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Design of a Timber Howe Truss Highway Bridge


Fox, Joseph (1921) Design of a Timber Howe Truss Highway Bridge. Engineer's thesis, California Institute of Technology. doi:10.7907/8XPH-AA75.


The span of the bridge was assumed as 100 feet. The type of bridge used is the timber Howe Truss. The height of truss was taken as 20 feet between center lines of top and bottom chords. The width was taken as 18 feet center to center of trusses. The truss was divided up into five panels 20 feet long.

It was designed according to the "General Specifications for Steel Highway Bridges" by Ketchum. For the live load for the floor and its supports, a load of 80 pounds per square foot of total floor surface or a 15 ton traction engine with axles 10 feet centers and 6 feet gage, two thirds of load to be carried by rear axles.

For the truss a load of 75 pounds per square foot of floor surface.

For the wind load the bottom lateral bracing is to be designed to resist a lateral wind load of 300 pounds per foot of span; 150 pounds of this to be treated as a moving load.

The top lateral bracing is to be designed to resist a lateral wind force of 150 pounds per foot of span.

The timber to be used in the bridge is to be Douglas fir.

The unit stresses used for timber are those of the American Railway Engineering Association.

Item Type:Thesis (Engineer's thesis)
Subject Keywords:Civil Engineering
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Civil Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Unknown, Unknown
Defense Date:1 January 1921
Record Number:CaltechTHESIS:10122015-111225961
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9212
Deposited On:13 Oct 2015 15:14
Last Modified:16 Aug 2023 22:04

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