薄壁圆钢管再生混合中长柱的轴压与偏压试验研究

通过36根薄壁圆钢管再生混合中长柱的轴压与偏压试验,考察废弃混凝土混合比、钢管壁厚、荷载偏心距等因素对试件受压性能的影响。基于新、旧混凝土的组合强度,根据国内外钢管混凝土结构设计标准,对试件的受压承载力进行计算对比。试验和分析结果发现:①采用25%或40%的废弃混凝土替换新混凝土后,钢管再生混合中长柱的受压承载力分别比全现浇钢管混凝土中长柱降低5.77%～9.71%和10.65%～15.63%,但前者的初始刚度、屈服性能和延性特征与后者基本相当;②为使钢管再生混合中长柱的计算受压承载力具有与全现浇钢管混凝土中长柱相近的安全性,可对前者计算结果乘以调整系数0.95;③总体来看,设计标准DBJ 13-51-2003和ANSI/AISC 360-05对轴压试件受压承载力的预测结果相对较好,JCJ 01-89对偏压试件受压承载力的预测结果相对较好。研究表明,薄壁圆钢管柱内放置废弃混凝土块体是废弃混凝土循环利用的一条有效途径。

Tests on slender circular thin-walled steel tubular columns filled with demolished concrete lumps under concentrically/eccentrically compressive loadings

Tests of 36 slender circular thin-walled steel tubular columns filled with demolished concrete lumps(DCLs) under concentrically or eccentrically compressive loadings were conducted,and influences of the mix ratio of demolished concrete,thickness of steel tube,and load eccentricity on the mechanical properties of the specimens were investigated.Based on the concept of combined strength of new and old concrete,and using the domestic and foreign design codes for concrete-filled steel tubular(CFST) structures,compressive strengths of the specimens were calculated and compared with the test results.It can be seen that:(a) when 25% or 40% of the new concrete were replaced by the demolished concrete,the compressive strengths of the specimens with DCLs were,respectively,5.77%~9.71% and 10.65%~15.63% less than those without DCLs,but the initial stiffness,yield behavior and ductile performance of the specimens with DCLs were similar to those without DCLs;(b) to ensure that the safety margin of the calculated compressive strength for a steel tubular column filled with DCLs is similar to that without DCLs,an adjustment factor of 0.95 is suggested;and(c) the strengths of axially loaded specimens predicted using DBJ 13-51-2003 and ANSI/AISC 360-05,and the strengths of the eccentrically loaded specimens predicted using JCJ 01-89,are better on the whole.Utilizing DCLs in circular thin-walled steel tubular columns is an effective approach to recycle of waste concrete.