Research On Dynamic Characteristics And Nonlinear Buckling Of Long-span Steel Arch Through Bridge

As a prime style of bridge, the arch bridge has been over three thousand years old since ancient times. Nowadays, with the increase of the span, the problem of stability is becoming more and more evident and it is one of the most important factors which controls arch bridge designing. For another, the study on dynamic response of the long-span arch bridge under dynamic loads such as vehicles, wind and earthquake is in need and the natural vibration characteristics are the most essential information for dynamic analysis.This paper bases on the steel through arch bridge within tie member which spans 108 meters of an oil wharf in Hainan Province.First of all, on the basis of existing dynamic theories of arch bridge, we established 3-D finite element model of this bridge by utilizing the large finite element analysis software and we analyzed its natural vibration characteristics by sub-space iterative method. Then we obtained the frequency spectrum properties. And our results show that this bridge presents three principal vibration models, vertical, lateral and torsional shapes. By comparing the effects of different parameters, we indicate that the factor of rise-to-span ratio affects the natural vibration characteristics most obviously. The frequency of the first set reaches the maximum value when the rise-to-span ratio is around 1/10. We also find that the frequencies of the second and the subsequent sets increase slowly when the number of suspenders is more than 5 pairs. Other parameters, such as stiffness of arch rib, bending rigidity of tie member and axial stiffness of suspender are correspondingly less obvious factors of natural vibration characteristics.Besides, within the guidance of existing theories, we make stability analysis on this long-span steel arch bridge from two points, both the eigenvalue stability and ultimate load-carrying capacity. Moreover, we discuss several parameters which affect its stability. These parameters include: load patterns, initial imperfections, material nonlinearity patterns, yield strength of steel, stiffness of arch rib, stiffness of tie...