The design of reinforced concrete beams has usually focused on the ultimate flexural capacity and disregarded the lateral stability of the beams. However, the development of high-strength concrete and the implementation of new construction techniques increase the use of longer and deeper concrete beams, which makes the lateral instability a primary concern of failure in concrete bridges. In particular, the lateral stability should be more taken into consideration in the construction and erection phases due to inadequate lateral supports. Thus, an experimental study was carried out to evaluate the lateral torsional buckling of reinforced concrete beams with initial geometric imperfections. The lateral flexural and torsional rigidity expressions, which could account for the flexural, torsional, and shrinkage cracking of concrete, the contribution of longitudinal and shear reinforcement, and the nonlinearity of materials, were proposed for rectangular reinforced concrete beams. Finally, this study proposed an analytical formula to estimate the buckling loads of initially imperfect reinforced concrete beams. The estimates of the study showed close agreement with the experimental values.
Influence of boundary conditions and geometric imperfections on lateral–torsional buckling resistance of a pultruded FRP I-beam by FEA
