C-2.12.1 rectangular filled composite members

2.1.1 Limitations

Lai and Varma (2018) and Alghossoon and Varma (2020) evaluated the behavior of rectangular filled composite members constructed from steel and/or concrete with strengths above the limits given in Section II.3. The range of parameters included by Lai and Varma (2018) were used to define the limitations of this section. At the boundary of material strength transitions, the equations provided in this appendix are moderately conservative for members made from normal strength materials.

2.1.2 Compressive Strength

The detailed parametric studies conducted by Lai and Varma (2018) were used to develop Equations A-2-1 and A-2-2. These equations account for the effects of local buckling of the compression steel elements on the available compressive strength of the rectangular filled composite members.

2.1.4 Combined Flexure and Axial Force

Equations A-2-3 and A-2-4 represent the axial compressive load-bending moment $(P-M)$ interaction behavior of rectangular filled composite members (Alghossoon and Varma, 2020). This $P-M$ interaction can be used along with the direct analysis method for designing structures with such members.