Key concepts

A short glossary of the terms used throughout SES.

Geometry

• Slab — a load-bearing area. Loads applied to a slab are distributed to the supports around and beneath it.
• Beam / wall / column — supports that collect load from slabs. Walls and columns carry load vertically down the building.
• Grid — reference lines for laying out and snapping geometry.

Loads

• Dead load (DEAD) — permanent self-weight of the structure and finishes.
• Live load (LIVE) — variable occupancy/usage load.
• Area / line / point loads — how a load is applied geometrically. Area loads (UDLs) are pressures over a region; line loads run along a member; point loads act at a node.

Analysis

• Tributary area — each support is assigned the slab region closest to it (a Voronoi-style partition). Loads in that region flow to that support.
• FEM reactions — instead of a geometric partition, the slab is meshed and solved as finite-element plates (DKT triangles) to obtain support reactions. This captures stiffness effects a tributary partition cannot.
• Load run-down — accumulating reactions from each floor down through the supporting elements to the foundations.

When to use tributary vs FEM

Tributary is fast and intuitive for regular layouts. FEM is more accurate for irregular geometry, stiffness-sensitive layouts, and partial-area loads. SES can compute both and compare them side by side.