Dynamic analysis of multi-story building-type structures under earthquake effects using continuous model approach

In the analysis and evaluation of building-type structures under earthquake effect, it is essential to accurately predict the responses that will occur in the structure. The most important step in structural analysis is to create a model that can accurately represent the behavior of the structure under external loads. Continuous models are approximate methods that help to perform this step quickly and accurately by requiring very few information about the structure. The overall objective of this study is to develop a simple and efficient continuous model approach for predicting the structural behavior of multi-story building-type structures under earthquake ground motion. In this thesis, a novel continuous model approach is proposed to predict the lateral displacement and inter-story drift responses of structures subjected to earthquake loading. This model is defined as an equivalent continuum structure, that is comprised of a combination of a flexural cantilever beam and a shear cantilever beam. In the solution of the continuous model, the rotational boundary condition at the base is expressed as the ground story drift ratio. The governing equation of motion of the model was established in closed form and the dynamic characteristics of the structure were obtained by free vibration analysis. Response spectrum analysis have been used to estimate the lateral displacement, the maximum inter-story drift ratio and the variation of the inter-story drift ratio along the building height. A simple equation for the lateral stiffness ratio (α) parameter, which controls the building behavior, is also proposed based on the number of building stories (N) and the beam-to-column stiffness ratio (ρ). The structural responses have been obtained from sample model solutions using the proposed continuous model approach and equation α. The same models have been compared with the responses obtained from the finite element models created in the SAP2000 program and the results have been observed to be close. Higher mode effects (HME) on the seismic response of structures are also parametrically investigated through the proposed continuous model approach. Dimensionless and generalized modal equations are derived using the design acceleration spectrum defined in TBDY (2018). The HME on the lateral displacement, inter-story drift ratio, shear force and overturning moment responses are evaluated in terms of N, ρ and r1B parameters defined as the ratio of the first period of the building to the spectrum corner period. It is shown that the HME varies according to the type of structural response and that there are cases that should not be neglected.