Research Article Investigation of Axial Strengthened Reinforced Concrete Columns under Lateral Blast Loading Mohammad Esmaeilnia Omran and Somayeh Mollaei Department of Civil Engineering, University of Kurdistan, Sanandaj, Iran Correspondence should be addressed to Somayeh Mollaei; s.mollaei@eng.uok.ac.ir Received 26 May 2017; Revised 25 August 2017; Accepted 6 September 2017; Published 16 October 2017 Academic Editor: Abdul Qadir Bhatti Copyright © 2017 Mohammad Esmaeilnia Omran and Somayeh Mollaei. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Diferent factors can afect blast response of structural components. Hence, experimental tests could be the best method for evaluating structures under blast loading. Terefore, an experimental explosion loading has been done on RC members by the authors. Four RC components, with identical geometry and material, with and without axial load were imposed to air blast. Observed data of the members’ response under blast loading was used for validation of fnite element modeling process using ABAQUS sofware. With respect to complexity, limitations, and high costs of experimental tests, analytical studies and sofware modeling can be good alternatives. Accordingly, in this paper, the behavior of 6 diferent models of normal and strengthened RC columns under blast loading was evaluated using ABAQUS. Strengthening confgurations considered here were designed for enhancing axial capacity of RC columns. Terefore, we can investigate the efectiveness of axial strengthening of column on its blast resistance capacity and residual axial strength. Te considered strengthening methods were diferent steel jacket confgurations including steel angle, channel, and plate sections. Te results showed that retroftting signifcantly improves blast performance of the columns. Moreover, residual strength capacity of the columns strengthened with steel channel is higher than the other models. 1. Introduction A wide range of engineering structures such as high-rise buildings, bridges, tunnels, dams, platforms, and military and security shelters are constructed by reinforced concrete materials. Tere has been much attention to reinforced con- crete (RC) structures performance under static and seismic loads but evaluation of RC structures’ behavior under blast loading and identifcation of their dynamic characteristics are important for valid design of concrete structures given that many structures may face extreme dynamic loading such as explosion in their lifetime. Columns are the key load bearing elements in building structures and in case of an explosion event near the building, columns are mostly the frst structural elements which are afected by lateral loading caused by explosion. Studying the explosion of explosives has been considered by scientists and researchers and the eforts of scientists and researchers in the feld of shock wave physics became important since the 20th century [1]. One of the pioneers in this feld is Hopkinson (1915) who conducted extensive research and tests and formed the Hopkinson- Cranz scaling law [1, 2]. Recently, many diferent studies have been conducted on diferent types of concrete structures such as columns under explosion loads [3–7]. With respect to complexity, limitations, and high cost of laboratory researches in this feld, analytical studies and sofware modeling can be a good alternative to laboratory and experimental methods. Finite element analysis method is a powerful and useful tool for researchers and structural designers to have an accurate estimation of behavior of structures under blast loading without requiring high costs and great difculty. Shi et al. (2008) defned a failure criterion based on residual axial capacity for reinforced concrete columns and drew -  (pressure-impulse) diagrams for columns based on this failure criterion using numerical modeling by LS-DYNA sofware [8]. Bao and Li (2010) conducted parametric studies on RC columns using numerical modeling in LS-DYNA [3]. In line with the most important results, reinforced concrete columns must be designed in such a way that their moment Hindawi Shock and Vibration Volume 2017, Article ID 3252543, 18 pages https://doi.org/10.1155/2017/3252543