EXCEPTIONAL ACTIONS: BLAST LOADS ON REINFORCED CONCRETE STRUCTURES

The paper deals with the flexural failure of Reinforced Concrete elements under blast loads. The main topics and results of a PhD thesis are here summarized, whose aim was to develop theoretical dynamic and energy models capable of evaluating the dynamic response of R.C. elements under explosive load. In the original work, models with different levels of complexity were presented, but for sake of simplicity only the simplest Single Degree Of Freedom (SDOF) system has been here discussed. Strain-rate effects are also accounted for. A sensitivity analysis to determine the key parameters in beam response under blast load has been developed by means of the SDOF model. Results of numerical simulations obtained in terms of deflection and velocity have been fitted by proper polynomial least-square interpolation. Among the various interpolations considering several parameters (peak load, positive phase duration, slenderness, span length, concrete strength, reinforcement ratio etc.) slenderness (corresponding to stiffness) and peak load prove to be the most important parameters, but span length (corresponding to mass) is also a key parameter. Other variables such as concrete strength and reinforcement ratio do not seem to have a high correlation with results. Lastly some suggestions for blast-resistant bridge design are presented