纵向预应力对下承式组合桥面系钢桁架拱桥受力性能的影响研究

Study on Effect of Longitudinal Prestressing on Mechanical Properties of Through-type Composite Deck System Steel Truss Arch Bridge

针对下承式组合桥面系钢桁架拱桥桥面系设计的3种思路,即增设柔性系杆、施加桥面板纵向预应力和通过加强配筋来控制桥面板裂缝,以一座组合下承式桥面系连续钢桁架拱桥为背景,以不施加纵向预应力的方案为比较基准,通过全桥有限元模型计算,分析多种工况下纵向预应力对拱肋、钢系梁、混凝土桥面板的受力性能的影响。研究表明:纵向预应力明显分担了拱脚推力,但增强了拱肋、钢系梁的温度敏感性;纵向预应力大多分配到了钢结构上,作用效应频遇组合工况下,桥面板难以达到A类预应力混凝土构件的控制要求。

There are three kinds of design methods for the deck system of through-type composite deck system steel truss arch bridge,such as setting flexible tie bar,applying longitudinal prestressing of bridge deck and strengthening reinforcement to control the deck cracks.Based on a through-type composite deck system continuous steel truss arch bridge,compared with the scheme of not applying longitudinal prestressing,through the finite element model calculation of the whole bridge,the effects of longitudinal prestressing on the mechanical properties of arch rib,steel tie girder and concrete deck slab under various working conditions are analyzed.The study shows that the longitudinal prestressing significantly shares the thrust of arch foot,but enhances the temperature sensitivity of arch rib and steel tie beam.The longitudinal prestressing is mostly distributed to the steel structure.Under the condition of the action effect frequently encountering combination,the bridge deck is difficult to achieve the control requirements for Class A prestressed concrete members.