887-B399-02_Shore Bridge Support Calculations_Rev(-)_signed.pdf

NSF McMurdo Offload Infrastructure 9 June 2023 Shore Bridge Support Calculations 1 Doc. 887-B399-02, Rev -

NSF MCMURDO OFFLOAD INFRASTRUCTURE

Shore Bridge Support Calculations

PREPARED FOR:

Moffatt & Nichol Seattle, WA

BY:

Jamie S. Demers

NAVAL ARCHITECT

CHECKED:

Andrew L. Girdler, PE

SENIOR NAVAL ARCHITECT

APPROVED:

Stephen D. White, PE

PRINCIPAL-IN-CHARGE

DOC. #:

887-B399-02

REV:

FILE:

22105.01

DATE:

9 June 2023

References

1. US Army Corps of Engineers, Scope of Work 3438 NSF McMurdo Station Offload Infrastructure Project Contract Level Design and Specification, MDC Project 3438, W912EE-21-D-0005, Tracking Number 0001.

2. ABS Steel Barge Rules, 2023.

3. ABS Marine Vessel Rules, 2023.

4. AASHTO, LRFD Bridge Design Specifications, 6th Edition, 2012.

5. Glosten, Deck and Bottom Structure, 887-B307-01.

6. Glosten, Side Plating, 887-B307-02.

7. Glosten, Shore Bridge Support, 887-B330-01.

8. LinkBelt, TCC1400 Technical Data, 5861-0522-T3, 2022.

9. Moffatt & Nichol, Design Calculations for Bridges and Abutments, 212288/99, Rev 0, 21 April 2023.

10. Siemens, Simcenter Femap with Nastran, Version 2301, 2023

11. Moffatt & Nichol, 65% Bridge Plans, Drawing No. 887-B355-04, Rev. P0, 21 April 2023.

12. Clausen, E., Moffatt & Nichol, email to A. Girdler, Glosten, “McMurdo Bearing Capacity”, 24 May 2023

13. Clausen, E., Moffatt & Nichol, email to A. Girdler, Glosten, “RE: McMurdo Barge Deflections”, 2 June 2023

14. Glosten, 887_Corbel Calcs_Rev(-).xlsx

Summary

The United States Army Corps of Engineers (USACE) is supporting the US National Science Foundation (NSF) to develop a contract level design for the permanent offload infrastructure to support resupply operations at McMurdo Station, Antarctica (Ref. 1). This report presents the results of the structural scantling calculations and finite element analysis for the shore bridge support component of the proposed infrastructure.

Steel Barge requirements from the American Bureau of Shipping (ABS, Ref. 2) and Guidance on Finite Element Analysis in the Marine Vessel Rules (Ref. 3) govern the size and arrangement of scantlings on the barge. The calculations (Ref. 14) and analyses herein show that the proposed

Shore Bridge Support Calculations 2 Doc. 887-B399-02, Rev -scantlings of the shore bridge support, hereby referred to as the corbel, satisfy the ABS Steel Barge and Marine Vessel Rules.

Finite Element Analysis

A finite element analysis (FEA) of the corbel structure was performed to verify that the corbel structure can withstand the loads from the bearings and the pin and safely transfer those loads into the barge side shell structure.

Modeling Principles

The corbel finite element model (FEM) was constructed using Simcenter Femap with Nastran (Ref. 10). All structure was modeled with plate elements. These plate elements mainly consist of quad elements. A small number of tri elements were used to represent plate where necessary in areas of structural transition. Plate elements have stiffness in and out of plane. The model is meshed with 2” elements.

Model Geometry

The corbel extends six feet outboard of the barge side shell. Reference 7 details the structural design of the corbel. In addition to the corbel structure itself, the barge vertical side shell (Ref. 6) was modelled to verify that no additional side shell structure was required in way of the corbel.

Figure 1 shows the extents of the FEM with 1/2" plate elements shown in blue and 1" plate elements shown in red. Figure 2 shows the corbel portion in way of the bridge bearings with the top deck and bottom closure plate removed. This reveals the underdeck structure consisting of transverse webs spanning the depth of the corbel, longitudinal flat bar stiffeners, transverse flat bar stiffeners in way of the bearing footprints, and the pin socket and supporting stiffeners.

Figure 1 Corbel finite element model with 1/2" plate shown in blue and 1" plate shown in red

Shore Bridge Support Calculations 3 Doc. 887-B399-02, Rev -

Figure 2 Corbel finite element model with top deck and bottom closure plate hidden and 1/2" plate shown in blue

Material Properties

The corbel is constructed of EH36 steel. Table 1 provides details of the material properties assigned in the model.

Table 1 Material properties of EH36 steel

Property Value Units Yield Strength 51 ksi Ultimate Strength 71 ksi Elastic Modulus 29,000 ksi Poisson's Ratio 0.32 --- Density 0.28 lbm/in3

Loading Conditions

The total weight supported by the corbel is comprised of the weight of a LinkBelt TCC-1400 crane (Ref. 8), the largest vehicle expected to be using the bridge, and half of the bridge dead load, assuming a timber covering (Ref. 9). This is combined with a Multiple Presence Factor of

1.2 on the crane weight to arrive at the 379.96 kips design force (Ref. 4 §3.6.1.1.2). The footprint area of the bridge bearings was calculated to be 186.5 in2 using the drawings supplied by Moffatt & Nichol (Ref. 11). The symmetric design pressure per bearing of 510 psi assumes that the design force will be equally distributed between the four bearings.

An asymmetric set of design pressures was developed to model the loads on the bearings in the case that the crane is on the edge of the bridge. Figure 3 shows the distribution of bridge and

Shore Bridge Support Calculations 4 Doc. 887-B399-02, Rev -vehicle loads resulting in the resultant loads on each bearing. This asymmetric loading results in a maximum bearing pressure of 858 psi.

Figure 3 Distribution of bridge and vehicle loads resulting in an asymmetric loading of bearings

The bridge bearings impart the pressure loading into the corbel much like a wheel, so the ABS Steel Barge Vehicle Loading rule (Ref. 2) was applied to calculate the minimum thickness of the corbel deck in way of the bearings. For the purposes of this calculation, the maximum bearing capacity per Moffatt & Nichol (Ref. 12) was used. The bearings footprints are circles, while the wheel load calculation assumes a rectangular imprint. In this case, a square imprint with sides equaling the bearing footprint diameter (15.4") is used. This results in a required deck thickness of 0.72". The corbel deck thickness in way of the bridge bearings was selected to be 1".

A pin lined with fenders rests in a recess in the corbel deck to resist horizontal motions. The barge is permanently moored using mooring struts connected to the shore. Additionally, the shore side end of the bridge is free to move horizontally within a certain boundary. Therefore, the pin is assumed to take 60% of the bridge transverse loads and 100% of the bridge longitudinal forces due to potential varying conditions such as snow.

A combination and forces and pressures were used to apply the loads described above to the corbel FEM. For the bearing symmetric load, a uniform pressure of 510 psi was applied downward to elements on the corbel deck plate located in way of the bearing footprints (Ref. 11).

For the bearing asymmetric load, separate pressures were applied to elements on the corbel deck plate located in way of the separate bearing footprints as shown in Table 2. For the pin load, nodal forces are applied to sum to the transverse and longitudinal forces shown in Table 2.

Appendix A also shows the calculation of the total design force supported by the corbel and the calculation of minimum deck plate thickness due to wheel loads.

Shore Bridge Support Calculations 5 Doc. 887-B399-02, Rev -

Table 2 Summary of loads applied to corbel FEM where fwd/aft is from barge reference and transverse/longitudinal is from bridge reference

Load Case Aft Bearing Pressure (psi)

Center-Aft Bearing Pressure (psi)

Center-Fwd Bearing Pressure (psi)

Fwd Bearing Pressure (psi)

Pin Transverse Load (kip)

Pin Longitudinal Load (kip)

1 510 510 510 510 20 123

2 510 510 510 510 28 106

3 510 510 510 510 40 108

4 510 510 510 510 117 34

5 858 643 402 134 20 123

6 858 643 402 134 28 106

7 858 643 402 134 40 108

8 858 643 402 134 117 34

Figure 4 shows the load vectors as they are applied to the FEM and Figure 5 shows the resultant forces due to the loads with the winter maximum transverse force load case. Note that the bearing force slightly exceeds the design load due to the approximation of a circular bearing footprint using quad elements.

Figure 4 Loads applied to corbel finite element model with bearing pressure loads shown in yellow and sample pin lateral force shown in orange, looking directly inboard with outboard closure plate and longitudinal stiffeners hidden

Shore Bridge Support Calculations 6 Doc. 887-B399-02, Rev -

Figure 5 Free body diagram of loads applied in Figure 3 in pounds

Boundary Conditions

The corbel FEM includes the barge vertical side shell plating. This side shell plating is constrained using pinned connections along the transverse frames every 16 inches, where the shell meets the main deck above, and where the vertical side shell meets the angled side shell below (Ref. 5). Figure 6 shows the constraints applied to the corbel FEM, where T stands for translation, as in those areas are fixed in translation.

Shore Bridge Support Calculations 7 Doc. 887-B399-02, Rev -

Figure 6 Constraints applied to corbel finite element model with surfaces transparent to see underdeck structure

Von Mises Stress

Allowable von Mises stress level was determined in accordance with the ABS MVR 3-2-20/9.1 (Ref. 3). Allowable stress is determined by the formula 𝑐 𝑆 𝑓 , where 𝑐 0.78 for a static stress limit with the selected mesh size and stiffener spacing. The strength reduction factor 𝑆 was determined to be 0.908 for HT 36 steel. Thus, the allowable von Mises stress is 36.12 ksi (Appendix B).

Results

A linear static analysis of the corbel FEM was performed with the loads and boundary conditions described above. The maximum stress resulting from the FEA is 31,963 psi, showing that the corbel structure and connection to the barge can withstand the design load. Figure 7 shows a contour plot of the FEA results showing the maximum stress resulting from the winter maximum transverse pin load and asymmetric bearing load. The color legend uses the maximum allowable stress as the upper bound. Figure 8 shows a contour plot of the FEA from the same load case but with the corbel top deck and bottom closure plate hidden. This shows that the maximum stress in the underdeck structure is 27,348 psi.

Shore Bridge Support Calculations 8 Doc. 887-B399-02, Rev -

Figure 7 Von Mises stress contour plot due to worst case load

Figure 8 Von Mises stress contour plot due to worst case load with deck plates hidden to show underdeck structure

Conclusions

The maximum stress within the model utilizing net scantlings shows that the design passes the requirements of MVR Part 3-2-20/9.1 for allowable stress (Ref. 3).

Shore Bridge Support Calculations A-1 Doc. 887-B399-02, Rev -

Appendix A Calculation of Loads

Corbel Structure Calculation File 22105

Date 6/7/2023

By: JSD

Checked ALG

Total Weight Load

Bridge weight Wbridge = 200 kip Reference 9

Crane weight Wcrane = 233.3 kip Reference 8, Page 11

Multiple Presence Factor m = 1.2 Reference 4 AASHTO 3.6.1.1.2, single lane

Design Force P = 379.96 kip

Footprint Area of Bearing A = 186.49 in² Reference 11

Pressure per Bearing, Symmetric Loading Pbearing = 509.36 psi

Aftmost Bearing Assym Force J = 160.00 kip Bridge + 50% of crane load, 80% of bearing capacity

Aft Center Bearing Assym Force H = 120.00 kip Bridge + 33% of crane load

Fwd Center Bearing Assym Force G = 75.00 kip Bridge + 17% of crane load

Fwdmost Bearing Assym Force F = 25.00 kip Bridge Dead Weight Only

Aftmost Bearing Assym Pressure PJ = 857.95 psi

Aft Center Bearing Assym Pressure PH = 643.47 psi

Fwd Center Bearing Assym Pressure PG = 402.17 psi

Fwdmost Bearing Assym Pressure PF = 134.06 psi

Wheel Load Calculation

ABS Steel Barges 2023, [3-2-3] 17, Vehicle Loading, Reference 2

K = 0.072 n = 1.000 = 1.0 where l/s >= 2.0 and 0.85 where l/s= 1, interpolate b/w values

C = 1.10 = For Operating in Port

Wheel Load W = 89.29 LT Bearing capacity, Reference 12 a = 15.41 in Reference 11 b = 15.41 in Reference 11

FB spacing s = 10.395 in length of the pl panel l = 21.76 in l / s ratio l/s= 2.093 a / s ratio a/s= 1.482 b / s ratio b/s= 1.482 treq'd = 0.72 in toffered = 1 in

PASS: Margin = 1.4

Pin Lateral Loads

FL = 123 kip Reference 13

FT = 20 kip Reference 13

FL = 106 kip Reference 13

FT = 28 kip Reference 13

FL = 108 kip Reference 13

FT = 40 kip Reference 13

FL = 34 kip Reference 13

FT = 117 kip Reference 13

Winter Max Long'l Force

Winter Max Trans Force

= wheel imprint || to longer edge of pl panel

= wheel imprint to longer edge of pl panel

= [21.99 + 0.316(a/s)2 – 5.328(a/s) + 2.6(a/s)(b/s) – 0.895(b/s)2

– 7.624(b/s)]10−2

Summer Max Long'l Force

Summer Max Trans Force

= P / 4 / A · 1000

= l / s

= a / s

= b / s

= Kn(CW)

= Wbridge / 2 + mWcrane

= 1000J / A

= 1000H / A

= 1000G / A

= 1000F / A

NSF McMurdo Offload Infrastructure Shore Bridge Support Calculations

A-2 9 June 2023 Doc. 887-B399-02, Rev -

Shore Bridge Support Calculations B-1 Doc. 887-B399-02, Rev -

Appendix B Calculation of Allowable Stress

Corbel Structure Calculation File 22105

Date 6/7/2023

By: JSD

Checked ALG

Mesh Size = 2 in

Stiff Spacing = 16 in

Ratio = 0.125

Minimum Yield Strength = 51,000 psi Reference 3

Sm = 0.908 Reference 3

Static Stress Limit EH36 = 36,120 psi Reference 3

Max VM stress EH36 = 31,963 psi

PASS: Margin = 1.1

NSF McMurdo Offload Infrastructure Shore Bridge Support Calculations

B-2 9 June 2023 Doc. 887-B399-02, Rev -jsd Rectangle