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This paper seeks to explore the vulnerability of a typical reinforced concrete (RC) building against progressive collapse as a consequence of internal blast. The emphasis has been on the local model analysis for which two approaches - one involving the use of CONWEP and another using fluid-structure interaction through Alternate Lagrangian Eulerian (ALE) element formulation - have been employed. The finite element model of the structure was created using LS-DYNA, which uses explicit time integration algorithms for solution. The results of the study are proposed to be used to control or prevent progressive collapse of the building. In order to validate the employed numerical models, blast test results of a RC column available in literature were validated using LS-DYNA modeling of the RC column. The deformation response of the column was compared which showed acceptable prediction. [ABSTRACT FROM AUTHOR]

The recent terrorist attacks all around the world and the evidence of the threats found especially in the Kingdom of Saudi Arabia have prompted the concerned authorities to address the risks to the critical infrastructure of the Kingdom. Understanding of the progressive collapse mechanism is an essential step to protect buildings against blast attacks. Buildings are very vulnerable to progressive collapse if one or more columns are lost due to extreme loadings. It is also important to study the likelihood of progressive collapse of buildings in Riyadh to avoid catastrophic events. The paper presents progressive collapse analysis of a typical multi-storey steel framed building in Riyadh to establish its vulnerability when subjected to accidental or terrorist attack blast scenarios. A commercial finite element (FE) package (LS-DYNA) was used to simulate the building response under blast generated waves. The numerical modeling was validated using the results of a published example of tubular steel beam subjected to blast load. Based on the FE analysis results, recommendations are given to mitigate (or control) the progressive collapse potential of steel buildings. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of blast loads generated as a result of explosive charges on the existing exterior RC circular columns of a typical building in the city of Riyadh. A procedure has been developed for evaluating the dynamic characteristics of the circular column with and without retrofitting. A wide range of parametric studies have been performed as part of this investigation to examine the effects of stand-off distance, charge weight and the presence of CFRP retrofitting on the level of damage to the RC column. The nonlinear finite element analysis was carried out using LS-DYNA software with explicit time integration algorithms. Different charge weights of 100, 200, 500 and 1000 kg equivalent weight of TNT at stand-off distances of 1, 4 and 15 m were considered. Results described in this paper indicate that CFRP strengthening could be an effective solution to limit the damage caused by moderate explosions. The stand-off distance was found to play a very important role in mitigating the adverse effects of a blast. The results also indicate that the maximum lateral deflection experienced by the column decreased exponentially with the increase in the stand-off distance and also decreased for the columns strengthened with CFRP, compared with the unstrengthened columns. [ABSTRACT FROM AUTHOR]

The paper seeks to explore some aspects of the current state of knowledge on progressive collapse in the technical literature covering blast loads and structural analysis procedure applicable to reinforced concrete (RC) buildings. The paper describes the progressive collapse analysis of a commercial RC building located in the city of Riyadh and subjected to different blast scenarios. A 3-D finite element model of the structure was created using LS-DYNA, which uses explicit time integration algorithms for solution. Blast loads were treated as dynamic pressure-time history curves applied to the exterior elements. The inherent shortcomings of notional member removal have been taken care of in the present paper by simulating the damage of structural elements through the use of solid elements with the provision of element erosion. Effects of erosion and cratering are studied for different scenarios of the blast. [ABSTRACT FROM AUTHOR]