Analysis Of Static And Dynamic Mechanical Properties Of Concrete Filled Steel Tube Arch Bridge

It had been carried out to anylisis of static and dynamic behavior as well as parameter study for the existing issues in spatial structure of concrete filled steel tube (CFST) arch bridge. The main research contents of this thesis are shown below:(1) There were investigated for history of arch bridge and stress mechanism features of CFSTDevelopment status of CFST arch bridge in world-wide as well as research status of seismic performance. There were described in static and dynamic analysis.(2) They were performed for discussions of the mechanical theories of CFST structure According to composite structure theory, contrastive analysis had been done in concrete-filled steel tube structure which is made up of steel and concrete and confinement effect. It was used for Limit equilibrium theory to solve the corresponding calculation equations. The steel tube and the core concrete could be regard as an integral whole due to yield rule. Based on incremental method, load-displacement curve was got step-by-step by measuring the constitutive relation between steel tube and core concrete.(3) Based on research object, finite element models were established. The influence of the CFST structure under the effect of dead load, live load, extra-internal force and temperature were researched. From the result of calculation, the effect of shrinkage and creep of concrete and extra-internal force of pre-stressed member could not be neglect; there was more significant influence in the arch rib when it compared to the girder under the effect of temperature. Comparative study had been done by using two different kinds of CFST sections in order to reveal the structural response of the whole structure. Result showed that there was no significant influence in static analysis when section properties stayed the same.(4) There were performed for parameter analysis of self-vibration characteristics. Influence of pipe wall thickness of steel tube, diameter of section of concrete in steel tube, rise-span ratio and lateral brace arrangement on the natural vibration characteristics were analyzed and compared. It was known from the result that there was no significant influence on dynamic performance of the structure when changing the parameter cross section of arch rib; adjusting the rise-span ratio was an effective way to control the dynamic performance; resistance-distortion ability of arch rib could be increased in the case of setting more lateral bracings between arch ribs. I was also showed that anti-twisted abilities could be increased when taking use of X and K shape lateral bracings.(5) The influence of diameter of section of concrete in steel tube, rise span ratio and lateral brace arrangement on the earthquake resistance of CFST arch bridges that were based on response spectrum method and time history method were analyzed. It was shown that maximum bending moment was found in the position of arch springing; there were no significant influence on seismic performance of the structure in all directions when changing the parameter cross section of arch rib; Seismic performance of the structure could be increased when adopting rational rise-span ratio; Seismic performance of arch rib could be increased in the case of setting more lateral bracings between arch ribs, while there was no significant change in girder’s. I was also showed that anti-twisted abilities under seismic action could be increased when taking use of X and K shape lateral bracings.Above all, laws of structural static and dynamic as well as anti-seismic characteristics were indicated in the parameter analysis which included the changes of pipe wall thickness of steel tube, diameter of section of concrete in steel tube, rise-span ratio and lateral brace arrangement. Research results could be taken as references for the design of the same type of CFSR arch bridge.