The Seismic Response Analysis Of Long-Span Cable-Stayed Bridge

Long-span cable-stayed bridge is one of the most important modern bridge types. As a result of increasing bridge span, deck flexibility and structure complexity, the seismic response analysis of long-span cable-stayed bridge already became one of the most concern problems in bridge engineering field.The Main Spans of Yumenkou Yellow River bridge in Shanxi province is a PC cable-stayed bridge designed as PES7 thermo-polyethylene parallel steel wire stay cables, twin towers, double cable planes, longitudinal elastic floating structural system and edge box-girders box beam edge floating system cable-stayed bridge, which main span is 352m and full-length is 700m.Because of its complex structure, typical structure system and important geographical location, the seismic response analysis is very important and significant. In this thesis, on the basis of the study achievements at home and abroad, this paper took a comprehensive and systematic study of dynamic characteristics and the seismic response for Yumenkou Yellow River bridge. the main jobs which were studied as follows:(1) After investigating the properties of Double cable-stayed bridge component, i.e. the cables, deck and joints in detail, with the advanced analysis program ANSYS, 3-D elements, element BEAM188,element LINK10,element COMBIN14 and element MASS21 are used to establish two finite element models with reference to the Main Spans of Yumenkou Yellow River bridge for seismic analysis separately. The dynamic characteristic is discussed under two different boundary conditions at the bottom of the bridge tower: The fixed end and the interaction of pile-soil. Thus, it can reach the influence of pile-soil interaction in dynamic analysis of such bridge.(2) According to specific structure and construction sites geological characteristics of the Main Spans of Yumenkou Yellow River Bridge in Shanxi province, this paper choose the standard response spectrum curve and suitable damping-modified formula and modified the response spectrum curve. Inputing the modified response spectrum curve along the longitudinal, transverse and multidimensional direction-horizontal combined vertical, this paper analysis the seismic response of the Double cable-stayed bridge In order to ensure accuracy in calculation, the SRSS method is applied to combinate vibration modes. (3) The response spectral analysis is linear so the nonlinear factors can not be taken into account. The El_Centro earthquake wave(1940) is chosen to analyze the seismic response of the Main Spans of Yumenkou Yellow River Bridge in Shanxi province with dynamic time-history analysis considering the nonlinear factors which under the same load case and combination condition. The seismic response is gained after comparing the calculation results of the two methods detailedly.(4) The Main Spans of Yumenkou Yellow River Bridge in Shanxi province is a longitudinal elastic floating structural systems, while the aseismatic capability of cable-stayed bridge lies on the selected structural system. So this paper analyzed the seismic response according to its design structural system and furtherly presented some constructive measures for the aseismatic work.Finally, this paper summarized all the study work and drew some conclusions, besides, the further research problems are indicated. These laws can be used as the basis of seismic design of the main spans of Yumenkou Yellow River Bridge in Shanxi province and is useful for directing seismic response analysis of such kind bridge.