Research On Aseismic Design Of The Main Girder Of Cable-stayed Bridge

Earthquake damage is the main form of damages to the cable-stayed bridge. Strong earthquake will cause fracture of the cable, girder crack, main tower broken, bearing damage, etc. It will cause heavy loss for the security of people’s life and property. In the design of large span cable-stayed bridge, the choice of the main girder form is relatively small, confined to mixed beam and steel box girder. Compared to the large span cable-stayed bridge design, the design of span under 400 meters middle span cable-stayed bridge, the choice of the girder form is flexible, mainly includes: concrete beam, mixed beam, composite beam, steel box girder and other forms. Hence, In cable-stayed bridge preliminary design stage, many design professionals are often plagued by the choice of the form of main girder; the reason is that the determination of main girder forms is a very complex task, comprehensive decision by a variety of factors. More importantly, girder forms often decide the arrangement of bridge spans of cable-stayed bridge, the cable tower form and height, the base type, and overall cost etc. However, In the region which seismic design for cable-stayed bridge construction are the control factors, the ground motion is the decisive factors in cable-stayed bridge girder form selection. As a result, the comparison of cable-stayed bridge girder scheme based on the seismic performance is particularly important.Based on the rongjiang super-large bridge engineering as analysis object, based on the seismic performance in preliminary design stage of this bridge main girder form scheme comparison. By establishing the finite element analysis model, on the basis of detailedly analyzing the dynamic characteristics of three kinds of forms of main girder cable-stayed bridge, contrast analysis the earthquake response of the cable-stayed bridge main structure under the two seismic loads of the acceleration E1 response spectrum and seismic acceleration time history analysis. Containing the contrast analysis of the main girder and the cable tower and the cable internal force change, the contrast analysis of the main tower and main girder displacement change, the contrast analysis of internal force and stress on cable-stayed bridge seismic damageable parts. This article elaborate the advantages and disadvantages of each main girder scheme under the different seismic load. It is concluded that the overall seismic performance of composite beam cable-stayed bridge is the optimal, and the overall seismic performance of hybrid girder cable-stayed bridge is the worst. For the cable-stayed bridge engineering design, especially in the preliminary design, this article conclusion has a certain guiding role.