Modeling of built up section with lacing bars and cover plates

When modeling steel built-up section in section designer consisting of the main members and secondary lacing and cover plate members that hold the main member together, it is usually not necessary to input the cover plates and lacing members in the section designer section.

If multiple shapes are entered into a section designer section, all the shapes are assumed to act as a unit. Let's say that you need to model a built-up steel (box) section consists of 4 angles in the corners and these 4 angles are connected by lacing bars. This would typically be modeled by the 4 angles and the contribution of the lacing bars to the axial and bending stiffness would be neglected. If you need to consider the contribution of the lacing bars and cover plates, it would need to be established from a detailed 3D model or from experimental data.

To account for the additional weight (and stiffness as described above) of the lacing bars and cover plates, you could assigning property modifiers either to the frame section or to the frame elements.