Seismic Analysis in Linear or Nonlinear Domain, Using Two or Three-Dimensional Modelling.

Abstract

Three-Dimensional dynamic analysis is required for a large number of different types of structures, specially constructed in seismic region. Design of structures is done through linear analysis, but taking in consider the nonlinear behavior depending on plastic properties presented by the structural behavior structures. General guidelines for reinforced concrete structures are those given in EC-2, and more explicit are given in EC-8. It's convenient to run the linear analysis in 3-D model using the finite element approach, but it is rather difficult to use 3-D modeling for nonlinear behavior. A simplified 2-D model can be used for such analysis based on a strong engineering experience. For traditional structures, the use of shear walls in combination with frame structures forming a dual structures, wide spread for the sake of they performance. The positioning of shear walls in plane and the shape of their cross-section has a crucial importance in behavior of the whole structure. Their influence can be observed in stiffness, strength and ductility of the structures. Based on soil properties to the site, to avoid the resonant condition, the engineer can choose the right position and amount of shear walls besides the alternative solution. The following study illustrates by numerical analysis the behavior of dual structures depending to the shear wall position and their shapes. Also, a change of building stories is observed as well. As outputs the fundamental periods, lateral displacements, base forces and ductility are provided. Based on these parameters, some comments and conclusions are derived.