钢纤维高强混凝土四桩承台受弯性能及承载力计算方法研究

Flexural property and bearing capacity calculation of steel fiber reinforced high strength concrete four-pile caps

为研究钢纤维高强混凝土四桩承台的受力性能,基于17个钢纤维高强混凝土承台试件的受弯试验,分析了不同钢纤维体积率、承台有效厚度、钢筋配筋率、混凝土强度承台的裂缝开展和破坏形态、荷载-挠度曲线、钢筋和混凝土应变特征以及承台破坏机理。结果表明:底部配筋率为0.16%～0.52%的钢纤维高强混凝土四桩承台呈现受弯破坏形态,弯曲拉应力由钢筋和钢纤维混凝土共同承担;随着承台有效厚度和钢纤维体积率的增加,承台受弯承载力显著提高。依据研究结果提出了钢纤维高强混凝土四桩承台受弯破坏计算模型,建立了钢纤维高强混凝土四桩承台受弯承载力计算式,为完善CECS38:2004《纤维混凝土结构技术规程》提供参考。

In order to study the flexural performance of steel fiber reinforced high strength concrete（SFHSC） four-pile caps,the experiments of 17 specimens,which have various steel fiber volume ratio,effective thickness,reinforcement ratio and concrete strength,were conducted to observe and analyze the crack distribution,load-deflection curve,concrete strain and longitudinal reinforcement strain,and failure mechanism.The results indicate the failure mode of the SFHSC four-pile caps with the moderate reinforcement is the flexural failure.The flexural tensile stress is resisted by reinforcement and steel fiber reinforced concrete.The ultimate moment capacity of the pile cap is improved evidently with the increase of the effective thickness and the steel fiber volume ratio.The calculation model and formula of ultimate moment capacity for the SFHSC four-pile caps is put forward,which serves as a reference for the CECS 38：2004 ＇Technical specification for fiber reinforced concrete structure＇ in China.