887-B410-03_Tow Foundation Calculations Report_Rev(-)_signed.pdf
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- Solicitation number
- W912BU-23-B-0016
About this file
This report summarizes tow foundation calculations for a floating pier barge to be used at McMurdo Station, Antarctica under solicitation number W912BU-23-B-0016 issued by the Department of the Army Corps of Engineers Engineering District Philadelphia. The report evaluates the primary and emergency tow pad eyes and supporting structure for the 328-foot barge to confirm the strength and structural integrity for the intended towing service. Calculations show the pad eyes and structure have sufficient section modulus, shear strength, bearing capacity and weld strengths to withstand the minimum breaking strength of 604,000 pounds for the selected towline. Stress levels in the pad eyes, welds and supporting transverse deck and longitudinal bulkhead structures are below the allowable limits for the 50 ksi steel material.
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NSF MCMURDO OFFLOAD INFRASTRUCTURE 9 June 2023 Tow Foundation Calculations 1 Doc. 887-B410-03, Rev -
NSF MCMURDO OFFLOAD INFRASTRUCTURE
Tow Foundation Calculations
PREPARED FOR:
Moffatt & Nichol Seattle, WA
BY:
Nate M. Seelig, PE
PROJECT ENGINEER
CHECKED:
Andrew L. Girdler, PE
NAVAL ARCHITECT
APPROVED:
Bradley G. Lamkin, PE
PRINCIPAL-IN-CHARGE
DOC. #:
887-B410-03
REV:
FILE:
22105.01
DATE:
9 June 2023
References
1. Glosten, Towing Arrangement, 887-B410-02.
2. Glosten, 887_Towing Foundations Calculations_Rev(-).xlsx.
3. Glosten, Local Scantling Calculations, 887-B399-01.
4. Glosten, Midship Section, 887-B301-01.
5. Glosten, Transverse Structure, 887-B309-01.
6. Glosten, Deck and Bottom Structure, 887-B307-01.
7. Glosten, Longitudinal Structure, 887-B311-01.
8. ABS Marine Vessel Rules, 2023.
Summary
This report presents the results of the Tow Foundation Calculations for the primary and emergency tow pad eyes and underdeck support structure for the McMurdo Barge Pier (328'×100'×18'). The vessel is to be classed ✠A1, Deck Cargo Barge by the American Bureau of Shipping (ABS).
Approach
First principles were adopted to evaluate the tow pad eyes (Reference 1) and supporting barge structure (References 4-7) assuming the towline breaking strength from the selected towline shown in Reference 1 and an allowable stress of material yield as per Reference 8, 3-2-7/4. The primary tow pad eyes were evaluated with no side load because the chocks prevent side loading in the pad eye.
The overturning moment from the primary tow pad eye resulted in a force couple reaction in way of the deck transverse at the forward end and the longitudinal bulkhead at the aft end. Section properties of the deck transverse was taken from Reference 3. The emergency tow pad eye is aligned with a longitudinal diaphragm, therefore the minimum section modulus of the pad eye and the diaphragm was used to verify structural adequacy.
Results
The calculations presented in Appendix A are from Reference 2. The calculations show that the pad eyes and their supporting structure have sufficient strength for the intended service.
NSF MCMURDO OFFLOAD INFRASTRUCTURE 9 June 2023 Tow Foundation Calculations A-1 Doc. 887-B410-03, Rev -
Appendix A Tow Pad Eye and Foundation Calculations
Primary Pad Eye Structural and Weld Calculations
References:
1. Glosten, Towing Arrangement , 887-B410-02, Rev (-), 9 June 2023
Purpose:
To verify the size of the pad eye, pad eye structure, emergency padeye and the welds used to attach to the deck.
The calculations are verified against first principles.
Summary Stress Allowable Margin ksi ksi
57.9 70.0 1.2
14.4 30.0 2.1
14.4 50.0 3.5
13.5 30.0 2.2
4.3 50.0 11.7
3.3 30.0 9.2
11.69 50.0 4.3
9.13 30.0 3.3
Pad Eye Material Material: 50 ksi Steel Pick from Dropdown u = 70 ksi y = 50 ksi yield= 30 ksi
Ω = 1.00 allow = 50.0 ksi allow= 30.0 ksi
Pad Eye & Shackle Characteristics Pad Eyes:
(See sketch below for variable definitions) Assumes that there are two doublers of the thickness defined by t_dbl h = 7 in w = 65 in tweld = 0.75 in Base weld (assumes fillet welds)
Dpin = 3.125 in tweld_dbl = 0.5625 in Doubler Pl weld (assumes fillet welds) tdbl = 0.625 in Ddbl = 10.5 in tpad = 3 in Dpad = 14 in
Total Load W = 604.0 kips towline breaking
Pad Eye Structural Properties Section Modulus of Pad Eyes
SMpad_y = 2112.5 in3 =t_pad*w 2 /6
SMpad_x = 97.5 in3 =w*t_pad 2 /6
Section Modulus of Pad Eye Base Weld
End Weld t = 0.5303 in
End Weld Width = 3 in
Side Weld t = 0.5303 in
Side Weld Length = 64.470 in
Pad Eye Base Weld Principal Stress Pad Eye Based Weld Maximum Shear Stress
Pin Axial Stress Tear Out
Shear Stress in Doubler Plate Weld
Pad Eye Principal Stress Pad Eye Maximum Shear Stress
Shear Stress to Deck
Pad Eye Strength Check
Stress Description
Pin Bearing Stress Pin Shear Tear Out
Pade Eye Weld Check
Pin Hole Related Check
NSF MCMURDO OFFLOAD INFRASTRUCTURE
Tow Foundation Calculations
A-2 9 June 2023 Doc. 887-B410-03, Rev -
Weld Characteristics:
Strong Axis
Note: Reference distance to plate - web interface.
Item Thickness Area Y A*Y A*Y^2 I
(in^2) (in) (in^3) (in^4)
End 0.53 1.59 -0.27 -0.42 0.11 0.04
Side 0.53 34.19 32.23 1101.95 35521.28 11840.43
Side 0.53 34.19 32.23 1101.95 35521.28 11840.43
End 0.53 1.59 64.73 102.98 6666.20 0.04
Totals 71.55 2306.46 77708.88 23680.93
Weld Area = 71.55 in Inertia about NA = 27041.39 in4
Center of Weld (NA) = 32.23 in SM = 825.31 in3
Weak Axis
Note: Reference distance to plate - web interface.
Y A*Y A*Y^2 I
1.500 2.386 3.5791875 1.19
-0.265 -9.063 2.4029129 0.801
3.265 111.619 364.4486 0.801
1.500 2.386 3.5791875 1.1930625
107.328 374.00989 3.988066924
Center of Weld (NA) = 1.50 in
Inertia about NA = 217.01 in4
SM = 106.89 in3
SMweld_y = 825.31 in3
SMweld_x = 106.89 in3
Aweld_y = 3.18 in2
Aweld_x = 68.93 in2
NSF MCMURDO OFFLOAD INFRASTRUCTURE
Tow Foundation Calculations
A-3 9 June 2023
Design Loads Load on Each Pad Eye
T = 604.0 kips
Components of Tension Force
Fh = 604.0 kips
Pin Bearing Stress bearing = 57.9 ksi u = 70.0 ksi
Bearing Stress < Ultimate Stress, OK
Pin Shear Tear Out tear = 14.4 ksi allow = 30.0 ksi
Tear Out Stress < Allowable Shear Stress, OK
Pin Axial Stress Tear Out tear = 14.4 ksi allow = 50.0 ksi
Tear Out Stress < Allowable Stress, OK
Shear Stress in Doubler Plate Weld dbl_pl_weld = 13.5 ksi allow = 30.0 ksi
Weld Shear Stress < Allowable Shear Stress, OK
)_2_(4 1 dbltpadtDpin
T bearing dbltDpindblDpadtDpinpadD tear
_2_ tear _2___ dblweld weldpldbl tdblD dbltDpin
707.0_
A-4 9 June 2023
Combined Stress in Pad Eyes
Pad Eye Bending Stress Load
Bx_pad = 2.0 ksi
Pad Eye Shear Stress xy1_pad= 3.1 ksi
Pad Eye Principal Stress p_pad= 4.26 ksi allow = 50.0 ksi
Principal Stress < Allowable Stress, OK
Pad Eye Maximum Shear Stress max= max= 3.26 ksi allow= 30.0 ksi
Shear Stress < Allowable Stress, OK
_ 22 padxy padypady padp ypad padBx
SM
hFh padtw
Fh padxy __1
2 padxy pady
A-5 9 June 2023
Stress in Base Weld
Pad Eye Base Weld Bending Stress
B1_base_weld= 5.12 ksi
Pad Eye Base Weld Shear Stress weld_x= 8.8 ksi
Pad Eye Base Weld Principal Stress p_pad= 11.69 ksi allow = 50.0 ksi
Principal Stress < Allowable Stress, OK
Pad Eye Based Weld Maximum Shear Stress max= max= 9.13 ksi allow= 30.0 ksi
Shear Stress < Allowable Stress, OK yweld weldbaseB SM hFh
__1 xweld xweld A
Fh
_ 22 totalweld weldbaseweldbase weldp
A-6 9 June 2023
Primary Pad Eye Foundation Calculations
Assumptions:
1. Force applied to the padeye is turned into a force couple
2. Load is min breaking strength of towline
3. The section modulous of the frame is taken from the Local Scantling Calculations
Actual Allowable Margin psi psi
27,610 50,000 1.81
5,703 30,000 5.26
43,364 50,000 1.15
43,364 50,000 1.15
Loads
Towline Breaking Strength, P= 604000 lbs
Pin Hieght off Deck, h= 7 in
Moment from Applied load above deck, MO= 4228000 lbs‐in couple arm 65 in
Force couple Magnitude (W) 65046 lbs
Analyzing the frame for under pad eye
Simply Supported
W= 65046 lbs
Length of frame, L= 160 in distence from BHD to end of Padeye on frame, a= 32 in distence from padeye to other end of frame, b= 128 in
Location of interest, x= 32 in
Reaction at Bulkhead, Ra= 52037 lbs `=W/L*(L‐a)
Reaction at other end of Frame, Rb= 13009 lbs `=W*a/L
Max Moment, Mmax= 1665181.5 lb‐in
Beam Requirements
Section Moduous Required, SM_req= 33.30 in3 `=Mmax/σallowable σallowable= 50000 σactual= 27610 psi `=Mmax/SM
Shear Check
Shear Area of Frame, Afr= 9.125 τallowable= 30000.00 psi τactual= 5702.68 `=Ra/Afr
Bearing Stress σBearingAllow= 50000 psi σBearingActual= 43364 psi `=W/(3*0.5)
BHD Area check.
Stress in tension on bhd σallowable= 50000.0 psi σtension= 43,364.10 psi `=W/(4*0.375)
Summary
Description
Frame Section Modulous
Frame Shear Stress
Bearing Stress of Material at Frame
Bulkhead Tension Stress
NSF MCMURDO OFFLOAD INFRASTRUCTURE
Tow Foundation Calculations
A-7 9 June 2023
Emergency Pad Eye Structural and Weld Calculations
Assumptions
1. the pad eye section modulous is greater than the under deck structure.
2. the under deck structure is used for determining the pad eye feasability Summary
Stress Allowable Margin ksi ksi
57.9 70.0 1.2
14.4 30.0 2.1
14.4 50.0 3.5
13.5 30.0 2.2
20.3 50.0 2.5
10.6 30.0 2.8
16.79 50.0 3.0
12.42 30.0 2.4
Pad Eye Material Material: 50 ksi Steel u = 70 ksi y = 50 ksi yield= 30 ksi
Ω = 1.00 allow = 50.0 ksi allow= 30.0 ksi
Pad Eye & Shackle Characteristics Pad Eyes:
(See sketch below for variable definitions) Assumes that there are two doublers of the thickness defined by t_dbl h = 7 in w = 49 in tweld = 0.75 in Base weld (assumes fillet welds)
Dpin = 3.125 in tweld_dbl = 0.5625 in Doubler Pl weld (assumes fillet welds) tdbl = 0.625 in Ddbl = 10.5 in tpad = 3 in Dpad = 14 in
Total Load W = 604.0 kips towline breaking
Pad Eye Structural Properties Section Modulus of Pad Eyes
SMpad_y = 1200.5 in3 =t_pad*w 2 /6
Section Modulus of Bulkhead Strong Axis Note: Reference distance to plate - web interface.
Item Base Height Centroid Area A*Y A*Y^2 I Y (in^2) (in^3) (in^4)
Flange 3.00 0.5 -0.25 1.50 -0.38 0.09 0.03 Web 0.38 48 24 18.00 432.00 10368.00 3456.00
Flange 3.00 0.5 48.25 1.50 72.38 3492.09 0.03 Totals 21.00 504.00 13860.19 3456.06
Area = 21.00 in Inertia about NA = 5220.25 in4
Center of Shape (NA) = 24.00 in SMBHD = 217.51 in3
Pin Shear Tear Out Pin Bearing Stress
Stress Description
Pad Eye Based Weld Maximum Shear Stress Pad Eye Base Weld Principal Stress
Bulkhead Maximum Shear Stress Bulkhead Principal Stress Bulkhead Strength Check
Pad Eye Weld Check
Shear Stress to Deck Shear Stress in Doubler Plate Weld
Pin Axial Stress Tear Out
Pin Hole Related Check
NSF MCMURDO OFFLOAD INFRASTRUCTURE
Tow Foundation Calculations
A-8 9 June 2023
Section Modulous Compare SMBHD= 217.51 in3
SMpad_y = 1200.5 in3
The Bulkhead section under the pad eye has a lower section modulous than the pad eye itself The bulkhead will be used to verify the feasability of the structure.
Section Modulus of Pad Eye Base Weld
Weld Characteristics:
End Weld t = 0.5303 in
End Weld Width = 3 in Side Weld t = 0.5303 in
Side Weld Length = 48.470 in
Strong Axis Note: Reference distance to plate - web interface.
Item Thickness Area Y A*Y A*Y^2 I (in^2) (in) (in^3) (in^4)
End 0.53 1.59 -0.27 -0.42 0.11 0.04 Side 0.53 25.70 24.23 622.86 15095.00 5031.67 Side 0.53 25.70 24.23 622.86 15095.00 5031.67 End 0.53 1.59 48.73 77.53 3778.17 0.04
Totals 54.58 1322.83 33968.28 10063.41
Weld Area = 54.58 in Inertia about NA = 11973.10 in4
Center of Weld (NA) = 24.23 in SM = 483.47 in3
SMweld_y = 483.47 in3
SMweld_x = 80.65 in3
Aweld_y = 3.18 in2
Aweld_x = 51.96 in2
NSF MCMURDO OFFLOAD INFRASTRUCTURE
Tow Foundation Calculations
A-9 9 June 2023
Design Loads Load on Each Pad Eye
T = 604.0 kips
Pin Bearing Stress bearing = 57.9 ksi u = 70.0 ksi
Bearing Stress < Ultimate Stress, OK
Pin Shear Tear Out tear = 14.4 ksi allow = 30.0 ksi
Tear Out Stress < Allowable Shear Stress, OK
Pin Axial Stress Tear Out tear = 14.4 ksi allow = 50.0 ksi
Tear Out Stress < Allowable Stress, OK
Shear Stress in Doubler Plate Weld dbl_pl_weld = 13.5 ksi allow = 30.0 ksi
Weld Shear Stress < Allowable Shear Stress, OK
)_2_(4 1 dbltpadtDpin tear
_2_ tear _2___ dblweld weldpldbl tdblD dbltDpin
707.0_
A-10 9 June 2023
Combined Stress in Pad Eye(taken at the Bulkhead under deck) Bulkhead Bending Stress Loads
Bx_pad = 3.5 ksi σBHD= 19.4 ksi
Bulkhead Shear Stress xy1_pad= 4.1 ksi
Bulkhead Principal Stress p_pad= 20.27 ksi allow = 50.0 ksi
Principal Stress < Allowable Stress, OK
Bulkhead Maximum Shear Stress max= max= 10.55 ksi allow= 30.0 ksi
Shear Stress < Allowable Stress, OK
_ 22 padxy padypady padp ypad padBx SM hFh padtw
Fh padxy __1
A-11 9 June 2023
Stress in Base Weld
Pad Eye Base Weld Bending Stress
B1_base_weld= 8.75 ksi
Pad Eye Base Weld Shear Stress weld_x= 11.6 ksi
Pad Eye Base Weld Principal Stress p_pad= 16.79 ksi allow = 50.0 ksi
Principal Stress < Allowable Stress, OK
Pad Eye Based Weld Maximum Shear Stress max= max= 12.42 ksi allow= 30.0 ksi
Shear Stress < Allowable Stress, OK yweld weldbaseB SM hFh
__1 xweld xweld A
Fh
_ 22 totalweld weldbaseweldbase weldp
A-12 9 June 2023
| 887-B410-03_Tow Foundation Calculations Report_Rev(-) |
| 887_Towing Foundations Calculations_Rev(-) |
| 2023-06-09T14:08:13-0400 | |
| Nate Seelig |
File details come from the government source that posted it. Updated .