Effect Of Steel Ratio On Mechanical Behavior Of Long Span CFST Arch Bridge

In recent years,the Concrete-filled Steel Tubular Arch Bridges has been developed vigorously in our country,and its calculation theory is also in constant improvement.At present,the CFST arch bridge already have the national standard,the profession standard and the local standard.Milestone is in December 2015,Ministry of Transport of the People’s Republic of China issued a steel tube concrete arch bridge design specifications,namely"specification for Design of Highway Concrete-filled Steel Tubular Arch Bridges ”,which makes the CFST arch bridge design rules to follow.In this paper,the focus is CFST Arch-sectional design parameters of the steel ratio problem.steel ratio is an important design parameter of large span CFST arch bridge,not only affects the empty tube erection of the degree of difficulty,full bridge of material consumption and construction cost,also affect the mechanical behavior of the arch rib under the serviceability and ultimate limit state of carrying capacity.To study the influence of steel ratio of large span CFST arch bridge mechanical behavior,provide a reference for designers reasonable choice of steel ratio,a Midas spatial finite element analysis model is established for the engineering background of the Zong Xi River Bridge,which Based on the"specification for Design of Highway Concrete-filled Steel Tubular Arch Bridges ”.The variation of mechanical behavior of arch rib steel tube and concrete filled steel tube with different steel ratio was studied.The following are main research contents and achievement:(1)The effect of steel ratio on the mechanical properties along the arch rib direction is analyzed was analyzed.In view of equal thickness and variable thickness of the wall thickness of arch rib steel tube in the design binding the spatial finite element model of Zong Xi river.The influence of these two kinds of cross section on the performance of the arch rib is analyzed and compared in the two-section steel consumption essentially the same conditions,which could provide reference for design.(2)The effect of steel ratio on the mechanical properties of the mechanism is studied.In order to study the effect of steel ratio on the stress of arch rib and concrete in the arch rib and imitate the construction process of concrete filled steel tube arch bridge,the mechanism of the effect of steel ratio on the stress of arch rib is analyzed by using the three stage stress superposition method.At the same time,the corresponding formulas are deduced.(3)The effect of steel ratio on the mechanical properties with overall change of steel pipe wall thickness is analyzed was analyzed.Analysis of the influence of concrete stress effect of steel ratio on the stress of arch rib and concrete in the arch rib of large span CFST arch bridge and investigate the feasibility of concrete pipe as part of the composite structure to its full strength of materials.And also the three-stage stress superposition method of derivation using the finite element method is validated.