Page 428 - Design of Reinforced Masonry Structures

6.78 CHAPTER SIX

these walls do not function as gravity load–carrying elements. For analytical purposes,
MSJC-08 Section 1.6 [6.1] distinguishes nonload-bearing walls from load-bearing walls as
the latter carrying superimposed load vertical load of at least 200 per lineal foot in addition
to their own weight. However, nonload-bearing walls must be able to resist their own dead
weights and lateral loads (e.g., due to wind and earthquake).
Design and analysis of nonload-bearing walls do not present any special difficulty.
Principles and methods discussed in previous sections for analyzing and designing load-
bearing walls are equally applicable to nonload-bearing walls. Since these walls do not
carry any gravity load, except their own weight, the axial compressive stresses are very
small. Design of fence walls and highway sound barrier walls are discussed in the next two
sections. It should be noted that both types of walls are subjected to a wide range of load-
ing conditions, temperatures, and moisture variations. Therefore, the selection of proper
materials and proper workmanship is very important for satisfactory structural performance
and durability of these walls.

6.10.2 Design of Fence Walls
A discussion on concrete masonry fence walls can be found in several references [6.8, 6.33,
6.34], which is briefly summarized here. Concrete masonry fence walls are constructed to
serve many functions. They include:
1. Privacy
2. Security and protection
3. Ornamentation
4. Screening from unwelcome views
5. Excellent sound insulation
6. Shade
7. Wind protection
Availability of CMU in a wide range of colors and textures gives concrete masonry a
unique advantage in that they can be used to enhance aesthetic qualities of the wall, comple-
ment adjacent architectural styles, or blend in with the natural landscape.
NCMA TEK 14-16A [6.34] recommends design of fence walls to ensure stability accord-
ing to the following five methods:
1. As cantilever walls stabilized by continuous footings
2. As walls spanning between pilasters which are, in turn, stabilized by a footing or a
caisson
3. As walls spanning between wall returns which are adequate to stabilize the wall

4. As curved walls with an arc to chord relationship that gives stability
5. As a combination of above methods
Fence walls must be deigned to carry their own weight and the governing lateral loads
(due to wind or earthquake). The only dead load on fence walls is their own weight. Methods
of calculating these loads were discussed in Section 6.5. The magnitude of the lateral seis-
mic force F can be determined from Eq. (6.7):
p
04 aS ⎛ z ⎞
.
+
F = p DS ⎜ 12 ⎟ W (6.7 repeated)
p ⎛ R ⎞ ⎝ h ⎠ p
⎜ ⎝ p I ⎠ ⎟
p