超高性能混凝土(UHPC)包覆钢管混凝土叠合构件抗弯性能试验研究

Experimental Research on Flexural Performance of UHPC Encased CFSTs Under Pure Bending

UHPC包覆钢管混凝土叠合构件具有承载力高和耐久性能优越等优点。为研究其抗弯性能,完成了5根UHPC包覆钢管混凝土叠合构件纯弯试验,主要参数为钢纤维掺量和含钢管混凝土率。基于试验研究,考察了不同参数对试件的破坏形态、跨中弯矩-挠度曲线、极限抗弯承载力、抗弯刚度和延性的影响规律,结果表明:外包UHPC钢管混凝土叠合构件抗弯性能优异,受弯状态下各组件能保持良好的协同工作,试件的抗弯承载力随着外包UHPC钢纤维掺量和含钢管混凝土率的增大而增大,尤其在钢纤维掺量由0%变化为1%时承载力提升幅度尤为明显。采用现行规程公式计算本研究UHPC包覆钢管混凝土叠合构件抗弯承载力偏于安全11%~38%,计算抗弯刚度总体上偏于保守。

Ultra-high-performance concrete(UHPC)encased concrete-filled steel tubes(CFST)have advantages such as high bearing capacity and superior durability.In order to study their flexural performance,five pure bending tests of UHPC encased CFSTs members were designed.The main parameters were the steel fiber content and the ratio of concrete-filled steel tube.Based on the experimental study,the effects of different parameters on failure mode,midspan load-deflection curves,ultimate flexural capacity,flexural stiffness,and ductility were investigated.The results showed that UHPC encased CFSTs members exhibited excellent performance.Under bending,each component could maintain good collaboration.The flexural capacity increased with the increase of the UHPC steel fiber content and the ratio of concrete-filled steel tube,especially when the steel fiber content increased from 0%to 1%,the increase in bearing capacity was particularly significant.The predictions by current codes and standards for flexural capacity of UHPC encased CFST members were 11%-38%lower than the measured ones,and the predicted flexural stiffness was generally conservative.