Evaluation of a simple method for the preliminary design of low-to-medium rise reinforced concrete structures

Abstract

A simple method is evaluated in this study for suitability to the preliminary design of low-to-medium rise reinforced concrete building-type structures without significant irregularity problems. The method discussed herein, originally proposed by Ersoy (2013) is based on essential rules and guidelines of earthquake engineering such as member ductility and global ductility. Two main classes of structures are considered: buildings consisting solely of frames and buildings with frames and shear walls (also referred to as dual systems). In frame systems, the seismic loads are resisted entirely by columns, whereas in dual systems it is assumed that the columns take 30% and the shear walls take 100% of the lateral loads. It is also assumed that the locations of the shear walls are well configured on the plan so that the lateral loads are distributed fairly throughout the entire frame and the concentration of forces around a specific region is prevented. In an effort to ensure flexural failure of the members, the dimensions of the vertical members are determined under the action of gravity loads and seismic loads. Simple expressions representing the demand are derived as a function of plan area of the stories, column tributary areas, dead loads and live loads. Once the demands and required capacities are specified, dimensions of the load bearing members are determined by taking into account restrictions regarding certain effects leading to brittle failure such as axial stress, shear stress and interstory drifts. For the flexural and shear reinforcements, certain ratios of minimum reinforcements are adopted for the analysis. The buildings are modeled as per ASCE 41-13 with the aforementioned criteria and nonlinear static pushover analyses are performed to validate the expected performance level.