A parametric study is presented to determine the end reactions in a reinforced concrete beam under dynamic loading conditions, arising out of impact or blast. The main variables in the study are the material properties of the beam, the beam geometry, and peak value, duration, distribution and time of rise of loads. The dynamic loads are approximated by a rectangular (pure) pulse or triangular load-time function with peak pressure at zero time and decreasing linearly to zero. The parametric study is executed using the equivalent single degree of freedom method of analysis, which assumes perfectly elastic-plastic material properties for reinforced concrete. In order to assess the validity and demonstrate the effectiveness of this technique, a two-dimensional finite element program FEABRS which takes into account the effects of the non-linear behaviour of concrete as well as strain rate effects is employed. A confirmation of these two approaches is obtained by carrying out some of the analyses with the aid of a general purpose finite element program DYNA3D. On the basis of the predictions of the analytical and numerical experimentation, it is concluded that for uniform loads of very pure impulsive nature, the end shear forces obtained from the single degree of freedom approach can be relied upon for general preliminary design of structural components. The results obtained show that the end shear forces obtained using the analytical technique were generally about 1-15 percent higher than the corresponding values obtained using the finite element method for the triangular blast load, thus being conservative and on the safe side. For the ramp load, the Biggs method gave only an underestimate of 6 percent.

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