887-B399-04_Miscellaneous Foundation Calculations Report_Rev(-)_signed.pdf

NSF MCMURDO OFFLOAD INFRASTRUCTURE 9 June 2023 Miscellaneous Foundation Calculations 1 Doc. 887-B399-04, Rev -

NSF MCMURDO OFFLOAD INFRASTRUCTURE

Miscellaneous Foundation Calculations

PREPARED FOR:

Moffatt & Nichol

Seattle, WA

BY:

Calder J. Hartigan

PROJECT ENGINEER

CHECKED:

Andrew L. Girdler, PE

NAVAL ARCHITECT

APPROVED:

Stephen D. White, PE

PRINCIPAL-IN-CHARGE

DOC. #:

887-B399-04

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. Glosten, Fendering, 887-B410-01.

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

4. ABS Marine Vessel Rules, 2023.

5. Dassault Systemes, SOLIDWORKS, SP5.0, 2022.

6. ShibataFenderTeam, Product Catalog, August 2021.

7. Glosten, Mooring Design Report, 887-B175-01.

8. Glosten, Shore Bridge Support Calculations, 887-B399-02.

Revision History

Rev Description Date Appd

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 (Reference 1). This report presents the results of the finite element analysis (FEA) of the interface of the topsides frames with the fender foundations (Reference 2) and shore bridge support, referred to as the corbel (Reference

3).

Guidance on Finite Element Analysis in the Marine Vessel Rules (Reference 5) govern the criteria of the FEA. The calculations and analyses herein show that the topside frame with the proposed foundations satisfy the ABS Steel Barge and Marine Vessel Rules.

Fender Foundations Finite Element Analysis

Modeling Principles

The topsides frame finite element model (FEM) was constructed using SOLIDWORKS

Simulation (Reference 5). One side frame with integrated clip, one ice frame, and associated

Miscellaneous Foundation Calculations 2 Doc. 887-B399-04, Rev -effective topsides plating were included. All structure was modeled using shell elements constructed of tri elements.

Foundation Model Geometry

The fender foundation is designed based on the characteristics of the nominal

ShibataFenderTeam SPC 900 cone fender, which meets the required fender characteristics described by Reference 2. The fender foundation is shown by the green surfaces in Figure 1 and detailed by Reference 2. For each fender, a 3’-6”-diameter, 1/2” thick rolled plate pedestal supports the cone fender and intersects two side frames and one transverse bulkhead at six locations.

Figure 1 Fender foundation (green)

The topsides frame surfaces were split at the points at which the fender foundation would intersect the topsides frame to allow the fender mooring forces to be applied at those intersections. Figure 2 shows the extents of the FEM with 1” plate elements shown in light blue and 1/2” plate elements shown in dark blue.

Miscellaneous Foundation Calculations 3 Doc. 887-B399-04, Rev -

Figure 2 Topsides frame FEM for fender foundation analysis, 1” plate shown in light blue and 1/2” plate shown in dark blue

Material Properties

The topsides plate is constructed of EH36 steel, while the ice frames, topsides frames, and fender foundation are constructed of AH36 steel. The material properties of ASTM A36 steel were used for conservatism. Table 1 provides details of the material properties assigned in the model.

Table 1 Material properties of H36 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

A maximum mooring force supported by the fender foundation of 157.4 kip (700 kN) was used based on the reaction force of the ShibataFenderTeam SPC 900 for the hardest rubber grade described in Reference 6. This mooring force is greater than the maximum mooring force identified by Reference 7. The total reaction force was assumed to be distributed evenly between the six intersections between the fender foundation and the side frames and bulkhead. Therefore, two 26.2-kip forces were applied to 4 ½” long sections of the side frame at the points shown in

Figure 3.

Miscellaneous Foundation Calculations 4 Doc. 887-B399-04, Rev -

Figure 3 Fender loads applied to topsides frame finite element model

Boundary Conditions

The inboard end of the clip and the bottom edge of the ice frame were fixed in all degrees of freedom. The top and bottom edges of the topsides plate and the top of the clip were fixed only in transverse and longitudinal motion. Figure 4 shows fixed geometry with green constraints and geometry fixed in transverse and longitudinal motion with blue constraints.

Figure 4 Topsides frame finite element model constraints for fender foundation FEA

Miscellaneous Foundation Calculations 5 Doc. 887-B399-04, Rev -

Allowable Stresses

The allowable von Mises stress level was determined in accordance with the ABS MVR 3-2-

20/9.1 (Reference 1). Allowable stress is determined by the formula 𝑐𝑓𝑆𝑚𝑓𝑦, where 𝑐𝑓 = 0.82 for a static stress limit with the selected mesh size and stiffener spacing. The strength reduction factor 𝑆𝑚 was determined to be 0.908 for HT 36 steel. Thus, the allowable von Mises stress is

37.97 ksi (Appendix A).

Results

Stresses in topsides frame

A linear static analysis of the topsides frame FEM was performed with the loads and boundary conditions described above. The von Mises stresses in the side frame are shown in Figure 5. The greatest stress is approximately 15.3 ksi, showing that the topsides frame structure can withstand the design fender load as designed.

Figure 5 Von Mises stresses in topsides frame under fender load

Shear Check

The shear force experienced in the welds between the pedestal and the side frames was calculated based on the total reaction force, number of connections between the pedestal and the side structure, and weld throat area for a 1” double continuous weld (Appendix A). Allowable shear stress levels were determined in accordance with the ABS MVR 3-2-20/9.1 (Reference 1).

Allowable stress is determined by the formula 𝑓𝑦/𝐹𝑆, where 𝐹𝑆 = 2.50 for a static shear stress limit. Thus, the allowable shear stress is 20.4 ksi (Appendix A).

The maximum shear stress in the weld throat is 4.12 ksi, which indicates that failure in shear between the fender foundation and topsides frame is not of concern by comparison with the allowable stress of 20.4 ksi.

Miscellaneous Foundation Calculations 6 Doc. 887-B399-04, Rev -

Conclusions

The maximum stress within the model shows that the design passes the requirements of MVR

Part 3-2-20/9.1 for allowable stress. The fender foundation is adequate to develop the mooring reaction forces from the fender into the supporting transverse structure.

Bridge Corbel Finite Element Analysis

Modeling Principles

A topsides frame finite element model similar to the FEM used for the fender foundation analysis was constructed using SOLIDWORKS Simulation. One side frame with integrated clip, one ice frame, and associated effective plating were included. All structure was modeled using shell elements constructed of tri elements.

Bridge Corbel Model Geometry

The topsides frame surfaces were split at the points where the top and bottom of the bridge corbel intersect the topsides shall plating, as well as at 2” intervals between these points to match the mesh size used in Reference 8. The bridge corbel and topsides framing is shown in Figure 6, with a cutaway to show the corbel internal structure and intersection with the topsides plate. The

FEM mesh was identical to that shown in Figure 2.

Figure 6 Bridge corbel and topsides framing cutaway to show corbel internal structure

Miscellaneous Foundation Calculations 7 Doc. 887-B399-04, Rev -

Material Properties

Material properties were identical to those used in the fender foundations FEA (Table 1).

Loading Conditions

Figure 7 shows the maximum transverse bridge corbel reaction forces as calculated by Reference

8.

Figure 7 Bridge corbel reaction forces (Reference 8)

The nodal reaction forces shown in Figure 7 were applied to corresponding sections of the topsides frame structure backing the bridge corbel. Figure 8 shows the application of these reaction forces to the topsides frame.

Figure 8 Bridge corbel reaction forces applied to topsides frame, colors alternating for clarity

Miscellaneous Foundation Calculations 8 Doc. 887-B399-04, Rev -

Boundary Conditions

Boundary conditions were identical to those used in the fender foundations FEA (Figure 4).

Allowable Stresses

Von Mises Stress

The allowable von Mises stress is 37.97 ksi as in the fender foundations FEA (see Appendix A).

Results

A linear static analyses of the topsides frame FEM was performed with the loads and boundary conditions described above. The von Mises stresses in the side frame are shown in Figure 9. The greatest stress is approximately 35.9 ksi, showing that the topsides frame structure can withstand the design fender load as designed.

Figure 9 Von Mises stresses in unbracketed topsides frame under bridge corbel load

Conclusions

The maximum stresses within the model show that the design passes the requirements of MVR

Part 3-2-20/9.1 for allowable stress in both bracketed and unbracketed configurations. The typical topsides frames are adequate to withstand the reaction forces from the bridge corbel.

However, brackets will be included for conservatism to ease the transition between the bridge corbel and side frames.

Miscellaneous Foundation Calculations A-1 Doc. 887-B120-01, Rev -

Appendix A Allowable Stress Calculations

Fender Foundation Calculation File 22105

Date 6/6/2023

By: CJH

Checked

Mesh Size = 1 in

Stiff Spacing = 16 in

Ratio = 0.0625

Minimum Yield Strength = 51,000 psi Reference 3

Sm = 0.908 Reference 3

Static Stress Limit H36 = 37,973 psi Reference 3

Max VM stress H36 = 15,310 psi

PASS: Margin = 2.5

NSF McMurdo Offload Infrastructure

Miscellaneous Foundation Calculations A-2 9 June 2023

Doc. 887-B399-04, Rev -

Fender Foundation Shear Check

Date 6/7/2023

By: CJH

Checked

Allowable Shear Stress

Minimum Yield Strength = 51,000 psi Reference 3

FS = 2.5 Reference 3

Static Stress Limit H36 = 20,400 psi Reference 3

Shear Stress in Weld

Reaction force per connection

Reaction force 700 kN per fender

157.4 kip

No. of connections 6

Force per connection 26.23 kip

Throat area (per connection)

Weld leg 0.375 in

Weld throat 0.530 in

Weld length 4.5 in

Throat area 2.39 in2

Shear stress 10.99 ksi

PASS: Margin = 1.9 for double continous fillet weld, only 1x DC weld used for conservatism

NSF McMurdo Offload Infrastructure

Miscellaneous Foundation Calculations A-3

Corbel Backing Structure Calculation

Date 6/7/2023

By: CJH

Checked

Mesh Size = 1 in

Stiff Spacing = 16 in

Ratio = 0.0625

Minimum Yield Strength = 51,000 psi Reference 3

Sm = 0.908 Reference 3

Static Stress Limit H36 = 37,973 psi Reference 3

Max VM stress H36 = 35,860 psi

PASS: Margin = 1.1

NSF McMurdo Offload Infrastructure

Miscellaneous Foundation Calculations A-4