Static Behaviors Analysis Of Half-through Tied Arch Bridge With Steel Box Arch-ribs

Half-through tied arch bridge with steel box arch-ribs has obvious spatial effects, and complex mechanical behavior. The bridge analysis was concerned by designers, as well as the structural behavior, and the force rationality, etc. On the basis of the MingZhou Bridge which main span is 450m and under construction, the static performance of half-through tied-arch bridges with steel box arch ribs was studied.The author summarized the development of steel arch bridge, and the mechanical properties. Besides, the present researches and the existing problem of static analysis were also presented in this dissertation.The theory of grillage model was adopted in the special analysis in static calculation. The example showed that the precision of the grillage model meeted the requirement in projects. Based on these approaches, Mingzhou Bridge was modeling with MIDAS/Civil.Through the static analysis of the dead load of Mingzhou bridge in construction stage and completion stage, as well as truck loading. The results showed that it is necessary for large span arch bridge to reserve a part of the tensile stress at arch foot when adjusting internal force before the closure of main arch. To construct tied arch bridge on the soft soil foundation, the jumper stays should be tensiled in batches to ensure the horizontal reaction under control at the bottom of frusta. Under the live load, the changing range of internal force in middle suspender is bigger than it in the ends suspenders. Through discussing the effect of suspender damage and the suspender breaking, the author believed that the internal force in suspender might be redistributed when the suspender damage happened and suspender broke, meanwhile, the two suspenders near the broke one would interlockingly damage and break.According to the British Bridge rules (BS-5400), as well as taking account of temperature rise and temperature gradient, the temperature effect at the closure stage and completion stage of Mingzhou bridge was analyzed. It showed sunlight thermal great influenced the arch deformation before the main arch closure; the temperature effect on deformation at completion stage surpassed that from live load. Jumper stays behaviors as unloading 10% under temperature load.According the wind-resistant design specification for highway bridges, and the wind tunnel tests, the static gust loading effect at the cantilever construction stage and completion stage was analyzed. The resultes showed that Mingzhou bridge is possessed of sufficient safety factor under static gust. The safety factor of stay cable is 2.11.