冷弯薄壁型钢T形拼合柱轴压性能研究与承载力计算

Axial Compressive Performance and Bearing Capacity Calculation for T-shaped Cold-Formed Thin-Walled Steel Built-Up Columns

冷弯薄壁型钢(CFS)全螺栓垫板连接T形拼合柱是一种新型拼合截面柱,在全螺栓连接框架结构中承受集中荷载。目前关于全螺栓连接T形CFS拼合柱轴心受力性能的研究报道较少。基于已有的试验研究成果,建立准确可靠的T形CFS拼合柱数值分析模型,选取构件长细比、板材厚度、垫板的纵向间距等参数,研究在轴压作用下各重要参数对T形CFS拼合柱极限承载力和屈曲模态的影响。结果表明:随着长细比的增大,T形CFS拼合柱的屈曲模式由局部与畸变相关屈曲逐渐转变为整体屈曲,当长细比<104.7时,长细比变化对构件承载力的影响不明显;板厚对构件的承载力变化具有显著影响,在长细比较大的情况下可以改变构件的屈曲模式;垫板的纵向间距对构件的承载力和屈曲模式影响较小,不同垫板纵向间距的构件极限承载力变化均在4.5%以内。最后,将试验和数值分析结果与北美规范中直接强度法计算的名义承载力对比,评估直接强度法对于此类拼合柱承载力计算的适用性。

Cold-formed thin-walled steel(CFS)fully bolted plate connection T-shaped built-up column is a new type of composite section column,which bears concentrated load in the frame structure with full bolt connection.The research on the axial performance of T-shaped CFS composite columns with full bolt connection is still limited.Based on the existing experimental research results,an accurate and reliable numerical analysis model of a T-shaped CFS composite column is established.The parameters such as slenderness ratio,plate thickness,and longitudinal spacing of the backing plate are selected for variable parameter analysis.The influence of various important parameters on the ultimate bearing capacity and buckling mode of the composite columns is further studied.The results show that with the increase in slenderness ratio,the buckling mode of the T-shaped CFS composite column gradually changes from local and distortion-related buckling to overall buckling.When the slenderness ratio<104.7,the influence of the slenderness ratio on the bearing capacity of the component is not obvious.The plate thickness has a significant impact to the bearing capacity,and the buckling mode can be changed when the slenderness ratio is large.The longitudinal spacing of the backing plate has little effect on the bearing capacity and buckling mode,and the ultimate bearing capacity of the members with different plate spacing is within 4.5%.Finally,the test and numerical analysis results are compared with the nominal bearing capacity calculated by the direct strength method in the North American code to evaluate the applicability of the direct strength method for the bearing capacity calculation of this type of composite columns.