预制混凝土管组合柱-钢梁节点核心区受力性能分析

Mechanical Behavior Analysis of Panel Zone in Concrete-Filled Precast Concrete Tube Column-to-Steel Beam Connections

建立了预制混凝土管组合柱-钢梁节点在往复荷载作用下受力性能分析的精细化有限元计算模型.根据已完成的6个“弱节点”试验结果,对比分析试验与模拟试件的破坏模式、梁端荷载-位移骨架曲线和特征点荷载,验证了有限元模型的准确性.研究了预制混凝土管组合柱-钢梁节点核心区受力全过程工作机理,并对各关键组件的应力、应变发展规律及其相互作用进行分析.通过有限元模型参数化分析,研究了轴压比、钢套箍厚度、钢套箍延伸高度、预制混凝土管强度及芯部混凝土强度等因素对节点承载力和变形能力的影响.分析结果表明:在梁端往复荷载作用下,钢套箍屈服“拉力带”和核心区混凝土“斜压杆”机构共同抵抗节点剪力;峰值荷载时钢套箍以刚体变形为主,极限荷载时钢套箍腹板大面积屈服;芯部混凝土、钢套箍与预制混凝土管之间界面接触相互作用力分布不均匀;轴压比、钢套箍厚度、预制混凝土管和芯部混凝土强度对节点承载力及变形能力影响较大,增大钢套箍厚度可以显著提高节点承载力及变形能力;钢套箍延伸高度增加可以提高节点变形能力,但对承载力影响不明显.建立了预制混凝土管组合柱-钢梁节点受剪计算模型,理论值与模拟值吻合较好且偏于安全.

The mechanical behavior of concrete-filled precast concrete tube(CFPCT)columns-to-steel beam connections under cyclic loading was studied using precise finite element models.Based on the experimental results of six“weak-joint”specimens,the failure modes,beam end skeleton curves,and characteristic loads were compared,validating the accuracy of the finite element models.The full-range behavior of the panel zone was investigated,and the development rules of stress and strain on key components as well as their interaction relationships were analyzed.The influence of axial compression ratio,steel jacket thickness,extended steel jacket height,precast concrete strength,and filled concrete strength on joint strength and deformation capacity were studied using parametric analysis of the finite element model.The results show that the tension band provided by the yielded steel jacket and diagonal compression strut provided by the panel zone concrete worked together to resist shear loading.The deformation of the steel jacket is mostly rigid when the peak load is reached.However,when the ultimate load is reached,the steel jacket yields over a large area.Hence,the distribution of interactions between the filled and precast concrete tubes,steel jacket,and the precast concrete tube is heterogeneous.The axial compression ratio,steel jacket thickness,precast concrete strength,and filled concrete strength have a significant impact on joint strength and deformation capacity.The load-bearing and deformation capacity of joints improve with an increase in steel jacket thickness.The influence of extended steel jacket height is not obvious,and the deformation ability of the joints increases as height increases.The shear model of the CFPCT column-to-steel beam joint is proposed in this study.The results show that the theoretical results agree well with the simulated ones and are conservative.