火电厂主厂房型钢混凝土变柱边节点抗震性能及参数影响研究

Study on seismic performance and influencing parameters of SRC exterior joints with the variable column in main building for thermal power plants

型钢混凝土柱-型钢混凝土梁变柱异型边节点与型钢混凝土柱-钢筋混凝土梁变柱异型边节点是火电厂型钢混凝土混合结构主厂房中存在的两种典型节点类型。通过2个1/5缩尺比试件的伪静力试验及非线性有限元分析研究该类节点的破坏模式与抗震性能。研究结果表明:该类异型节点属于"强梁弱柱型"节点,且"弱柱"特性主要体现在下柱;两类节点的破坏过程均可以分为初裂、通裂、极限以及破坏4个阶段,但破坏模式不同;型钢混凝土柱-型钢混凝土梁节点发生核心区剪切破坏,而型钢混凝土柱-钢筋混凝土梁节点发生柱端塑性铰破坏;受强梁弱柱不利特性的影响,两者的滞回性能、承载能力相差不大,但型钢混凝土柱-型钢混凝土梁节点的延性性能优于型钢混凝土柱-钢筋混凝土梁节点;随着含钢率的提高,两类节点的破坏模式均向梁端破坏发展,且承载力在含钢率提高到一定值时,增大效果不明显;轴压比的增大不能提高该类异型节点的承载力,且导致延性急剧下降;随着混凝土强度等级的提高,节点承载力有一定程度的提高。

SRC column-SRC beam variable column abnormal exterior joint and SRC column-RC beam variable col- umn abnormal exterior joint are two kinds of typical joints in SRC hybrid structure for main building in the thermal power plants. Two specimens in 1/5 scale of the prototype model were tested under low-cyclic reversed loading and nonlinear finite element analysis were made in order to study the failure mode and seismic behavior of these two kinds of joints. The results show that： these two kinds of joints belong to ＂strong column-weak beam＂ joints, and the weak beam characteristics appear in the lower prop ; the failure process of the two types joints both can be divid- ed into four stages： the initial cracking, the full cracking, the ultimate and the failure stage, but the failure mode are different; for SRC column-SRC beam joint the shear damage is caused in core area, while for SRC column-RC beam joint the plastic hinges failure results at column ends; the hysteretic performance and bearing capacity are similar for the two kinds of joints because of the adverse strong column-weak beam characteristics; the failure mode of the two kinds of joints both changes to the beam failure with the increases of steel ratio, but when the steel ratio increase to a certain value, the effect of increase of the bearing capacity is not obvious; the bearing capacity of these two kinds of abnormal joints can＇ t be enhanced with the increase of the axial compression ratio, and the duc- tility performance declines sharply; the bearing capacity could increase to some extent by enhancing the concrete strength grade.