Study on Shear Strength of Reinforced Concrete Beams Subjected to Dynamic Loading

钢筋混凝土结构的剪切破坏一般为非延性破坏。因此，必须努力遏制这种失败。钢筋混凝土梁在静载作用下发生弯曲破坏时，往往会先在剪力作用下发生破坏，然后才发生弯曲破坏，本文对钢筋混凝土梁在动载作用下的剪切破坏进行了试验研究。试验中采用的主要因素有抗拉配筋率、剪跨比、反复加载的有效截面高度和配箍量，以及疲劳试验加载时的环境条件。试验结果表明，由于剪力变大，剪切破坏容易导致重复加载的早期阶段。在这种情况下，增加箍筋量以避免破坏的影响变得很小。此外，钢筋混凝土梁在水中的疲劳强度比在空气中的疲劳强度低15-25%，在广泛的试验条件下，剪切破坏是导致疲劳破坏的原因。

Shear failure of reinforced concrete structure is nonductile in general. So, an attempt must be made to suppress such a failure. It is known that the reinforced concrete beam which is designed to cause the flexural failure under static loading, sometimes happens to fail by shear forces prior to cause flexural failure.In this study, shear failures of reinforced concrete beams subjected to the dynamic loading such as the actions repeated reversed large deformations and fatigue, were investigated experimentally. The main factors adopted in this experimental works, are tensile reinforcement ratio, shear span ratio, effective depth of the cross section and the amount of stirrup for reversed repeated loading tests, and environment conditions during loading for fatigue tests.Experimental results show that the shear failure tend to cause earlier stage of repeated loading according to the shear forces becomes large. And under such conditions, the effects of increasing the amount of stirrup to avoid the failure, becomes small. Also, fatigue strength of reinforced concrete beams subjected in water is 15-25% inferior to that of subjected in air and shear failure causes in wide range of testing conditions.