A post-correction modal superposition method for nonlinear dynamic analysis

A post-correction algorithm developed for the dynamic analysis of simple nonlinear and hysteretic structures is extended for the analysis of building structures under earthquake loadings. The nonlinearities in the system are moved to the right-hand-side of the equations of motion and treated as a generalized loading. At each time step, the equations of motion for the resulting linear system are solved either numerically using the constant acceleration method, or analytically using modal superposition. The effect of the nonlinear generalized forces is made equivalent to a series of impulse forces acting on the resulting linear system. The method does not require the re-factorization of the effective tangent stiffness matrix at each step of the integration. (author)