Inelastic analysis and behavior of steel I-BEAMS curved in plan

An I-beam curved in plan and subjected to vertical loading experiences prim ary bending and nonuniform torsion actions. Because of this, the vertical d eflections are coupled with twist rotations. These primary actions and defo rmations couple together to produce second-order bending actions about the minor axis. The interactions between these actions can grow rapidly, produc e early nonlinear behavior and yielding, and lead to significant reductions of the ultimate load-carrying capacities. This paper develops a curved bea m finite-element model for the geometric and material nonlinear analysis of I-beams curved in plan. Comparisons with existing results show that the fi nite-element model is accurate, effective,, and economical. The numerical r esults show that when the initial curvature of a curved beam is small, bend ing is the major action and the nonlinear inelastic behavior is similar to the inelastic flexural-torsional buckling of a straight beam. However, if t his initial curvature is not small, both nonuniform torsion and bending are dominant and nonlinear inelastic behavior develops very early. The behavio r differs markedly from the inelastic flexural-torsional buckling behavior of a straight beam.