Analysis and Design of R.C. Frame Building Using Capicity Design Method

Abstract

An earthquake resisting building is one that has been deliberately designed in such a way that; remains safe and suffer no appreciable damage during destructive earthquake. However, it has been seen that during past earthquakes many of the buildings were collapsed due to failure of vertical members. Therefore, it is necessary to provide vertical member strong so as to sustain the design earthquake without catastrophic failure. Capacity Design Concept is aiming towards providing vertical members stronger compared to horizontal structural elements. A structure designed with Capacity Design Concept does not developed undesirable failure mechanism or modes of inelastic deformation which cause the failure of the structures. In Capacity Design of earthquake resisting structures, elements of primary lateral load resisting system are chosen suitably and designed & detailed for energy dissipations under sever inelastic deformations.

Present study was aiming towards applying Capacity Design Concept to 3-D R.C frame building designed by Conventional Design Methodology. An attempt has been made towards comparison of parameters like Storey Drift, Ductility Ratio and Displacement Ratio for 3-D R.C frame building. However, before exploring actual 3-D R.C frame building, a fundamental understanding of a Capacity Design Method has been obtain through the solution of 2-D frame. The 2-D frame was analyzed and designed using IS: 456-2000 and IS: 1893-2002 (Part – I) considering moderate seismic zone. A Capacity Design Concept in the form of proper strength hierarchy, detailing of critical regions and predefined hinge zones were applied to 2-D frame. The same methodology had later on used for the solution of 3-D R.C frame Building.

A Nonlinear Static Analysis (Pushover Analysis) had been used to obtain the inelastic deformation capability of building with Capacity Design Concept. The Pushover curve for user defined Nonlinear Hinges based on FEMA 273 & ATC-40 were implied through commercially available software ETABS – 8.5.1 of CSI Berkley, USA available at P.G Computer Center of Civil Engineering Department, Institute of Technology, Nirma University, Ahmedabad. It was found that Capacity Design Concept helps R.C Frame to undergo substantial inelastic deformation before collapse and makes structure to behave ductile.