基于纤维梁单元的薄壁圆钢管再生混合柱受压承载力随机分析

Stochastic Analysis of Compressive Capacity of Thin-Wall Circular Steel Tubular Columns Filled with Demolished Concrete Blocks Based on Fiber Beam Element

首先，基于纤维梁单元的计算框架，在积分点截面引入随机生成和投放废弃混凝土块体的技术，提出了薄壁圆钢管再生混合柱受压承载力的一种随机数值分析方法，并据此编写了相应的纤维梁单元计算程序；然后，通过程序计算结果与已有文献中试验结果的对比初步验证了该方法的有效性，同时对比结果表明，是否考虑柱截面内废弃混凝土的不均匀分布对预测薄壁圆钢管再生混合柱的初始刚度影响不大，对预测薄壁圆钢管再生混合柱的受压弱化行为有一定影响，且随着钢管壁厚的减小该影响逐渐增大；最后，运用该方法考察了柱子长径比、钢管壁厚、废弃混凝土取代率，以及新、旧混凝土强度差等参数对薄壁圆钢管再生混合柱受压承载力的影响。结果表明：废弃混凝土取代率在25％～40％之间变化或新、旧混凝土强度差不大于15 MPa时，废弃混凝土不均匀分布对薄壁圆钢管再生混合柱受压承载力的影响相差不大；偏心距较小时，随着钢管壁厚或长径比减小，废弃混凝土不均匀分布对薄壁圆钢管再生混合柱受压承载力的影响有所增大；随着偏心距增加，废弃混凝土随机分布对薄壁圆钢管再生混合柱受压承载力的影响呈减小趋势。

First,based on the calculation framework of the fiber beam element model,a stochastic numerical method to analyze the compressive capacity of thin-wall circular steel tubular columns filled with demolished con-crete blocks（DCBs）and fresh concrete（FC）is proposed by introducing the technique of generating random DCBs particles and subsequently packing them randomly in the cross-sections at integration points of a fiber beam ele-ment.Then,a computer program is accordingly developed,and the validity of the proposed method is initially veri-fied by comparing the numerical results with the published test ones.The comparison shows that the non-uniform distribution of DCBs in column cross-sections has no significant effect on the initial stiffness of the columns,but has a certain effect,which increases with the decrease of steel wall thickness,on the compressive softening behavior. Finally,with the help of the proposed method,the compressive capacity of the columns affected by such parameters as the length-to-diameter ratio,the steel wall thickness,the replacement ratio of DCBs and the strength difference between the new and the old concrete in the steel tube,is investigated.The results indicate that,when the replace-ment ratio of DCBs varies from 25%to 40%or the strength difference between the new and the old concrete is not larger than 15 MPa,the influence of the non-uniform distribution of DCBs on the compressive capacity of the columns is similar,while the influence increases with the decrease of the steel wall thickness or the length-to-diam-eter ratio at small eccentricity as well as with the decrease of the eccentricity.