Evaluating Impact Resistance of Externally Strengthened Steel Fiber Reinforced Concrete Slab with Fiber Reinforced Polymers

School of Civil, Environmental and Architectural Engineering, Korea University, Seoul 136-713, KoreaABSTRACT Recently, as construction technology improved, concrete structures not only became larger, taller and longer butwere able to perform various functions. However, if extreme loads such as impact, blast, and fire are applied to those structures,it would cause severe property damages and human casualties. Especially, the structural responses from extreme loading are totallydifferent than that from quasi-static loading, because large pressure is applied to structures from mass acceleration effect of impactand blast loads. Therefore, the strain rate effect and damage levels should be considered when concrete structure is designed. Inthis study, the low velocity impact loading test of steel fiber reinforced concrete (SFRC) slabs including 0%~1.5% (by volume)of steel fibers, and strengthened with two types of FRP sheets was performed to develop an impact resistant structural member.From the test results, the maximum impact load, dissipated energy and the number of drop to failure increased, whereas the max-imum displacement and support rotation were reduced by strengthening SFRC slab with FRP sheets in tensile zone. The test resultsshowed that the impact resistance of concrete slab can be substantially improved by externally strengthening using FRP sheets. Thisresult can be used in designing of primary facilities exposed to such extreme loads. The dynamic responses of SFRC slab strength-ened with FRP sheets under low velocity impact load were also analyzed using LS-DYNA, a finite element analysis program withan explicit time integration scheme. The comparison of test and analytical results showed that they were within 5% of error withrespect to maximum displacements.Keywords : low velocity impact load, strain rate, steel fiber reinforced concrete, fiber reinforced polymer, LS-DYNA