Abstract:To investigate the behavior of precast concrete （PC） beams with pressed steel sleeves under impact loads， a total of 6 beams with pressed steel sleeves connection of 3 different assembly types， and 2 cast-in-place reinforced concrete （RC） beams were tested under free-falling drop-weights， while 4 corresponding beams were tested under static load. The assembly form included mid-span splice， end splice， and composite beam forms. The research focused on the effects of different hammer masses and impact velocities on the dynamic responses of the precast concrete beams under the same impact energy， including failure modes， mid-span deflection， impact force， and deformation energy. The results obtained are as follows： the failure modes and crack development of RC and PC beams with different splicing types are basically consistent， but the cracks in mid span splicing beams are more concentrated at the splicing part， and the overlapping of splicing sections and impact positions is more unfavorable to the structure. The pressed steel sleeve is reliable as the assembly and connection form of precast concrete beams. When the impact energy of 6 762 J remains unchanged， the increase of impact mass from 230 kg to 400 kg has little effect on the peak impact force. But the average impact force has increased， and the increase in amplitude of the three types of splicing PC beams exceeds 25%. The maximum deformation energy consumption of PC beams with different splicing types is equivalent to that of RC beams， with a ratio of input energy ranging from 50% to 70%. Except for the mid-joint precast beam， increasing the impact mass at the constant energy increased the maximum deformation energy consumption of the test beam more than 15%.

Abstract:Based on the existing experimental results, the dynamic response of RC beams under impact loading is divided into local response stage and overall response stage. As RC beams are vulnerable to shear failure during the local response stage, this study investigates the transient response of the components in this stage. Thus, the effect of inertial force and reverse reaction on the internal force distribution at the local response stage is also discussed. Based on the basic principles of force equilibrium and parametric analysis results, a computing method for the internal force of RC beams is proposed. The results show that both the inertial force and negative reverse reaction affect the internal force distribution of beams during the local response stage, and the reverse reaction is approximately linear to the span-depth ratio and peak impact force. The assumption that the distribution of inertial force is linear can well reflect the actual force state of the beam.