The lateral confinement of stirrups can effectively restrain the unstable lateral expansion of confined concrete and improve the load capacity and the ductility of concrete. The lateral response of stirrups affects the effective confinements on confined concrete and the dilation of core concrete. However, the lateral response of confined concrete has not received enough attention. In this paper, the lateral responses of 24 ultra‐high performance concrete (UHPC) and ultra‐high fiber‐reinforced performance concrete (UHPFRC) columns confined with high strength stirrups were obtained by experiments. The investigated parameters included concrete strength, stirrups volumetric ratio, and steel fibers contents. The axial stress‐lateral strain curves and lateral strain‐axial strain responses of specimens were presented to understand the dilation of concrete. The results showed that high strength concrete and high steel fibers contents decreased the dilation of concrete, when stirrups volumetric ratio increased from 1.0 to 2.0%, the dilation of concrete increased by 1.45~2.09 times. Furthermore, the lateral strain‐axial strain response prediction models were developed by introducing the effects of steel fibers, which were suitable for predicting the lateral strain‐axial strain of confined concrete.

中文翻译：

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约束高强度螺旋箍筋的超高性能混凝土柱的横向响应

箍筋的横向约束可以有效地抑制承压混凝土的不稳定横向膨胀，提高混凝土的承载能力和延性。箍筋的横向响应影响了对约束混凝土的有效约束以及对核心混凝土的膨胀。但是，承压混凝土的横向响应尚未引起足够的重视。本文通过实验获得了24根用高强度箍筋约束的超高性能混凝土（UHPC）和超高纤维增强混凝土（UHPFRC）柱的横向响应。研究的参数包括混凝土强度，箍筋体积比和钢纤维含量。给出了试样的轴向应力-横向应变曲线和横向应变-轴向应变响应，以了解混凝土的膨胀。结果表明，高强度混凝土和高钢纤维含量减少了混凝土的膨胀，当箍筋体积比从1.0％增加到2.0％时，混凝土的膨胀增加了1.45〜2.09倍。此外，通过引入钢纤维效应建立了横向应变-轴向应变响应预测模型，该模型适用于预测承压混凝土的横向应变-轴向应变。