钢管煤矸石混凝土轴压短柱极限承载力计算方法研究

为促进煤矸石在钢管混凝土结构中的应用,选取辽宁地区的煤矸石作为粗骨料,开展6根钢管混凝土和12根钢管煤矸石混凝土短柱轴压试验。根据构件破坏形式与荷载-应变曲线讨论材料强度、钢管约束和取代率对构件轴压承载力的影响规律,进行了设计参数与承载力的相关性分析,在此基础上,讨论规范GB 50936—2014和规程T/CECS 625—2019中的轴压短柱极限承载力计算方法对钢管煤矸石混凝土的适用性,给出圆钢管煤矸石混凝土短柱极限承载力计算公式的建议修正系数。结果表明:轴向压缩试验下构件呈现出局部鼓曲与剪切破坏形态; 与钢管普通混凝土短柱相比,钢管对核心煤矸石混凝土具有更好的横向约束效应; 相同取代率下提高套箍系数与含钢率将显著提升构件承载力,构件的轴压承载力随煤矸石取代率提升而降低,但最大降低幅度未超过11%:煤矸石粗骨料对承载力的相关系数为-0.33且不具有显著性; 现有的规范GB50936—2014和规程T/CECS 625—2019中相关计算方法适用于钢管煤矸石混凝土短柱,引入修正系数后承载力计算的平均相对误差在3%以内。

Steel tube coal gangue concrete axial pressure short column ultimate bearing capacity calculation method research

In order to promote coal gangue application in concrete-filled steel tubular(CFST)structures, coal gangue produced in Liaoning province was selected as coarse aggregate, then the axial compression tests on 6 CFST short columns and 12 CFST short columns using spontaneous-combustion coal gangue aggregate(SCGA)were carried out. Based on the failure mode and load-strain curve of the component, the influences of material strength, steel tube confinement and replacement rate of SCGA on the axial compression bearing capacity of the component were discussed. The correlation analysis between design parameters and axial compression capacity was carried out. On this basis, the applicability of the ultimate bearing capacity calculation method of axial compression short column in GB 50936—2014 and T/CECS 625—2019 to coal gangue CFST was discussed, and the recommended correction coefficient of the calculation formula of ultimate bearing capacity of circular coal gangue CFST short column was given. The results show that the components under axial compression test show local buckling and shear failure modes. Compared with ordinary CFST short column, steel tube has better lateral restraint effect on core coal gangue concrete. Under the same replacement rate, increasing the confinement coefficient and steel ratio will significantly increase the bearing capacity of the component. The axial compression bearing capacity of the component decreases with the increase of the coal gangue replacement rate, but the maximum reduction does not exceed 11%. The correlation coefficient of coal gangue coarse aggregate to bearing capacity is -0.33 which is not significant, The relevant calculation methods in the existing specifications GB 50936—2014 and T/CECS 625—2019 are applicable to the short column of coal gangue CFST. The average error of bearing capacity calculation is less than 3%.