Damage Assessment Of RC Slabs Subjected To Blast Load

Assessment of structural damage under blast load is a complex subject imbued with uncertainty and vagueness. There are many simplified methods to deal with it, one of which is pressure-impulse (P-I) diagram method. P-I diagrams are commonly used in the preliminary design or assessment of protective structures to establish safe response limits for given blast load.In this paper, firstly, the dynamic response of a SDOF system is introduced. The parameters effecting the maximum deflection of the slabs, such as the ratio of reinforcement and boundary conditions, are studied using software LS-DYNA. Then, the damage modes of two-way RC slabs subjected to blast load are analyzed. Thirdly, P-I diagram method is applied to two-way RC slabs to assess their damage level. Current practice in generating the pressure-impulse diagram for structure components is primarily based on the simplified SDOF model, which is not suitable for RC slabs. Therefore, a new damage criterion for RC slabs is defined, i.e., residual load carrying capacity. In this paper, the static load carrying capacity of a two-way RC slab before and after blast loading is studied through numerical analysis. With a series of numerical simulations, P-I diagrams are generated according to the defined damage criterions. Based on the numerical results, analytical formulae to generate the pressure-impulse diagram for two-way RC slabs are also derived.Some main conclusions are drawn as follows: The thickness, boundary conditions and standoff distance influence the maximum deflection of the blast loaded slab significantly; There are three main damage modes of RC slabs when they are subjected to blast load, namely flexural damage, brittle damage and the combination of the two; The damage criterion defined is suitable for the assessment of slab damage levels.