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lateral

Technical Library | Design | Empirical Masonry Design Guide

Lateral support

Lateral support refers to how the wall is going to perform against applied horizontal loads (i.e. wind) . This analysis looks at a wall plane as a simply supported flexural element (beam) spanning between two points of support. In the traditional sense, the wall is looked at as spanning vertically. That is, the wall is attatched to the ground, and the roof/floor diaphragm. When the wind blows the wall wants to deflect like a beam. This bending stress creates tension on one side of the wall and compression on the other. As we saw in the compressive stress part of this guide, masonry is quite fortuitous in compression. Tension, however, is not handled very efficiently by the masonry wall system. For this reason, the slenderness ratios which follow are critical to designing a safe, code-compliant structure. These calculations result in an adequately engineered structure when and only when all lateral support connections are made. During construction ,when walls are not tied into any structure at the top, walls must be adequately braced to protect the lives of the tradespersons working on the building and any passerby.

 

  • Masonry walls shall be laterally supported in either the horizontal or the vertical direction at intervals not exceeding those given below

 Construction

 Maximum l/t or h/t

 Bearing walls

Solid units or fully grouted

All other

 

20

18

 Nonbearing walls

Exterior

Interior

 

18

36
One can add the nominal thicknesses of multiwythe walls for thickness

Java enabled calculator for hollow bearing walls and exterior non-load bearing walls (h/t = 18)

Enter wall height in feet and the calculator displays minimum thickness in inches

  • Cantilever Walls which are not supported at the top must have a ratio of height to thickness not exceeding 6
  • Lateral support can be provided by cross walls, butresses or structural frame members when the limiting distance is taken horizontally. Or by floors, roofs acting as diaphragms or structural frambers when the limiting distance is taken vertically
  • Mimimum thickness of bearing walls more than one story in height shall be 8 inches
  • Bearing walls of one story buildings shal not be less than 6 inches.
  • Corbelling - the maximum projection beyond the face of the wall shall not be more than one half the wall thickness or one half the wythe thickness for hollow walls. The maximum projection of one unit shall neither exceed one-half the height of the unit nor one-third it's thickness at right angles to the wall.

 

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