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试验旨在研究在较高轴压比条件下,钢纤维对超高强混凝土短柱抗震延性的改善作用。短柱试件的剪跨比均为2.0,强度为103.6~114.8MPa,钢纤维的体积含纤率分别为0.5%、1.0%、1.5%。采用简支梁加载图式进行了低周反复荷载试验。观测了试件在荷载作用下的开裂和破坏的发展过程,分析了不同钢纤维含量对短柱的破坏形态、滞回特性的影响。试验结果表明:未掺钢纤维的试件,在高轴压作用下,发生了脆性特征明显的剪切破坏,延性很差;随着钢纤维含量的增加,试件的破坏形态向具有一定延性特征的弯剪破坏转变;同时延性得到大大改善,位移延性和极限弹塑性位移角分别可最大增加50.2%、96.1%,最后给出了抗震设计条件下的最小钢纤维体积含纤率的建议值。
The purpose of this experiment is to investigate the effect of steel fiber on the seismic ductility of ultra high strength concrete short columns under high axial compression ratio. The shear-span ratio of the short column specimen is 2.0, the strength is 103.6 ~ 114.8MPa, the volume fiber content of the steel fiber is 0.5%, 1.0%, 1.5% respectively. The low-cycle repeated load test was carried out by using simply supported beam loading scheme. The development process of cracking and failure under load was observed, and the influence of different steel fiber content on the failure morphology and hysteretic characteristics of short columns was analyzed. The test results show that the specimen with no steel fiber has obvious brittle fracture under the action of high axial pressure, and the ductility is very poor. With the increase of the steel fiber content, the failure morphology of the test piece has a certain ductility And the ductility is greatly improved. The displacement ductility and the ultimate elastic-plastic displacement angle can be increased by 50.2% and 96.1%, respectively. Finally, the recommended value of the minimum steel fiber volume content in the seismic design condition is given .