Civil Engineering Reference
In-Depth Information
Step 3:
Design of vertical and horizontal column strips.
The vertical and horizontal column strips of unit width are then
designed as slender columns in accordance with BS 8110: Clause
3.8.3, with the additional moment for the horizontal strips to be taken
as the greatest additional moment (see Step 1) calculated for the
vertical strips.
10.3.3
CIRIA Guide Appendix C: Single-Panel Method
The Single-Panel Method is one of the two methods given in Appendix C of
the CIRIA Guide for a more accurate estimate of the effective heights and
effective lengths, using interaction diagrams to allow for the effects of the
in-plane biaxial stresses due to bending and shear. The procedure for the
Single-Panel Method is outlined below.
Step 1:
Division of beam into panels.
The deep beam is divided into panels by adequate restraints. If there
are lateral restraints at the top and bottom edges only, then the
whole beam forms one panel. Each panel is to be considered
individually in the following steps.
Step 2:
Determination of equivalent panel.
If the actual panel is non-rectangular, it is to be replaced by a
notional safe equivalent panel which comprises a rectangular plate,
with its edges either simply supported or free. The width
L
p
(the
height
h
p
) of the equivalent panel is taken as equal to the width (the
height) of the actual panel at the point where the actual horizontal
stress (the actual vertical stress) is at a maximum, as shown in
Figure 10.5
. Further recommendations are also given in the CIRIA
Guide (1977) to take into account the effect of rotational restraint
along the edges of the panel.
Step 3:
Determination of equivalent applied stresses.
The equivalent applied stresses acting on the equivalent panel
comprise linearly varying axial compressive stresses [
N
v
,
N
h
]
applied to the edges and a constant shear stress
t
. The equivalent
applied stresses are chosen such that
(a)
The axial stresses [
N
v
,
N
h
] produce compressive stresses within
the panel that are at no point less than the actual stresses;
(b)
The shear stress
is equal to the algebraic mean of the actual
average vertical shear stresses applied at the ends of the panel.
Where the actual stresses are tensile, they should be treated as
if they were zero.
t
Step 4:
Determination of elastic critical stresses.
Depending upon the edge restraint, the critical axial and shear
stresses are found, each in the absence of any other applied stresses
from the charts given in the CIRIA Guide (1977). The effect of the
shear stress and the in-plane biaxial stresses are then allowed for
