Selecting the Criteria > Effective Length command will cause the Column Effective Length dialog box to appear. Note that this criterion is not utilized for ACI unless the user has selected to consider column slenderness in the Criteria-Analysis dialog box (see Section 2.5.2). The Effective Length affects the column slenderness calculation in accordance with ACI318-02, BS8110 3.8.1.6.1.and AS 3600 10.5.3.

Per ACI 10.13.1 The Effective Length Factor for sway frames will be limited to a value larger than or equal to 1.0 when the nomograph is selected in the Effective Length Factor Criteria Dialog Box. Cracked section properties as defined by the user in the RAM Modeler are considered when calculating member stiffness for the purpose of calculation of effective length (k) factors using the nomograph approach.

The Effective Length Factor can be indicated in one of two ways: entering specific values for the major axis and minor axis or allowing the program to choose these values. To enter Major or Minor axis values for columns, click the Use button and then enter values in the edit boxes. To have the program calculate the Effective Length Factors based on the Nomograph Values, click the Use Nomograph Values button. Effective Length Factor can also be set in a column by column basis by selecting Assign-Column Effective Length Factor command. If Use Nomograph (ACI) or Use Sec 2.5:BS8110:Part2 (BS8110) is selected, the effective length will be calculated based on the nomographs of 10.12.3 (ACI), the same formulas are used for the AS3600 design, or equations of BS8110:Part2:1985 Section 2.5 (BS8110) depending on if the column is sway or non-sway in the axis being calculated.

Clicking OK will save the settings. Modifying this criterion after an analysis or code check has been performed will invalidate the results of that analysis and/or code check.