Understanding the Structural Engineering of Building Loads

1. STRUCTURAL ENGINEERING Structure of a Building • The primary function of a building structure is to support and transmit the loads and forces to the ground. “Tracing the Loads” or “Chasing the Loads”

2. Characteristics of a Structure • Stability – needed to maintain shape. The structure is dependent upon balanced forces and equilibrium • Strength - ability of the structure to withstand the applied forces, usually includes a “factor of safety” • Economic Value – includes choices made about the design, materials, and function of the structure

3. Forces and Loads Design Loads • Dead Loads (DL) –fixed loads • building materials/components and the weight of structural components • Live Loads (LL) –transient and moving loads • Occupancy loads and furnishing loads (bldg usage) • Snow loads • Construction loads • Live Load maybe variable during structures lifetime • Building codes specify these loads for floor and roof loadings

4. Design Loads Snow Live Load Roof Materials & Structure Dead Load Walls, Floors, Materials &Structure Dead Load Occupants, Moveable Fixtures & Furniture Live Load

5. Design Loads (continued) WIND • Wind Load (WL) – Resulting loads yields • Lateral load on walls • Downward and upward pressure on roofs Pressure Uplift Suction

6. Design Loads (continued) • Earthquake Loads (EQ) • Seismic load based on building mass , type and configuration. • Vertical and lateral forces (dynamic) • Building codes can simplify loading Epicenter Seismic Forces at Base of Building Hypocenter

7. Loads & Load Paths • Snow or roof load for non-snow areas • Use and occupancy • Self weight of structure • Ground reaction