Dynamic Behavioral Study Of Concrete-filled Steel Tubular Arch Bridges

As a new multiple construction material, concrete-filled steel tube has been used widely in civil engineering hi the past years. At the same time, concrete-filled steel tubular arch bridge has been deeply developed in our country since 1990. But the research of design theory of concrete-filled steel tubular arch bridge trails the engineering practice; especially the study of dynamic performance trails the study of static performance.Because the greatest internal force and displacement of every section when the structure is under the dynamic loads are nearly correlative with the frequencies and the vibrational formats when the structure is under the natural vibration, seeking natural vibration frequencies and modes is the precondition and base to carry through every dynamic analysis. In the thesis, on the basis of existing data collected of arch bridges and dynamics, taking the example of Qingchuan Bridge, establish 3-D finite element model of it with software ANSYS, and calculate and analyze its natural vibration frequencies, and analyze the effects of natural vibration feature of the differences of structure parameters. Some factors, such as design parameters (the ratio between height vector and span, the ratio between width and span), Furthermore, because of the different bridge structure, such as the arrangements of cross braces, the structure to pass on force, and the arrangements of suspenders, and the distinctness of material characteristics of bridge components, such as the rigidity of bridge deck and arch rib, the natural vibration characteristic is influenced. The thesis analyzes the effects. According to the theory analysis of natural vibration feature, the use of natural vibration feature in bridge test is analyzed combined with engineering testing practice.As concrete-filled steel tubular arch bridges develop in the direction of large-span and lightweight style, the study on dynamical response of the structure under live loads such as vehicles, wind and earthquake is in need. During the transient dynamic analysis of Qingchuan Bridge, the tune history responses of the structure under uniform velocity moving load and impact load are analyzed, and the amplification coefficients of deflection and internal factors of the structure are intensively analyzed.At last, the results calculated by finite element software and the results under the test of moved loads are compared and analyzed. The analytic results suggest that the discrimination between both is little, so the results simulated by finite element software can reflect the dynamic characteristic of the bridge.By the finite element simulation to Qingchuan Bridge dynamic characteristic, the thesis discusses manifold factors which influence the dynamic characteristic of half-through concrete filled steel tubular arch bridge, and gets some conclusions. It will offer reference to the bridge dynamic test, and provide basic datum for the health examination and maintenance during its use.