#N/A Job No.
:
By:
ELS Design Chkd:
Primary Strut Checking Date: 8-May-19
Structural Steel Design - Primary Strut
(Structural steel design based on "Code of Practice for the Structural Use of Steel 2005"
with reference to "The Design and Construction of Sheet-Piled Cofferdams by B P Williams and D Waite")
Plan
Primary Strut
Secondary Strut
Waling
S/2 S S/2
Section
Strut B y
y T
q
t
D x x x
x d
y T y
Wall a
1. Section Properties
Try Section : Single 254 x 254 x 73 UC Grade 43 Hot Rolled
Distance between centre line a = 0 mm Neglect Spacing
Depth of Section D = 254 mm Elastic Modulus (X-Axis) Zx = 894000 mm3
Width of Section B = 254 mm Elastic Modulus (Y-Axis) Zy = 304724 mm3
Web Thickness t = 8.6 mm Plastic Modulus (X-Axis) Sx = 989000 mm
3
Flange Thickness T = 14.2 mm Plastic Modulus (Y-Axis) Sy = 462000 mm3
Depth between Fillets d = 200.3 mm Buckling Parameter u = 0.849
Second Moment of Area (X-Axis) Ix = 114000000 mm
4
Torsional Index x = 17.3
Second Moment of Area (Y-Axis) Iy = 38700000 mm
4
Area of Section Ag = 9290 mm2
Radius of Gyration (X-Axis) rx = 111.0 mm Mass per Length w = 73.00 kg/m
2
Radius of Gyration (Y-Axis) ry = 64.54 mm Design Strength py = 275 N/mm
The Modulus of Elasticity for steel E = 205000.00 MPa
2. Ultimate Design Load
Maximum inclined prop load from Plaxis = 36.00 kN/m
Stiffness of Strut for Plaxis Input, EA = (205,000 x 10^3) x (9,290 / 10^6) /2 = 9.522E+05 kN/m
Maximum prop force, F = 36.00 kN/m
Minimum inclination of strut to waling, a = 90.00 degree
Load in the direction of strut, Pa = F / sin a = 36.00 / sin 90.0 = 36.0 kN/m
Maximum strut spacing, S = 2.00 m
Maximum compression, P = Pa x S = 36.00 x 2.00 = 72.0 kN
Inclination of strut to wall, q = 90.00 degree
Unrestrain length of strut on plan (X-Axis), Lx' = 2.00 m
Actual unrestrain length of strut (X-Axis), Lx = Lx' / sin q = 2.00 / sin 90.0 = 2.00 m
Unrestrain length of strut on plan (Y-Axis), Ly' = 2.00 m
Actual unrestrain length of strut (Y-Axis), Ly = Ly' / sin q = 2.00 / sin 90.0 = 2.00 m
Construction Load, Qc = 0.00 kPa
Maximum Bending Moment (unfactored) = 0.125 x (73.0 x 9.81 + 0.0 x 254.0 x 1) x 10^-3 x 2.0^2 = 0.4 kNm
Maximum Shear Force (unfactored) = 0.5 x (73.0 x 9.81 +0.0 x 254.0 x 1) x 10^-3 x 2.0 = 0.7 kN
Load Factor = 1.60
spacing 1
Design Bending Moment (X-Axis) Mx = 160.0 kNm Design Shear Force V = 120.0 kN
Design Bending Moment (Y-Axis) My = 0.0 kNm Axial Force Fc = 115.2 kN
3. Section Classification (Table 7.1)
ε = [275 / py]1/2 = 1.0 b/T = 8.9 < 9.0 ε (Compact) (Table 7.1, Outstand element of compression flange)
d/t = 23.3 < 80 ε (Plastic) (Table 7.1, Web with neutral axis at mid-depth)
Class of Section = Compact Section
Primary Strut, SteelChk - Strut (Rev. D) 20190508
#N/A Job No.:
By:
ELS Design Chkd:
Primary Strut Checking Date: 8-May-19
4. Shear Buckling Resistance (Clause 8.4.6)
d/t = 23.3 < 70ε = 70.0
Therefore, Not Required to Check for Shear Buckling
5. Check Shear Capacity (Clause 8.2.1)
Shear Area Av = 2184 mm2
Shear Capacity Vc = pyAv/(3)^0.5
= 347 kN
Design Shear Force V = 120.0 kN < Pv = 347 kN Check Shear OK
Since, 0.6Vc = 208 kN > V Low Shear
7. Check Lateral Torsional Buckling (Clause 8.3)
Unrestrain length (Y-Axis) Ly = 2.00 m
Effective Length LEy = 1.0 L = 2.0 m (Clause 8.3.4)
Minor Axis Slenderness l = LEy / ry = 31.0
Buckling parameter u = 0.85 (Clause 8.3.5.3)
l/x = 1.79
2 0.25
Slenderness factor n = 1/(1+0.05(l/x) ) (Clause 8.3.5.3 Eqn 8.27)
= 0.963
bw = 1.000 (Clause 8.3.5.3 Eqn 8.28, 8.29)
l LT
0.5
Equivalent Slenderness = uvl(b w) = 25.3 (Clause 8.3.5.3 Eqn 8.25)
Design strength py = 275.00 N/mm2
Buckling strength pb = 275.0 N/mm2 (Table 8.3a for rolled section)
Buckling resistance moment Mb = 272.0 kNm (Clause 8.3.5.2 Eqn 8.20, 8.21, 8.22, 8.23, 8.24)
Equivalent uniform moment factor mLT = 0.93 (Table 8.4a for no intermediate lateral restraint)
mLTMx = 148.80 < Mb= 272.0 kNm (Clause 8.3.5.2 Eqn 8.18)
and Mx = 160.00 < Mcx= 272.0 kNm (Clause 8.3.5.2 Eqn 8.19)
Lateral Torsional Buckling Resistance OK
8. Cross-section Capacity Check (Clause 8.9.1)
Fc Mx My 115.2 160.0 0.0
+ + = + +
Agpy Mcx Mcy 2554.8 272.0 100.6
= 0.05 + 0.59 + 0.00
= 0.63
< 1 Cross-section Capacity OK
Primary Strut, SteelChk - Strut (Rev. D) 20190508
#N/A Job No.:
By:
ELS Design Chkd:
Primary Strut Checking Date: 8-May-19
9. Member Buckling Resistance Check (Clause 8.9.2)
Axis of buckling = x-x
Unrestrain length (X-Axis) Lx = 2.00 m
Effective Length (X-Axis) LEx = 1.0 Lx = 2.00 m (Clause 8.3.4)
Major Axis Slenderness lx = LEx / rx = 18.0 ≈ 20
Maximum Thickness T = 14.2 mm ≤ 40 mm
Type of Section = Rolled H-section ≤ 40mm
Designation of buckling curves for different section types: Buckling Curve b) (Table 8.7)
2
Compressive Strength pcx = 272.00 N/mm (Table 8.8(b))
Axis of buckling = y-y
Unrestrain length (Y-Axis) Ly = 2.00 m
Effective Length (Y-Axis) LEy = 1.0 Ly = 2.00 m (Clause 8.3.4)
Minor Axis Slenderness ly = LEy / ry = 31.0 ≈ 35
Maximum Thickness T = 14.2 mm ≤ 40 mm
Type of Section = Rolled H-section ≤ 40mm
Designation of buckling curves for different section types: Buckling Curve c) (Table 8.7)
2
Compressive Strength pcy = 247.00 N/mm (Table 8.8(c))
Design Compressive Strength pc = min. of pcx & pcy = 247.0 N/mm2
Moment equivalent factor m for flexural buckling
mx = 0.95 (Table 8.9)
my = 0.95 (Table 8.9)
Amplication Factor
fx = 1.00
fy = 1.01
Axis of buckling = x-x
Unrestrain length (X-Axis) Lx = 2.00 m
Effective Length (X-Axis) LEx = 1.0 Lx = 2.00 m (Clause 8.3.4)
Major Axis Slenderness lx = LEx / rx = 18.0 ≈ 20
Maximum Thickness T = 14.2 mm ≤ 40 mm
Type of Section = Rolled H-section ≤ 40mm
Designation of buckling curves for different section types: Buckling Curve b) (Table 8.7)
Primary Strut, SteelChk - Strut (Rev. D) 20190508
#N/A Job No.:
By:
ELS Design Chkd:
Primary Strut Checking Date: 8-May-19
Compressive Strength pcx = 272.00 N/mm2 (Table 8.8(b))
Axis of buckling = y-y
Unrestrain length (Y-Axis) Ly = 2.00 m
Effective Length (Y-Axis) LEy = 1.0 Ly = 2.00 m (Clause 8.3.4)
Minor Axis Slenderness ly = LEy / ry = 31.0 ≈ 35
Maximum Thickness T = 14.2 mm ≤ 40 mm
Type of Section = Rolled H-section ≤ 40mm
Designation of buckling curves for different section types: Buckling Curve c) (Table 8.7)
2
Compressive Strength pcy = 247.00 N/mm (Table 8.8(c))
2
Design Compressive Strength pc = min. of pcx & pcy = 247.0 N/mm
Cross-section capacity
Fc mxMx myMy 115.2 160.0 0.0
+ + = + + (Clause 8.9.1 Eqn 8.78)
Agpc Mcx Mcy 2554.8 272.0 100.6
= 0.05 + 0.59 + 0.00
= 0.63
< 1 Overall Capacity OK
Member buckling resistance
Fc mxMx myMy 0.0 152.0 0.0
+ + = + + (Clause 8.9.2 Eqn 8.79)
Agpc Mcx Mcy 2294.6 272.0 100.6
= 0.00 + 0.56 + 0.00
= 0.56
< 1 Overall Capacity OK
Fc mxMx myMy 0.0 152.3 0.0
+ + = + + (Clause 8.9.2 Eqn 8.80)
Agpc Mcx Mcy 2294.6 272.0 100.6
= 0.00 + 0.56 + 0.00
= 0.56
< 1 Overall Capacity OK
Fc mxMx myMy 0.0 148.8 0.0
+ + = + + (Clause 8.9.2 Eqn 8.81)
Agpc Mcx Mcy 2294.6 272.0 100.6
= 0.00 + 0.55 + 0.00
= 0.55
< 1 Overall Capacity OK
10. Check Welding Connection between the Strut and Waling
Axial Force Fc = 115.2 kN
Minimum inclination of strut to waling a = 88.00 degree (Refer to P.1 drawing)
Inclination of strut to wall q = 88.00 degree (Refer to P.1 drawing)
Mass per Length Span Length Width of Section Factored Self-weight Factored Construction load
Structural Members w (kg/m) L (m) B (mm) (kN) (kN)
Design Strut 73.0 2.00 254.0 1.15 0.00
Connected Strut 1 0.0 0.00 0.0 0.00 0.00
Connected Strut 2 0.0 0.00 0.0 0.00 0.00
Total 1.15 0.00
Horizontal Shear Force FH = Fc cosa = 4.0 kN
Vertical Shear Force FV = Fc cosq + Self-weight + Construction load
= 5.17 kN
Total Shear Force Induced by Strut V = (FH2 + FV2)0.5
= 6.5 kN
Provide 6 mm fillet weld at Flange Max. Thickness = 12.2 mm (Clause 9.2.5.1.2a)
Provide 6 mm fillet weld at Web Max. Thickness = 6.6 mm Thickness OK
Design Strength of fillet weld pw = 220 N/mm2 (Table 9.2a)
Weld at Flange
Leg Length s = 6 mm
Throat Size a = 0.7 s = 4.2 mm
Weld Shear Capacity per unit Length PL = pw a = 0.924 kN/mm (Clause 9.2.5.1.6 Eqn 9.4)
Weld Length L = 4B - 2t + 4T = 1055.6 mm
Weld Shear Strength Provided PL L = 975.4 kN
Primary Strut, SteelChk - Strut (Rev. D) 20190508
#N/A Job No.:
By:
ELS Design Chkd:
Primary Strut Checking Date: 8-May-19
Weld at Web
Leg Length s = 6 mm
Throat Size a = 0.7 s = 4.2 mm
Weld Shear Capacity per unit Length PL = pw a = 0.924 kN/mm (Clause 9.2.5.1.6 Eqn 9.4)
Weld Length L = 2D - 4T = 451.2 mm
Weld Shear Strength Provided PL L = 416.9 kN
Total Weld Shear Strength Provided = 975.4 + 416.9
= 1392.3 kN > V= 6.5 kN Welding Connection OK
Primary Strut, SteelChk - Strut (Rev. D) 20190508
