Stability - ICE Manual of Structural Design: Buildings - page 251

Cellular block construction
A further arrangement of cross walls in low‑rise construc‑
tion is the cellular block plan shown below in Figure 15.14 .
Load‑bearing walls arranged orthogonally on plan provide a
robust and extremely stable form of construction.

15.3.2.3 Wind load carried by an asymmetrical arrangement
of shear walls
When shear walls are arranged in an asymmetrical layout the
line of action of the applied wind load is no longer coincident
with the shear centre. As a consequence, a twisting action is
applied to the shear walls. The distribution of wind load to the
shear walls is therefore not only dependent upon the relative
stiffness of the walls but also the twisting moment from the
applied wind load caused by the eccentric shear centre. The
principles involved are shown in Figure 15.16 .
The design wind load F d acting on the centre line of the
building can be replaced by F d acting through the shear centre
together with a twisting moment F d e as shown in Figure 15.16 .
Since the load F d is now applied through the shear centre, the
wind action is distributed between the shear walls in propor‑
tion to the wall stiffness as follows:

15.3.2.2 Wind load carried by symmetrical arrangement of
shear walls
The distribution of wind load carried by a symmetrical arrange‑
ment of shear walls is readily determined and is proportional to
the stiffness of the walls. Figure 15.15 and the example below
demonstrate the principle involved.

Design wind load on building = F d

Total moment of inertia of resisting walls ΣI = I A + I B + I C

= FI
I

Therefore design shear carried by wall (A) F Ad

dA
F dA FI
∑

F I

dA
F dA FI

Design shear carried by wall (A) F Ad =

(I I I )

+ + I ++ I

ABC A ++ AB

I

AB
I ++ I

AB
I

Where I A = tℓ A 3 /12

= FI
I

dA
F dA FI
∑
Design shear carried by wall (B) F Bd = F I
I

= F I
I

Design shear carried by wall (B) F Bd

dB
F dB FI
∑

dB
F dB FI
∑

Where I B = tℓ B 3 /12
Design shear carried by wall (C) F Cd is the same as wall (A)

= FI
I

and by wall (C) F Cd

dC
F dC FI
∑

Cross Walls
(Load Bearing)

Gable Shear Wall Gable Shear Wall

Corridor or Spine walls

Glazed Elevation

Figure 15.13 Layout plan showing cross wall construction

A B C

t t t

Wind F d

Figure 15.15 Symmetrical arrangement of shear walls resisting
wind load Figure 15.14 Cellular block plan