大跨径预应力钢混组合连续箱梁结构设计及仿真计算过程中的关键点分析与研究

Analysis and Research on Key Points in the Structural Design and Simulation Calculation of Long-Span Pre-Stressed Steel-Concrete Composite Continuous Box Girder

摘要: 大跨径钢混组合连续箱梁的墩顶负弯矩区混凝土桥面板在使用状态下易因拉应力过大而开裂，因而结构设计时经常需要配置相应的预应力钢束。考虑到组合梁刚度的绝大部分由钢主梁提供，配置钢束后的预应力效应必然主要向钢主梁转移，而不足以抵消外荷载产生的拉应力。为了解决这个难题，结构设计考虑在预应力作用区域设置抗拔不抗剪连接件，保证预应力效应对桥面板的绝对影响，这就使得组合梁的结构设计和仿真计算分析显得异常复杂。本文通过选取某在建工程的大跨预应力钢混组合连续箱梁，按照普通钢筋混凝土桥面板、预应力混凝土桥面板和钢主梁三种构件，同时考虑钢与混凝土的普通抗剪效应、抗拔不抗剪效应、预应力效应、施工阶段划分等多种因素和关键点，对大跨径组合梁进行整体仿真计算分析和研究，得到的成果用来指导本工程的组

Abstract: The concrete bridge deck at the negative moment position on the top of the pier of the long-span steel-concrete composite continuous box girder is prone to cracking due to excessive tensile stress in operation period, so the corresponding pre-stressed steel strands are often required in the structural design. Considering that most of the rigidity of the composite beam is provided by the steel main girder, the pre-stressed effect is inevitably transferred to the steel main girder, which is not sufficient to offset the tensile stress generated by the external load. In order to solve this problem, the structural design still needs to be equipped with Uplift-Restricted and Slip-Permitted Connection keys in the pre-stressing area to ensure the absolute influence of the pre-stressed effect on the bridge deck. This makes the structural design and simulation calculation analysis of the composite beam extremely complicated. This paper selects a large-span pre-stressed steel-concrete composite continuous box girder for a certain project under construction, according to the three components of ordinary reinforced concrete deck, pre-stressed concrete deck and steel main girder, while considering various factors and key points such as the ordinary shear effect of steel and concrete, Uplift-Restricted and Slip-Permitted effect, pre-stressed effect, construction stage division, etc. and carries out overall simulation calculation analysis and research on long-span composite beams. The results obtained are used to guide the design of the composite beam structure of this project, and have certain reference value for the structural design and simulation calculation of other large-span pre-stressed composite bridges on the highway.