PERFORMANCE BASED DESIGN OF RC MEMBERS SUBJECTED TO BLAST LOADING

Abstract

The response of reinforced concrete (RC) against extreme loading is very complex. After reaching a certain amount of elastic deformation, elastic-plastic behaviour is observed. Finally, failure may be caused due to several mechanisms, such as flexure, direct shear, diagonal shear, or flexure-shear. Analytical modelling solution for RC structural element against blast loads is of great interest in engineering applications. Acquiring such knowledge may be of great significance to enable the engineers to understand the failure mechanism and to carry out response and design assessment studies of structures taking cognizance of various types of failure modes against wide-ranged blast scenarios. For many years, the design of RC structural elements has been carried out on the basis of Biggs’ design approach that considers only the flexure deformation behaviour of the structure. However, experimental studies display that the response of structures remains flexure dominant for a very narrow range of blast scenarios (i.e., distant blast scenarios), and subsequently failure modes like direct shear and diagonal shear are observed for a wide range of blast loading. In view of it, the direct shear-support slip failure mode concept is gaining ever-wider acceptance in the design procedures to make the design more rational and accurate. Knowledge of the actual collapse mode and the ultimate strength of structural elements significantly improves the ability of the designer to construct damage-tolerant structures. Within the framework of performance-based design, the structures are commonly designed to satisfy pre-requisite targets in the form of damage, displacement, or ductility. The requirements for any mathematical model applied to engineering problems are to be able to predict response accurately and economically. For this reason, mathematical models have to be carefully studied and fully understood before they can be applied. The primary objective of the research was to computationally evaluate the behaviour/ response of reinforced concrete structural elements subjected to a varying range of blast scenarios. The formulation of an improvised coupled SDOF system is employed as the basic tool for the analysis, which offers the interaction between the direct shear–slip at the support and the flexure response for blast-loaded reinforced concrete members.