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为了研究箍筋约束效应和率相关效应对混凝土单轴受压性能的影响,采用MTS815试验机对一批设计强度等级为C30、C70混凝土的普通箍筋约束试件进行了单轴受压试验。选取4种不同的配箍等级,对每一种配箍等级试件分别进行加载应变率为10-5、10-2/s的试验,得到了相应的应力-应变全曲线。研究发现:混凝土单轴受压性能会受到配箍率、应变率和混凝土强度等级三者的共同影响;增大配箍率提高了约束混凝土试件的峰值应力、峰值应力对应应变和延性系数,当配箍率达到3.4%时,最大提高幅值比例约为1∶2∶4,但其弹性模量受到的影响可以忽略不计;增大加载应变率提高了约束混凝土试件的弹性模量、峰值应力和峰值应力对应应变,但其延性系数有所降低,当应变率达到10-2/s时,上述特征值最大提高或降低幅值比例约为1∶5∶4∶4;箍筋约束效应与率相关效应相互耦合,当二者共同存在时,会削弱彼此对约束混凝土试件峰值应力、峰值应力对应应变和延性系数的提高或降低作用,当配箍率为0%~3.4%、应变率为10-5~10-2/s时,削弱幅值不超过60%,提高混凝土强度等级会增强该削弱作用,弹性模量受耦合效应的影响可以忽略不计。
In order to study the influence of stirrups restraint and rate-dependent effects on the uniaxial compressive properties of concrete, uniaxial compression tests were carried out on a batch of ordinary stirrups constrained specimens with C30 and C70 concrete designed strength classes by MTS815 testing machine. Four kinds of hoop grades were selected, and each kind of hoop grade specimens were respectively loaded with strain rates of 10-5 and 10-2 / s, and the corresponding stress-strain curves were obtained. The results show that the uniaxial compressive behavior of concrete is affected by both the coupling rate, the strain rate and the concrete strength grade. Increasing the stirrup ratio increases the peak stress and peak stress corresponding strain and ductility coefficient of the concrete specimens, When the stirrup ratio reaches 3.4%, the maximum amplitude ratio is about 1: 2: 4, but its elastic modulus is negligible. Increasing the loading strain rate increases the elastic modulus of the restrained concrete specimen, The peak stress and the peak stress correspond to the strain, but the ductility coefficient decreases. When the strain rate reaches 10-2 / s, the maximum increase or decrease of the above eigenvalue is about 1: 5: 4: 4; When the two are co-existing, the peak stress and peak stress corresponding strain and ductility coefficient of the concrete specimens will be weakened. When the stirrup rate is 0% ~ 3.4% When the strain rate is 10-5 ~ 10-2 / s, the weakened amplitude does not exceed 60%. Increasing the concrete strength level will enhance the weakened effect. The elastic modulus is negligible by the coupling effect.