腹板加劲冷弯薄壁拼合H形钢压弯构件畸变性能试验研究

为研究偏心荷载作用下拼合构件的畸变屈曲性能，并评估现行中美规范计算方法适用性，对22个腹板V形加劲及开孔的冷弯薄壁拼合H形钢柱进行受压性能试验，得到了不同柱长、不同开孔位置及个数、不同偏心距以及绕强轴和弱轴弯曲方向的拼合构件的破坏模式和承载力。试验结果表明：所有腹板V形加劲及开孔的冷弯薄壁拼合H形钢柱均发生了畸变屈曲或以畸变为主的相关屈曲，畸变半波的分布受孔洞和加劲的影响；绕强轴和绕弱轴偏心方向及偏心距大小对承载力有显著影响。基于现行中美规范计算方法对腹板V形加劲及开孔的冷弯薄壁拼合H形钢柱承载力进行研究，结果表明：计算绕强轴压弯承载力时，按GB 50018—2002《冷弯薄壁型钢结构技术规范》、JGJ/T 421—2018《冷弯薄壁型钢多层住宅技术标准》以及美国NAS100-16的承载力公式计算结果均偏于安全；计算绕弱轴压弯承载力时，试验结果与按GB 50018—2002和美国NAS100-16的承载力公式计算结果的比值平均值为1.16、1.15，偏于安全且较为合理，与按JGJ/T 421—2018的计算结果的比值平均值为1.66，较为保守，建议拼合构件的双肢可靠连接时，按拼合整体截面计算绕弱轴稳定承载力。

Experimental investigation on distortional performance of cold-formed steel built-up channel columns with web stiffeners under eccentric compression

The compression tests of 22 cold-formed built-up H-shaped steel columns with V-shaped web stiffeners and openings were carried out to study the distortion buckling performance of the built-up members under eccentric load. The applicability of calculation methods in the current Chinese and American standard was evaluated. The failure mode and ultimate bearing capacity of each specimen were obtained by changing the length of the column, the position and number of openings, the bending direction around the strong axis and the weak axis, and the size of the eccentricity. The test results show that all specimens present distortion buckling or buckling mainly due to distortion, and the distribution of distortional half-waves is affected by holes and stiffeners. The direction and size of the eccentricity around the strong axis and that around the weak axis have a significant effect on the ultimate bearing capacity. The test ultimate capacity was studied using the calculation method in the current Chinese and American standards. The results show that the calculation results of GB 50018—2002, JGJ/T 421—2018, and NAS100-16 are all safe when calculating the eccentric compression bearing capacity around JP2]the strong axis. When calculating the eccentric compression bearing capacity around the weak axis, the calculation results of GB 50018—2002 and NAS100-16 are both safe and reasonable. The average ratios of the test results divided by GB 50018—2002 and NAS100-16 codes are 1.16 and 1.15, respectively, while that of the test results to the calculated results of JGJ/T 421—2018 is 1.66, which is relatively conservative. It is recommended that when the two limbs of the built-up member are reliably connected, the eccentric compression bearing capacity around the weak axis should be calculated according to the overall section.