超高性能混凝土(UHPC)包覆钢管混凝土叠合柱偏压性能试验研究

Research on Mechanical Properties of UHPC Encased CFSTs Under Eccentrically Compressive Loading

UHPC包覆钢管混凝土叠合构件具有耐久性能优越和承载力高等优势。为研究其偏压性能,进行了4根UHPC包覆钢管混凝土叠合柱偏压试验,主要参数为偏心距和长细比。基于试验结果,考察了不同参数对试件的破坏特征、荷载-变形关系曲线、极限承载力、二阶效应和延性的影响规律,结果表明:钢纤维的存在减轻了外围UHPC的破坏程度,内钢管混凝土的存在使试件具有较好的延性。试件偏压承载力随偏心距的增加下降明显,其中偏心距从0~80 mm时对承载力影响最显著。同时,二阶效应对试件偏压承载力影响显著,随着偏心距和长细比的增加,二阶效应产生的弯矩占总弯矩比重达到36.5%。基于试验实测结果,探讨了采用现行规范提供的方法计算UHPC包覆钢管混凝土叠合柱偏压承载力的适用性。

This study investigates the behavior of ultra-high-performance concrete(UHPC)encased concrete-filled steel tubes(CFST)under eccentric loading,focusing on their superior durability and high load-bearing capacity.Ultral-high-performance concrete(UHPC)encased concrete-filled steel tubes(CFST)have advatages such as superior durability and high bearing capacity.Four CFST columns with varying eccentricity and slenderness ratios were experimentally tested to examine their mechanical properties.Based on the test results,the failure characteristics,load-deformation responses,ultimate eccentric bearing capacity,second-order effects,and ductility were investigated.The results revealed that the incorporation of steel fibers significantly reduced the failure degree of the outer UHPC,while the inner CFST offered the column specimens good ductility.It was noted that the eccentric bearing capacity decreased markedly with the increasing eccentricity,particularly in the range of 0-80 mm.Moreover,second-order effects had a substantial impact on the eccentric bearing capacity,contributing up to 36.5%of the total moment as eccentricity and slenderness ratio increased.The study’s findings were used to discuss the applicability of existing code provisions for calculating the eccentric bearing capacity of UHPC encased CFST columns.