Analysis of Security Wall Panels Under Blast Loading Using Computer Aided Tools

Abstract

Frequent terrorist’s activities, the use of vehicle bomb blast and Improvised explosive devices (IEDs) has put the task of protection against blasts at the fore front for Engineers. Terrorists mostly fixated targets where human loss and economic loss is significantly high. Blast event near buildings may damage structural and non-structural members. Major damage causing from blast explosion is due to huge dynamic force, which are mainly more than anticipated design load and resultantly, structures collapsed. It is more challenging to analyze and design structures against blast loading because of incalculable blast scenarios. It is very difficult to study effect of blast loading on structures due to numerous aspects i.e kind of detonation charge, material, placement and standoff distance etc. Hence for designing of blast resistant structures, maximum possible scenarios are necessary to be cogitated and which may not be achievable without use of software. RCC wall panels are commonly used for protecting the important installations/ buildings. In this research, investigation of different blast parameters have been carried out i.e pressure - time history, peak pressures, displacements, kinetic energy and misses stresses. For this purpose, an existing arrangement of NESCOM Hospital, FaqirApi Road Islamabad, Pakistan has been selected. Huge computational efforts were required to model the whole building. To reduce computational efforts, 3x walls (RCC wall panels, boundary wall and structural wall) have been considered. Three RCC wall panels placed side by side having dimensions of each (3 ft length, 10 ft height, 3 ft – 4 inch thickness from bottom and 8 inch thickness from top) in front of boundary wall at a distance of 3 ft. Dimensions of boundary wall are (9 ft – 3 inch length, 10 ft height and 4.5 inch thickness) whereas structural wall having dimension (9 ft – 3 inch length, 10 ft height and 9 inch thickness) are placed apart at a distance of 20 ft. ANSYS AUTODYN 3D hydrocode software have been used to simulate the model and to study different blast parameters. A total of four charge weights have been simulated on basis that a motor cycle can carry 50 Kg TNT, motor car can carry 100 Kg TNT, Mazda can carry 400 Kg TNT and Truck can carry 600 Kg TNT. Blast parameters have been studied considering all four TNT explosion at face of RCC wall panels and explosion at a distance of 10 ft. Analysis have been carried out and weaknesses of existing arrangements identified. Literature was reviewed for suggesting the strengthening technique for existing structures against blast loading. It vi was found that steel strips are one of most locally feasible technique for strengthening existing structures and significantly enhances the blast performance of structures. It has significantly reduced Z-direction displacements, kinetic energy, misses stresses and pressure wave. Keywords: Blast loading, TNT Explosion, RCC wall panels, Strengthening Technique