Ultra-high performance concrete (UHPC) is an cement-based composite material with excellent durability and mechanical properties. Compared with normal concrete (NC), its composition is different and its strength is ultrahigh. As an alternative to NC, more and more attention has been paid to its performance especially for shear performance of working with steel bars. In this paper, the shear performance of 14 reinforced UHPC rectangular section beams with different shear span ratio, stirrup ratio, steel fiber volume ratio, reinforcement ratio and longitudinal reinforcement strength was studied. The failure mode and shear capacity calculation model based on plasticity theory of the beams were discussed. The results show that increasing the beams’ shear span ratio in a certain range can obviously decrease the beams’ shear capacity. Increasing the beams’ stirrup ratio, reinforcement ratio and longitudinal reinforcement strength in a certain range can slightly increase the beams’ shear capacity. When the steel fiber volume ratio is less than 1%, the shear capacity of the beams is low and the failure mode shows obvious brittleness. For beams without web reinforcement, when the shear span ratio is 1.5, the failure mode is diagonal compression failure and when the shear span ratio ranged from 1.75 to 3, it shows shear compression failure. There is a main obviously diagonal crack from the support to the loading point when the beams with stirrup ratio less than 0.45% fail. When the stirrup ratio is increased from 0.25% to 0.45%, the shear ductility is obviously improved. The calculation model based on plasticity theory can well estimate the shear capacity of beams with “shear compression failure” mode. The applicable conditions of the model should not be ignored.

超高性能混凝土（UHPC）是一种水泥基复合材料，具有出色的耐久性和机械性能。与普通混凝土（NC）相比，其成分不同，强度极高。作为NC的替代品，人们对其性能的关注越来越多，尤其是在钢筋加工中的剪切性能方面。研究了14种不同剪跨比，箍筋比，钢纤维体积比，配筋率和纵向配筋强度的UHPC矩形截面梁的抗剪性能。讨论了基于梁塑性理论的破坏模式和抗剪承载力计算模型。结果表明，在一定范围内提高梁的剪跨比可以明显降低梁的抗剪承载力。在一定范围内增加梁的箍筋比，增强比和纵向增强强度可以稍微增加梁的抗剪承载力。钢纤维体积比小于1％时，梁的抗剪承载力低，破坏模式表现出明显的脆性。对于没有腹板加固的梁，当剪跨比为1.5时，破坏模式为对角压缩破坏，当剪跨比为1.75至3时，则表示剪切压缩破坏。当箍筋比小于0.45％的梁失效时，从支座到荷载点会出现一条明显的对角裂纹。当箍筋比从0.25％增加到0.45％时，剪切延展性明显提高。基于可塑性理论的计算模型可以很好地估计“剪切压缩破坏”模式的梁的抗剪承载力。模型的适用条件不容忽视。