大宽厚比对称填板双角钢十形组合构件轴压试验与设计方法对比

Experimental study on axial compressive strength and evaluation of design criteria for closely star-battened angle column with symmetrical battens of large width-to-thickness ratio

对于扭转长细比大于弯曲长细比的大宽厚比对称填板双角钢十形组合构件而言,各规范采用不同方法来计算其稳定系数,填板的构造规定也有所不同,有必要结合试验实测数据,检验不同方法的计算精度和填板构造方式对承载力的影响。为此,进行了2类对称填板,共32个双角钢十形组合试件的轴压试验,得到了试件的应变、极限载荷等。试件横截面各测点应变差异较大,且破坏后轴线明显弯曲,该现象表明,虽然各试件的扭转长细比明显大于弯曲长细比,但所有试件最终发生了弯曲失稳。根据试件实测结果检验了不同设计方法的稳定系数计算精度,结果表明：扭转长细比大于弯曲长细比或试件两端之间仅有1个填板时,试件均表现出了良好的承载能力;按GB 50017—2003《钢结构设计规范》中扭转长细比确定的稳定系数远低于研究所得的试件实测值,而弯曲长细比对应的稳定系数与试验的实测值很接近;大多短角钢填板双角钢十形组合试件的轴向承载力略高于焊接填板试件,但前者的造价较低,推荐使用。

For the large width-to-thickness ratio closely star-battened angle column of symmetric battens whose slenderness of torsion is larger than that of bending, different methods of the codes are given to determine its compressive reduction factor and some constructional details about battens are also different. Therefore, it is essential to evaluate the accuracy of the methods to determine the reduction factor and constructional details based on the experimental study. Therefore, axial compression experiments involving two kinds of battens and 32 columns were conducted, and the key data such as strain and load capacity were recorded. The difference between the strain measured by the strain gauges on the same cross section is large and the axes of the specimens are obviously curved, which shows that： though the slenderness about the torsion of the columns is much larger than that about bending, the columns still fail because of bending. The reduction factors of the columns by the experiment and different methods of the codes are compared, and the results are ： when the slenderness ratio about torsion is larger than that of bending or there is only one batten between the two ends of the column, the compressive capacity of the column is still high ; the reduction factors determined by the slenderness ratio about torsion according to the codes such as GB 50017--2003 ＇ Code for design of steel structures＇ is far less than those tested, while the reduction factors determined by the slenderness ratio of bending are quite near to those tested; the axial compressive capacity of the great majority of the columns with short angle battens is slightly higher than that of welded cross battens, and the former is cheaper. Therefore, the column with short angle battens is recommended to be used.