Design of RC Beam/SLab Framework

PERUNDING JA SCAFFOLDING DESIGN 28/1/21

Date:
Material Data Sheet Sheet: 1
Table for various size of timber bearer (Strength group B)

Table for various size of timber bearer

Basic Size m (B x D) 50 x 100 50 x 75 50 x 125

Finished Size 47 x 97 47 x 72 47 x 120

Section Modules, Z 73.7x10^3 40.61x10^3 11.28x10^4

(mm³)

Moment Inertia, I 3.57x10^6 1.46x10^6 6.77x10^6

(mm4)

Area (mm²) 4559 3384 5640

Characteristic Basic Size (Timber Grade A)

Individual Loaded Timber Load Sharing Timber
50 x 75 50 x 100 50 x 125 50 x 75 50 x 100 50 x 125

Bending Stiffness 8.3 20.36 38.6 12.5 30.54 57.9

EI (kNm²)

Moment of 0.95 1.663 2.49 1.04 1.829 2.73

Resistance, kNm

Shear Load, kN 6.8 9.1 11.3 10.2 10 16.9

According to Table 4 & 5, Extract from `Formwork Guide to Good Practice'

by ISTRUCTE

Characteristic Basic Size

12.5mm Thick

Bending Stiffness 2.237

EI (kNm²)

Moment of 0.262
Resistance, kNm

Shear Load, kN 3.8

Comparison to Table 8, Structural properties of wood-based sheet materials
General Formwork and Soffit Application
 Design of RC Beam/SLab Framework
PERUNDING JA SCAFFOLDING DESIGN Date: 19/10/19
Material Data Sheet Sheet: 2

Characteristic Basic Size

Side Formwork
25 x 50 35 x 70

Bending Stiffness 2.23 8.56

EI (kNm²)

Moment of 0.133 0.35

Resistance, kNm

Shear Load, kN 1.25 2.45

Design Notes and Data

- All Structural timber shall be of Strength Class SC4 complying with BS 5268: Part 2:1984.
-All structural steel shall be Grade 43 complying with BS 4360: 1986.
The design shall be in accordance with the Structural Use of Steel, Hong Kong, 1987
- Form tie shall be high yield bar with minimum permissible tensile strength of 230MPa.
- The allowable deflection for formwork shall be less than (span/270)
as recommende by Section 2.7, "Formwork - A Guide to Good Practice".
- The determination of maximum concrete pressure on formwork is in accordance with CIRIA
Report 108.

Material properties
For structural timber of strength class SC4 to BS 5268 as wall formwork
Bending stress parallel to grain = 20 N/mm²
Compressive stress parallel to grain = 17 N/mm²
Compressive stress perpendicular to grain = 2 N/mm²
Shear stress parallel to grain = 3 N/mm²
Modulas of elasticity E = 8554 N/mm²

For Grade A
 Design of RC Beam/Slab Framework
PERUNDING JA SCAFFOLDING DESIGN Date: 10/10/19
150 thick RC SLAB Sheet: 1

B Falsework design for 150 thick RC slab

Loading accessment
Self weight of RC Slab = 3.6 kN/m2
where, (Concrete density = 24 kN/m3
(Thickness of RC Slab = 150 mm
Construction Load = 1.5 kN/m2
self weight of Soffit Formwork = 0.5 kN/m2

Total UDL, w = 5.6 kN/m2

B1) Check 12.5mm thick plywood

Maximum Span = 400 mm

= 0.4 m
Check B > 2t
B = 50 > 2t = 25
=
W = 5.1 x 0.4
= 2.0 kN per m run

a) Check Bending
Max. Bending Moment = 0.095 WL
= 0.078 kNm per m run
< Moment of Resistance = 0.262 kNm
OK
Moment Capacity Check OK

b) Check Sheat stress

Max. Shear Stress = 0.525 W(L - B - t)
L
= 0.90 kN per m run
< Shear Resistance = 3.8 kN
OK

c) Check Deflection
Max. Deflection = 0.0066 WL³ EI = 2.237 kNm²
EI
= 0.385 mm

Allowable Deflection = L / 270

= 1.5 mm
> Actual Deflection = 0.385 mm
OK
 Design of RC Beam/Slab Framework
PERUNDING JA SCAFFOLDING DESIGN Date: 10/10/19 PERUNDING JA
150 thick RC SLAB Sheet: 2

B2) Check 50 x 75 Secondary Timber Bearer @ 400 mm c/c B3) Check

Maximum Span, L = 1.219 m Distance betwe

w = 5.6 x 0.40
= 2.24 kN/m

W = wxL
= 2.7 kN

a) Check Bending
Max. Bending Moment = 0.1 WL
= 0.333 kNm
< Moment of Resistance = 0.45 kNm
OK a)
Moment Capacity Check OK Max. Bending

b) Check Sheat stress

Max. Shear Stress = 0.6 W

= 1.64 kN per m run

< Shear Resistance = 3.47 kN b)
OK Max. She

c) Check Deflection
Max. Deflection = 0.00541 WL³ EI =
EI 12.5 kNm2
= 2.14 mm
c)
Allowable Deflection = L / 270 Max. D
= 4.5 mm
> Actual Deflection = 2.14 mm
OK

Allowable D
 Design of RC Beam/Slab Framework
PERUNDING JA SCAFFOLDING DESIGN Date: 10/10/19 PERUNDING JA
150 thick RC SLAB Sheet: 3

2 nos 50 x 125 Primary Timber Bearer B4) Check Capacity o Scaffol

Distance between Rows of Scaffold = 1219 mm Scaffold Fram

Spacing between Scaffold = 1800 mm Maximum Vertical load p

W = 5.6 x (1219+1219)/1000/2 x 1.8 Capacty of S

= 12.3 kN

Max Reaction = 1.1 W

= 13.5 kN

Check Bending
Max. Bending Moment = 0.1 WL
= 2.214 kNm
< Moment of Resistance = 2x1.13 kNm
OK
Moment Capacity Check OK

Check Sheat stress

Max. Shear Stress = 0.6 W
= 7.38 kN per m run
< Shear Resistance = 2x5.24. kN
OK

Check Deflection
Max. Deflection = 0.00688 WL³
EI
= 1.99 mm

EI = 2x38.61 kNm2
= 77.22 kNm2

Allowable Deflection = L / 270

= 6.667 mm
> Actual Deflection = 1.99 mm
OK
 Design of RC Beam/Slab Framework
PERUNDING JA SCAFFOLDING DESIGN Date: 10/10/19
150 thick RC SLAB Sheet: 4

B4) Check Capacity o Scaffold Frame

Scaffold Frame @ 1219 c/c

Maximum Vertical load per Scaffold leg = 5.6 x (1219 + 1219)) / 1000/2 x 1.8 x 1.1
= 13.5 kN

Capacty of Scaffold Frame = 24.5 kN per leg

> 13.5 kN
OK

Adopt Light Duty Scaffold @ 1219 x 1800 mm c/c

.
 Design of RC Beam/Slab Framework
PERUNDING JA SCAFFOLDING DESIGN 19/10/19 PERUNDING JA
Date:
125 X 650 RC BEAM Sheet: 1

C Falsework design for 125 x 650 thick RC Beam C3) Check

Width Depth
Loading accessment
Size of RC beam = 125 x 650 (mm)
Thickness of RC Slab = 0 mm thick
Self weight of RC Beam = 15.6 kN/m2 (Include slab thick)
where, (Concrete density = 24 kN/m3
Self weight of RC Slab = 0 kN/m2
Construction Load = 1.5 kN/m2
self weight of Soffit Formwork = 0.5 kN/m2
Total UDL, w = 17.6 kN/m2

C1) Check 12.5mm thick plywood Ra

Maximum Span = 400 mm Ra

= 0.4 m
Check B > 2t
B = 50 > 2t = 25 a)
Max. Bending M
W = 17.1 x 0.4
= 6.8 kN per m run

a) Check Bending
Max. Bending Moment = 0.095 WL
= 0.260 kNm per m run
< Moment of Resistance = 0.262 kNm b)
OK Max. Shea
Moment Capacity Check OK

b) Check Sheat stress

Max. Shear Stress = 0.525 W(L - B - t) c)
L Max. De
= 3.03 kN per m run
< Shear Resistance = 3.8 kN
OK

c) Check Deflection
Max. Deflection = 0.0066 WL³ EI =
EI 2.237 kNm2
= 1.292 mm

Allowable Deflection = L / 270

= 1.5 mm
> Actual Deflection = 1.29 mm
OK
 Design of RC Beam/Slab Framework
PERUNDING JA SCAFFOLDING DESIGN 19/10/19 PERUNDING JA
Date:
125 X 650 RC BEAM Sheet: 2

50 x 75 Secondary Timber Bearer @ 400 mm c/c C2) Check 2

Spacing between Timber Joist = 0.4 m
Maximum Span, L = 1.219 m Distance between Rows of Scaffo
Maximum Moment at x = 0.5 L Spacing between Scaffo
ws = 2 x 0.4
= 0.80 kN/m .

w = 15.6 x 0.4
= 6.2 kN/m

a = (1.219 - 0.125 )/2

= 0.55 m
= 0.80 x 1.219 / 2 + (b / 2 + a) x w x b / 1.219)
= 0.88 kN
= 0.80 x 1.219 / 2 + (b / 2 + a) x w x b / 1.219)
= 0.88 kN w =

Check Bending =
Max. Bending Moment = wb (a + b/4) wsL²
+
2 8 Max Reaction
= 0.226 + 0.15
= 0.374
a) Check Bending
< Moment of Resistance = 0.45 kNm Max. Bending Moment
OK
Check Shear stress
Max. Shear Stress = 0.88 kN
< Shear Resistance = 3.47 kN
OK
b) Check Shear stress
Check Deflection Max. Shear
Max. Deflection = wb(8L³-4Lb²+b³)+5wsL⁴
384 EI
= 4.18 mm

EI = 12.5 kNm²
Bending Stiffness c) Check Deflection
Max. Deflection
Allowable Deflection = L / 270
= 4.5 mm
> Actual Deflection = 4.18 mm
OK Allowable Deflection
 Design of RC Beam/Slab Framework Design of
SCAFFOLDING DESIGN 19/10/19 PERUNDING JA SCAFFOLDING
Date:
125 X 650 RC BEAM Sheet: 3 125 X 650 RC BEAM

Nos 50 x 100 Primary Timber Bearer C4) Check Capacity of Scaffold Frame

istance between Rows of Scaffold = 1219 mm Scaffold Frame @

Spacing between Scaffold = 1800 mm Maximum Vertical load per Scaffold leg
= 1.8 m

Capacity of Scaffold Frame

Adopt Light Duty Scaffold @

( 15.6 x 0.13 ) +
(3.6 + 1.5 + 0.5) x(1.219 + 1.219) / 2 x 1.8
6.1 kN

= 1.10 W
= 6.76 kN

Check Bending
Max. Bending Moment = 0.1 WL
= 1.106 kNm (2nos 50 x 100)
< Moment of Resistance x 2
= 1.48 kNm BEAM SIDE FORMWORK ARR
OK

Check Shear stress

Max. Shear = 0.6 W
= 3.69 kN (2nos 50 x 100)
< Shear Resistance x 2
= 8.48 kN
OK

Check Deflection
Max. Deflection = 0.00688 WL⁴ EI =
EI 20.36 x 2 kNm²
= 6.05 mm 40.72 kNm²

Allowable Deflection = L / 270

= 6.667 mm
> Actual Deflection = 6.05 mm
OK BEAM SIDE FORMWORK STRU
 Design of RC Beam/Slab Framework Design of RC Beam/Sl
SCAFFOLDING DESIGN 19/10/19 PERUNDING JA SCAFFOLDING DESIGN
Date:
125 X 650 RC BEAM Sheet: 4 125 X 650 RC BEAM
DESIGN OF BEAM SIDE FORMWORK
of Scaffold Frame
D1) Check 35 x 70
Scaffold Frame @ 1800 mm c/c Spacing between Timber Joi
al load per Scaffold leg = 6.76 kN

acity of Scaffold Frame = 25.00 kN per leg a) Concrete pressure on side formwork
> 6.76 kN
OK

ght Duty Scaffold @ 1800 c/c

Maximum reaction, Ra=Rb

a) Check Bending
Max. Bending Moment =

b) Check Shear stress

BEAM SIDE FORMWORK ARRANGEMENT Max. Shear Stress =

c) Check Deflection
Max. Deflection =

Allowable Deflection =
=

BEAM SIDE FORMWORK STRUT SUPPORT DETAIL

 Design of RC Beam/Slab Framework Design of RC Beam/Slab Framewo
SCAFFOLDING DESIGN 19/10/19 PERUNDING JA SCAFFOLDING DESIGN
Date:
0 RC BEAM Sheet: 5 125 X 650 RC BEAM
650 DEPTH DESIGN OF BEAM SIDE FORMWORK 650

Secondary Timber Bearer @ 300 mm c/c E1) Check 35 x 70 Primar Timber Bearer
Spacing between Timber Joist = 0.3 m Spacing of strut/ Tertiary bearer nail joint
Beam Depth, L = 0.65 m Maximum span, L
Bearer effective L = 0.6 m

n side formwork = D*h kN/m² . w

14.4 kN/m²

D = Density of concrete
= 24 kN/m³
h = 0.6 m Maximum reaction, R

w = 14.4 x 0.3 a) Check Bending

= 4.32 kN/m Max. Bending Moment = wL²
10
ximum reaction, Ra=Rb = 1.30 kN = 0.092
<

wL²
8 b) Check Shear stress
0.194 kN/m Max. Shear Stress = 1.15
< Moment of Resistance = 0.352 kNm <
OK

c) Check Deflection
1.30 kN Max. Deflection = 5wL⁴
< Shear Resistance = 2.45 kN 384EI
OK = 0.22

Allowable Deflection = L
0.00688 WL⁴ EI = = 1.48
EI 8.558 kNm² >
0.45 mm

L / 270 E2) CHECK TERTIARY BEARER/ DIAGONAL STRUT

2.222 mm Tertiary bearer = diagonal strut = primary bearer, no check requ
> Actual Deflection = 0.45 mm
OK E3) CHECK NAIL SUPPORT ON TERTIARY BEARER AND STRUT

Nail, diameter = 3
As of nail = 7.07
Shear stress of nail = 240
Shear strength of nail = 1.7

Provide nail at 400mm to beam secondary bearer

Design of RC Beam/Slab Framework Design of RC Beam/Slab Framework
FFOLDING DESIGN 19/10/19 PERUNDING JA SCAFFOLDING DESIGN
Date:
Sheet: 6 125 X 650 RC BEAM
DEPTH DESIGN TIMBER PROP FOR INTERMEDIATE BEAM

Primar Timber Bearer F1) Check 1nos 50x75 Timber Joist as Vertical Supporting Member for Beam
ertiary bearer nail joint = 400 mm
Maximum span, L = 0.4 m Maximum size of beam = 125

Maximum Width of beam = 125 mm

= 14.4 x 0.4 Maximum Spacing = 0.4 m
5.76 kN/m
wslab = (0 + 1.5 + 0.5) x
= 0 kN/m

= 2.30 kN w = 15.6 + 1.5

= 1.15 kN = 17.6 kN/m² x
(On top & bottom) = 7.04 kN

Ra = Rb = 7.04 kN
kN/m
Moment of Resistance = 0.352 kNm Loading to support = 1.1 Ra/ Rb
OK = 1.1 x
= 7.744 kN

kN a) Check compressive stress

Shear Resistance = 2.45 kN
OK Compressive stress perpendicular to grain = 3.07 N/mm2

Area of timber joist = 4559 mm2 ( 50x75 timber joist)

EI =
8.558 kNm² Compressive Capacity = 4559 x 3.07
mm = 14 kN
OK
/ 270
mm
Actual Deflection = 0.22 mm
OK

t = primary bearer, no check require.

EARER AND STRUT

mm
mm²
N/mm²
kN > 1.15 kN
OK
m secondary bearer
 C Beam/Slab Framework
DESIGN 19/10/19
Date:
Sheet: 7

rting Member for Beam

x 650

0 (No slab at roof)

+ 0.5
0.4

7.04

n = 3.07 N/mm2

m2 ( 50x75 timber joist)

4559 x 3.07
> 7.744 kN