Experimental And Numerical Investigation Of Clay Brick Masonry Walls Strengthened With Spary Polyurea Elastomer Under Blast Loads

The masonry structure is an architecture which has a long historical standing and still widespread used over the application area today.Due to the materials' brittleness of masonry structure,masonry structure's bending strength,lengthening strength and shearing strength are very low.The damage of masonry structure is more serious,especially in terrorist attack and explosion hazard.Research suggests that most casualties of terrorist attack are due to fragmentation of walls and windows.The existing strengthening techniques focus the design methods of seismic defensive criterion.Correspondingly,there is less study on the anti-blast ability of masonry wall.So it is of great applied significance to do new design and engineering techniques on increasing explosion resisting capacity of target structure to deal with the threat of terrorist attacks.The use of spray polyurea elastomer technology in structure reinforcement is a new-style strengthening technology.Polyurea elastomer materials have some virtues such as high elongation,high strength,high resistance to impact,and high resistance to corrosion,anti-aging.And polyurea elastomer materials have the advantages about various subjects,such as coating,rubber,plastics and glass fiber reinforced polymer.Spray polyurea elastomer technology have various virtues such as shorter construction period,quickly solidified,solvent-free material and anti-flow linked.Compared with other kind of materials,polyurea elastomer has more extensive of usage scope and more remarkable characteristics.The study of the spray polyurea elastomer using on masonry structure have rapid development in recent years.Research suggests that spray polyurea elastomer improve the anti-blasting ability of masonry structure,reduce fragmentation of walls and windows.Experimental study in the world of spray polyurea elastomer using on masonry structures focus on the masonry build by hollow aerated concrete block which have different structural and material characteristics compared to masonry structure in our country.The block surface of masonry structure common occurred broke in the blast side which has a negative effect on the study of anti-explosion mechanism of spray polyurea elastomer strengthening.The reports about the experimental study of spray polyurea elastomer strengthening masonry structure have not yet seen.The finite element method focuses on the experimental study of spray polyurea elastomer strengthening masonry structure abroad.This paper focuses on variation effect of strengthening thickness,strengthening modes,material parameters of spray polyurea elastomer on the anti-blasting ability of clay block masonry wall structure strengthening by spray polyurea elastomer.The unsupported experiments about 2 clay block masonry unit walls without strengthening and 1 clay block masonry unit walls double-sided strengthening by spray polyurea elastomer were carried out under blast loading.The reinforcement effect of spray polyurea elastomer on clay block masonry unit walls and failure mode in different reinforcement plans was discussed.The results showed that spray polyurea elastomer can significantly improve the anti-blast ability of full-scale clay brick masonry unit wall without supported.The supported experiment about 1 clay brick masonry unit wall without strengthening,1 clay brick masonry unit wall with blast-side strengthening and 7 clay brick masonry unit wall with double-sided strengthening by spray polyurea elastomer were carried out under blast loading.The effect of strengthening mode and strengthening thickness of polyurea on clay masonry were discussed in different reinforcement plans.The results showed that back spray polyurea elastomer can wrap around the fragmentation of walls under blast loading.Spray polyurea elastomer can significantly reduce the displacement and deformation of clay brick masonry unit wall,increase the anti-blast ability of wall.The strengthening experiments about 6 reduced-scale clay block masonry filler walls with double-sided spry polyurea elastomer were carried out under blast loading.It focus on the failure mode and bearing explosive limit pressure of reduced-scale clay brick masonry filler wall without reinforcement.The reinforcement mechanism of spray polyurea elastomer increasing the anti-blast ability of clay brick masonry filler wall was discussed.It discussed the effectiveness that existing failure judgment criteria on masonry wall were applied to the failure judgment of reduced-scale clay brick masonry unit wall strengthen by spray polyurea elastomer.The results showed masonry wall strengthening by spray polyurea on double-sided have more anti-blast ability than other strengthening modes.The spray polyurea elastomer on the back surface can wrap around the explosive debris of walls.The existing failure judgment criteria did not apply to the failure judgment of clay brick masonry strengthening by spray polyurea elastomer.Using LS-DYNA finite element analysis software,the separate finite element models of 15 reduced-scale clay brick masonry filler walls were established.It focuses on the dynamic response of reduced-scale clay brick masonry filler wall under different operating conditions.The effect of explosive charges,strengthening mode and strengthening thickness on anti-blast ability of clay brick masonry reinforcement by spray polyurea elastomer were study.The reinforcement mechanism of blast-sided coat and back coat were discussed.The results showed that the thickness increasing of blast-sided coat can significantly improve the anti-blast ability of reinforcement masonry.But the thicknesses increasing of back surface coat do not affect the anti-blast ability of reinforcement masonry.The anti-blast ability of double-sided reinforcement mode is significantly greater than other reinforcement modes.Using LS-DYNA finite element analysis software,the separate finite element models of 12 reduced-scale clay brick masonry filler walls were established.The modulus and density of blast-sided coat and back coat were successive increase respectively.It studied the effect of modulus and density change in values on anti-blast ability of clay brick masonry wall reinforcement by spray polyurea elastomer.The results showed that modulus increasing can significantly improve the anti-blast ability of reinforcement clay brick masonry wall.But density increasing can significantly reduce the anti-blast ability of reinforcement clay brick masonry wall.