Abstract: The concrete strength of the structure can be significantly increased when the structure is under dynamic loading conditions.The increasing effects are normally discussed via concrete DIF,dynamic increasing factor,which is the ratio between the dynamic and static strength.The paper studied the concrete DIF numerically compared with the tests results in both in tension and compression,and pointed out that the compressive DIF as observed from standard sample tests is mainly attributable to the dynamic structural effects,whereas for concrete under tension the DIF is deemed to be governed by different mechanisms,probably more from the material and micro-fracture level.