Abstract
During an earthquake structures are subjected to dynamic loading. The strength and mode of failure of RC members are influenced by high strain rate. However, there is no sufficient data available to fully document the effect. In this study, column specimens were tested during either static or dynamic horizontal loading under the high axial load ; the effect of strain rate on strength and mode of failure of RC members was investigated. The results obtained in this study could be summarized as follows : 1) The strain rate just prior to the maximum strength value was about 2×104 μ/sec during dynamic loading ; the maximum strength and mode of failure were influenced by the strain rate. 2) For flexural failure, the crack patterns during dynamic loading were slightly different from the ones during static loading ; however, the modes of failure were similar. For shear failure, the crack patterns, the processes of failure and the degree of damage during dynamic loading were different from those during static loading. 3) For the effects of strain rates, the values of initial stiffness during the dynamic loading were 10 % greater than those during static loading ; the values of stiffness at the yielding of members were 15 %, the maximum strengths of flexural failure were 10 % and of shear failure were 25 % greater than those during static loading. 4) When material strengths were increased with the increase of the strain rate, the ratios of the experimental values to the calculated values during dynamic loading were similar to those during static loading. 5) For flexural failure, in the plastic zone the strengths were also influenced by strain rates ; the strengths during dynamic loading were 10 % greater than those during static loading.
