大跨径预应力混凝土盖梁主动托换参数分析与结构优化设计

Analysis on Parameters and Structural Optimization Design of Active Underpinning For Long Span Prestressed Concrete Cap Beam

为了探讨结构参数对大跨径预应力混凝土盖梁托换后的影响和盖梁截面的优化设计,对截面优化方法的比较和不同计算参数下截面的受力特性进行研究。以广河高速公路春岗互通主线桥右幅82#墩为依托,采用MIDASCivil建立有限元模型,分析墩梁连接方式、盖梁跨高比、墩刚度比和预应力钢束数量对盖梁挠度和内力的影响规律,结合ANSYS和MATLAB对盖梁进行截面优化。结果表明:在设计截面不变时,盖梁与墩的连接方式对挠度值的影响较小;在相同的连接方式下,盖梁跨高比对跨中截面的挠度和弯矩影响较大,墩刚度比对跨中截面的挠度和弯矩影响较小,预应力钢束数量对其跨中截面处的挠度和弯矩影响较大;两端固结的连接方式引起的挠度值和弯矩值略优于其它连接方式。ANSYS有限元软件和遗传算法优化的最终结果相接近,两者优化后的截面宽度相对误差为5%,高度相对误差为3%。

To study the influences of structural parameters of long-span prestressed concrete cap beam on active-underpinning and the optimization design of the section, the comparison of the section optimization methods and the mechanics characteristics of the sections under different structural parameters have been investigated.TakingPier No.82 of Guanghe Expressway as an example, a finite element model has been establish with MIDAS Civil to analyze the connection method, the span-to-height ratio of the girder, the stiffness ratio of the pier and the influence of the prestressed steel beam on the deflection and mechanics of the girder with the section being optimized with the software of ANSYS and MATLAP.The results have demonstrated that when the original section is unchanged, the connection between cap beam and pier has less influence.Under the same constraints, the span-to-height ratio has a great influence on the deflection and bending moment of the mid-span section.Being compared with the deflection and bending moment at the mid-span section, the prestressed steel bundle has a great influence on the deflection and bending moment at the mid-span section.The deflection value and bending moment value caused by the joints fixed at both ends are slightly better than other connection methods.The final result of software ANSYS and genetic algorithm optimization is close.The relative error of the section width is 5% and the height relative error is3%.