1. Trusses – An Engineering Marvel
Dilpreet Bajwa
Daniel Tuhy
Michael Brown

2. Basic Building Structure
Foundation
Floors
Walls
Roof
Doors/Windows
Stairs
Frame
Roof Trusses

3. What is a Truss?
It is an assembly of structural members connected by pins that forms a rigid network of triangles
Engineered Truss structure comprises of five or more triangular units.
Origin- French Trousse
(Collection of things bound together)
18th-19th Century – Churches, Mills, Bridges

4. Common Materials used in Trusses
Wood
Steel
Hollow Pipes
Solid Pipes
Bamboo

5. Application of Trusses
Buildings
Bridges
Electric Poles
Conveyors
Crane Booms

6. Components of the Trusses
Top Chord
Bottom Chord
Web
Metal Gussets
Bearing Points

7. Types of Trusses Parallel Triangular Common Types King Post (16’)
Queen Post (22’ -44’)
Howe (36’)
Scissors
Fink (33’-60’)

8. Wood Trusses Wood – Southern Pine, Douglas Fir, Hem-Fir
Hard Fibrous Material
Orthotropic Nature
Longitudinal – Parallel to grain/fibers
Radial – Normal to growth
Size of lumber – 2x4s …4x10s
Quality of lumber
Kiln Dried/Seasoned
Straightness
Machine Stress Rated

9. Types of Loads on the Roof
Live Load - Structural loads or actions are forces.
Eg. Impact, Vibration, Vehicle on bridge etc.
Dead Load - Dead loads are static forces that are relatively constant for an extended time.
Eg. Weight of structure, roof weight

10. Forces in Trusses Compression Tension Reaction Shear Forces
Bending Moments
Truss Deflection (Elongation under load)
Axial, Shear and Rotational Displacement

11. Truss Testing and Certification
American National Standards Institute (ANSI)
Truss Plate Institute
Structural Analysis
Computing Stress Indices
Selecting Wood Sizes, Grades, Connectors

12. How Trusses are Designed Trusses Design
Questions ??