Many studies have focused on reinforced concrete(RC)slender beams,while there is a paucity of studies on deep beams.Furthermore,there is a lack of studies on the impact performance of FRP-reinforced concrete beams.In ...Many studies have focused on reinforced concrete(RC)slender beams,while there is a paucity of studies on deep beams.Furthermore,there is a lack of studies on the impact performance of FRP-reinforced concrete beams.In this study,a 3-D numerical model was established to explore the impact behavior of the basalt fiber reinforced polymer(BFRP)and steelreinforced concrete beams with different span-to-depth ratios(l0/h).The effects of impact mass and tension reinforcement ratio were analyzed and discussed.It is determined that the impact behavior of the shortest beam with l0/h=1.5 corresponds to punching shear failure,which is distinctive from the other deep beam.When l0/h exceeds 3.0,the failure mode gradually changes from shear dominant to flexural dominant.The increase in the impact mass leads to a linear increase in the max midspan deflection,the duration of the contact between the hammer and member,and the duration of the dynamic reaction force.The max midspan deflection has a negative correlation with the reinforcement ratio.The max reaction force increases with an increase in the reinforcement ratio,which is more evident for higher l0/h.The failure mode of the BFRP-reinforced concrete beam is similar to that of the steel-reinforced beam.Under the impact condition,in this study,part of the steel bars yield,whereas BFRP bars exhibit no signs of fracture because of their higher tensile strength and better deformability.A simplified calculational method based on energy is proposed in this study,and the method accurately predicts the residual deflection of the concrete beams with different l0/h.Furthermore,it is established that it is difficult to reproduce the impact response of the deep beams via the singledegree-of-freedom(SDOF)model,which is based on the assumption of the same deflection shape as that of slender beams.Hence,a more rational simplified model for deep beams under impact loads is still required.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.51822801,51978022)。
文摘Many studies have focused on reinforced concrete(RC)slender beams,while there is a paucity of studies on deep beams.Furthermore,there is a lack of studies on the impact performance of FRP-reinforced concrete beams.In this study,a 3-D numerical model was established to explore the impact behavior of the basalt fiber reinforced polymer(BFRP)and steelreinforced concrete beams with different span-to-depth ratios(l0/h).The effects of impact mass and tension reinforcement ratio were analyzed and discussed.It is determined that the impact behavior of the shortest beam with l0/h=1.5 corresponds to punching shear failure,which is distinctive from the other deep beam.When l0/h exceeds 3.0,the failure mode gradually changes from shear dominant to flexural dominant.The increase in the impact mass leads to a linear increase in the max midspan deflection,the duration of the contact between the hammer and member,and the duration of the dynamic reaction force.The max midspan deflection has a negative correlation with the reinforcement ratio.The max reaction force increases with an increase in the reinforcement ratio,which is more evident for higher l0/h.The failure mode of the BFRP-reinforced concrete beam is similar to that of the steel-reinforced beam.Under the impact condition,in this study,part of the steel bars yield,whereas BFRP bars exhibit no signs of fracture because of their higher tensile strength and better deformability.A simplified calculational method based on energy is proposed in this study,and the method accurately predicts the residual deflection of the concrete beams with different l0/h.Furthermore,it is established that it is difficult to reproduce the impact response of the deep beams via the singledegree-of-freedom(SDOF)model,which is based on the assumption of the same deflection shape as that of slender beams.Hence,a more rational simplified model for deep beams under impact loads is still required.
