PERFORMANCE ASSESSMENT OF SEISMICALLY-DESIGNED STEEL MOMENT RESISTING FRAMES AGAINST NUMERICAL SIMULATED OF BLAST WAVE

One of the important threats for critical structures is the terrorist attacks. Therefore, performance assessment of critical structures, which are designed, based on seismic regulations, against the effects of blast wave is of great importance to policymakers. In this paper, the main goal is to present the explosion load time-history through the realistic modelling of 3-D block of the structure and the surrounded air. Besides, towards the structural performance assessment, the finite element model of the sampled seismically-designed structure is excited by the achieved realistic time-history of the explosion load. To this end, firstly, the sensitivity of computational fluid dynamic (CFD) simulation of the blast wave to the mesh size and cubic dimension of the air flow, surrounding the structure, is presented. In order to study the free propagation of blast waves in air, a 28 m by 28 m by 8 m volume of air was numerically modelled with five different mesh sizes: 25, 50, 100, 150 and 300 mm. The pressure response on the building block is compared with that of calculated by empirical formulations. Furthermore, the sensitivity of pressure response to the mesh size is studied for various scaled distances and the suitable mesh size, to simulate the accurate blast pressure on the building, is proposed. Secondly, the performance of seismically-designed 10-story steel moment-resisting frame is investigated against the simulated blast wave pressure. Numerical simulation of the blast wave for various mesh sizes reveals that the difference between the numerical and experimental responses is increased when the scaled distance decreases. Furthermore, the more scaled distance is considered the less will be the relevant sensitivity to the mesh size. The accuracy of the empirical formulations is suitable for moderate and far scaled distances. Regarding the structural performance, the results show that the performance of the assumed structure is not affected by the side, rear and roof blast pressure. Rather it is affected by the blast pressure on the front side of the structure

Keywords:

Simulated Blast Wave , Steel Moment-Resisting Frame , Performance Assessment , Seismic Design