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D4.B.6.4 Members Subject to Combined Forces

Axial compression and bending

The member strength for sections subjected to axial compression and uniaxial or biaxial bending is obtained through the use of interaction equations. In these equations, the additional bending caused by the action of the axial load is accounted for by using amplification factors. Clause 13.8 of the code provides the equations for this purpose. If the summation of the left hand side of these equations exceed 1.0 or the allowable value provided using the RATIO parameter (Refer to D4.B.7 Design Parameters), the member is considered to have failed under the loading condition.

Axial tension and bending

Members subjected to axial tension and bending are also designed using interaction equations. Clause 13.9 of the code is used to perform these checks. The actual RATIO is determined as the value of the left hand side of the critical equation.