纵向粘钢筋加固冷弯薄壁C型钢长柱试验研究

Experimental study on cold-formed thin-walled C-section steel long columns strengthened longitudinally by steel bars

本文在现有冷弯薄壁C型钢柱加固方法的基础上,提出了用钢筋纵向加固冷弯薄壁C型钢柱的方法。为了研究截面形式和初始应力比对加固柱轴压性能的影响,进行了一系列轴压试验。试验试件包括两种截面形状、四种初始应力比的轴心加载试件,共16个。结果表明:采用纵向贯通粘贴钢筋加固冷弯C型钢长柱,在用钢量变化不大的基础上,可显著提高试件轴心受压极限承载力;钢柱加固效果随负载加固试件初应力比β的增大线性递减,本文建议采用卸载或部分卸载加固,初始应力比应小于0.2,对于腹板尺寸为100mm的试件,可放宽至0.4。最后,将试验结果与我国现行规范(GB 50018-2002)和北美规范(AISI)关于冷弯薄壁型钢构件轴压承载力计算结果进行对比,发现完全卸载加固条件下,现行北美规范直接强度法计算结果与试验结果吻合较好。

Based on the existing methods of reinforcing cold-formed steel lipped channel column, the cold-formed thin-walled C-section steel column reinforced longitudinally with steel bars is proposed in this paper. In order to study the influence of section forms and initial stress ratio on axial compression behavior of columns, a series of pin-pin ends axial compression tests are conducted. The experiment specimens contain 16 axial compression specimens with two cross-section shapes, four initial stress ratios, respectively. It is shown that when reinforcing column longitudinally with bonded steel bars, under axial compression, the ultimate bearing capacity of the specimens can significantly increase with little change in the quantity of steel. Moreover, the reinforcing effect of the column decreases linearly with an increase in the initial stress ratio(β) of the load-strengthened specimens. Here, unloading or partial unloading reinforcement is recommended, and the initial stress ratio should be lower than 0.2. For the section with 100 mm web size, it can be relaxed to 0.4. Furthermore, the experimental results are compared with the calculation results for the axial bearing capacities of the columns based on the current Chinese standard(GB 50018-2002) and North American standard(AISI). It is shown that, under the condition of complete unloading reinforcement, the bearing capacities of the long columns calculated by the direct strength method(DSM) of AISI have a good match with the test results.