In this study, the influences of the P-Δ effect on the behavior of low rise unbraced steel frames and the validity of factor B2, which is suggested by KBC 2008 (draft) to consider the P-Δ effect, were evaluated using the experimental approach. Seven specimens, one story-one bay unbraced steel frames, were tested under static loading conditions. The main parameters of the tests were the stiffness ratio of the column to the beam, and the axial load ratio. As revealed by the experimental research that was conducted, the axial load and the decrement of frame stiffness are the main factors that govern the P-Δ effect and that influence the P-Δ effect on the frame behavior. The story stiffness of the frame, which is related to factor B2, was dramatically decreased when the nonlinear behavior started. Factor B2 was compared with the moment amplification factor obtained in the test that had been conducted, and it was found that factor B2, which is based on the linear elastic theory, does not properly estimate the P-Δ effect of an unbraced frame when its assumptions are not satisfied. Thus, careful consideration is needed to apply factor B2 if the design is made using the inelastic part of the material.

中文翻译：

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低层无支撑钢框架的P-Δ效应的实验研究

在这项研究中，通过实验评估了KBC 2008（草稿）建议的考虑P-Δ效应对低层无支撑钢框架性能和因素B2有效性的影响（草案），以考虑P-Δ效应。方法。在静态载荷条件下测试了七个标本，一个楼层为一个海湾的无支撑钢框架。测试的主要参数是柱与梁的刚度比以及轴向载荷比。正如进行的实验研究所揭示的那样，轴向载荷和框架刚度的减小是控制P-Δ效应并影响P-Δ对框架行为的主要因素。当非线性行为开始时，框架的故事刚度与B2因子有关，因此大大降低了。将因子B2与已经进行的测试中获得的力矩放大因子进行了比较，发现基于线性弹性理论的因子B2不能正确地估计无支撑框架的P-Δ效应。假设不满足。因此，如果使用材料的非弹性部分进行设计，则需要仔细考虑应用因子B2。