方钢管混凝土短柱轴压承载力尺寸效应

Size Effect of Axial Strength of Concrete-Filled Square Steel Tube Columns

目的方钢管混凝土短柱轴心受压承载力存在尺寸效应,为了提高大尺寸方钢管混凝土轴心受压承载力设计计算的准确性,研究了考虑尺寸效应的方钢管混凝土短柱轴压承载力计算方法.方法笔者介绍了日本AIJ规范、美国AISC-LRFD规程、欧洲EC4规范和我国韩林海等提出的方钢管混凝土短柱轴压承载力计算公式,并用这些公式对收集的大量实验结果进行了计算分析,然后在已有的计算公式基础上引入尺寸效应模型,采用修正后的计算公式进行计算并与未修正的计算结果进行比较.结果现有的方钢管混凝土短柱轴压承载力计算公式的计算结果存在明显的尺寸效应,而在这些计算公式中引入尺寸效应模型进行修正后,计算结果的尺寸效应得到了明显改善.结论笔者探讨的4种计算公式都存在随着构件尺寸增大计算结果比实验值偏大的趋势,即计算公式无法准确反映构件轴压承载力存在的尺寸效应;通过引入混凝土材料的尺寸效应模型,对方钢管混凝土轴压承载力计算公式进行修正,可以有效减小方钢管混凝土轴压承载力的尺寸效应影响,从而为方钢管混凝土轴心受压承载力设计计算提供参考.

Concrete-filled square steel tube columns with very large sectional sizes are widely applied in recent years.However,the existing axial strength models of concrete-filled square steel tube column are proposed mostly based on small sectional size specimens.Thus,the accuracy of existing models for large specimens,viz the size effect of these models,need further investigation.In this work,the design methods to calculate the axial strength of concrete-filled square steel tube column proposed by the AIJ code of Japan,the AISC-LRFD design specification of the United States,the EC4 code of Europe and Han of China are introduced.Based on 252 test specimens,the comparisons between the test results and the computational results by different design methods are conducted.It can be concluded from the comparison that the design methods for the axial strength of concrete-filled square steel tube columns have obvious size effects.The existing design models may overestimate the strength of the specimens with large sectional size.By introducing the size effect model of concrete,the design methods are modified and the predicted results are obviously improved.This method considering size effect may provide a reference on calculating the axial strength of concrete-filled square steel tube columns with large size.