钢-混组合桥塔结合段承载性能模型试验研究

Experimental Study on Bearing Capacity of Joint Segment of Steel-concrete Hybrid Pylon

为了揭示钢-混组合塔结合段承载性能及传力机理,在分析前承压板式、后承压板式和插入式结合段受力的基础上,结合肇庆市阅江大桥钢-混组合桥塔结合段构造,建立了后承压板式有限元模型。根据模型计算结果,后承压板式结合段剪力钉竖向剪力从上往下呈现出逐渐增加的趋势,距离承压板越远,剪力钉承受的剪力越大,在结合段底部达到峰值,承压板传递的轴力占总轴力的比例为68%,其余轴力通过剪力钉传递,传力效果较好。并对后承压板式结合段进行了1∶4缩尺模型试验,测试了结构变形和应力分布。有限元和试验结果表明:结合段的连接件剪力分布规律取决于结合段类型以及承压板的位置,后承压板式结合段具有较高的承载能力和传力流畅性;加载至约为2倍设计荷载,模型试件仍然表现为较强线性行为;结合段钢结构应力从上至下逐渐减小,混凝土应力逐渐增加,整个加载过程中钢-混凝土最大滑移量不超过0.1 mm,传力可靠性高,具有较好的应用前景。针对承压板下部分混凝土应力水平稍高的试验结果,实际设计钢混结合段内混凝土C60采用钢纤维混凝土,改善了结构抗压能力。同时为改善钢混结合段承压板和壁板转角合围处混凝土存在应力集中现象,施工时采用试拌试验、压浆等方式保证了钢材和混凝土之间的密实度,达到了良好的使用效果。

To investigate the bearing capacity and force transmission mechanism of steel-concrete joint segment in hybrid pylon,on the basis of analyzing the stress of front bearing plate,rear bearing plate and plug-in joint segment,the finite element model concerning with back bearing plate is established based on a specified pylon joint segment of Yuejiang Bridge in Zhaoqing City.According to the calculation result of the model,the vertical shear force of the shear studs in the back bearing plate joint segment increases gradually from top to bottom,the farther away from the bearing plate,the greater the shear force borne by the shear studs,and the peak value is reached at the bottom of the joint segment.The axial force transmitted by the bearing plate accounts for 68%of the total axial force,and the other axial forces are transmitted through shear studs,which has a good force transmission effect.The 1∶4 scale model test is carried out on the back bearing plate joint segment to test the structural deformation and stress distribution.The results of FEM and test show that(1)The distribution of the shear forces of the connectors in the joint segment depends on the type of joint segment and the position of the bearing plate,the joint segment with back bearing plate has an excellent bearing capacity and can transfer force fluently.(2)The tested specimen basically kept a linear behavior in the whole loading process when loaded to about 2 times the design load.(3)The steel plates in the connection hold a gradually decreasing stress distribution downward,while the distribution of concrete is opposite.The maximum relative deformation between steel and concrete is about 0.1 mm in this test.The hybrid connection with back bearing plate has a good application in engineering hopefully.In view of the test result that the stress level of the concrete under the bearing plate is slightly higher,the C60 concrete with steel fiber in the steel-concrete joint segment is used to improve the compressive capacity of the structure.At the same time,in order to reduce the stress concentration phenomenon of concrete at the corner of bearing plate and wall plate in steel-concrete joint segment,trial mixing test and grouting are used to ensure the compactness between steel and concrete,and good use effect is achieved.