Nonlinear Dynamic Analysis of Discrete Structural System

Abstract

The linear-static analysis of structure is a widely used and accepted analysis technique. During abnormal conditions or ultimate loading conditions, the linear-static analysis of structure unable to understand the actual behaviour of the structure. Under these conditions, the linear dynamic and nonlinear dynamic analysis play an important role to reflect close to the actual behaviour of the structural system. Various dynamic loading conditions like Harmonic Excitations (Half-cycle sine pulse, Harmonic Periodic Excitation, Saw Tooth Excitation) and Arbitrary Excitations (Step Force Excitation, Ramp Force Excitation, Unit Impulsive Excitation, Earthquake Excitation) considered for the present study. Linear Discrete SDOF system, linear Discrete MDOF system and nonlinear Discrete SDOF system analysed under dynamic loading. Numerical integration methods like Central Difference Method, Newmark’s Method and Wilson’s Method are used for the analysis of linear Discrete SDOF and linear Discrete MDOF system while the combination of Newmark’s Method and Newton-Raphson’s Method used for the analysis of nonlinear Discrete SDOF system. Computer programs using MATLAB software developed for all numerical methods. A lumped mass SDOF system considered as a linear SDOF and a nonlinear SDOF system. A 3-storey plan symmetric structure considered a linear Discrete MDOF system. The dynamic response of the linear system graphically compared while peaks compared with the response of senior’s thesis. In the present study nonlinearity of the SDOF system is considered by considering the Elasto-Plastic force-deformation relation. Nonlinear dynamic analysis of Steel Portal Frame carried out considering Elasto-Plastic Constitutive Model and Ramberg & Osgood Constitutive Model under Harmonic Periodic Excitation. The Constitutive Models developed by excreting experimental results of Steel Coupon Specimen from Senior’s Thesis.