配筋增强钢管混凝土柱尺寸效应和承载力分析

Size Effect and Bearing Capacity Analysis of Concrete-filledSteel Tube Column Strengthened with Steel Bars

进行了不同尺寸配筋增强钢管混凝土(R-CFST)短柱的轴压试验,旨在明确尺寸效应对受力性能的影响及R-CFST短柱承载力计算方法。将横截面的尺寸作为主要变化参数,制备了大尺寸和小尺寸两组试件,其中对应每一组包括两根R-CFST重复试件,为了对比分析同时准备对应于R-CFST的普通钢管混凝土(CFST)试件。对大、小尺寸试件的破坏模式、受力、刚度、约束效应和承载力等特性开展对比分析,结果表明:套箍系数因径厚比而产生的尺寸效应对以上性能指标产生显著影响;可以忽略R-CFST箍筋的贡献而将承载力的提高归因于纵筋,依此修正规范CFST公式给出R-CFST的统一理论公式,新公式的结果同样偏安全且稳定。

Aiming at determining the size effect on performance and strength prediction method of reinforced concrete-filled steel tube(R-CFST)column,compression test is carried out with different sizes of diameters.Using the size of the cross section as main parameter,R-CFST and concrete-filled steel tube(CFST)column specimens are prepared in big and small sized two groups in which it includes two duplicated specimens of R-CFST and CFST,respectively.Based on the test results,the failure mode,loading performance,stiffness,confinement effect and bearing capacity of large and small size specimens are compared and discussed.The results show that except for the ferrule coefficient,the size effect due to the diameter-to-thickness ratio has a significant impact on the mention performances.Contribution of hoops in R-CFST can be ignored,and improvement of strength is attributed to the longitudinal reinforcement,and thereby CFST formula in the code is then modified and a new formula for R-CFST is proposed in accordance with the unified theory.The prediction results of new formula are also safe and stable.