| Summary: | 碩士 === 國防大學理工學院 === 軍事工程碩士班 === 98 === High Strength Concrete can provide better blast-resistant capacity than normal strength concrete, but effect of volume fraction of steel fiber is not clear. In this study, volume fractions 0.0%, 0.5%, 1.0% and 1.5% of steel fiber were considered for high strength concrete slabs with a dimension of 50*50*15 cm. Compressive strength of high strength concrete was controlled within 75〜100 MPa. Slabs were subjected to contact explosion of explosive C 4 with a weight of 30, 50, 65, 100, 135 and 170 g. The shape of explosive was spherical. After explosion, crater sizes at front and back sides of slabs were investigated. For explosions of different weights of explosive, the results showed that steel fiber with volume fraction of 0.5% to 1.5% can reduce crater diameter 35% and depth 80% at front side of slabs, compared with slabs without steel fiber. The crater at back side was controlled by volume fraction of steel fiber for 100g C 4 explosive and no crater occurred beyond 1% volume fraction. The compressive strength and splitting tensile strength can be improved respectively 16% and 48% for tests with steel fiber. Besides, the flexural strength can be improved 8% for toughness. For explosion test of high strength concrete with steel fiber, the diameter and depth of front crater decreased 35% and 80%. However, the destructive range of crater at the back side can be controlled by volume fraction. For numerical simulation, shear strain erosion effect of elements is main parameter of destructive range at the front side. Besides, phenomenon of the front crater is also investigated for high strength concrete after explosion. The research shows that failure shear strain is main controlled factor for the destruction of high strength slabs. With increasing the failure shear strain, the front destructive diameters of high strength concrete slabs are decreasing. Hence, the value of failure shear strain is proposed as 0.001 for high strength concrete without steel fiber, but 0.004 for volume fraction 0.5-1.5% 0f steel fiber.
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