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7/29/2019 Kenyan Timber Stresses
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Issue: Page
P.O. Box Date:
Revised by: GM
Checked by: GM
CODE OUTPUT
DATA
UNITS
M.
KN/M
N/mm2
M2
Kg/M3
Kg PITCH, 22.5 Degrees 0.3925
2.6143825
N 2.4155736
Rafters & Bottom Tie 100 x 50 0.005 m2
Truss Webs 100 x 50 0.005 m2
GCI Sheeting Purlins 75 x 50 0.00375 m2
Tiling Battens 50 x 50 0.0025 m2
Ceiling Brandering 50 x 50 0.0025 m2
Intermediate Rafter 100 x 50 0.005 m2
Underpurlins 100 x 50 0.005 m2
Density of Wood 500 Kg/m3
Weight
Bottom-Tie Length 7.2 m 18.00 Kg
Total Rafter Length 9.09 m 22.73 KgTotal Web Length 8.18 m 20.46 Kg
Truss Spacing 1.2 m 61.19 Kg
Tiling Battens Spacin 0.3 m
Purlin Spacing 1.2 m
Brandering Spacing 0.6 m
Intermediate Rafer 0.6 m
Weight of Truss
Weight of Main plate 61.2 Kg
Weight of Nailing plate 15.3 Kg
Weight of Nails 7.6 Kg
84.1 Kg = 0.84 kN/truss
Weight of Tiles 0.7 kN/m2
7.64 kN/trus 0.70
Weight of tiling battens (50x50) 0.015 kN/Batte 0.45 " 0.04
Weight of GCI Sheeting 0.1 kN/m2
1.09 " 0.10
Weight of Purlins (75x50) 0.0225 kN/Purlin 0.17 " 0.02
9.35 kN/truss
Roof imposed load 0.25 kN/m2
Weight of Ceiling 0.25 kN/m 2.16 kN/truss
Issue: Page
P.O. Box Date:
Revised by: GMDEVELOPMENT ON BLOCK 40/(2,3,4&5)
Project:DEVELOPMENT ON BLOCK 40/(2,3,4&5)
MAVOKO
1
CALCULATIONS
Nairobi2
7/29/2019 Kenyan Timber Stresses
2/99
Checked by: GM
REF OUTPUT
Weight of Ceiling Brandering (75x50) 0.015 kN/Brand 0.45 "
2.61 "
Total Load per Truss = 12.81 kN/truss
No. Panels 0n the Rafter 4 On Rafter
No. Panels 0n the Bottom-Tie 3 On Bottom Tie
Truss Loading at Rafter Level 2/3 of Total Load = 8.54Nodal Loading at Rafter Level
Truss Loading at Ceiling Level 1/3 of Total Load = 4.27
Nodal Loading at Ceiling Level
CP3 WIND LOAD x
CP3 Chp V Basic Wind Speed for NAIROBI V = 28 m/s V = 28 m/s
Pt2 4.3 Topography factor S1 = 1.0 S1 = 1.0
Statistical factor S2 = 0.9 S1 = 0.9
Topography factor S3 = 1.0 S1 = 1.0
CP3 Chp V Height to Eaves, h = 16.2 Pitch = 22.5
5.4 Building Class = B Width = 7.9
Table 3 Ground roughness Category = 3
Height (eaves to apex) = 1.64
CP3 Chp V Total height to apex, H = 17.84 m
5.6
Design Wind Speed Vs = VxS1xS2xS3 = m/s
28 x 1 x 0.9 x 1 = 25.2
Vs= 25.2
6.0 Dynamic Pressure q = KVs x Vs Where K = 0.613
therefore, q= 0.613 x 0.613 x 0.613 = 389 N/m2
N
= 0.389 N/m2
KN
External Pressure Coefficients, Cpe
Height to eaves, h = 16.2 m
Width w = 9.425 m h/w = 1.719
CP3 Chp V Slope = 22.5 Deg. Cpe = -0.575 Wind on
Table 8 Cpe = -0.5 Side
Cpe = -0.8 Wind on
Cpe = -0.65 End
Internal Pressure Coefficients, Cpi
CP3 Cpi = 0.2
Appendix E ./ ( ) - x Cpi = -0.3
CP3 Wind Load F = (Cpe -Cpi).q.A A =
7.2
Max. roof Uplift = (-0.8-0.2)qA = -0.389
Min Downward Load = (-0.8--0.3)qA = -0.195
UPLIFT
Design for Uplift force of Fmax = -0.389
Fmin = -0.195
Truss Spacing = 1.2 m xTruss Span = 7.2 m
Overall Span = 7.2 m 1.2x7.2 = 8.64 m2
therefore. Max. Uplift = Fmax = 3.37 kN/truss
Fmin = 1.682 kN/truss
Issue: Page
P.O. Box Date:
Revised by: GM
Checked by: GM
MAVOKO
CALCULATIONS
Nairobi3
tributary area to
truss
Project:DEVELOPMENT ON BLOCK 40/(2,3,4&5)
MAVOKO
ributary area to trus
7/29/2019 Kenyan Timber Stresses
3/99
REF OUTPUT
Battens
Area Supported / Batten, Ab = 0.3x0.6
Batten Spacing = 0.3 m Ab = 0.18
Batten Span = 0.6 m Max. Batten Uplift = 13 x 0.18 = -0.071 kN/batten
GRAVITY LOADS
Imposed Load:
Imposed Load = 0.25
Dead Loads :
Truss self Weight = 84 Kg = 0.84 kN
Distributed Load = 0.84 / 7.2 x 1.2 = 0.10 kN/m2
Tiles+ Battens = 0.75 kN/m2
GCI Sheets + Purlins = 0.12 kN/m2
total = 0.97
Ceil ing + Brandering = 0.28 kN/m2
1) At the rafter level 0.97 KN/M2
Total DL = 8.39 = 5.6
kN/truss
Total IL = 2.16 = 1.44 kN/truss
total 7.04
2) At the Ceiling level
1.87
kN/truss
0.72
total 0.72
3) Batten
Imposed = = 0.05 KN
Dead = 0.75 x 0.3 x 0.6 = 0.07 KN
CP3 LOAD SUMMARY x
BS 5268 Total Span = 9092
Pt 2 1996 Load Type of Load
2.8 and Duration Load Batten Duration
Table 14 Rafter Level Ceiling Level Factor K3
Long Dead 7.04 1.87 0.07 1.0
Term Only
Medium Dead + 7.04 1.87 0.070
Term Temp. Li 1.44 0.72 0.05
TOTAL 8.48 2.59 0.120 1.25
Very Short Dead + 7.04 1.87 0.07
Term Wind 3.37 -0.071
TOTAL 3.67 0.00 1.75
Issue: Page
P.O. Box Date:
Revised by: GM
Checked by: GM
REF OUTPUT
BATTEN DESIGN Span , L 0.6 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 0.120 kN DL + WL = F = -0.001 kN
0.25 x 0.3 x 0.6
Total DL =
CALCULATIONS
Project:
CALCULATIONS
Typical Load
Nairobi4
DEVELOPMENT ON BLOCK 40/(2,3,4&5)
MAVOKO
Truss
Total IL =
0.25 x 7.2 x 1.2 =
0.97 x 7.2 x 1.2 =
7/29/2019 Kenyan Timber Stresses
4/99
Mmax =FL/8 = 0.009 kNm Mmax =FL/8 = 0.000 kNm
Reaction FL/2 = 0.036 kN Reaction FL/2 = 0.000 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade .K3.K7.K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 0.009
Zreq. = M/dm = 799.201 mm3
25x50
For 25 x 50 mm Battens
Zprov. = bd2/6 = 10417 mm3
therefore Bending OK
Deflection Check
Emin = 3600 N/mm2
Emin = 3600 N/mm2
I = bd3/12 = 260417 mm4
Max deflection, dmax dmax = 0.15 mm
Max allowable deflection = 0.003L = = 1.8 mm
1.8 > 0.15
Deflection OK
Adopt
BS 5268 TRUSS T1- FORCE
Pt 2 1996 Design for Medium Term Loading
2.8 and Total Load at Rafter = 8.48 Cantileverd end = 750 mm
Table 14 Total Load at Ceiling = 2.59 Total Truss Load = = 11.07 kN
Total No. of Panels on Rafter = 4 Truss Span = 7200 mm
Total No. of Panels on Bottom Tie = 3 Total Span = 8700 mm
P1 = 8.48/4= 2.120 2.593= P3 = 0.863
P2 = 2.12/= 1.060 P4 = 0.432
R = 11.07/= 5.535 -0.432 = 5.103 kN
Member length coeff force unit force
1 2098 3.92 8.31374 kN 1.31 kN
2 2098 3.54 7.50284 kN 1.31 kN
3 2098 0.92 1.95879 kN 0.00 kN
4 2098 3.62 7.68152 kN 0.00 kN
5 2098 3.54 7.50284 kN 1.21 kN
6 2098 0.92 1.95879 kN 1.21 kN
Issue: Page
P.O. Box Date:
Revised by: GMChecked by: GM
REF OUTPUT
RAFTER DESIGN
Critical Member is: 1
BS 5268 F = 8.31 kN Compression
Pt 3 L = 2098 mm 50x150
6.5.5 Le = 1888.2 mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 150
Project: DEVELOPMENT ON BLOCK 40/(2,3,4&5)MAVOKO
25x50
TENSION
C
OMP.
5
CALCULATIONS
Refer to Truss Diagram above
Nairobi
7/29/2019 Kenyan Timber Stresses
5/99
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 1E+07
Pt 2 r = 43.30 A = 7500
2.11.4 l = 43.61 Zprov. = bd2/6 = 2E+05
< 180 Slender Ratio OK
2.11.5 ince l > 5 l SQD = 1901 Multiply grade stress by K12 x
BS 5268 h = 0.005 l = 0.218 N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.877551 dc = 6x1.25= 7.5 K3 = 1.25 For very short term( ) = 1.5123548 )SQD = 2.287 () = 1.662 K12 = 1.12
Annex B K3 = 1.5 K12 = 1.00
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = 10.096 N/mm2
(Permissible Compression Stress)
da(c) F/A = = 1.108 N/mm2
(Applied Compression Stress)
< 10.096 Section OK
BS 5268 Check for Combined Compression and Bending for Rafter
Pt 3 Man Point Load P = 0.9 kN K3 = 1.5 Duration Factor
6.4.2 F = 8.3137 kN K7 = (300/d)^0.11
L = 2098 mm K7 = 1.08 Depth Factor
Le = 1888.2 mm K8 = 1.1 Load Sharing F.
Mmax = PLe/4 = 0.425 kNm (Max Bending Moment, PL/4)
dadm(b) = dgrade x K3K7K8 =
= 10.684 da(b) .= M/Z = 2.27 N/mm2
(Applied Bending Stress)BS 5268 da(c) = 1.108 + 2.27 de = PI^2E 35559
Pt 2 adm(c) dadm(b) (1-1.5dadm(c) x K1 10.0963 10.6844 0.9 l 2 1901.5
2.11.6 de de = 18.701
= 0.110 + 0.236 = 0.3454
Adopt 50x150 since < 1
BOTTOM TIE DESIGN
Critical Member is 4
F = 7.6815 kN Tension
Try GS grade Cypress = 100 x 150
I = bd3/12 = 2.8E+07 use 100x150
A = 15000
BS 5268 bd2/6 = 375000
Pt 2
2.12 dgrade = 3.00 N/mm2
K14 = (300/d)^0.11K14 = 1.08
dadm(t) = dgrade x K14
= 3.24 N/mm2
(Permissible Tensile Stress)
da(t) F/A = 0.51 N/mm2
(Applied Tensile Stress)
< 3.24
Issue: Page
P.O. Box Date:
Revised by: GM
Checked by: GM
REF OUTPUT
INTERNAL MEMBER DESIGNCritical Member is 6
F = 1.9588 kN Tension
Try GS grade Cypress = 50 x 100
dgrade = 3.00 N/mm2
K14 = (300/d)^0.11 A = 5000 mm2
K14 = 1.13
dadm(t) = dgrade x K14
= 3.39 N/mm2
(Permissible Tensile Stress)
da(t) F/A = 0.39 N/mm2
(Applied Tensile Stress)
Project:DEVELOPMENT ON BLOCK 40/(2,3,4&5)
MAVOKO
CALCULATIONS
.+ da(b)
100x150
Section OK
Nairobi
50x100
6
187500
14062500
7/29/2019 Kenyan Timber Stresses
6/99
< 3.39
Critical Member is 3
BS 5268 F = 1.9588 kN Compression
Pt 3 L = 2098 mm 50x100
6.5.5 Le = 1888 mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 100
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 4E+06
Pt 2 r = 28.87 A = 5000
2.11.4 l = 65.40 Zprov. = bd^2/6 = 83333
< 180 Slender Ratio OK
2.11.5 ince l > 5 l SQD = 4277 Multiply grade stress by K12 x
BS 5268 h = 0.005 l = 0.327 N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.88 dc = 6x1.75= 10.5 K3 = 1.75 For very short term
Annex B ( ) = 0.86 )SQD = 0.74 () = 0.53 K12 = 0.82
K3 = 1.5
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = 7.34 N/mm2
(Permissible Comp. Stress)
da(c) F/A = = 0.39 N/mm2
(Applied Comp. Stress)
< 7.34461 Section OK
CP3 LOAD SUMMARYBS 5268 Total Span = 8700
Pt 2 1996 Load Type of Load
2.8 and Duration Load Duration
Table 14 Rafter Level Factor K3
Long Dead 3.52 1.0
Term Only
Medium Dead + 3.52
Term Temp. Li 0.72
TOTAL 4.24 1.25
Very Short Dead + 1.76
Term Wind 1.69
TOTAL 0.08 1.75
Issue: Page
P.O. Box Date:
Revised by: GM
Checked by: GM
REF OUTPUT
INTERMEDIATE RAFTER DESIGN Span , L 3 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 4.240 kN DL + WL = F = 1.685 kN
Mmax =FL/8 = 1.590 kNm Mmax =FL/8 = 0.632 kNmReaction FL/2 = 6.360 kN Reaction FL/2 = 2.528 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade x K3K7K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
CALCULATIONS
Typical Load
Project:DEVELOPMENT ON BLOCK 40/(2,3,4&5)
MAVOKO
4166666.7
83333.3
Nairobi7
Section OK
7/29/2019 Kenyan Timber Stresses
7/99
dm = 11.26 N/mm2
M = 1.590
Zreq. = M/dm = 141192 mm3 50x150
For 50 x 150 mm
Zprov. = bd2/6 = 187500 mm
3therefore Bending OK
Deflection Check
Emin = 3600 N/mm2
I = bd3/12 = 2E+06 mm4 Max deflection, dmax dmax = 53 mmMax allowable deflection = 0.003L = = 9 mm
9 > 53
Deflection NOT O
Adopt Redesign
7/29/2019 Kenyan Timber Stresses
8/99
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
CODE OUTPUT
DATA
UNITS
M.
KN/M
N/mm2
M2
Kg/M3
Kg PITCH, 15 Degrees 0.26167
3.86561806
N 3.73403308
Rafters & Bottom Tie 100 x 50 0.005 m2
Truss Webs 100 x 50 0.005 m2
GCI Sheeting Purlins 75 x 50 0.00375 m2
Tiling Battens 50 x 50 0.0025 m2
Ceiling Brandering 50 x 50 0.0025 m2
Intermediate Rafter 100 x 50 0.005 m2
Underpurlins 100 x 50 0.005 m2
Density of Wood 500 Kg/m3
Weight
Bottom-Tie Length 6.8 m 17.00 Kg
Total Rafter Length 8.28 m 20.71 KgTotal Web Length 7.45 m 18.63 Kg
Truss Spacing 1.2 m 56.34 Kg
Tiling Battens Spacing 0.3 m
Purlin Spacing 1.2 m
Brandering Spacing 0.6 m
Intermediate Rafer 0.6 m
Weight of Truss
Weight of Main plate 56.3 Kg
Weight of Nailing plate 14.1 Kg
Weight of Nails 7.0 Kg
77.5 Kg = 0.77 kN/truss
Weight of Decra Tiles 0.25 kN/m2
2.48 kN/trus 0.25
Weight of tiling battens (50x50) 0.015 kN/Batten 0.41 " 0.04
Weight of GCI Sheeting 0.1 kN/m2
0.99 " 0.10
Weight of Purlins (75x50) 0.0225 kN/Purlin 0.16 " 0.02
4.05 kN/truss
Roof imposed load 0.25 kN/m2
Weight of Ceiling 0.25 kN/m2
2.04 kN/truss
Weight of Ceiling Brandering (75x50) 0.015 kN/Brande 0.41 "
2.45 "
Total Load per Truss = 7.28 kN/truss
Nairobi
Project:truss
CALCULATIONS
7/29/2019 Kenyan Timber Stresses
9/99
No. Panels 0n the Rafter 4 On Rafter
No. Panels 0n the Bottom-Tie 3 On Bottom Tie
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
Truss Loading at Rafter Level 2/3 of Total Load = 4.86
Nodal Loading at Rafter Level
Truss Loading at Ceiling Level 1/3 of Total Load = 2.43
Nodal Loading at Ceiling Level
CP3 WIND LOAD x
CP3 Chp V Basic Wind Speed for NAIROBI V = 28 m/s V = 28 m/s
Pt2 4.3 Topography factor S1 = 1.0 S1 = 1.0
Statistical factor S2 = 0.9 S1 = 0.9
Topography factor S3 = 1.0 S1 = 1.0
CP3 Chp V Height to Eaves, h = 16.2 Pitch = 15
5.4 Building Class = B Width = 7.9Table 3 Ground roughness Category = 3
Height (eaves to apex) = 1.06
CP3 Chp V Total height to apex, H = 17.26 m
5.6
Design Wind Speed Vs = VxS1xS2xS3 = m/s
28 x 1 x 0.9 x 1 = 25.2
Vs= 25.2
6.0 Dynamic Pressure q = KVs x Vs Where K = 0.613
therefore, q= 0.613 x 0.613 x 0.613 = 389 N/m2
= 0.389 N/m2
External Pressure Coefficients, Cpe
Height to eaves, h = 16.2 m
Width w = 9.425 m h/w = 1.719
CP3 Chp V Slope = 15 Deg. Cpe = -0.575 Wind onTable 8 Cpe = -0.5 Side
Cpe = -0.8 Wind on
Cpe = -0.65 End
Internal Pressure Coefficients, Cpi
CP3 Cpi = 0.2
Appendix E ./ ( ) - x Cpi = -0.3
CP3 Wind Load F = (Cpe -Cpi).q.A A =
7.2
Max. roof Uplift = (-0.8-0.2)qA = -0.389
Min Downward Load = (-0.8--0.3)qA = -0.195
UPLIFT
Design for Uplift force of Fmax = -0.389Fmin = -0.195
Truss Spacing = 1.2 m x
Truss Span = 6.8 m
Overall Span = 6.8 m 1.2x6.8 = 8.16 m2
therefore. Max. Uplift = Fmax = 3.18 kN/truss
Fmin = 1.588 kN/truss
Nairobi
Project:truss
CALCULATIONS
tributary area to
truss
tributary area to truss
7/29/2019 Kenyan Timber Stresses
10/99
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
BattensArea Supported / Batten, Ab = 0.3x0.6
Batten Spacing = 0.3 m Ab = 0.18
Batten Span = 0.6 m Max. Batten Uplift = 13 x 0.18 = -0.071 kN/batte
GRAVITY LOADS
Imposed Load:
Imposed Load = 0.25
Dead Loads :
Truss self Weight = 77 Kg = 0.77 kN
Distributed Load = 0.77 / 6.8 x 1.2 = 0.10 kN/m2
Tiles+ Battens = 0.3 kN/m2
GCI Sheets + Purlins = 0.12 kN/m2
total = 0.52
Ceil ing + Brandering = 0.28 kN/m2
1) At the rafter level 0.52 KN/M2
Total DL = 4.25 = 2.84
kN/truss
Total IL = 2.04 = 1.36 kN/truss
total 4.20
2) At the Ceiling level
0.95
kN/truss
0.68
total 0.68
3) Batten
Imposed = = 0.05 KN
Dead = 0.3 x 0.3 x 0.6 = 0.03 KN
CP3 LOAD SUMMARY x
BS 5268 Total Span = 8282
Pt 2 1996 Load Type of Load
2.8 and Duration Load Batten Duration
Table 14 Rafter Level Ceiling Level Factor K3
Long Dead 4.20 0.95 0.03 1.0
Term Only
Medium Dead + 4.20 0.95 0.030
Term Temp. Li 1.36 0.68 0.05
TOTAL 5.56 1.63 0.080 1.25
Very Short Dead + 4.20 0.95 0.03
Term Wind 3.18 -0.071
TOTAL 1.02 -0.041 1.75
Design Worx Limited Issue: DesignP.O. Box 7136-001 Date:
Nairobi
Project:truss
CALCULATIONS
0.52 x 6.8 x 1.2 =
0.25 x 6.8 x 1.2 =
Total DL =
Total IL =
0.25 x 0.3 x 0.6
Typical Load
Truss
Nairobi
7/29/2019 Kenyan Timber Stresses
11/99
Revised by: Test1
Checked by: Test2
REF OUTPUT
BATTEN DESIGN Span , L = 0.6 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 0.080 kN DL + WL = F = -0.041 kN
Mmax =FL/8 = 0.006 kNm Mmax =FL/8 = -0.003 kNmReaction FL/2 = 0.024 kN Reaction FL/2 = -0.012 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade .K3.K7.K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 0.006
Zreq. = M/dm = 532.8005 mm3
25x50
For 25 x 50 mm Battens
Zprov. = bd2/6 = 10417 mm3
therefore Bending OK
Deflection CheckEmin = 3600 N/mm
2Emin = 3600
I = bd3/12 = 260417 mm4
Max deflection, dmax dmax = 0.1
Max allowable deflection = 0.003L = = 1.8
1.8 > 0.1
Deflection OK
Adopt
BS 5268 TRUSS T1- FORCE
Pt 2 1996 Design for Medium Term Loading
2.8 and Total Load at Rafter = 5.56 Cantileverd end = 750
Table 14 Total Load at Ceiling = 1.63 Total Truss Load = = 7.19
Total No. of Panels on Rafter = 6 Truss Span = 6800
Total No. of Panels on Bottom Tie = 6 Total Span = 8300
P1 = 5.56/6= 0.930 1.636= P3 = 0.272
P2 = 0.93/= 0.465 P4 = 0.136R = 7.19/= 3.595 -0.136 = 3.459 kN
Member length coeff force unit force
1 2098 9.66 8.987562 kN 1.93 kN
2 2098 9.66 8.987562 kN 1.93 kN
3 2098 7.73 7.19005 kN 1.93 kN
4 2098 2.12 1.969702 kN 0.00 kN
5 2098 2.39 2.227297 kN 0.00 kN
6 2098 9.34 8.681627 kN 1.87 kN
7 2098 7.47 6.945302 kN 1.87 kN
8 2098 5.60 5.208976 kN 1.87 kN
Design Worx Limited Issue: DesignP.O. Box 7136-001 Date:
Revised by: Test1
Project:truss
CALCULATIONS
25x50
Refer to Truss Diagram above
COMP.
Nairobi
TENSION
7/29/2019 Kenyan Timber Stresses
12/99
Checked by: Test2
REF OUTPUT
RAFTER DESIGN
Critical Member is: 1
BS 5268 F = 8.99 kN Compression
Pt 3 L = 2098 mm 50x150
6.5.5 Le = 1888.2 mm Effective Length Le = 0.9 x LTry GS grade Cypress = 50 x 150
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 1E+07
Pt 2 r = 43.30 A = 7500
2.11.4 l = 43.61 Zprov. = bd2/6 = 2E+05
< 180 Slender Ratio OK
2.11.5 Since l > 5 l SQD = 1901 Multiply grade stress by K12 x
BS 5268 h = 0.005 l = 0.218 N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.87755102 dc = 6x1.25= 7.5 K3 = 1.25 For very short ter
( ) = 1.51235477( )SQD = 2.287 () = 1.662 K12 = 1.12
Annex B K3 = 1.5 K12 = 1.00
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = 10.096 N/mm2
(Permissible Compression Stress)
da(c) F/A = = 1.198 N/mm2
(Applied Compression Stress)
< 10.096 Section OK
BS 5268 Check for Combined Compression and Bending for Rafter
Pt 3 Man Point Load P = 0.9 kN K3 = 1.5 Duration Factor
6.4.2 F = 8.98756 kN K7 = (300/d)^0.11
L = 2098 mm K7 = 1.08 Depth Factor
Le = 1888.2 mm K8 = 1.1 Load Sharing F.
Mmax = PLe/4 = 0.425 kNm (Max Bending Moment, PL/4)
dadm(b) = dgrade x K3K7K8 =
= 10.6844 da(b) .= M/Z = 2.27 N/mm2
(Applied Bending Stress)
BS 5268 da(c) = 1.198 + 2.27 de = PI^2E
Pt 2 dadm(c) dadm(b) (1-1.5dadm(c) x K1 10.09629 10.6844 0.89 l 2
2.11.6 de de =
= 0.119 + 0.238 = 0.357
Adopt 50x150 since < 1
BOTTOM TIE DESIGNCritical Member is 7
F = 6.9453 kN Tension
Try GS grade Cypress = 100 x 150
I = bd3/12 = 2.8E+07 use 100x150
A = 15000
BS 5268 bd2/6 = 375000
Pt 2
2.12 dgrade = 3.00 N/mm2
K14 = (300/d)^0.11
K14 = 1.08
dadm(t) = dgrade x K14
= 3.24 N/mm2
(Permissible Tensile Stress)
da(t) F/A = 0.46 N/mm2
(Applied Tensile Stress)
< 3.24
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
truss
CALCULATIONS
Section O
Nairobi
Project:truss
CALCULATIONS
14062500
187500
.+ da(b)
100x150
7/29/2019 Kenyan Timber Stresses
13/99
INTERNAL MEMBER DESIGN
Critical Member is #REF!
F = #REF! kN Tension
Try GS grade Cypress = 50 x 100
dgrade = 3.00 N/mm2
K14 = (300/d)^0.11 A = 5000
K14 = 1.13dadm(t) = dgrade x K14
= 3.39 N/mm2
(Permissible Tensile Stress)
da(t) F /A = #REF! N/mm2
(Applied Tensile Stress)
#REF! 3.39
Critical Member is 3
BS 5268 F = 7.19005 kN Compression
Pt 3 L = 2098 mm 50x100
6.5.5 Le = 1888 mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 100
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 4E+06
Pt 2 r = 28.87 A = 5000
2.11.4 l = 65.40 Zprov. = bd^2/6 = 83333
< 180 Slender Ratio OK
2.11.5 Since l > 5 l SQD = 4277 Multiply grade stress by K12 x
BS 5268 h = 0.005 l = 0.327 N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.88 dc = 6x1.75= 10.5 K3 = 1.75 For very short ter
Annex B ( ) = 0.86 )SQD = 0.74 () = 0.53 K12 = 0.82
K3 = 1.5
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = 7.34 N/mm2
(Permissible Comp. Stress)
da(c) F/A = = 1.44 N/mm2
(Applied Comp. Stress)
< 7.34461 Section OK
CP3 LOAD SUMMARY
BS 5268 Total Span = 8300
Pt 2 1996 Load Type of Load
2.8 and Duration Load Duration
Table 14 Rafter Level Factor K3
Long Dead 2.10 1.0
Term Only
Medium Dead + 2.10
Term Temp. Li 0.68
TOTAL 2.78 1.25
Very Short Dead + 1.05
Term Wind 1.59
TOTAL -0.54 1.75
Design Worx Limited Issue: DesignP.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
INTERMEDIATE RAFTER DESIGN Span , L = 3 m
Project:truss
50x100
#REF!
4166666.7
CALCULATIONS
83333.3
Typical Load
Nairobi
7/29/2019 Kenyan Timber Stresses
14/99
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 2.780 kN DL + WL = F = 1.590 kN
Mmax =FL/8 = 1.043 kNm Mmax =FL/8 = 0.596 kNm
Reaction FL/2 = 4.170 kN Reaction FL/2 = 2.385 kN
Bending Check
Zreq. = M/dmPermissible stress in bending parrallel to grain, dm = grade x K3K7K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 1.043
Zreq. = M/dm = 92574.09 mm3 50x150
For 50 x 150 mm
Zprov. = bd2/6 = 187500 mm
3therefore Bending OK
Deflection Check
Emin = 3600
I = bd3/12 = 1562500 mm
4Max deflection, dmax dmax = 34.75
Max allowable deflection = 0.003L = = 9
9 > 34.75Deflecti
Adopt Redesign
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N/mm2
mm
mm
mm
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mm
mm
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35559
1901.5
18.701
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N/mm2
mm
mm
n NOT O
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Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
CODE OUTPUT
DATA
UNITS
M.
KN/M
N/mm2
M2
Kg/M3
Kg PITCH, 15 Degrees 0.26167
3.86561806
N 3.73403308
Rafters & Bottom Tie 100 x 50 0.005 m2
Truss Webs 100 x 50 0.005 m2
GCI Sheeting Purlins 75 x 50 0.00375 m2
Tiling Battens 50 x 50 0.0025 m2
Ceiling Brandering 50 x 50 0.0025 m2
Intermediate Rafter 100 x 50 0.005 m2
Underpurlins 100 x 50 0.005 m2
Density of Wood 500 Kg/m3
Weight
Bottom-Tie Length 6.8 m 17.00 Kg
Total Rafter Length 8.28 m 20.71 KgTotal Web Length 7.45 m 18.63 Kg
Truss Spacing 1.2 m 56.34 Kg
Tiling Battens Spacing 0.3 m
Purlin Spacing 1.2 m
Brandering Spacing 0.6 m
Intermediate Rafer 0.6 m
Weight of Truss
Weight of Main plate 56.3 Kg
Weight of Nailing plate 14.1 Kg
Weight of Nails 7.0 Kg
77.5 Kg = 0.77 kN/truss
Weight of Decra Tiles 0.25 kN/m2
2.48 kN/trus 0.25
Weight of tiling battens (50x50) 0.015 kN/Batten 0.41 " 0.04
Weight of GCI Sheeting 0.1 kN/m2
0.99 " 0.10
Weight of Purlins (75x50) 0.0225 kN/Purlin 0.16 " 0.02
4.05 kN/truss
Roof imposed load 0.25 kN/m2
Weight of Ceiling 0.25 kN/m2
2.04 kN/truss
Weight of Ceiling Brandering (75x50) 0.015 kN/Brande 0.41 "
2.45 "
Total Load per Truss = 7.28 kN/truss
Nairobi
Project:truss
CALCULATIONS
7/29/2019 Kenyan Timber Stresses
23/99
No. Panels 0n the Rafter 4 On Rafter
No. Panels 0n the Bottom-Tie 3 On Bottom Tie
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
Truss Loading at Rafter Level 2/3 of Total Load = 4.86
Nodal Loading at Rafter Level
Truss Loading at Ceiling Level 1/3 of Total Load = 2.43
Nodal Loading at Ceiling Level
CP3 WIND LOAD x
CP3 Chp V Basic Wind Speed for NAIROBI V = 28 m/s V = 28 m/s
Pt2 4.3 Topography factor S1 = 1.0 S1 = 1.0
Statistical factor S2 = 0.9 S1 = 0.9
Topography factor S3 = 1.0 S1 = 1.0
CP3 Chp V Height to Eaves, h = 16.2 Pitch = 15
5.4 Building Class = B Width = 7.9Table 3 Ground roughness Category = 3
Height (eaves to apex) = 1.06
CP3 Chp V Total height to apex, H = 17.26 m
5.6
Design Wind Speed Vs = VxS1xS2xS3 = m/s
28 x 1 x 0.9 x 1 = 25.2
Vs= 25.2
6.0 Dynamic Pressure q = KVs x Vs Where K = 0.613
therefore, q= 0.613 x 0.613 x 0.613 = 389 N/m2
= 0.389 N/m2
External Pressure Coefficients, Cpe
Height to eaves, h = 16.2 m
Width w = 9.425 m h/w = 1.719
CP3 Chp V Slope = 15 Deg. Cpe = -0.575 Wind onTable 8 Cpe = -0.5 Side
Cpe = -0.8 Wind on
Cpe = -0.65 End
Internal Pressure Coefficients, Cpi
CP3 Cpi = 0.2
Appendix E ./ ( ) - x Cpi = -0.3
CP3 Wind Load F = (Cpe -Cpi).q.A A =
7.2
Max. roof Uplift = (-0.8-0.2)qA = -0.389
Min Downward Load = (-0.8--0.3)qA = -0.195
UPLIFT
Design for Uplift force of Fmax = -0.389Fmin = -0.195
Truss Spacing = 1.2 m x
Truss Span = 6.8 m
Overall Span = 6.8 m 1.2x6.8 = 8.16 m2
therefore. Max. Uplift = Fmax = 3.18 kN/truss
Fmin = 1.588 kN/truss
Nairobi
Project:truss
CALCULATIONS
tributary area to
truss
tributary area to truss
7/29/2019 Kenyan Timber Stresses
24/99
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
BattensArea Supported / Batten, Ab = 0.3x0.6
Batten Spacing = 0.3 m Ab = 0.18
Batten Span = 0.6 m Max. Batten Uplift = 13 x 0.18 = -0.071 kN/batte
GRAVITY LOADS
Imposed Load:
Imposed Load = 0.25
Dead Loads :
Truss self Weight = 77 Kg = 0.77 kN
Distributed Load = 0.77 / 6.8 x 1.2 = 0.10 kN/m2
Tiles+ Battens = 0.3 kN/m2
GCI Sheets + Purlins = 0.12 kN/m2
total = 0.52
Ceil ing + Brandering = 0.28 kN/m2
1) At the rafter level 0.52 KN/M2
Total DL = 4.25 = 2.84
kN/truss
Total IL = 2.04 = 1.36 kN/truss
total 4.20
2) At the Ceiling level
0.95
kN/truss
0.68
total 0.68
3) Batten
Imposed = = 0.05 KN
Dead = 0.3 x 0.3 x 0.6 = 0.03 KN
CP3 LOAD SUMMARY x
BS 5268 Total Span = 8282
Pt 2 1996 Load Type of Load
2.8 and Duration Load Batten Duration
Table 14 Rafter Level Ceiling Level Factor K3
Long Dead 4.20 0.95 0.03 1.0
Term Only
Medium Dead + 4.20 0.95 0.030
Term Temp. Li 1.36 0.68 0.05
TOTAL 5.56 1.63 0.080 1.25
Very Short Dead + 4.20 0.95 0.03
Term Wind 3.18 -0.071
TOTAL 1.02 -0.041 1.75
Design Worx Limited Issue: DesignP.O. Box 7136-001 Date:
Nairobi
Project:truss
CALCULATIONS
0.52 x 6.8 x 1.2 =
0.25 x 6.8 x 1.2 =
Total DL =
Total IL =
0.25 x 0.3 x 0.6
Typical Load
Truss
Nairobi
7/29/2019 Kenyan Timber Stresses
25/99
Revised by: Test1
Checked by: Test2
REF OUTPUT
BATTEN DESIGN Span , L = 0.6 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 0.080 kN DL + WL = F = -0.041 kN
Mmax =FL/8 = 0.006 kNm Mmax =FL/8 = -0.003 kNmReaction FL/2 = 0.024 kN Reaction FL/2 = -0.012 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade .K3.K7.K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 0.006
Zreq. = M/dm = 532.8005 mm3
25x50
For 25 x 50 mm Battens
Zprov. = bd2/6 = 10417 mm3
therefore Bending OK
Deflection CheckEmin = 3600 N/mm
2Emin = 3600
I = bd3/12 = 260417 mm4
Max deflection, dmax dmax = 0.1
Max allowable deflection = 0.003L = = 1.8
1.8 > 0.1
Deflection OK
Adopt
BS 5268 TRUSS T1- FORCE
Pt 2 1996 Design for Medium Term Loading
2.8 and Total Load at Rafter = 5.56 Cantileverd end = 750
Table 14 Total Load at Ceiling = 1.63 Total Truss Load = = 7.19
Total No. of Panels on Rafter = 8 Truss Span = 6800
Total No. of Panels on Bottom Tie = 8 Total Span = 8300
P1 = 5.56/8= 0.700 1.638= P3 = 0.204
P2 = 0.7/= 0.350 P4 = 0.102R = 7.19/= 3.595 -0.102 = 3.493 kN
Member length coeff force unit force
1 2098 13.53 9.470764 kN 1.93 kN
2 2098 13.53 9.470764 kN 1.93 kN
3 2098 11.60 8.117798 kN 1.93 kN
4 2098 9.66 6.764832 kN 1.93 kN
5 2098 2.12 1.482571 kN 0.00 kN
6 2098 2.39 1.67646 kN 0.00 kN
7 2098 2.74 1.915207 kN 0.00 kN
8 2098 13.07 9.148381 kN 1.87 kN
9 2098 11.20 7.841469 kN 1.87 kN
10 2098 9.34 6.534558 kN 1.87 kN
11 2098 7.47 5.227646 kN 1.87 kN
Project:truss
CALCULATIONS
25x50
Refer to Truss Diagram above
COMP.
TENSION
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Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
RAFTER DESIGN
Critical Member is: 1BS 5268 F = 9.47 kN Compression
Pt 3 L = 2098 mm 50x150
6.5.5 Le = 1888.2 mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 150
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 1E+07
Pt 2 r = 43.30 A = 7500
2.11.4 l = 43.61 Zprov. = bd2/6 = 2E+05
< 180 Slender Ratio OK
2.11.5 Since l > 5 l SQD = 1901 Multiply grade stress by K12 x
BS 5268 h = 0.005 l = 0.218 N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.87755102 dc = 6x1.25= 7.5 K3 = 1.25 For very short ter
( ) = 1.51235477( )SQD = 2.287 () = 1.662 K12 = 1.12
Annex B K3 = 1.5 K12 = 1.00
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm
2
dadm(c) = 10.096 N/mm2
(Permissible Compression Stress)
da(c) F/A = = 1.263 N/mm2
(Applied Compression Stress)
< 10.096 Section OK
BS 5268 Check for Combined Compression and Bending for Rafter
Pt 3 Man Point Load P = 0.9 kN K3 = 1.5 Duration Factor
6.4.2 F = 9.47076 kN K7 = (300/d)^0.11
L = 2098 mm K7 = 1.08 Depth Factor
Le = 1888.2 mm K8 = 1.1 Load Sharing F.
Mmax = PLe/4 = 0.425 kNm (Max Bending Moment, PL/4)
dadm(b) = dgrade x K3K7K8 =
= 10.6844 da(b) .= M/Z = 2.27 N/mm2
(Applied Bending Stress)
BS 5268 da(c) = 1.263 + 2.27 de = PI^2E
Pt 2 dadm(c) dadm(b) (1-1.5dadm(c) x K1 10.09629 10.6844 0.89 l 2
2.11.6 de de == 0.125 + 0.238 = 0.3634
Adopt 50x150 since < 1
BOTTOM TIE DESIGN
Critical Member is 10
F = 6.53456 kN Tension
Try GS grade Cypress = 100 x 150
I = bd3/12 = 2.8E+07 use 100x150
A = 15000
BS 5268 bd2/6 = 375000
Pt 2
2.12 dgrade = 3.00 N/mm2
K14 = (300/d)^0.11
K14 = 1.08
dadm(t) = dgrade x K14
= 3.24 N/mm2
(Permissible Tensile Stress)
da(t) F/A = 0.44 N/mm2
(Applied Tensile Stress)
< 3.24
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Nairobi
Project:truss
CALCULATIONS
14062500
187500
.+ da(b)
100x150
Section O
Nairobi
7/29/2019 Kenyan Timber Stresses
27/99
Revised by: Test1
Checked by: Test2
REF OUTPUT
INTERNAL MEMBER DESIGN
Critical Member is #REF!
F = #REF! kN Tension
Try GS grade Cypress = 50 x 100dgrade = 3.00 N/mm
2
K14 = (300/d)^0.11 A = 5000
K14 = 1.13
dadm(t) = dgrade x K14
= 3.39 N/mm2
(Permissible Tensile Stress)
da(t) F /A = #REF! N/mm2
(Applied Tensile Stress)
#REF! 3.39
Critical Member is 4
BS 5268 F = 6.76483 kN Compression
Pt 3 L = 2098 mm 50x100
6.5.5 Le = 1888 mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 100
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 4E+06
Pt 2 r = 28.87 A = 50002.11.4 l = 65.40 Zprov. = bd^2/6 = 83333
< 180 Slender Ratio OK
2.11.5 Since l > 5 l SQD = 4277 Multiply grade stress by K12 x
BS 5268 h = 0.005 l = 0.327 N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.88 dc = 6x1.75= 10.5 K3 = 1.75 For very short ter
Annex B ( ) = 0.86 )SQD = 0.74 () = 0.53 K12 = 0.82
K3 = 1.5
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = 7.34 N/mm2
(Permissible Comp. Stress)
da(c) F/A = = 1.35 N/mm2
(Applied Comp. Stress)
< 7.34461 Section OK
CP3 LOAD SUMMARY
BS 5268 Total Span = 8300Pt 2 1996 Load Type of Load
2.8 and Duration Load Duration
Table 14 Rafter Level Factor K3
Long Dead 2.10 1.0
Term Only
Medium Dead + 2.10
Term Temp. Li 0.68
TOTAL 2.78 1.25
Very Short Dead + 1.05
Term Wind 1.59
TOTAL -0.54 1.75
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2Project:
truss
Project:truss
CALCULATIONS
50x100
#REF!
4166666.7
83333.3
Typical Load
Nairobi
7/29/2019 Kenyan Timber Stresses
28/99
REF OUTPUT
INTERMEDIATE RAFTER DESIGN Span , L = 3 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 2.780 kN DL + WL = F = 1.590 kN
Mmax =FL/8 = 1.043 kNm Mmax =FL/8 = 0.596 kNm
Reaction FL/2 = 4.170 kN Reaction FL/2 = 2.385 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade x K3K7K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 1.043
Zreq. = M/dm = 92574.09 mm3 50x150
For 50 x 150 mm
Zprov. = bd2/6 = 187500 mm
3therefore Bending OK
Deflection Check
Emin = 3600I = bd
3/12 = 1562500 mm
4Max deflection, dmax dmax = 34.75
Max allowable deflection = 0.003L = = 9
9 > 34.75
Deflecti
Adopt Redesign
CALCULATIONS
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1901.5
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Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
CODE OUTPUT
DATA
UNITS
M.
KN/M
N/mm2
M2
Kg/M3
Kg PITCH, 15 Degrees 0.26167
3.86561806
N 3.73403308
Rafters & Bottom Tie 100 x 50 0.005 m2
Truss Webs 100 x 50 0.005 m2
GCI Sheeting Purlins 75 x 50 0.00375 m2
Tiling Battens 50 x 50 0.0025 m2
Ceiling Brandering 50 x 50 0.0025 m2
Intermediate Rafter 100 x 50 0.005 m2
Underpurlins 100 x 50 0.005 m2
Density of Wood 500 Kg/m3
Weight
Bottom-Tie Length 6.8 m 17.00 Kg
Total Rafter Length 8.28 m 20.71 KgTotal Web Length 7.45 m 18.63 Kg
Truss Spacing 1.2 m 56.34 Kg
Tiling Battens Spacing 0.3 m
Purlin Spacing 1.2 m
Brandering Spacing 0.6 m
Intermediate Rafer 0.6 m
Weight of Truss
Weight of Main plate 56.3 Kg
Weight of Nailing plate 14.1 Kg
Weight of Nails 7.0 Kg
77.5 Kg = 0.77 kN/truss
Weight of Decra Tiles 0.25 kN/m2
2.48 kN/trus 0.25
Weight of tiling battens (50x50) 0.015 kN/Batten 0.41 " 0.04
Weight of GCI Sheeting 0.1 kN/m2
0.99 " 0.10
Weight of Purlins (75x50) 0.0225 kN/Purlin 0.16 " 0.02
4.05 kN/truss
Roof imposed load 0.25 kN/m2
Weight of Ceiling 0.25 kN/m2
2.04 kN/truss
Weight of Ceiling Brandering (75x50) 0.015 kN/Brande 0.41 "
2.45 "
Total Load per Truss = 7.28 kN/truss
Nairobi
Project:truss
CALCULATIONS
7/29/2019 Kenyan Timber Stresses
37/99
No. Panels 0n the Rafter 4 On Rafter
No. Panels 0n the Bottom-Tie 3 On Bottom Tie
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
Truss Loading at Rafter Level 2/3 of Total Load = 4.86
Nodal Loading at Rafter Level
Truss Loading at Ceiling Level 1/3 of Total Load = 2.43
Nodal Loading at Ceiling Level
CP3 WIND LOAD x
CP3 Chp V Basic Wind Speed for NAIROBI V = 28 m/s V = 28 m/s
Pt2 4.3 Topography factor S1 = 1.0 S1 = 1.0
Statistical factor S2 = 0.9 S1 = 0.9
Topography factor S3 = 1.0 S1 = 1.0
CP3 Chp V Height to Eaves, h = 16.2 Pitch = 15
5.4 Building Class = B Width = 7.9Table 3 Ground roughness Category = 3
Height (eaves to apex) = 1.06
CP3 Chp V Total height to apex, H = 17.26 m
5.6
Design Wind Speed Vs = VxS1xS2xS3 = m/s
28 x 1 x 0.9 x 1 = 25.2
Vs= 25.2
6.0 Dynamic Pressure q = KVs x Vs Where K = 0.613
therefore, q= 0.613 x 0.613 x 0.613 = 389 N/m2
= 0.389 N/m2
External Pressure Coefficients, Cpe
Height to eaves, h = 16.2 m
Width w = 9.425 m h/w = 1.719
CP3 Chp V Slope = 15 Deg. Cpe = -0.575 Wind onTable 8 Cpe = -0.5 Side
Cpe = -0.8 Wind on
Cpe = -0.65 End
Internal Pressure Coefficients, Cpi
CP3 Cpi = 0.2
Appendix E ./ ( ) - x Cpi = -0.3
CP3 Wind Load F = (Cpe -Cpi).q.A A =
7.2
Max. roof Uplift = (-0.8-0.2)qA = -0.389
Min Downward Load = (-0.8--0.3)qA = -0.195
UPLIFT
Design for Uplift force of Fmax = -0.389Fmin = -0.195
Truss Spacing = 1.2 m x
Truss Span = 6.8 m
Overall Span = 6.8 m 1.2x6.8 = 8.16 m2
therefore. Max. Uplift = Fmax = 3.18 kN/truss
Fmin = 1.588 kN/truss
Nairobi
Project:truss
CALCULATIONS
tributary area to
truss
tributary area to truss
7/29/2019 Kenyan Timber Stresses
38/99
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
BattensArea Supported / Batten, Ab = 0.3x0.6
Batten Spacing = 0.3 m Ab = 0.18
Batten Span = 0.6 m Max. Batten Uplift = 13 x 0.18 = -0.071 kN/batte
GRAVITY LOADS
Imposed Load:
Imposed Load = 0.25
Dead Loads :
Truss self Weight = 77 Kg = 0.77 kN
Distributed Load = 0.77 / 6.8 x 1.2 = 0.10 kN/m2
Tiles+ Battens = 0.3 kN/m2
GCI Sheets + Purlins = 0.12 kN/m2
total = 0.52
Ceil ing + Brandering = 0.28 kN/m2
1) At the rafter level 0.52 KN/M2
Total DL = 4.25 = 2.84
kN/truss
Total IL = 2.04 = 1.36 kN/truss
total 4.20
2) At the Ceiling level
0.95
kN/truss
0.68
total 0.68
3) Batten
Imposed = = 0.05 KN
Dead = 0.3 x 0.3 x 0.6 = 0.03 KN
CP3 LOAD SUMMARY x
BS 5268 Total Span = 8282
Pt 2 1996 Load Type of Load
2.8 and Duration Load Batten Duration
Table 14 Rafter Level Ceiling Level Factor K3
Long Dead 4.20 0.95 0.03 1.0
Term Only
Medium Dead + 4.20 0.95 0.030
Term Temp. Li 1.36 0.68 0.05
TOTAL 5.56 1.63 0.080 1.25
Very Short Dead + 4.20 0.95 0.03
Term Wind 3.18 -0.071
TOTAL 1.02 -0.041 1.75
Design Worx Limited Issue: DesignP.O. Box 7136-001 Date:
Nairobi
Project:truss
CALCULATIONS
0.52 x 6.8 x 1.2 =
0.25 x 6.8 x 1.2 =
Total DL =
Total IL =
0.25 x 0.3 x 0.6
Typical Load
Truss
Nairobi
7/29/2019 Kenyan Timber Stresses
39/99
Revised by: Test1
Checked by: Test2
REF OUTPUT
BATTEN DESIGN Span , L = 0.6 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 0.080 kN DL + WL = F = -0.041 kN
Mmax =FL/8 = 0.006 kNm Mmax =FL/8 = -0.003 kNmReaction FL/2 = 0.024 kN Reaction FL/2 = -0.012 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade .K3.K7.K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 0.006
Zreq. = M/dm = 532.8005 mm3
25x50
For 25 x 50 mm Battens
Zprov. = bd2/6 = 10417 mm3
therefore Bending OK
Deflection CheckEmin = 3600 N/mm
2Emin = 3600
I = bd3/12 = 260417 mm4
Max deflection, dmax dmax = 0.1
Max allowable deflection = 0.003L = = 1.8
1.8 > 0.1
Deflection OK
Adopt
BS 5268 TRUSS T1- FORCE
Pt 2 1996 Design for Medium Term Loading
2.8 and Total Load at Rafter = 5.56 Cantileverd end = 750
Table 14 Total Load at Ceiling = 1.63 Total Truss Load = = 7.19
Total No. of Panels on Rafter = 4 Truss Span = 6800
Total No. of Panels on Bottom Tie = 3 Total Span = 8300
P1 = 5.56/4= 1.390 1.633= P3 = 0.543
P2 = 1.39/= 0.695 P4 = 0.272R = 7.19/= 3.595 -0.272 = 3.323 kN
Member length coeff force unit force
1 2098 5.80 8.059814 kN 1.93 kN
2 2098 5.80 8.059814 kN 1.93 kN
3 2098 2.12 2.943963 kN 0.00 kN
4 2098 5.60 7.785459 kN 1.87 kN
5 2098 3.73 5.190306 kN 1.87 kN
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
RAFTER DESIGN
Project:truss
CALCULATIONS
25x50
Refer to Truss Diagram above
CO
MP.
TENSI
ON
Nairobi
Project:truss
CALCULATIONS
7/29/2019 Kenyan Timber Stresses
40/99
Critical Member is: 1
BS 5268 F = 8.06 kN Compression
Pt 3 L = 2098 mm 50x150
6.5.5 Le = 1888.2 mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 150
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 1E+07
Pt 2 r = 43.30 A = 7500
2.11.4 l = 43.61 Zprov. = bd2/6 = 2E+05< 180 Slender Ratio OK
2.11.5 Since l > 5 l SQD = 1901 Multiply grade stress by K12 x
BS 5268 h = 0.005 l = 0.218 N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.87755102 dc = 6x1.25= 7.5 K3 = 1.25 For very short ter
( ) = 1.51235477( )SQD = 2.287 () = 1.662 K12 = 1.12
Annex B K3 = 1.5 K12 = 1.00
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = 10.096 N/mm2
(Permissible Compression Stress)
da(c) F/A = = 1.075 N/mm2
(Applied Compression Stress)
< 10.096 Section OK
BS 5268 Check for Combined Compression and Bending for Rafter
Pt 3 Man Point Load P = 0.9 kN K3 = 1.5 Duration Factor
6.4.2 F = 8.05981 kN K7 = (300/d)^0.11L = 2098 mm K7 = 1.08 Depth Factor
Le = 1888.2 mm K8 = 1.1 Load Sharing F.
Mmax = PLe/4 = 0.425 kNm (Max Bending Moment, PL/4)
dadm(b) = dgrade x K3K7K8 =
= 10.6844 da(b) .= M/Z = 2.27 N/mm2
(Applied Bending Stress)
BS 5268 da(c) = 1.075 + 2.27 de = PI^2E
Pt 2 dadm(c) dadm(b) (1-1.5dadm(c) x K1 10.09629 10.6844 0.9 l ^2
2.11.6 de de =
= 0.106 + 0.236 = 0.3421
Adopt 50x150 since < 1
BOTTOM TIE DESIGN
Critical Member is #REF!
F = #REF! kN Tension
Try GS grade Cypress = 100 x 150
I = bd3/12 = 2.8E+07 use 100x150
A = 15000
BS 5268 bd2/6 = 375000
Pt 2
2.12 dgrade = 3.00 N/mm2
K14 = (300/d)^0.11
K14 = 1.08
dadm(t) = dgrade x K14
= 3.24 N/mm2
(Permissible Tensile Stress)
da(t) F/A = #REF! N/mm2
(Applied Tensile Stress)
#REF! 3.24
Design Worx Limited Issue: DesignP.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
INTERNAL MEMBER DESIGN
Critical Member is #REF!
F = #REF! kN Tension
14062500
187500
.+ da(b)
100x150
#REF!
Nairobi
Project:truss
CALCULATIONS
7/29/2019 Kenyan Timber Stresses
41/99
Try GS grade Cypress = 50 x 100
dgrade = 3.00 N/mm2
K14 = (300/d)^0.11 A = 5000
K14 = 1.13
dadm(t) = dgrade x K14
= 3.39 N/mm2
(Permissible Tensile Stress)
da(t) F /A = #REF! N/mm2
(Applied Tensile Stress)
#REF! 3.39
Critical Member is #REF!
BS 5268 F = #REF! kN Compression
Pt 3 L = #REF! mm 50x100
6.5.5 Le = #REF! mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 100
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 4E+06
Pt 2 r = 28.87 A = 5000
2.11.4 l = #REF! Zprov. = bd^2/6 = 83333
#REF! 180 #REF!
2.11.5 Since l > 5 l SQD = #REF! Multiply grade stress by K12 x
BS 5268 h = 0.005 l = #REF! N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.88 dc = 6x1.75= 10.5 K3 = 1.75 For very short ter
Annex B ( ) = #REF! )SQD = #REF! () = #REF! K12 = #REF!K3 = 1.5
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = #REF! N/mm2
(Permissible Comp. Stress)
da(c) F/A = = #REF! N/mm2
(Applied Comp. Stress)
#REF! #REF! #REF!
CP3 LOAD SUMMARY
BS 5268 Total Span = 8300
Pt 2 1996 Load Type of Load
2.8 and Duration Load Duration
Table 14 Rafter Level Factor K3
Long Dead 2.10 1.0
Term Only
Medium Dead + 2.10
Term Temp. Li 0.68
TOTAL 2.78 1.25
Very Short Dead + 1.05
Term Wind 1.59
TOTAL -0.54 1.75
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:Revised by: Test1
Checked by: Test2
REF OUTPUT
INTERMEDIATE RAFTER DESIGN Span , L = 3 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 2.780 kN DL + WL = F = 1.590 kN
Mmax =FL/8 = 1.043 kNm Mmax =FL/8 = 0.596 kNm
Project:truss
50x100
#REF!
4166666.7
CALCULATIONS
83333.3
Typical Load
Nairobi
7/29/2019 Kenyan Timber Stresses
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Reaction FL/2 = 4.170 kN Reaction FL/2 = 2.385 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade x K3K7K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 1.043
Zreq. = M/dm = 92574.09 mm3 50x150
For 50 x 150 mm
Zprov. = bd2/6 = 187500 mm
3therefore Bending OK
Deflection Check
Emin = 3600
I = bd3/12 = 1562500 mm
4Max deflection, dmax dmax = 34.75
Max allowable deflection = 0.003L = = 9
9 > 34.75
Deflecti
Adopt Redesign
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N
KN
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n
Page
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N/mm2
mm
mm
mm
kN
mm
mm
Page
1 of 3
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35559
1901.5
18.701
Page
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mm2
Page
1 of 3
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N/mm2
mm
mm
n NOT O
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50/99
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
CODE OUTPUT
DATA
UNITS
M.
KN/M
N/mm2
M2
Kg/M3
Kg PITCH, 20 Degrees 0.34889
2.92522668
N 2.74899093
Rafters & Bottom Tie 100 x 50 0.005 m2
Truss Webs 100 x 50 0.005 m2
GCI Sheeting Purlins 75 x 50 0.00375 m2
Tiling Battens 50 x 50 0.0025 m2
Ceiling Brandering 50 x 50 0.0025 m2
Intermediate Rafter 100 x 50 0.005 m2
Underpurlins 100 x 50 0.005 m2
Density of Wood 500 Kg/m3
Weight
Bottom-Tie Length 6.8 m 17.00 Kg
Total Rafter Length 8.51 m 21.28 KgTotal Web Length 7.66 m 19.16 Kg
Truss Spacing 1.2 m 57.44 Kg
Tiling Battens Spacing 0.3 m
Purlin Spacing 1.2 m
Brandering Spacing 0.6 m
Intermediate Rafer 0.6 m
Weight of Truss
Weight of Main plate 57.4 Kg
Weight of Nailing plate 14.4 Kg
Weight of Nails 7.2 Kg
79.0 Kg = 0.79 kN/truss
Weight of Decra Tiles 0.25 kN/m2
2.55 kN/trus 0.25
Weight of tiling battens (50x50) 0.015 kN/Batten 0.43 " 0.04
Weight of GCI Sheeting 0.1 kN/m2
1.02 " 0.10
Weight of Purlins (75x50) 0.0225 kN/Purlin 0.16 " 0.02
4.16 kN/truss
Roof imposed load 0.25 kN/m2
Weight of Ceiling 0.25 kN/m2
2.04 kN/truss
Weight of Ceiling Brandering (75x50) 0.015 kN/Brande 0.43 "
2.47 "
Total Load per Truss = 7.42 kN/truss
Nairobi
Project:truss
CALCULATIONS
7/29/2019 Kenyan Timber Stresses
51/99
No. Panels 0n the Rafter 4 On Rafter
No. Panels 0n the Bottom-Tie 3 On Bottom Tie
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
Truss Loading at Rafter Level 2/3 of Total Load = 4.95
Nodal Loading at Rafter Level
Truss Loading at Ceiling Level 1/3 of Total Load = 2.48
Nodal Loading at Ceiling Level
CP3 WIND LOAD x
CP3 Chp V Basic Wind Speed for NAIROBI V = 28 m/s V = 28 m/s
Pt2 4.3 Topography factor S1 = 1.0 S1 = 1.0
Statistical factor S2 = 0.9 S1 = 0.9
Topography factor S3 = 1.0 S1 = 1.0
CP3 Chp V Height to Eaves, h = 16.2 Pitch = 20
5.4 Building Class = B Width = 7.9Table 3 Ground roughness Category = 3
Height (eaves to apex) = 1.44
CP3 Chp V Total height to apex, H = 17.64 m
5.6
Design Wind Speed Vs = VxS1xS2xS3 = m/s
28 x 1 x 0.9 x 1 = 25.2
Vs= 25.2
6.0 Dynamic Pressure q = KVs x Vs Where K = 0.613
therefore, q= 0.613 x 0.613 x 0.613 = 389 N/m2
= 0.389 N/m2
External Pressure Coefficients, Cpe
Height to eaves, h = 16.2 m
Width w = 9.425 m h/w = 1.719
CP3 Chp V Slope = 20 Deg. Cpe = -0.575 Wind onTable 8 Cpe = -0.5 Side
Cpe = -0.8 Wind on
Cpe = -0.65 End
Internal Pressure Coefficients, Cpi
CP3 Cpi = 0.2
Appendix E ./ ( ) - x Cpi = -0.3
CP3 Wind Load F = (Cpe -Cpi).q.A A =
7.2
Max. roof Uplift = (-0.8-0.2)qA = -0.389
Min Downward Load = (-0.8--0.3)qA = -0.195
UPLIFT
Design for Uplift force of Fmax = -0.389Fmin = -0.195
Truss Spacing = 1.2 m x
Truss Span = 6.8 m
Overall Span = 6.8 m 1.2x6.8 = 8.16 m2
therefore. Max. Uplift = Fmax = 3.18 kN/truss
Fmin = 1.588 kN/truss
Nairobi
Project:truss
CALCULATIONS
tributary area to
truss
tributary area to truss
7/29/2019 Kenyan Timber Stresses
52/99
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
BattensArea Supported / Batten, Ab = 0.3x0.6
Batten Spacing = 0.3 m Ab = 0.18
Batten Span = 0.6 m Max. Batten Uplift = 13 x 0.18 = -0.071 kN/batte
GRAVITY LOADS
Imposed Load:
Imposed Load = 0.25
Dead Loads :
Truss self Weight = 79 Kg = 0.79 kN
Distributed Load = 0.79 / 6.8 x 1.2 = 0.10 kN/m2
Tiles+ Battens = 0.3 kN/m2
GCI Sheets + Purlins = 0.12 kN/m2
total = 0.52
Ceil ing + Brandering = 0.28 kN/m2
1) At the rafter level 0.52 KN/M2
Total DL = 4.25 = 2.84
kN/truss
Total IL = 2.04 = 1.36 kN/truss
total 4.20
2) At the Ceiling level
0.95
kN/truss
0.68
total 0.68
3) Batten
Imposed = = 0.05 KN
Dead = 0.3 x 0.3 x 0.6 = 0.03 KN
CP3 LOAD SUMMARY x
BS 5268 Total Span = 8513
Pt 2 1996 Load Type of Load
2.8 and Duration Load Batten Duration
Table 14 Rafter Level Ceiling Level Factor K3
Long Dead 4.20 0.95 0.03 1.0
Term Only
Medium Dead + 4.20 0.95 0.030
Term Temp. Li 1.36 0.68 0.05
TOTAL 5.56 1.63 0.080 1.25
Very Short Dead + 4.20 0.95 0.03
Term Wind 3.18 -0.071
TOTAL 1.02 -0.041 1.75
Design Worx Limited Issue: DesignP.O. Box 7136-001 Date:
Nairobi
Project:truss
CALCULATIONS
0.52 x 6.8 x 1.2 =
0.25 x 6.8 x 1.2 =
Total DL =
Total IL =
0.25 x 0.3 x 0.6
Typical Load
Truss
Nairobi
7/29/2019 Kenyan Timber Stresses
53/99
Revised by: Test1
Checked by: Test2
REF OUTPUT
BATTEN DESIGN Span , L = 0.6 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 0.080 kN DL + WL = F = -0.041 kN
Mmax =FL/8 = 0.006 kNm Mmax =FL/8 = -0.003 kNmReaction FL/2 = 0.024 kN Reaction FL/2 = -0.012 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade .K3.K7.K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 0.006
Zreq. = M/dm = 532.8005 mm3
25x50
For 25 x 50 mm Battens
Zprov. = bd2/6 = 10417 mm3
therefore Bending OK
Deflection CheckEmin = 3600 N/mm
2Emin = 3600
I = bd3/12 = 260417 mm4
Max deflection, dmax dmax = 0.1
Max allowable deflection = 0.003L = = 1.8
1.8 > 0.1
Deflection OK
Adopt
BS 5268 TRUSS T1- FORCE
Pt 2 1996 Design for Medium Term Loading
2.8 and Total Load at Rafter = 5.56 Cantileverd end = 750
Table 14 Total Load at Ceiling = 1.63 Total Truss Load = = 7.19
Total No. of Panels on Rafter = 4 Truss Span = 6800
Total No. of Panels on Bottom Tie = 3 Total Span = 8300
P1 = 5.56/4= 1.390 1.633= P3 = 0.543
P2 = 1.39/= 0.695 P4 = 0.272R = 7.19/= 3.595 -0.272 = 3.323 kN
Member length coeff force unit force
1 2098 7.31 10.16516 kN 1.46 kN
2 2098 6.11 8.493023 kN 1.46 kN
3 2098 6.63 9.214809 kN 1.46 kN
4 2098 1.27 1.77173 kN 0.00 kN
5 2098 1.27 1.77173 kN 0.00 kN
6 2098 2.75 3.821097 kN 0.00 kN
7 2098 6.87 9.552743 kN 1.37 kN
8 2098 4.12 5.731646 kN 1.37 kN
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Project:truss
CALCULATIONS
25x50
Refer to Truss Diagram above
Nairobi
TENSION
COMP.
7/29/2019 Kenyan Timber Stresses
54/99
Revised by: Test1
Checked by: Test2
REF OUTPUT
RAFTER DESIGN
Critical Member is: 1
BS 5268 F = 10.17 kN Compression
Pt 3 L = 2098 mm 50x1506.5.5 Le = 1888.2 mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 150
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 1E+07
Pt 2 r = 43.30 A = 7500
2.11.4 l = 43.61 Zprov. = bd2/6 = 2E+05
< 180 Slender Ratio OK
2.11.5 Since l > 5 l SQD = 1901 Multiply grade stress by K12 x
BS 5268 h = 0.005 l = 0.218 N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.87755102 dc = 6x1.25= 7.5 K3 = 1.25 For very short ter
( ) = 1.51235477( )SQD = 2.287 () = 1.662 K12 = 1.12
Annex B K3 = 1.5 K12 = 1.00
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = 10.096 N/mm2
(Permissible Compression Stress)
da(c) F/A = = 1.355 N/mm2
(Applied Compression Stress)< 10.096 Section OK
BS 5268 Check for Combined Compression and Bending for Rafter
Pt 3 Man Point Load P = 0.9 kN K3 = 1.5 Duration Factor
6.4.2 F = 10.1652 kN K7 = (300/d)^0.11
L = 2098 mm K7 = 1.08 Depth Factor
Le = 1888.2 mm K8 = 1.1 Load Sharing F.
Mmax = PLe/4 = 0.425 kNm (Max Bending Moment, PL/4)
dadm(b) = dgrade x K3K7K8 =
= 10.6844 da(b) .= M/Z = 2.27 N/mm2
(Applied Bending Stress)
BS 5268 da(c) = 1.355 + 2.27 de = PI^2E
Pt 2 dadm(c) dadm(b) (1-1.5dadm(c) x K1 10.09629 10.6844 0.88 l 2
2.11.6 de de =
= 0.134 + 0.241 = 0.3752
Adopt 50x150 since < 1BOTTOM TIE DESIGN
Critical Member is 7
F = 9.55 kN Tension
Try GS grade Cypress = 100 x 150
I = bd3/12 = 2.8E+07 use 100x150
A = 15000
BS 5268 bd2/6 = 375000
Pt 2
2.12 dgrade = 3.00 N/mm2
K14 = (300/d)^0.11
K14 = 1.08
dadm(t) = dgrade x K14
= 3.24 N/mm2
(Permissible Tensile Stress)
da(t) F/A = 0.64 N/mm
2
(Applied Tensile Stress)< 3.24
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
Project:truss
CALCULATIONS
.+ da(b)
100x150
Section O
Nairobi
Project:truss
14062500
187500
7/29/2019 Kenyan Timber Stresses
55/99
REF OUTPUT
INTERNAL MEMBER DESIGN
Critical Member is 8
F = 5.73 kN Tension
Try GS grade Cypress = 50 x 100
dgrade = 3.00 N/mm2
K14 = (300/d)^0.11 A = 5000K14 = 1.13
dadm(t) = dgrade x K14
= 3.39 N/mm2
(Permissible Tensile Stress)
da(t) F/A = 1.15 N/mm2
(Applied Tensile Stress)
< 3.39
Critical Member is 3
BS 5268 F = 9.21481 kN Compression
Pt 3 L = 2098 mm 50x100
6.5.5 Le = 1888 mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 100
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 4E+06
Pt 2 r = 28.87 A = 5000
2.11.4 l = 65.40 Zprov. = bd^2/6 = 83333
< 180 Slender Ratio OK
2.11.5 Since l > 5 l SQD = 4277 Multiply grade stress by K12 x
BS 5268 h = 0.005 l = 0.327 N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.88 dc = 6x1.75= 10.5 K3 = 1.75 For very short term
Annex B ( ) = 0.86 )SQD = 0.74 () = 0.53 K12 = 0.82
K3 = 1.5
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = 7.34 N/mm2
(Permissible Comp. Stress)
da(c) F/A = = 1.84 N/mm2
(Applied Comp. Stress)
< 7.34461 Section OK
CP3 LOAD SUMMARY
BS 5268 Total Span = 8300
Pt 2 1996 Load Type of Load
2.8 and Duration Load DurationTable 14 Rafter Level Factor K3
Long Dead 2.10 1.0
Term Only
Medium Dead + 2.10
Term Temp. Li 0.68
TOTAL 2.78 1.25
Very Short Dead + 1.05
Term Wind 1.59
TOTAL -0.54 1.75
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
Project:truss
CALCULATIONS
50x100
Section O
4166666.7
CALCULATIONS
83333.3
Typical Load
Nairobi
7/29/2019 Kenyan Timber Stresses
56/99
INTERMEDIATE RAFTER DESIGN Span , L = 3 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 2.780 kN DL + WL = F = 1.590 kN
Mmax =FL/8 = 1.043 kNm Mmax =FL/8 = 0.596 kNm
Reaction FL/2 = 4.170 kN Reaction FL/2 = 2.385 kN
Bending CheckZreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade x K3K7K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 1.043
Zreq. = M/dm = 92574.09 mm3 50x150
For 50 x 150 mm
Zprov. = bd2/6 = 187500 mm
3therefore Bending OK
Deflection Check
Emin = 3600
I = bd3/12 = 1562500 mm
4Max deflection, dmax dmax = 34.75
Max allowable deflection = 0.003L = = 99 > 34.75
Deflecti
Adopt Redesign
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N/mm2
mm
mm
mm
kN
mm
mm
Page
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35559
1901.5
18.701
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N/mm2
mm
mm
n NOT O
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Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
CODE OUTPUT
DATA
UNITS
M.
KN/M
N/mm2
M2
Kg/M3
Kg PITCH, 15 Degrees 0.26167
3.86561806
N 3.73403308
Rafters & Bottom Tie 100 x 50 0.005 m2
Truss Webs 100 x 50 0.005 m2
GCI Sheeting Purlins 75 x 50 0.00375 m2
Tiling Battens 50 x 50 0.0025 m2
Ceiling Brandering 50 x 50 0.0025 m2
Intermediate Rafter 100 x 50 0.005 m2
Underpurlins 100 x 50 0.005 m2
Density of Wood 500 Kg/m3
Weight
Bottom-Tie Length 6.8 m 17.00 Kg
Total Rafter Length 8.28 m 20.71 KgTotal Web Length 7.45 m 18.63 Kg
Truss Spacing 1.2 m 56.34 Kg
Tiling Battens Spacing 0.3 m
Purlin Spacing 1.2 m
Brandering Spacing 0.6 m
Intermediate Rafer 0.6 m
Weight of Truss
Weight of Main plate 56.3 Kg
Weight of Nailing plate 14.1 Kg
Weight of Nails 7.0 Kg
77.5 Kg = 0.77 kN/truss
Weight of Decra Tiles 0.25 kN/m2
2.48 kN/trus 0.25
Weight of tiling battens (50x50) 0.015 kN/Batten 0.41 " 0.04
Weight of GCI Sheeting 0.1 kN/m2
0.99 " 0.10
Weight of Purlins (75x50) 0.0225 kN/Purlin 0.16 " 0.02
4.05 kN/truss
Roof imposed load 0.25 kN/m2
Weight of Ceiling 0.25 kN/m2
2.04 kN/truss
Weight of Ceiling Brandering (75x50) 0.015 kN/Brande 0.41 "
2.45 "
Total Load per Truss = 7.28 kN/truss
Nairobi
Project:truss
CALCULATIONS
7/29/2019 Kenyan Timber Stresses
65/99
No. Panels 0n the Rafter 4 On Rafter
No. Panels 0n the Bottom-Tie 3 On Bottom Tie
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
Truss Loading at Rafter Level 2/3 of Total Load = 4.86
Nodal Loading at Rafter Level
Truss Loading at Ceiling Level 1/3 of Total Load = 2.43
Nodal Loading at Ceiling Level
CP3 WIND LOAD x
CP3 Chp V Basic Wind Speed for NAIROBI V = 28 m/s V = 28 m/s
Pt2 4.3 Topography factor S1 = 1.0 S1 = 1.0
Statistical factor S2 = 0.9 S1 = 0.9
Topography factor S3 = 1.0 S1 = 1.0
CP3 Chp V Height to Eaves, h = 16.2 Pitch = 15
5.4 Building Class = B Width = 7.9Table 3 Ground roughness Category = 3
Height (eaves to apex) = 1.06
CP3 Chp V Total height to apex, H = 17.26 m
5.6
Design Wind Speed Vs = VxS1xS2xS3 = m/s
28 x 1 x 0.9 x 1 = 25.2
Vs= 25.2
6.0 Dynamic Pressure q = KVs x Vs Where K = 0.613
therefore, q= 0.613 x 0.613 x 0.613 = 389 N/m2
= 0.389 N/m2
External Pressure Coefficients, Cpe
Height to eaves, h = 16.2 m
Width w = 9.425 m h/w = 1.719
CP3 Chp V Slope = 15 Deg. Cpe = -0.575 Wind onTable 8 Cpe = -0.5 Side
Cpe = -0.8 Wind on
Cpe = -0.65 End
Internal Pressure Coefficients, Cpi
CP3 Cpi = 0.2
Appendix E ./ ( ) - x Cpi = -0.3
CP3 Wind Load F = (Cpe -Cpi).q.A A =
7.2
Max. roof Uplift = (-0.8-0.2)qA = -0.389
Min Downward Load = (-0.8--0.3)qA = -0.195
UPLIFT
Design for Uplift force of Fmax = -0.389Fmin = -0.195
Truss Spacing = 1.2 m x
Truss Span = 6.8 m
Overall Span = 6.8 m 1.2x6.8 = 8.16 m2
therefore. Max. Uplift = Fmax = 3.18 kN/truss
Fmin = 1.588 kN/truss
Nairobi
Project:truss
CALCULATIONS
tributary area to
truss
tributary area to truss
7/29/2019 Kenyan Timber Stresses
66/99
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
BattensArea Supported / Batten, Ab = 0.3x0.6
Batten Spacing = 0.3 m Ab = 0.18
Batten Span = 0.6 m Max. Batten Uplift = 13 x 0.18 = -0.071 kN/batte
GRAVITY LOADS
Imposed Load:
Imposed Load = 0.25
Dead Loads :
Truss self Weight = 77 Kg = 0.77 kN
Distributed Load = 0.77 / 6.8 x 1.2 = 0.10 kN/m2
Tiles+ Battens = 0.3 kN/m2
GCI Sheets + Purlins = 0.12 kN/m2
total = 0.52
Ceil ing + Brandering = 0.28 kN/m2
1) At the rafter level 0.52 KN/M2
Total DL = 4.25 = 2.84
kN/truss
Total IL = 2.04 = 1.36 kN/truss
total 4.20
2) At the Ceiling level
0.95
kN/truss
0.68
total 0.68
3) Batten
Imposed = = 0.05 KN
Dead = 0.3 x 0.3 x 0.6 = 0.03 KN
CP3 LOAD SUMMARY x
BS 5268 Total Span = 8282
Pt 2 1996 Load Type of Load
2.8 and Duration Load Batten Duration
Table 14 Rafter Level Ceiling Level Factor K3
Long Dead 4.20 0.95 0.03 1.0
Term Only
Medium Dead + 4.20 0.95 0.030
Term Temp. Li 1.36 0.68 0.05
TOTAL 5.56 1.63 0.080 1.25
Very Short Dead + 4.20 0.95 0.03
Term Wind 3.18 -0.071
TOTAL 1.02 -0.041 1.75
Design Worx Limited Issue: DesignP.O. Box 7136-001 Date:
Nairobi
Project:truss
CALCULATIONS
0.52 x 6.8 x 1.2 =
0.25 x 6.8 x 1.2 =
Total DL =
Total IL =
0.25 x 0.3 x 0.6
Typical Load
Truss
Nairobi
7/29/2019 Kenyan Timber Stresses
67/99
Revised by: Test1
Checked by: Test2
REF OUTPUT
BATTEN DESIGN Span , L = 0.6 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 0.080 kN DL + WL = F = -0.041 kN
Mmax =FL/8 = 0.006 kNm Mmax =FL/8 = -0.003 kNmReaction FL/2 = 0.024 kN Reaction FL/2 = -0.012 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade .K3.K7.K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 0.006
Zreq. = M/dm = 532.8005 mm3
25x50
For 25 x 50 mm Battens
Zprov. = bd2/6 = 10417 mm3
therefore Bending OK
Deflection CheckEmin = 3600 N/mm
2Emin = 3600
I = bd3/12 = 260417 mm4
Max deflection, dmax dmax = 0.1
Max allowable deflection = 0.003L = = 1.8
1.8 > 0.1
Deflection OK
Adopt
BS 5268 TRUSS T1- FORCE
Pt 2 1996 Design for Medium Term Loading
2.8 and Total Load at Rafter = 5.56 Cantileverd end = 750
Table 14 Total Load at Ceiling = 1.63 Total Truss Load = = 7.19
Total No. of Panels on Rafter = 4 Truss Span = 6800
Total No. of Panels on Bottom Tie = 3 Total Span = 8300
P1 = 5.56/4= 1.390 1.633= P3 = 0.543
P2 = 1.39/= 0.695 P4 = 0.272R = 7.19/= 3.595 -0.272 = 3.323 kN
Member length coeff force unit force
1 2098 5.80 8.059814 kN 1.93 kN
2 2098 3.87 5.373209 kN 1.93 kN
3 2098 1.93 2.686605 kN 0.00 kN
4 2098 5.60 7.785459 kN 1.87 kN
5 2098 5.60 7.785459 kN 1.87 kN
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
Project:truss
Project:truss
CALCULATIONS
CALCULATIONS
25x50
Refer to Truss Diagram above
Nairobi
TENSI
ON
COMP.
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RAFTER DESIGN
Critical Member is: 1
BS 5268 F = 8.06 kN Compression
Pt 3 L = 2098 mm 50x150
6.5.5 Le = 1888.2 mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 150
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 1E+07
Pt 2 r = 43.30 A = 75002.11.4 l = 43.61 Zprov. = bd2/6 = 2E+05
< 180 Slender Ratio OK
2.11.5 Since l > 5 l SQD = 1901 Multiply grade stress by K12 x
BS 5268 h = 0.005 l = 0.218 N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.87755102 dc = 6x1.25= 7.5 K3 = 1.25 For very short ter
( ) = 1.51235477( )SQD = 2.287 () = 1.662 K12 = 1.12
Annex B K3 = 1.5 K12 = 1.00
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = 10.096 N/mm2
(Permissible Compression Stress)
da(c) F/A = = 1.075 N/mm2
(Applied Compression Stress)
< 10.096 Section OK
BS 5268 Check for Combined Compression and Bending for Rafter
Pt 3 Man Point Load P = 0.9 kN K3 = 1.5 Duration Factor 6.4.2 F = 8.05981 kN K7 = (300/d)^0.11
L = 2098 mm K7 = 1.08 Depth Factor
Le = 1888.2 mm K8 = 1.1 Load Sharing F.
Mmax = PLe/4 = 0.425 kNm (Max Bending Moment, PL/4)
dadm(b) = dgrade x K3K7K8 =
= 10.6844 da(b) .= M/Z = 2.27 N/mm2
(Applied Bending Stress)
BS 5268 da(c) = 1.075 + 2.27 de = PI^2E
Pt 2 dadm(c) dadm(b) (1-1.5dadm(c) x K1 10.09629 10.6844 0.9 l ^2
2.11.6 de de =
= 0.106 + 0.236 = 0.3421
Adopt 50x150 since < 1
BOTTOM TIE DESIGN
Critical Member is 4
F = 7.79 kN Tension
Try GS grade Cypress = 100 x 150
I = bd3/12 = 2.8E+07 use 100x150
A = 15000
BS 5268 bd2/6 = 375000
Pt 2
2.12 dgrade = 3.00 N/mm2
K14 = (300/d)^0.11
K14 = 1.08
dadm(t) = dgrade x K14
= 3.24 N/mm2
(Permissible Tensile Stress)
da(t) F/A = 0.52 N/mm2
(Applied Tensile Stress)
< 3.24
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
INTERNAL MEMBER DESIGN
Critical Member is #REF!
100x150
Section O
Nairobi
Project:truss
CALCULATIONS
14062500
187500
.+ da(b)
7/29/2019 Kenyan Timber Stresses
69/99
F = #REF! kN Tension
Try GS grade Cypress = 50 x 100
dgrade = 3.00 N/mm2
K14 = (300/d)^0.11 A = 5000
K14 = 1.13
dadm(t) = dgrade x K14
= 3.39 N/mm2
(Permissible Tensile Stress)
da(t) F /A = #REF! N/mm2
(Applied Tensile Stress)#REF! 3.39
Critical Member is #REF!
BS 5268 F = #REF! kN Compression
Pt 3 L = #REF! mm 50x100
6.5.5 Le = #REF! mm Effective Length Le = 0.9 x L
Try GS grade Cypress = 50 x 100
BS 5268 Slenderness ratio l = Le/r r SQRT(I/A) I = bd3/12 = 4E+06
Pt 2 r = 28.87 A = 5000
2.11.4 l = #REF! Zprov. = bd^2/6 = 83333
#REF! 180 #REF!
2.11.5 Since l > 5 l SQD = #REF! Multiply grade stress by K12 x
BS 5268 h = 0.005 l = #REF! N = 1.5 dgrade = 6.00 N/mm2
Pt 2 pSQD = 9.88 dc = 6x1.75= 10.5 K3 = 1.75 For very short ter Annex B ( ) = #REF! )SQD = #REF! () = #REF! K12 = #REF!
K3 = 1.5
dadm(c) = dgrade x K3K12 = Emin = 3600 N/mm2
dadm(c) = #REF! N/mm2
(Permissible Comp. Stress)
da(c) F/A = = #REF! N/mm2
(Applied Comp. Stress)
#REF! #REF! #REF!
CP3 LOAD SUMMARY
BS 5268 Total Span = 8300
Pt 2 1996 Load Type of Load
2.8 and Duration Load Duration
Table 14 Rafter Level Factor K3
Long Dead 2.10 1.0
Term Only
Medium Dead + 2.10
Term Temp. Li 0.68
TOTAL 2.78 1.25
Very Short Dead + 1.05
Term Wind 1.59
TOTAL -0.54 1.75
Design Worx Limited Issue: DesignP.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
INTERMEDIATE RAFTER DESIGN Span , L = 3 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 2.780 kN DL + WL = F = 1.590 kN
Project:truss
50x100
#REF!
4166666.7
CALCULATIONS
83333.3
Typical Load
Nairobi
7/29/2019 Kenyan Timber Stresses
70/99
Mmax =FL/8 = 1.043 kNm Mmax =FL/8 = 0.596 kNm
Reaction FL/2 = 4.170 kN Reaction FL/2 = 2.385 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade x K3K7K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 1.043
Zreq. = M/dm = 92574.09 mm3 50x150
For 50 x 150 mm
Zprov. = bd2/6 = 187500 mm
3therefore Bending OK
Deflection Check
Emin = 3600
I = bd3/12 = 1562500 mm
4Max deflection, dmax dmax = 34.75
Max allowable deflection = 0.003L = = 9
9 > 34.75
Deflecti
Adopt Redesign
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N/mm2
mm
mm
mm
kN
mm
mm
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35559
1901.5
18.701
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N/mm2
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mm
n NOT O
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Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
CODE OUTPUT
DATA
UNITS
M.
KN/M
N/mm2
M2
Kg/M3
Kg PITCH, 20 Degrees 0.34889
2.92522668
N 2.74899093
Rafters & Bottom Tie 100 x 50 0.005 m2
Truss Webs 100 x 50 0.005 m2
GCI Sheeting Purlins 75 x 50 0.00375 m2
Tiling Battens 50 x 50 0.0025 m2
Ceiling Brandering 50 x 50 0.0025 m2
Intermediate Rafter 100 x 50 0.005 m2
Underpurlins 100 x 50 0.005 m2
Density of Wood 500 Kg/m3
Weight
Bottom-Tie Length 6.8 m 17.00 Kg
Total Rafter Length 8.51 m 21.28 KgTotal Web Length 7.66 m 19.16 Kg
Truss Spacing 1.2 m 57.44 Kg
Tiling Battens Spacing 0.3 m
Purlin Spacing 1.2 m
Brandering Spacing 0.6 m
Intermediate Rafer 0.6 m
Weight of Truss
Weight of Main plate 57.4 Kg
Weight of Nailing plate 14.4 Kg
Weight of Nails 7.2 Kg
79.0 Kg = 0.79 kN/truss
Weight of Decra Tiles 0.25 kN/m2
2.55 kN/trus 0.25
Weight of tiling battens (50x50) 0.015 kN/Batten 0.43 " 0.04
Weight of GCI Sheeting 0.1 kN/m2
1.02 " 0.10
Weight of Purlins (75x50) 0.0225 kN/Purlin 0.16 " 0.02
4.16 kN/truss
Roof imposed load 0.25 kN/m2
Weight of Ceiling 0.25 kN/m2
2.04 kN/truss
Weight of Ceiling Brandering (75x50) 0.015 kN/Brande 0.43 "
2.47 "
Total Load per Truss = 7.42 kN/truss
Nairobi
Project:truss
CALCULATIONS
7/29/2019 Kenyan Timber Stresses
79/99
No. Panels 0n the Rafter 4 On Rafter
No. Panels 0n the Bottom-Tie 3 On Bottom Tie
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
Truss Loading at Rafter Level 2/3 of Total Load = 4.95
Nodal Loading at Rafter Level
Truss Loading at Ceiling Level 1/3 of Total Load = 2.48
Nodal Loading at Ceiling Level
CP3 WIND LOAD x
CP3 Chp V Basic Wind Speed for NAIROBI V = 28 m/s V = 28 m/s
Pt2 4.3 Topography factor S1 = 1.0 S1 = 1.0
Statistical factor S2 = 0.9 S1 = 0.9
Topography factor S3 = 1.0 S1 = 1.0
CP3 Chp V Height to Eaves, h = 16.2 Pitch = 20
5.4 Building Class = B Width = 7.9Table 3 Ground roughness Category = 3
Height (eaves to apex) = 1.44
CP3 Chp V Total height to apex, H = 17.64 m
5.6
Design Wind Speed Vs = VxS1xS2xS3 = m/s
28 x 1 x 0.9 x 1 = 25.2
Vs= 25.2
6.0 Dynamic Pressure q = KVs x Vs Where K = 0.613
therefore, q= 0.613 x 0.613 x 0.613 = 389 N/m2
= 0.389 N/m2
External Pressure Coefficients, Cpe
Height to eaves, h = 16.2 m
Width w = 9.425 m h/w = 1.719
CP3 Chp V Slope = 20 Deg. Cpe = -0.575 Wind onTable 8 Cpe = -0.5 Side
Cpe = -0.8 Wind on
Cpe = -0.65 End
Internal Pressure Coefficients, Cpi
CP3 Cpi = 0.2
Appendix E ./ ( ) - x Cpi = -0.3
CP3 Wind Load F = (Cpe -Cpi).q.A A =
7.2
Max. roof Uplift = (-0.8-0.2)qA = -0.389
Min Downward Load = (-0.8--0.3)qA = -0.195
UPLIFT
Design for Uplift force of Fmax = -0.389Fmin = -0.195
Truss Spacing = 1.2 m x
Truss Span = 6.8 m
Overall Span = 6.8 m 1.2x6.8 = 8.16 m2
therefore. Max. Uplift = Fmax = 3.18 kN/truss
Fmin = 1.588 kN/truss
Nairobi
Project:truss
CALCULATIONS
tributary area to
truss
tributary area to truss
7/29/2019 Kenyan Timber Stresses
80/99
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Revised by: Test1
Checked by: Test2
REF OUTPUT
BattensArea Supported / Batten, Ab = 0.3x0.6
Batten Spacing = 0.3 m Ab = 0.18
Batten Span = 0.6 m Max. Batten Uplift = 13 x 0.18 = -0.071 kN/batte
GRAVITY LOADS
Imposed Load:
Imposed Load = 0.25
Dead Loads :
Truss self Weight = 79 Kg = 0.79 kN
Distributed Load = 0.79 / 6.8 x 1.2 = 0.10 kN/m2
Tiles+ Battens = 0.3 kN/m2
GCI Sheets + Purlins = 0.12 kN/m2
total = 0.52
Ceil ing + Brandering = 0.28 kN/m2
1) At the rafter level 0.52 KN/M2
Total DL = 4.25 = 2.84
kN/truss
Total IL = 2.04 = 1.36 kN/truss
total 4.20
2) At the Ceiling level
0.95
kN/truss
0.68
total 0.68
3) Batten
Imposed = = 0.05 KN
Dead = 0.3 x 0.3 x 0.6 = 0.03 KN
CP3 LOAD SUMMARY x
BS 5268 Total Span = 8513
Pt 2 1996 Load Type of Load
2.8 and Duration Load Batten Duration
Table 14 Rafter Level Ceiling Level Factor K3
Long Dead 4.20 0.95 0.03 1.0
Term Only
Medium Dead + 4.20 0.95 0.030
Term Temp. Li 1.36 0.68 0.05
TOTAL 5.56 1.63 0.080 1.25
Very Short Dead + 4.20 0.95 0.03
Term Wind 3.18 -0.071
TOTAL 1.02 -0.041 1.75
Design Worx Limited Issue: DesignP.O. Box 7136-001 Date:
Nairobi
Project:truss
CALCULATIONS
0.52 x 6.8 x 1.2 =
0.25 x 6.8 x 1.2 =
Total DL =
Total IL =
0.25 x 0.3 x 0.6
Typical Load
Truss
Nairobi
7/29/2019 Kenyan Timber Stresses
81/99
Revised by: Test1
Checked by: Test2
REF OUTPUT
BATTEN DESIGN Span , L = 0.6 m
Load Case (i) (DL+LL) Load Case (ii) (DL+WL)
DL + LL = F = 0.080 kN DL + WL = F = -0.041 kN
Mmax =FL/8 = 0.006 kNm Mmax =FL/8 = -0.003 kNmReaction FL/2 = 0.024 kN Reaction FL/2 = -0.012 kN
Bending Check
Zreq. = M/dm
Permissible stress in bending parrallel to grain, dm = grade .K3.K7.K8 =
dgrade = 5.00 N/mm2
K3 = 1.75 Load Duration Factor
K7 = 1.1 Load Sharing Factor
K8 = 1.17 Depth Factor
dm = 11.26 N/mm2
M = 0.006
Zreq. = M/dm = 532.8005 mm3
25x50
For 25 x 50 mm Battens
Zprov. = bd2/6 = 10417 mm3
therefore Bending OK
Deflection CheckEmin = 3600 N/mm
2Emin = 3600
I = bd3/12 = 260417 mm4
Max deflection, dmax dmax = 0.1
Max allowable deflection = 0.003L = = 1.8
1.8 > 0.1
Deflection OK
Adopt
BS 5268 TRUSS T1- FORCE
Pt 2 1996 Design for Medium Term Loading
2.8 and Total Load at Rafter = 5.56 Cantileverd end = 750
Table 14 Total Load at Ceiling = 1.63 Total Truss Load = = 7.19
Total No. of Panels on Rafter = 4 Truss Span = 6800
Total No. of Panels on Bottom Tie = 3 Total Span = 8300
P1 = 5.56/4= 1.390 1.633= P3 = 0.543
P2 = 1.39/= 0.695 P4 = 0.272R = 7.19/= 3.595 -0.272 = 3.323 kN
Member length coeff force unit force
1 2098 7.31 10.16516 kN 1.46 kN
2 2098 5.85 8.13213 kN 1.46 kN
3 2098 4.39 6.099098 kN 1.46 kN
4 2098 1.46 2.033033 kN 0.00 kN
5 2098 1.70 2.362688 kN 0.00 kN
6 2098 6.87 9.552743 kN 1.37 kN
7 2098 6.87 9.552743 kN 1.37 kN
8 2098 5.50 7.642195 kN 1.37 kN
Design Worx Limited Issue: Design
P.O. Box 7136-001 Date:
Project:truss
CALCULATIONS
25x50
Refer to Truss Diagram above
COMP.
TENSION
Nairobi
7/29/2019 Kenyan Timber Stresses
82/99
Revised by: Test1
Checked by: Test2
REF OUTPUT
RAFTER DESIGN
Critical Member is: 1
BS 5268 F = 10.17 kN Compression
Pt 3 L = 2098 mm 50x1506.5.5 Le = 1888.2 mm Effective Length Le =