方钢管轻骨料混凝土加劲TY型节点承载力研究

Study on bearing capacity of lightweight aggregate concrete-filled steel square hollow section TY-joints with stiffening plates

对方钢管轻骨料混凝土加劲T型节点和基本型节点进行了支管轴压试验,考察了加劲板和支主管截面宽度比对节点破坏模式、承载力等受力性能的影响.试验结果显示:节点的典型破坏模式有主管弯曲、主管上翼缘凹陷、主管腹板凸曲、支主管焊缝开裂、支管侧倾、加劲板屈曲和加劲板焊缝开裂等;加劲节点的承载力取决于包含加劲板应力扩散效应和轻骨料混凝土约束效应的方主管抗压弯强度和支主管焊缝承载强度,加劲节点的极限承载力较基本型节点提高15.0%~48.3%.建立了TY型节点方主管抗压弯计算模型和支主管焊缝开裂计算模型,推导了考虑加劲板应力扩散效应和轻骨料混凝土约束效应的加劲TY型节点方主管压弯承载力计算式和支主管焊缝开裂承载力计算式,验证了加劲TY型节点承载力计算式的精度.

Static loading tests under axial compression on brace were performed on lightweight aggregate(LWA) concrete-filled high strength steel square hollow section T-joints with stiffening plates and traditional joint.The effect of stiffening plates between brace and chord and width ratio of brace section to chord section on failure mode,bearing capacity of the T-joints were studied.Tests results show that bending of chord,concave of top flange of chord,convex of webs of chord,crack of weld between chord and brace,lateral instability of brace,buckling of stiffening plates,crack of weld between stiffening plates and brace are typical failure modes of the T-joints.The bearing capacity of the T-joints with stiffening plates depends on the compressive and bending strength of chord including the stress diffusion effect of stiffening plates and the confinement provided by chord for LWA concrete and the bearing strength of welds between brace and chord.The ultimate bearing capacity of the joints with stiffening plates increase by 15.0%~48.3% compared with that of the traditional T-joint.The compressive and bending calculation model of chord and the cracking calculation model of welds between brace and chord of TY-joints with stiffening plates were established.The formulas for calculating compressive and bending strength of chord and bearing strength of welds between brace and chord of TY-joints with stiffening plates including the stress diffusion effect of stiffening plates and the confinement provided by chord for LWA concrete were derived.The accuracy of the proposed formula for calculating the bearing capacity of TY-joints with stiffening plates was verified.