Trusses

Overview

Engineering reference data for Trusses in mechanics.

Key Formulas

Newton's Second Law

$F = ma$

Force = mass × acceleration.

Work

$W = Fd\cos\theta$

Work = force × displacement × cos(angle).

Kinetic Energy

$E_k = \frac{1}{2}mv^2$

Energy of motion.

Potential Energy

$E_p = mgh$

Gravitational potential energy.

Variables

Common Truss Types

The text identifies several standard truss configurations used in engineering. Each type is optimized for different load conditions, spans, and construction methods.

• Warren Truss: Features a series of equilateral triangles. The diagonal members are in tension under a typical distributed load, while vertical members (if present) handle compression.
• King Post Truss: The simplest form, consisting of two diagonal members meeting at a central vertical post (king post). It is commonly used for short spans, such as in roof construction.
• Pratt Truss: Characterized by diagonal members that slope toward the center of the span. Under a vertical load, the diagonal members are in tension and the vertical members are in compression, which is efficient for the common material properties of steel.
• Howe Truss: The opposite of a Pratt truss, with diagonal members sloping away from the center. This places the diagonals in compression and the verticals in tension, making it suitable for wooden trusses where wood handles compression well.
• English Howe Truss: A variant that includes both vertical and diagonal members, combining principles to distribute forces effectively.
• K Truss: A modification of the Pratt or Howe truss where the vertical members are subdivided by additional diagonal members to reduce the unsupported length of compression chords.
• Fink Truss: A lightweight, efficient truss form often used for roofs. It uses tension members extensively and can be designed with a variety of web configurations (e.g., single Fink, double Fink).
• Baltimore Truss: A Pratt truss variant with additional sub-diagonal members in the panels, used to support loads applied directly to the truss joints (like from a bridge deck).
• Parker Truss: A Pratt truss with a polygonal top chord, which provides greater depth at the center of the span for increased efficiency over long distances.
• Bowstring Truss: Has a curved (arched) top chord and a straight bottom chord, combining the action of an arch and a truss. The curved chord handles compression, while the straight chord handles tension.

References

• Original Source