A Beginner's Guide to Structural Mechanics/Analysis

Tributary Areas and Load Diagrams

(c) 2007, T. Bartlett Quimby

Overview
Gravity Loads
Lateral Loads
Non-Graphical Methods
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Section TA.1

Overview

Last Revised: 09/11/2007

The concept of tributary areas is very useful when computing the loading applied to structural elements.  If the tributary area can be identified, then it is not often necessary to compute the progression of load transfer through the load path.  The method does, however, have it's limitations.

The two principle conditions for using tributary area as a means for determining element loading are:

  • The load on the tributary area must be a constant pressure.
  • The supported elements must be simply supported, single span bending elements or can reasonably be assumed to transfer half of their supported load to the supporting element.

The second criteria is not strictly true, but if the supported members are not simply supported single span members, the method loses it's usefulness.