Full Program »

Nonlinear dynamic simulation of cable breakage events on long-span cable-stayed bridges under stochastic traffic and wind

The occurrence of abnormal loads may induce the breakage of cables on cable-stayed bridges, which poses a threat of successive damage or failure of the whole bridge structure. For long-span cable-stayed bridges, which are susceptible to the aerostatic and aerodynamic excitations, the geometric nonlinearity becomes more significant as approaching wind speed increases. Beyond wind excitations, strong coupling effects between long-span cable-stayed bridges and traveling vehicles may significantly change the local and global bridge behavior. Considering that cable breakage event may occur at random time instants with heavy traffic and wind, nonlinear dynamic analysis incorporating the coupling effects from traffic and wind becomes necessary in order to rationally predict the dynamic response of the bridge after the cable failure occurs. To achieve this, this paper establishes a finite element based simulation platform to perform the cable breakage analysis of the coupled bridge-traffic system under wind excitations. The stay cables are modeled as three-dimensional catenary cable element, in which the cable sag and pre-tensioning effect are fully considered using the analytical derivation of elastic catenary. The girders and towers are modeled using three-dimensional beam element based on the Timoshenko beam theory which can consider axial, bending, torsion and shear deformation at the same time. Geometric nonlinearity is implemented by updating the tangent stiffness matrix for cable and beam elements. Material nonlinearity is considered through the concentrated plastic hinge approach. It also incorporates comprehensive considerations of nonlinearities originated from aerodynamic and bridge-traffic interaction forces. A dynamic simulation methodology based on nonlinear iteration is further proposed for the cable breakage event starting from the initial state from a nonlinear static analysis. This study further takes a long-span cable-stayed bridge as a numerical example to demonstrate the simulation of cable-breakage events with stochastic traffic and wind excitations through the proposed nonlinear dynamic methodology.

Author(s):

Yufen Zhou    
Colorado State University
United States

Suren Chen    
Colorado State University
United States