方钢管钢纤维增强地聚物混凝土短柱轴压承载力计算方法

Calculation methods for axial load bearing capacity of steel fiber reinforced geopolymer concrete filled square stub steel tubular columns

  • 摘要: 为研究方钢管钢纤维增强地聚物混凝土(Steel fiber reinforced geopolymer concrete-filled square steel tubular, SFRGCFST)短柱的轴压性能,对20根SFRGCFST短柱、2根方钢管钢纤维增强普通混凝土(Steel fiber reinforced concrete-filled steel tube, SFRCFST)短柱以及2根普通混凝土短柱进行轴压试验,分析地聚物混凝土强度等级、钢管壁厚、钢纤维体积掺量和长径比等因素对其破坏特征、荷载-位移曲线和极限承载力的影响规律。结果表明:套箍系数是影响SFRGCFST短柱轴压性能和破坏形态的主要因素,当套箍系数大于0.88时,试件由剪切型破坏向腰鼓型破坏转变。SFRGCFST比普通钢管混凝土柱的极限承载力平均提升30%以上,当钢纤维体积掺量为0.9%时,SFRGCFST比SFRCFST的极限承载力提高了21.85%。钢纤维可有效提高SFRGCFST的变形性能,减小峰后荷载-位移曲线下降段坡度使峰后曲线变缓;基于多轴强度准则和方钢管混凝土柱截面力学平衡方程,建立了SFRGCFST短柱极限承载力计算公式,可准确预测SFRGCFST短柱轴压承载力,为相关规范完善提供参考依据。

     

    Abstract: Axial compression tests were conducted on 20 steel fiber reinforced geopolymer concrete-filled square steel tubular (SFRGCFST) columns, 2 steel fiber reinforced concrete-filled steel tube (SFRCFST) columns, and 2 plain concrete-filled steel tube (CFST) columns to examine the effects of steel tube thickness, concrete strength grade, steel fiber volume fraction and aspect ratio on the failure modes, load-deformation behavior, and ultimate resistance of SFRGCFST columns. The findings indicate that the coefficient index predominantly influences the axial compression performance and failure morphology of SFRGCFST stub columns, particularly when the coefficient index exceeds 0.88, leading to a transition in specimens from shearing to waist-drum failure. The ultimate bearing capacity of SFRGCFST columns shows an average increase of over 30% compared to CFST columns. Furthermore, when the steel fiber volume fraction reaches 0.9%, there is an additional 21.85% increase in the ultimate bearing capacity over that of SFRCFST columns. The inclusion of steel fiber (SF) significantly enhances the deformation and ductility of SFRGCFST and moderates the post-peak slope of the load-displacement curve, effectively decelerating the decline. Utilizing the multi-axial strength criterion and the mechanical equilibrium equation for square CFST, a formula for calculating the ultimate bearing capacity of SFRGCFST stub columns has been developed. This formula enables accurate predictions of the axial compressive load capacity of SFRGCFST stub columns and provides a basis for revising related standards.

     

/

返回文章
返回