WIND-INDUCED NONLINEAR LATERAL-TORSIONAL BUCKLING OF CABLE-STAYED BRIDGES

A finite element approach to calculate directly the critical wind velocity for the nonlinear lateral-torsional buckling instability of long-span cable-stayed bridges under the displacement-dependent wind loads is presented. An analytical modeling of wind-induced lateral-torsional buckling is formulated taking into account the three components of displacement-dependent wind loads as well as geometric nonlinearity. A combination of the eigenvalue analysis and the updated bound algorithm for wind velocity is applied to automatically calculate the critical wind velocity. The results show that the incorporation of the three components of displacement-dependent wind loads as well as the geometric nonlinearity in the analytical modeling of the lateral-torsional buckling instability results in significant reduction in the critical wind velocity compared with both the conventional nonlinear torsional divergence and linearized lateral-torsional buckling.