Dynamic Response Study of a Single Tower Cable Stayed Bridge using Finite Element Method

Muhammad Habib; Naik Muhammad; Saeedullah Jan Mandokhail; Zafar Baloch; Muhammad Irfan; Azmatullah Khan; Muhammad Akram; Gohram Khan; Anila Ali; Ali Asgher; Samiullah Khan

Cable stayed bridges are most widely used in the modern medium to long bridge construction due to their efficient response, economic viability, faster construction, and eye-catching aesthetics. The dynamic response of a single tower cable stayed bridge is studied by performing both nonlinear static and dynamic analyses using finite element method based software ANSYS. A three dimensional bridge model was developed using ANSYS. The steel cables were simulated using a single element approach to minimize the time and data use. Due to the complexity of cable stayed bridges, it is tried to avoid the convergence problems by adopting the displacement convergence approach. The bridge exhibits complex modal shapes due to the coupling effects for the free vibrations. The response of the bridge in vertical direction is more elastic and flexible as compared to the longitudinal and transverse direction. Response of the critical sections of girder, tower, and cables was also studied by time-history analysis using the ground acceleration data of the EICentro 1940 earthquake. A 10 second ground data with 0.0001 second time step was used. It was observed that stiffness in the vertical direction is a key player in the dynamic behavior of the cable stayed bridge. The response of the right and left span is similar which adds to the accuracy of the analysis. Time history analysis of the bridge shows that the largest displacements or peak responses are not related to the peak ground accelerations, rather they are dependent on many other factors like bridge stiffness, nature of the earthquake ground excitations and mass distribution. However, the results show the general trend of cable stayed bridges.