Page 430 - Design of Reinforced Masonry Structures

6.80 CHAPTER SIX

FIGURE 6.45 Typical details for a concrete masonry fence wall [6.34].

so. Depending on the magnitude of lateral loads and local code requirements, fence
walls may be built hollow and unreinforced. Under the action of lateral loads, the wall
can bend in either direction so that either face of the wall can be in tension. Therefore,
if the wall is reinforced, it is advisable to provide reinforcing at the center of the wall.
This results in the design depth of wall equal to half the actual thickness as discussed
in Section 6.7.4. The amount and spacing of reinforcement in fence walls depends on
load as well as on the minimum reinforcement requirements, which were discussed in
Section 6.7.3.
Garden walls may have serpentine or “folded wall” profile which add interesting and
pleasing character to the wall and enhance the landscape. From a structural standpoint,
the curvature in the wall’s profile adds additional stability to the wall so that the wall can
be built with a greater height than a wall with a straight profile in plan. Serpentine walls
are built using empirical design guidelines based on historically proven performance over
many years of experience. Reference 6.32 provides the following guidelines for design of
serpentine or folded-plate walls, which are illustrated in Fig. 6.46. Similar details are also
provided in Ref. 6.8.
1. The wall radius should not exceed twice the wall height.
2. Wall height should not exceed twice the width (or the depth of curvature, see Fig. 6.46).

3. Wall height should not exceed 15 times the wall thickness.
4. The free ends of the wall should have additional support such as a pilaster or a short-
radius return.
5. To control shrinkage cracking, joint reinforcement at 16 in. on centers. should be pro-
vided and that control joints be provided in accordance with local practice.
Reference 6.34 provides design details for cantilever fence walls for three wall
heights—4, 6, and 8 ft. In each case, reinforcing details are provided for three category
of lateral loads, viz., low lateral load (9 to 10 psf), moderate lateral load (14 to 16 psf),
and high lateral load (24 to 26 psf). Readers should consult this reference for additional
details.