Experimental Study On The Anti-Blast Performance And Load-Bearing Capacity Of Non-Treated,Reinforced And Damage-Repaired RC Slabs

As a key transportation hub,the bridge construction plays a very important role in social economy and national defense transportation.In war and terrorist attacks,Bridges are vulnerable targets.Reinforced concrete(RC)slabs are widely used in the field of bridge construction and it has increasingly become one of the research hotspots to study the reinforcement and repair technique at home and abroad.In this paper,the model tests were taken to study the anti-blast performance,anti-blast reinforcement methods of RC slabs and the load-bearing capacity after repaired.The main works and achievements are as follows:(1)The anti-blast performance of RC slabs has been studied by experiments.Based on the similarity theory,the scaled models of the RC bridge deck were designed and made,then the performance parameters of related materials were measured.The failure modes and damage parameters of RC slabs were obtained by the blast experiments with 4 different explosive quantities(150g?450g).The results show that under the action of contact blast,an infundibular crater with cracks around appears on each of the upper and lower surfaces of every RC slab.The damage degree of RC slabs deepened with the increase of explosive quantity.When the explosive quantity is 150 g,225g or 300 g,explosion spalling occurs on the RC slabs,with a certain bearing capacity remaining;when the explosive quantity is 450 g,the perforation appears in the RC slab because of punching shear failure,without load-bearing capacity remaining.(2)The strengthening methods for improving the anti-blast performance of RC slabs have been studied.The RC slabs were strengthened by bonding CFRP plates and spraying polyurea elastomer(SPUA)respectively,then the comparative test of anti-blast performance was carried out.The results show that the CFRP plates were detached from the RC slabs due to the reflection and stretching of the shock wave interface.The failure phenomenon and damage degree are similar to those of the unreinforced specimens with the same explosive quantity and the difference in damage parameters is within 15%,so this method is not feasible.The polyurea sprayed can prevent the back concrete from flying,which shows a certain protective performance.(3)The bearing capacity of RC slabs repaired with CFRP fabrics were studied by tests.The RC slabs were repaired and reinforced with CFRP fabrics,and the static tests of three dividing point loading were taken.The results show that the stiffness of the RC slab bonded with CFRP fabrics raises and the number of cracks decreases,with the ultimate bearing capacity of the slabs increasing by about 1.4 times.The tested specimens can basically be restored to the original load-bearing capacity after repaired.When the ultimate load-bearing capacity is reached,the unreinforced specimens are destroyed due to the yield of the tensile steel bar,while the strengthened specimens are destroyed due to the stripping of the bonding CFRP fabrics or the crushing of the concrete between oblique cracks.