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LIFT LUG CALCULATION

DATA:

Vessel erection weight (lb) W = 38,025

Lift lug hole to tail lug hole (in) L1 = 759.00

COG to tail lug hole (in) L2 = 382.00Lift lug hole to COG (in) L3 = 377.00

Tail lug hole to vessel Axis L4 = 32

Impact factor (eg. 1.25, 1.50, 1.75, 2.0 etc.) for Lug Eye IF1 = 1.80

 

Tensile strength of lug material (psi) TSL = 70,000

Yield strength of lug material (psi) YSL = 38,000

Yield strength of shell material (psi) YSS = 38,000

Consumable Tensil Strength (psi) CST 70,000

Lug hole diameter (in) Dh = 1.750

Tearout radius (in) r = 4.000

Distance, center of lug hole to top of weld (in) L8 = 13.100

Distance, top of weld to bottom of lug (in) L9 = 6.750Length of inner welds (in) L10 = 0.000

Width of lift lug (in) B = 9.000

Width of inner weld (in) B2 = 0.000

Thickness of lift lug (in) TL = 1.250

Thickness of lug reinforcement washers (in) Tw = 0.000 OK

Fillet weld leg size, lug-to-shell (in) Lw = 0.375

Fillet weld leg size req'd, reinf. washer-lug =2Tw/3 (in) Lr = 0.000

 Actual fillet weld leg size, washer-lug (in) Lp = 0.000 OK

Washer OD = 2(r - LP -.125) (in) Dw = 7.750

CALCULATE DESIGN LOAD @ EACH LUG (VERTICAL):

Design load @ lug = W/2 x IF1 (lb) Fv = 34,223Shackle rating (tons) Crosby G2130 = 17 OK

Shackle pin diameter (in) Dp = 1.630

CALCULATE DESIGN LOAD @ EACH LUG (HORIZONTAL):

Force @ lug in horiz position = W/2*L2/L1 (lb) fh = 9,569

Design load @ shell = fh x IF1 (lb) Fh = 17,224

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CALCULATE BENDING AND AXIAL STRESS IN LUG BODY:

Ft = ( W * L3 * COS(φ) ) / ( L1 * COS(φ) + L4 * SIN(φ) )

Fl = (W - Ft)/2 - Load per Lug with out impact Factor 

 Axial Stress Sa = FL / (TL * B) where FL = Fl * IF1 * SIN(φ)

Bending Stress Sb = (6 * FR * L8) / (TL * B2) where FR = Fl * IF1 * COS(φ)

Lift Angle Fl FL FR Sb Sa Sc

(deg) (Lbs) (Lbs) (Lbs) (psi) (psi) (psi)

0 9,569 0 17,224 13,371 0 13,371 

5 9,604 1,507 17,221 13,368 134 13,502 

10 9,639 3,013 17,086 13,264 268 13,531 

15 9,674 4,507 16,820 13,058 401 13,458 

20 9,712 5,979 16,427 12,752 531 13,283 

25 9,751 7,418 15,907 12,349 659 13,008 

30 9,793 8,814 15,266 11,851 783 12,635 35 9,840 10,159 14,508 11,263 903 12,166 

40 9,892 11,445 13,639 10,588 1,017 11,605 

45 9,951 12,665 12,665 9,832 1,126 10,958 

50 10,021 13,817 11,594 9,000 1,228 10,229 

55 10,105 14,900 10,433 8,099 1,324 9,424 

60 10,212 15,918 9,190 7,134 1,415 8,549 

65 10,352 16,888 7,875 6,113 1,501 7,614 

70 10,549 17,843 6,494 5,042 1,586 6,628 

75 10,853 18,869 5,056 3,925 1,677 5,602 

80 11,391 20,193 3,561 2,764 1,795 4,559 

85 12,640 22,665 1,983 1,539 2,015 3,554 

90 19,013 34,223 0 0 3,042 3,042 

Maximum Bending Stress = 13,371 psi

Maximum Axial Stress = 3,042 psi

Maximum Combined Stress = 13,531 psi

 Allowable stress = 0.6*YSL = Sa = 22,800 Okay

CALCULATE SHEAR STRESS IN LUG BODY (HORIZONTAL):

Shear stress = Fh/(2TL*r) (psi) Ss = 1,722  

 Allowable shear stress = 0.5Sa (psi) Ssa = 11,400 OK

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CALCULATE STRESSES IN LUG-TO-SHELL WELDS:

 

Weld throat = 0.7071 x Lw (in) tw = 0.27

Locate N.A. of weld group:

(L9 + L10 + B2*L10)/(B + 2L9 + 2L10) (in) = X = 2.03

Distance to extreme weld point C:

SQRT((L9 - X) +(B/2) )) (in) = Y = 6.53

Eccentricity of weld group = L9+L8-X (in) E = 17.83

Polar moment of intertia (PMI) of weld group:

r1 = (.5L9 - X) + (.5B) (in ) r1 = 22.1

PMI of L9 welds = 2L9*tw*(L9 /12 + r1 ) (in ) J1 = 93

r2 = (.5L10 - X) + (.5B2) (in ) r2 = 4.1

PMI of L10 welds = 2L10*tw*(L10 /12 + r2 ) (in ) J2 = 0.0

B1 = .5(B - B2) (in) B1 = 5

r3 = (.5B1 + .5B2) + X (in ) r3 = 9.2

PMI of B1 welds = 2B1*tw*(B1 /12 + r3 ) (in ) J3 = 26

r4 = |(L10 - X) | (in ) r4 = 4.1

PMI of B2 weld = B2*tw*(B2 + r4 ) (in ) J4 = 0.0

Polar moment of inertia = J1+J2+J3+J4 (in ) J = 118

Torsional shear stress = Fh1 x E x Y/J (psi) St = 16,906

 Angle of rotation for St = arctan (.5B/(L9-X) (rad) ø = 0.761

Horizontal component of St1 = St*sinø (psi) St1 = 11,659

Vertical component of St2 = St*cosø (psi) St2 = 12,242

Direct shear stress due to Fh1 = Fh1/(tw(B + 2L9 + 2L10)) (psi) Ssh = 2,887

 Allow. shear stress = 0.3CST per AISC 9th Edition = 21,000 OK

Max. shear stress (torsional + direct) - horizontal @ point C:((Ssh

+St2) + St1 )

.(psi) Sm = 19,100

 Allow. shear stress = 0.3*CST per AISC 9th Edition = 21,000 OK

Direct shear stress (vert) = Fv/(tw(B + 2L9 + 2L10)) (psi) Ssv = 5,736

 Allow. shear stress = 0.3*CST - per AISC 9th Edition = 21,000 OK

Check weld size based on leg welded to shell or Lift Lug

Torsional shear stress Sts = St*tw/lw (psi) Sts = 11,954

 Angle of rotation for Sts = arctan (.5B/(L9-X) (rad) ø = 0.761

Horizontal component of Sts1 = Sts*sinø (psi) Sts1 = 8,244

Vertical component of Sts2 = Sts*cosø (psi) Sts2 = 2,041

Weld Area based on weld Leg = Lw*(2*L9 + 2*L10 + B) in^2 = Warea = 8.4

Direct Shear stress (vert) = Fv/Warea = Ssv1 = 4,056

 Allowable = .3*YSL or 0.3*YSS (smaller) = 11,400

Safety Factor = YSS*IF1/Ssv1 per ANSI B30.20 Safety Factor = 17

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Direct shear stress due to Fh1 = Fh1/(Lw(B + 2L9 + 2L10)) (psi) Ssh1 = 2,041

 Allow shear stress = 0.3*YSL or 0.3*YSS = 11,400

Safety Factor = (YSS * IF1)/Ssh1 per ANSI B30.20 Safety Factor = 34

Max. shear stress (torsional + direct) - horizontal @ point C:

((Ssh1 + Sts2)) + (Sts1)̂ 2) . (psi) = 13,506

 Allow Shear Stress = 0.4*YSL or 0.4*YSS = 15,200

Safety Factor = (YSS * IF1)/(Max shear stress compared to yield) = 5.1

per ANSI B30.20

CALCULATE STRESSES IN LUG (Curved beam analysis):

Minimum radius of lug = 1.5 x hole dia. (in) rmin = 2.625

 Actual radius (in) r = 4.000 OK

H1 = r - Dh/2 (in) H1 = 3.125

H2 = 0.5(Dw - Dh) (in) H2 = 3.000

C = H1/2 (in) C = 1.563

R = (H1 + Dh)/2 (in) R = 2.438

z = -1 + (R/H1) x LN ((R + C)/(R-C)) z = 0.18546409

Moment = 0.5Fv x R(2/((π x (1+z)) -1) (in.lb.) MA = -19,310

Calculate stress A @ Y = -H1/2 (in) Y = -1.563

SA*A = Fv/2 + MA/R(1+Y/(z(R+Y))) ((lbf) SA*A = 85,466

Min section area = SA*A/Sa (in )  Amin = 3.75

Required washer thickness = 0.5(Amin-(TL x H1))/H2 (in) Twr = -0.026

 Actual washer thickness (in) Tw = 0.000 OK

Stress A = SA*A/(TL x H1 + 2Tw x H2) (psi) SA = 21,879

 Allowable stress (psi) Sa = 22,800 OK

Safety Factor compared to yield per ANSI B30.20 = YSL*IF1/SA Safety Factor = 3.13

Calculate stress B @ Y = -H/2 (in) Y = -1.563

Stress B = | (MA+.5Fv*R)/((TL*H1+2Tw*H2)*R) * (1+(Y/(z(R+Y)))) | (psi) SB = 20,297

 Allowable stress (psi) Sa = 22,800 OK

Safety Factor compared to yield per ANSI B30.20 = YSL*IF1/SB 3.4

Combined section thickness = TL + 2Tw (in) Tc = 1.25

Tearout stress = Fv/(2H2 x Tc) (psi) ST = 4,563

 Allowable Tearout stress (psi) = Sa/2 Sta = 11,400 OK

Bearing stress = Fv/(Tc*Dp) (psi) Sbr = 16,796

 Allowable bearing stress = 0.85YSL (psi) Sba = 32,300 OK

CALCULATE STRESSES IN REINFORCEMENT WASHER FILLET WELDS:

Load on washer = Tw/Tc x Fv (lb) Fw = 0

Shear stress = Fw/(Dw x ¶ x Lp) (psi) Ssw = #DIV/0!

 Allowable shear stress = Sa/2 (psi) = 11,400 #DIV/0!

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SUMMARY OF STRESSES

LOCATION DESCRIPTION CALC'D ALLOWABLE

Lug body Bending stress (psi) (horiz.) 13,371 22,800 OK

 Axial Stress (psi) (vert.) 3,042 22,800 OK

Combined Bending and Axial Stress (psi) 13,531 22,800 OK

Shear stress (psi) (horiz) 1,722 11,400 OK

Lug-shell welds Direct shear (horiz) (psi) 2,887 21,000 OK

Maximum shear (horiz) (psi) 19,100 21,000 OK

Direct shear (vert) (psi) 5,736 21,000 OK

Lug Circ stress SA (psi) 21,879 22,800 OK

Circ stress SB (psi) 20,297 22,800 OK

Tearout stress (psi) 4,563 11,400 OK

Bearing stress (psi) 16,796 32,300 OK

Washer filletwelds Shear stress (psi) #DIV/0! 11,400 #DIV/0!

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