名义荷载表示缺陷

In the AISC 360 – 14th Ed. C2.2, the direct analysis method requires initial imperfections to be taken into consideration. The important imperfection of recognition is column out-of-plumbness. According to C2.2a, the direct modeling of imperfections is one method to account for the effect of initial imperfections. However, in many situations, the expected displacements may not be known or easily predicted.

Section C2.2b states that another allowable method to account for imperfection is with the use of notional loads. 对于主要通过竖向柱，墙或框架承载重力荷载的结构，虚拟荷载是允许的。 The magnitude of the notional loads which are applied as lateral loads at all levels is in accordance with C2.2b(1), where Y_i is the applied gravity load at level i for the load case considered.

RFEM能够将这些理论荷载应用到杆件，杆件组或杆件列表中。在“插入”→“荷载”→“ 3.14缺陷”→“对话框”下，可以打开根据公式C2-1计算虚拟荷载的选项。用户可以选择“按照标准”： “ANSI/AISC 360‑10 (current loading)” or “ANSI/AISC 360‑10 (gravity load combination)” where a load case or load combination, respectively, can be used for gravity load application.

名义荷载系数基于l/500的误差预设为0.002。 However, Section C2.2b(3) allows the engineer to adjust this factor if desired. 必须根据LRFD或ASD分析的考虑来设置alpha系数。

作者

Amy Heilig 是位于费城的美国子公司的总裁。她负责北美市场的销售、技术支持和程序的持续开发。

链接

钢结构设计与分析软件

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