混合结构PBL剪力键的荷载-滑移特征曲线研究
STUDY ON LOAD-SLIP CHARACTERISTIC CURVE OF PERFOBOND SHEAR CONNECTORS IN HYBRID STRUCTURES
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摘要: 剪力键的荷载-滑移特征是混合结构简化有限元分析的基础。为研究混合结构PBL剪力键(Perfobond strip connectors)群的剪力传递,基于三批24组较大规模的PBL剪力键静载试验,借助于分布式光纤传感测试技术,深入分析了PBL剪力键的受力机理及影响其荷载-滑移的重要因素,提出了PBL剪力键极限承载力的计算公式;根据总体标准差的估算原理及回归分析,归纳出PBL剪力键弹性极限及承载能力极限状态下的荷载-滑移特征,得到了剪力键加载过程的荷载-滑移全曲线表达式。试验研究表明:设置穿孔钢筋的混合结构PBL剪力键具有较高的极限承载力和良好的延性性能,穿孔钢筋对PBL剪力键的荷载-滑移特征影响显著,开孔钢板与外围混凝土间的剪力-摩擦效应是PBL剪力键承载力构成的重要部分;PBL剪力键的弹性极限荷载对应于0.35倍的承载能力极限荷载,其屈服荷载约为极限承载力的0.695倍;荷载-滑移全曲线中弹性段可由直线表征,非线性段曲线服从对数分布。Abstract: The load-slip characteristics of shear connectors are the basis of simplified finite element analysis for hybrid structures. In order to investigate the shear transfer of perfobond strip connector (PBL) groups in hybrid structures, 24 groups of large-scale static PBL tests in three batches have been carried out with the assistance of distributed optic fiber sensors measurement techniques, based on which the mechanical mechanism and the important influencing factors for the load-slip relationship of PBL connectors are analyzed, and the corresponding formula on the ultimate bearing capacity of PBL connectors is proposed. According to the estimation method of population standard deviation and regression analysis, the load-slip characteristics of PBL connectors under elastic limit and ultimate limit states are generalized, while an expression of load-slip complete curve on PBL connectors under static loading is proposed. The results show that PBL connectors with perforated rebars in hybrid structures have higher ultimate bearing capacity and excellent ductility performance, while the perforated rebars have a significant effect on the load-slip characteristics of PBL connectors, and the shear-friction effect between perforated plates and surrounding concrete is an important component for the bearing capacity of PBL connectors. The elastic limit load and the yield limit load of PBL connectors is about 0.35 times and 0.695 times the ultimate limit load, respectively. The load-slip complete curve of PBL connectors consists of a straight line section in the elastic phase and a curve section following a logarithmic distribution in the nonlinear phase.