper takes account of the load bearing capacity of composite dowel,adhesive friction force and effect of elliptic holes,which has good engineering feasibility.