超高性能混凝土(UHPC)包覆钢管混凝土柱单边螺栓连接节点受力机理和设计方法

Stress Mechanism and Design Method of UHPC-Encased CFST Column-to-Beam One-Side Bolted Joints

单边螺栓连接技术有效解决了闭口截面柱难以应用全螺栓连接的难题,目前已有学者将单边螺栓连接技术用于钢管混凝土叠合柱-钢梁连接节点中,由于外部混凝土强度低,此类装配式连接节点表现出明显的柱壁破坏。提出采用UHPC包覆钢管混凝土叠合柱代替普通钢管混凝土叠合柱以避免采用单边螺栓连接节点时的柱壁失效,同时外部采用UHPC包覆可有效减少混凝土内的钢筋,便于单边螺栓的安装。基于ABAQUS有限元模型建立了UHPC包覆钢管混凝土叠合柱-钢梁连接节点的有限元模型,考虑了复杂材料本构以及节点域多接触的收敛问题,通过试验结果验证了模型的准确性,系统揭示了外部UHPC对内部钢管的约束作用,证明了此类节点可有效避免柱壁破坏。对典型的UHPC外包钢管混凝土叠合柱-钢梁装配式节点进行了参数分析。随后基于组件法,建立了节点弯矩承载力的设计方法,通过与有限元结果对比揭示了设计方法的准确性。研究结果表明,采用UHPC包覆钢管混凝土叠合柱-钢梁连接节点适合采用单边螺栓连接,并为此列连接节点提供了合理的设计方法。

One-side bolted connecting technique Blind bolting technology ensures the access of inside into the closed-section column,which has been used in the assembled joints between concrete encased CFST(CECFST)columns and steel beams.However,the bulge of steel tube and outer concrete were detected for one-side bolted normal CECFST column joints owing to the limited strength of outer concrete.Therefore,this paper adopts UHPC was adopted as outer concrete to replace the traditional outer concrete in CECFST columns,which aimed to avoid the steel tube from being failure effectively and to omit reinforcements in outer concrete for convenient installation in one-side bolted joints.A finite element model was established by ABAQUS considering the constitutive relations of complex materials and the convergence of multi-contact in joint region.The accuracy of the model was verified through test results,systematically revealing the restraining effect of outer concrete on interral steel tubes,and complex interactions and material properties.Failure mechanism and confinement between UHPC and steel tube of the joints were discussed,indicating that the UHPC could effectively restrict the bulge of steel tube.A parametric analysis were conducted on typical UHPC encased CFST composite columns one-side bolted to steel beam joints.Finally,the analytical models on the moment resistance were developed based on the component method.considering the dispersal effect of outer UHPC.The comparison results declared that the proposed analytical method provided a reasonable prediction of the moment resistance.The research results in the paper validated that replacing normal concrete of CECFST by UHPC could avoid column failure when using one-side bolted joints and gave a proper design method for UHPC-encased CFST composite column one-side bolted to steel beam joints.