ELASTIC RESPONSES OF RC BEAMS WITH VISCOUS-SPRING SUPPORTS SUBJECTED TO LOW VELOCITY IMPACT

The responses of reinforced concrete beams with viscous-spring supports subjected to low velocity impact are analyzed based on the theory of Euler-Bernoulli beams. The equations of dynamic responses for elastic phases are established according to the quasi-static Hertz contact theory and vibration equations of beams under dynamic loads, then the calculation methods of dynamic functions for both beams and supports are given. Calculation examples show that the peak displacements of beams with viscous-spring supports are reduced obviously, the times corresponding to peak displacements are delayed, and the impact resistances of the beams are enhanced. The values of dynamic functions for both beams and supports are reduced due to the additional forces on the supports, and the vibration frequencies of beams tend decrease because of the viscous-spring supports. The values of dynamic functions for both beams and supports decrease with the increasing of support dampings, and the attenuation values of dynamic functions are augmented by the support dampings. Except for the viscous-spring supports, the dynamic responses of beams can be reduced by shortening the duration of dynamic loads.