RISK REDUCTION AND EXTERNALLY FRP RETROFITTING OF RC COLUMNS SUBJECTED TO EXTREME LOADING CONDITIONS

Iran is a country of particular geopolitical significance owing to its location in the Middle East and central Eurasia. Owing to its strategic location, Iran has been the centre of attention for traders, businessmen and big powers for a long time. Therefore, it might be exposed at risk. The recognition necessity of risk and the resisting trend is essential for structural engineering. The analysis and design of reinforced concrete structures subjected to extreme loading condition such as blast loads require a detailed understanding of blast phenomena and the dynamic response of various structural elements. In this paper, the response of RC columns subjected to constant axial loads and lateral blast loads is examined. Different shapes of columns, i.e. square, rectangular and circular shape, are considered in this research. A nonlinear finite element program is used to model RC columns with different boundary conditions and using the mesh less method to reduce mesh distortions. For the response calculations, a constant axial force is first applied to the column and then, lateral blast load is applied and the response time history is calculated. Blast load effects on the columns quantified in terms of failure mechanisms through simulation of the whole column detailing in the nonlinear finite element program. According to the analysis results, a retrofitting scheme using FRP wraps is designed and validated with a blast load test. Comparison of results clearly demonstrates that columns with externally FRP retrofitting can withstand higher levels of blast loads. It means that retrofitting RC columns with FRP is a proficient way to ensure protection of buildings under the blast loading.