Structural Floor Panels Design Guide - Hebel Supercrete AAC ...

Worked Example Calculation
2.2.5.8 Determine which is the
Governing Diaphragm
Diaphragm D1 will be the governing diaphragm for
horizontal loads applied parallel to the panel axis as it has
the longest span.
Diaphragms D1 and D2 will be the governing diaphragms
for horizontal loads applied perpendicular to the panel axis.
2.2.5.9 Determine Wind and Seismic
Loads on a Single Diaphragm
The governing horizontal loads are from these seismic
forces as they total 189 kN compared with only 62.2 kN
for wind for the whole floor. This force applies to the full
area of the floor and can be proportioned by area for
each diaphragm. Therefore, the design force on governing
diaphragm D1 is as follows:
FlD1 = 189 x 4.8 x 9 = 60.5 kN
15 x 9
2.2.5.10 Analyse the Horizontal Loads
Parallel to the Panel Axis
The total load on this diaphragm is spread over the full
width of the structure of 9 m. This therefore equates to a
UDL of 60.5 = 6.72 kN/m
9
Tensile force in the reinforcing steel in the first joint:
T = (w x L) - (w x 0.6) = (6.72 x 9) - (6.72 x 0.6) = 26.2 kN
2
2
Steel area required for this tensile force
As = T = 26.2 x103 x 10-6 = 87 mm2 300 x106 fy
Area of single D12 bar =114 mm 2 > 87 mm 2,
therefore, single D12 bars in all panel joints will be sufficient.
Angle of diagonal compression force in panel where
= Tan -1(0.6)
( s )
= Tan -1(0.6) = 7.12˚
(4.8)
Diagonal compression force C = Tmax = 60.5
Cos 2 x Cos 7.12
C = 30.5 kN
This is based on the tensile force in the perimeter joint (i.e.
the “reaction” force in the end bracing wall) and not on the
force in the first joint. This force exceeds 10 kN, therefore
corner chamfers on the outer panels are required.
Chamfer length Lc = C = 30.5 x 103 = 45mm
0.6 x D x 4√2 0.6 x 200 x 4√2
As the tensile force in each panel joint reduces away from
the perimeter, the diagonal compression force also reduces.
This normally results in only the outer panels requiring
corner chamfers where the diagonal compression force
exceeds 10 kN.
The number of panels n that require a corner chamfer
n = L - 10
2 w
where L = width of diaphragm in metres
w = applied horizontal load along diaphragm edge in kN/m
n = 9 – 10 = 3 panels
2 6.7
Therefore, use a 50mm corner chamfer on all corners of
the outer 3 panels at each end of the floor diaphragm.
This calculation should be done for each diaphragm – in
this example, only D1 and D2 require the chamfers (see
diagram, page 40).
Tensile force in perimeter ring anchor steel
T = wL2 8 x 0.7 x S
T = 6.72 x 10 3 x 9 2 = 20.3 kN
8 x 0.7 x 4.8
Steel area required for this tensile force
As = T = 20.3 x103 x 10-6 = 67 mm2 300 x 106 Therefore, a single D12 bar will be sufficient
as 67 mm 2 < 114 mm 2
2.2.5.11 Analyse Horizontal Loads
Perpendicular to the Panel Axis
For this direction w = 60.5 = 12.6 kN/m
4.8
Calculate the maximum bending moment in each panel:
Mmax = wS2 = 12.6 x 4.82 = 2.5 kN-m
8n 8 x 14.5
Calculate the width of the compression block in the AAC
a = As x fy = 114 x 300 = 50.3 mm
3.4 x D 3.4 x 200
Calculate moment capacity of each panel
Mc = Ø.As.fy(600 – (0.5a)) x 10-3 = 0.9 x 114 x 300 x (600
– (0.5 x 50.3)) x 10-3 Mc = 17.7 kN-m
17.7 kN > 2.5 kN, therefore bending capacity is OK
Determine the shear force per metre that needs to be
transferred into the support walls
= wS = 12.6 x 4.8 = 3.45 kN
2L 2 x 8.74
This force is well within the shear capacity of the M12
vertical wall reinforcing which extends into the perimeter
ring anchor and is therefore OK. Cleat welds on the
support beam must also be able to exceed this capacity.
SFP 2012 42 Copyright © Supercrete Limited 2008
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