塔梁固结斜拉桥局部分析及优化设计研究

Research on Local Analysis and Optimal Design of Pylon-beam Consolidated Cable-stayed Bridge

摘要:

斜拉桥塔梁固结处的构造复杂，是整个斜拉桥体系关键受力位置，因此需要对其进行局部精细化分析，为塔梁固结处局部构造设计及配筋优化提供理论依据。为研究塔梁固结斜拉桥塔和主梁结合位置处的受力性能，以本溪市小华山大跨度塔梁固结斜拉桥为工程案例，采用三维有限元软件建立塔梁实体局部模型，分析原有设计方案下桥塔底部实心段与空心段结合面的纵横向应力、桥塔底部与主梁交接处的纵横向应力。具体分析过程为：基于正交试验方法的参数分析，选择桥塔底部过渡面倒角尺寸和实心段高度作为分析参数，提取桥塔底部实心段顶面的纵横向应力、桥塔底部与主梁结合面的纵横向应力这4个指标作为目标评价函数，然后定义综合目标评价函数W，确定设计参数最优组合；采用极差分析法和方差分析法对结构综合目标评价函数进行分析，获得结构设计参数的敏感性和显著性。结果表明：塔底实心段高度是对塔梁固结处局部应力影响程度最大、最敏感的参数；通过构造设计优化后的参数组合为：塔底过渡面倒角宽度550 mm、倒角高度1 500 mm；塔底实心段高度1 000 mm；与原设计方案相比，塔底实心顶面纵向应力减小了21.8%，横向应力减小了14.2%；塔梁结合面纵向应力减小了7.3%，横向应力减小了3.7%；参数敏感性程度由强到弱依次为：塔底实心段高度、塔底过渡面倒角宽度、塔底过渡面倒角高度。

Abstract:

The structure at the consolidation of pylon and beam of cable-stayed bridge is complex and is the key stress position of the whole cable-stayed bridge system. Therefore, it is necessary to carry out the local fine analysis to provide the theoretical basis for the local structure design and reinforcement optimization at the consolidation of pylon and beam. In order to study the mechanical performances at the combined position of the pylon and main beam of the pylon-beam consolidated cable-stayed bridge, taking the long-span pylon-bea consolidated cable-stayed bridge in Xiaohuashan of Benxi City as an engineering example, a local solid model of the pylon and beam is established by using the three-dimensional finite element software to analyze the longitudinal and transverse stress of the joint between the solid section and the hollow section at the bottom of the bridge pylon and the junction between the bottom of the bridge pylon and the main beam under the original design scheme. The specific analysis process is to select the chamfer size of the transition surface at the bottom of the bridge pylon and the height of the solid section as the analysis parameters, and to extract four indexes of the vertical and horizontal stress at the top surface of the solid section at the bottom of the bridge pylon and the interface between the bottom of the bridge pylon and the main beam as the objective function, and then the comprehensive objective function W is defined to determine the optimal combination of design parameters. The comprehensive objective function of the structure is analyzed by using the range analysis and variance analysis, and the sensitivity and significance of structural design parameters are obtained. The results show that the height of the solid section at the bottom of the pylon is the most sensitive and largest affecting parameter to the local stress at the consolidation of the pylon and beam. The parameter combination optimized by structural design is chamfer width 550 mm and chamfer height 1 500 mm of the transitional surface at the bottom of pylon, and the solid section height 1 000 mm at the bottom of pylon. Compared with the original design scheme, the longitudinal stress and transverse stress of the solid top surface at pylon bottom are reduced by 21.8% and 14.2% respectively. The longitudinal stress of the joint surface of the pylon and beam is reduced by 7.3%, and the transverse stress is reduced by 3.7%. The sensitivity of the parameters is from strong to weak. Its sequence is the height of the solid section, the chamfer width of transitional surface and the chamfer height of transitional surface at the bottom of the pylon.