高速铁路双箱混合梁斜拉桥钢-混结合段力学行为研究

Study on Mechanical Behaviour of Steel-Concrete Joint of High-speed Railway Hybrid Girder Cable-stayed Bridge with Twin-box Section

以我国首座高速铁路双箱混合梁斜拉桥钢-混结合段为背景,采用数值分析手段探究其在最不利工况下的应力分布特性、传力性能及变形性能,并通过模型试验考察其在1.0倍最不利工况、2.0倍最不利工况和破坏工况下的力学性能。数值分析结果表明:在最不利工况下,除应力集中区域外,结合段钢梁与混凝土纵向正应力分别小于-80.0、-13.2 MPa,传力较为顺畅;结合段钢梁和混凝土梁顶面应力横向分布不均匀系数分别在0.80~1.11、0.83~1.21之间;前承压板、后承压板、剪力钉和PBL连接件分别传递约5.8%、33.1%、36.3%、29.8%的轴力。试验结果表明,结合段具有足够的承载力,安全系数大于2.0;结合段变形平顺,最不利工况下,纵向竖曲线最小半径为12 013 m,刚度性能满足高速铁路行车要求。在破坏工况下,混凝土梁过渡段先于钢-混结合段破坏,且属于延性破坏。

Based on the first high-speed railway hybrid girder cable-stayed bridge with twin-box section in China, the stress distribution rule, force transmission characteristics and deformation performance under the most unfavorable conditions were obtained via numerical analysis method. The mechanical behaviour under the most unfavorable conditions, twice the most unfavorable condition and damage condition, was investigated via performing a model test. The numerical analysis results indicated that except for the stress concentration region, the longitudinal normal stresses of the steel and concrete structure in steel-concrete joint were less than-80.0 MPa and-13.2 MPa under the most unfavorable condition, respectively, with relatively smooth force transmission from steel girder to concrete girder. The transverse distribution nonuniformity coefficient of the steel and concrete surface in the steel-concrete joint was 0.80~1.11 and 0.83~1.21, respectively. Approximately 5.8%, 33.1%, 36.3% and 29.8% of the axial force were transferred by the front bearing plate, end bearing plate, shear studs and PBL connectors, respectively. The test results indicate that the steel-concrete joint exhibits sufficient bearing strength, with safety factor greater than 2.0. The steel-concrete joint shows excellent deformation performance and the minimum radius of vertical curve of 12 013 m, under the most unfavorable conditions, with the stiffness performance meeting the requirements of the operation of high-speed train. Under the damage condition, the concrete girder cracks earlier than the concrete filled in steel-concrete joint and the crack process belongs to ductility damage.