Damage Analysis Of Reinforced Concrete Floor Slab Subjected To The Combined Action Of The Explosion And Fire

As the frequency of the terrorist attacks, building gas explosions and otheraccidents, damage analysis of structure unit under a combined action of internal blastand fire has been an urgent problem calling for the solutions. This paper focuses onthe response of reinforced concrete floorslab under a combined action of internalblast and fire provides the basis for the preparation of orders of blast and fireresistant design on concrete structures.A three-step method is adapted to consider the combined action of internal blastand fire. The first is to acquire the initial damage of floorslab with an internal blastload acting alone. The second is to acquire the temperature distribution of floorslabunder fire load. The three step is to acquire the support reaction force which isequivalent to thermal stress and analyze combined action of internal blast and fireloads using finite element dynamic analysis software LS-DYNA.An analysis of a typical floorslab under combined action of internal blast andfire loads is presented, on the basis of initial damage under the internal blast load,with material strength and stiffness reduction at specific temperature distribution,applying reaction force which is equivalent to thermal stress, the result shows thatthe damage mode changes with the TNT equivalent of the internal blast, analysis ofthe temperature distribution by using finite element software LS-DYNAanastomosed preferably to the test result, the support reaction force which isequivalent to thermal stress is related to the initial damage under the internal blastload, the mid-span displacement increases under fire load, and the increaseamplitude of displacement is related to the internal blast load.The results show that the floor generates an initial damage under the blast loads,and the displacement increased with the action of following fire loads. The fire loadcan cause an obvious softening effect on the material and a more serious plasticfailure on the floor. The three-step method can obtain the reinforced concretefloorslab span displacement-time curve under a combined effect of indoor internalblast and fire, and thus can achieve a better engineering usability.