Damage Assessment of RC Columns Strengthened by UHPFRC Jackets against Blast Loading

Regarding the increase of terrorist threats and the possibility of blast events in the vicinity of industrial and residential buildings, the assessment of the resistance of all kinds of structures against the blast loads is very important. Concrete materials are more liable to threats than other kinds of structures Because of low ductility. One of the solutions is to use some kinds of engineered cementitious composites and fiber reinforced concretes. In this study, usage and employment of ultra-high performance fiber reinforced concretes (UHPFRC’s) that have high tensile strength and a considerable capacity of energy dissipation regarding the strengthening of the structures against the blast loading has been taken into consideration. In this regard, by choosing the material model based on the plasticity and damage for materials of ultra-high performance fiber reinforced concretes; first of all, the models of the columns made of UHPFRC during the field blast test done by other researchers’ studies, is simulated in a numerical manner and after ensuring the acceptable accordance of computational responses with recorded data during the blast test, using the modern method of jacketing with cover of ultra-high performance fiber reinforced concrete, the strengthening of the normal RC columns by using those jackets made of UHPFRC has been studied numerically. The results of numerical analyses show that the maximum displacement of models strengthened by UHPFRC will decrease considerably in proportion to unstrengthened models. For example, for 50 mm thick UHPFRC jacket, maximum mid-span displacement decreases about 63% (from 153 mm to 55 mm). Also, after generating the pressure-impulse (P-I) diagram, in order to assess the damage to the strengthened columns, it was made clear that by using the UHPFRC cover, the bearing capacity of the column against the blast load in the near and far field area, will increase considerably.