Analysis On Dynamic Characteristics Of Special-shape Arch Bridge

With the development of the arch bridge theory and construction technology,the new special-shape arch bridge which has the outstand esthetics effect is improving quickly. However,the construction of special-shape arch is particular.The dynamic behaviors,such as earthquakes,wind-induced vibration and vehicle vibration,are more important.These problems can not be avoided.So it is very necessary for us to research dynamic problems of special-shape arch.In this paper,The development process of the special-shaped arch is firstly reviewed.It is introduced how to use the methods of natural vibration characteristics in order to solve the natural vibration characteristics of arch bridge.Then a finite method analysis model is built by using these methods for a special -shape arch bridge—Tong-Tai bridge over Zhang Jia-kou Qing-Shui River.It is the arch's span is 180m,the main girder's span is 190m,the plan radius is 600m,the rise-span ratio is 0.3451 and the arch stride over the oblique main beam.(1) The natural vibration characteristics of Tong-Tai bridge is analyzed.Taking into account the major parameters of arch bridge(angle between the centerline of main beam and the centerline the arch,the ratio between height vector and span,the ratio between width and span,leaning angle,arch stiffness),the effects of these parameters on natural vibration characteristic is studied.(2) With the existing aseismatic theory,the aseismatic capability of the special shape bridge is analyzed by time-history analysis.Then the response characteristics is analyzed and compared between one-dimensional seismic ground motion and three-dimensional seismic ground motion.The results shows one-dimensional ground motion is not only important,but three-dimensional ground motion is also important.(3) The transient dynamic of vehicle vibration include the time-history responses when the vehicles move at different speeds and different Distance between vehicles through bridge, and the time-history responses when the bridge gets shock load.Then the riding comfort is also evaluated when the vehicles is runing.With considering the satisfaction,Tong-Tai bridge is better to riding.(4) E1 and E2 seismic load and dead load combinations are checked for the bridge,the result shows components of the bridge is still elastic condition and are not damaged.Then E1 and E2 seismic load and dead load combinations are compared with the vehicle load and dead load combinations,in order to get.design control load of main beam and arch rib.