Elastic Stability of Wood Transmission Structures

A finite element formulation, based on the displacement method, for the analyses of stability and geometric nonlinear large deflections of wood transmission structures is presented. The formulation admits both prismatic and nonprismatic elements and handles the special joints associated with wood connections. The nonlinear solution is performed in load increments with iterations at each step. Only the elastic stiffness matrix of large displacements is employed in the solution. A technique is proposed by which the incremental load vector is modified at initial and intermediate increments of loads in a way which ensures the absence of axial forces in the supporting columns of the structure and thus guarantees a correct solution. The overall buckling loads are efficiently predicted utilizing the Southwell plot method. Comparison of theoretical results with full-scale test results of actual structures validate the method.