DYNAMIC NON-LINEAR BEHAVIOUR OF CABLE STAYED BRIDGES UNDER SEISMIC LOADINGS

Abdel Seed, Fayez K.; Ahmed, Hamdy H.; Abdel Raheem, Shehata E; Abdel Shafy, Yasser

doi:10.21608/jesaun.2014.114273

DYNAMIC NON-LINEAR BEHAVIOUR OF CABLE STAYED BRIDGES UNDER SEISMIC LOADINGS

Document Type : Research Paper

Authors

¹ Staff in Civil Engineering Department, Faculty of Engineering, Assiut University.

² Staff in Civil Engineering Department, Faculty of Engineering, Assiut University

³ Civil Engineering Dept, Faculty of Engineering, Assiut University, Assiut 71516, Egypt.

⁴ Petroleum Projects and Technical Consultations Company PETROJET

10.21608/jesaun.2014.114273

Abstract

The cable stayed bridges represent key points in transport networks and their seismic behaviour need to be fully understood. This type of bridge, however is light and flexiable and has a low level of inherent damping. Consequenly, thery are susceptible to ambient excitation from seismic loads. Since the geometric and dynamic properities of the bridges as well as the characteristics of the excitations are complex, it is necessary to fully understand the mechanism of the interaction among the structural componenets with reasonable bridge shapes. This paper discuss the dynamic response of a cable stayed bridge under seismic loadings. All possible sources of nonlinearity, such cable sag, axial-force-bending moment interaction in bridge towers and girders and change of geometery of the whole bridge due to large displacement are based on the utilization of the tangent stiffness matrix of the bridge at the dead-load deformed state which is obtained from the geometry of the bridge under gravity load conditions ,iterative procedure is utilized to capture the non-linear seismic response and different step by step integration schemes are used for the integration of motion equations. In this study, three spans cable-stayed bridge with different cable systems has been analyzed by three dimensional nonlinearity finite element method. The three dimensional bridge model is prepared on SAP 2000 ver.14 software and time history analyses were performed to assess the conditions of the bridge structure under a postulated design earthquake of 0.5g. The results are demonstrated to fully understand the mechanism of the deck-stay interaction with the appropriate shapes of a cable stayed bridges.

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