5.6Surface Loads

Surface Loads option of spCad enables you to draw panels spanning over members of a floor and apply area loads to these panels. Working in a specific floor plan (XZ plane), the panels are drawn graphically on the screen. A panel is a slab-like element that is attached to the members it comes in contact with.

•A panel is drawn by drawing panel nodes that are connected with straight lines to form the panel boundaries. The shape or size of a panel may be modified by moving, editing, or deleting some of its nodes.

•Openings may exist within a panel.

•By default, each member that comes in contact with a panel is attached to it. A member may be detached from a panel to exclude the panel load on it. A member that does not touch the panel cannot be attached to it.

•Panels are loaded with one uniform area load under a particular load case. The area load is applied over the entire panel.

•Only gravity loads (including self weight) may be applied on a panel. The computed member loads are applied in the negative global Y direction.

•Each panel is divided into a grid of finite square elements. The area of each finite element is computed and assigned to the member closest to it. The total area of the segments assigned to a member constitutes its tributary area.

•The member load length is the member intersection with the panel. If the panel covers a member completely, the member load length is the entire length of the member.

•The tributary area of a member multiplied by the panel load is applied uniformly over the member. No variation of the load intensity is accounted for.

•Based on the member tributary area, a live load reduction can be computed. Load reduction may be computed for beams and columns. The load reduction factors are saved with the data file to be used by spFrame when combining the analysis results.