LCLS-II 2K Cold Box Valve Panel. Anchorage & Structural Calculations

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1 Author(s): Connor Kaufmann Page 1 of 16 LCLS-II 2K Cold Box Valve Panel Anchorage & Structural Calculations Revision History: Revision Date Released Description of Change - 02/12/2018 Original release, Issued for Project use Connor Kaufmann JLab Cryogenics Group Mechanical Engineer Nate Laverdure JLab Cryogenics Group Mechanical Engineering Lead Joe Matalevich JLab Cryogenics Group Lead LCLS-II Cold Design Mike Bevins JLab Cryogenics Group Deputy CAM CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 1

2 Table of Contents CSA Documentation-Calculations Author(s): Connor Kaufmann Page 2 of Introduction Anchorage Design Design Basis Anchorage Analysis for Bolts Fastened to Platform Anchorage Analysis for Bolts Fastened to Grating Analysis of Structural Frame Conclusion and Summary References Appendix A CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 2

3 Author(s): Connor Kaufmann Page 3 of Introduction The purpose of this Engineering Note is to document the analysis that was performed to ensure the structural and anchorage design of the LCLS-II Cryoplant 2K Cold Box Valve Panel is suitable for design forces and moments. Figure 1.1 provides a graphical representation of the 2K Cold Box Control Valve Panel Assembly ( ). This report discusses the anchorage design (Section 2), the basis of the analysis that was performed (Section 3), the calculations (Sections 4 through 6) and the summary / conclusion (Section 7). 2K Coldbox Valve Panel Platform Lifting Eyes Valve Panel Unistrut Frame Support Feet Figure 1.1: LCLS-II 2K Cold Box Valve Panel CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 3

4 Author(s): Connor Kaufmann Page 4 of Anchorage Design Prior equipment and analyses have incorporated anchorage systems developed for concrete slabs. As the 2K Coldbox valve panel is located on top of the LCLS-II Cryoplant structural platform, anchorage to concrete is not necessary. Instead, the valve panel is anchored to the steel structural platform in two different methods: 1. Anchorage of the panel frame to the platform structural members (I-beam flanges) via bolted assemblies 2. Anchorage of the panel frame to the platform grating via bolted assemblies The anchorage of the panel frame to the structural members gives the panel a rigid connection independent of potential grating movement, preventing a scenario in which the valve panel overturns by anchoring solely to the grating. This bolted connection also allows for clear path of load transfer from the panel to the support structure, with a defined force/moment imparted to the members. The structural bolt assemblies are characterized by the following elements: 1. Qty. (8) 5/8-11 x 4 LG Bolts: ASTM F3125 Gr. A325 Type 1 2. Qty. (16) 5/8 flat washers: ASTM F436 Type 1, HDG 3. Qty. (16) 5/8 heavy hex nuts: ASTM A563 Gr. DH, HDG The anchorage of the panel frame to the platform grating through additional bolting is necessary due to the limited width of the I-beam flanges. By adding a structural plate underneath the platform, the valve panel is supported by the grating. This connection also provides additional vertical support to the frame, and keeps the panel and platform co-planar. 1. Qty. (8) 5/8-11 x 4 LG Bolts: ASTM F3125 Gr. A325 Type 1 2. Qty. (16) 5/8 flat washers: ASTM F436 Type 1, HDG 3. Qty. (16) 5/8 heavy hex nuts: ASTM A563 Gr. DH, HDG 4. Qty. (4) steel plate, 4 x 6 x 3/8, ASTM A36 Since there is uncertainty in the final design and implementation in the structural platform (provided by others) in the current 3D model, provisions are necessary in order to guarantee sufficient anchorage for the valve panel. At this point in time, it is unclear if the structural bolts will be able to be positioned within the useable portion of the I-beam flanges. To mitigate this possibility, JLab proposes to include a contingency for a steel plate to welded to the outside of the I-beam flanges, to ensure that the frame has a rigid platform connection. Figure 2.1 shows the details of the 2K coldbox valve panel anchorage scheme with top and underside views. CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 4

5 Author(s): Connor Kaufmann Page 5 of 16 Structural Bolts Fastened to Platform I-Beam Flange Structural Bolts Fastened to Platform Grating Clamping Plate on Underside of Grating Figure 2.1: Valve Panel to Structural Platform Anchorage 3.0 Design Basis The applied seismic loads and load combinations are specified in the 2013 California Building Code (CBC) [1] and its reference standard ASCE 7-10 [2]. Per the LCLS-II Cryogenic Building Geotechnical Report [3] and the Cryogenic Plant Seismic Design Criteria [4], the site seismic design parameters include Site Class C, S D1 = and S DS = CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 5

6 Author(s): Connor Kaufmann Page 6 of 16 The substances used in the LCLS-II Cryoplant and the 2K cold box (namely inert cryogenics, gaseous helium) are not hazardous (neither highly toxic nor explosive / flammable) in accordance with CBC Table and the Cryogenic Plant Seismic Design Criteria. Thus, per ASCE 7-10 Table and the Cryogenic Plant Seismic Design Criteria, the Risk Category for the Cryogenic Building and its associated components is II. Per ASCE 7-10 Table and the Cryogenic Plant Seismic Design Criteria, the Seismic Importance Factor for the Cryogenic Building and its associated components is I e = 1.0. To be consistent with prior analyses (e.g P0001 pg. 10), an importance factor of 1.5 is used. Per ASCE and the site seismic design parameters (S 1 = 1.168), the Seismic Design Category for the Cryogenic Building and its associated components is E. Table 3.1 summarizes the site seismic data. LCLS-II Site Seismic Data Symbol Value Unit Name Note S DS g Design Spectral Acceleration LCLSII-4.8-EN-0227-R2 S D g LCLSII-4.8-EN-0227-R2 S g Design Spectral Acceleration 1s LCLSII-4.8-EN-0227-R2 - II - Risk Category ASCE 7-10 Table E - Seismic Design Category ASCE Table 3.1: Site Seismic Data As the 2K Coldbox valve panel is a self-supporting structure that carries gravity loads and is required to resist the effects of an earthquake, it is classified as a non-building structure per ASCE 7-10 Chapter 15. The valve panel is considered a steel ordinary moment frame per ASCE 7-10 Table Table 3.2 shows the computed seismic base shear. Seismic Base Shear Per ASCE 7-10 Chapter 15 Non-Building Structure (Skid Frame) Symbol Value Unit Name Note I e Importance Factor R Response Modification Factor ASCE 7-10 Table (Steel Ordinary Moment Frames) {Rp/2} Ω o 3 - Overstrength Factor ASCE 7-10 Table (Steel Ordinary Moment Frames) C d 3 - ASCE 7-10 Table (Steel Ordinary Moment Frames) h n 6.17 ft Structural Height C t Period Parameter Coefficient ASCE 7-10 Table (Steel Moment Frames) x Period Parameter Exponent ASCE 7-10 Table (Steel Moment Frames) T a s Approximate Fundamental Period ASCE 7-10 (12.8-7) C s,min, g Minimum Limit Seismic Base Shear ASCE 7-10 (15.4-1) C s,min, g Minimum Limit Seismic Base Shear ASCE 7-10 (15.4-4) C s,max, g Maximum Limit Seismic Base Shear ASCE 7-10 (12.8-3) {T << T L } V g Skid Frame Seismic Base Shear ASCE 7-10 (12.8-1,2) Table 3.2: 2K Cold Box Vacuum Skid Seismic Base Shear CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 6

7 Author(s): Connor Kaufmann Page 7 of 16 From the seismic base shear computed in Table 3.2 the seismic inertial loads can be computed for both non-overstrength and overstrength level loads. The inertial loads are calculated for the non-building structure (skid/frame). An additional 30% in-plane orthogonal load is applied in order to ensure that the most critical load direction need not be calculated. In order to calculate the design forces and moments, both the mass and location of the center of gravity relative to the anchor bolts is required. Estimates for the center of gravity are based off of the computed values within NX. The total weight of the system was rounded up from about 530 lbf to 750 lbf for the anchorage calculations in order to introduce additional conservatism. Additionally, the design forces and moments for the anchorage analysis must be consistent with the ASCE 7-10 Chapter 2 load combinations. Table 3.3 lists the applicable load combinations required for analysis. Using these design combinations, the most critical case is selected for each anchorage group. No. Load Combination ASD 5a ( S DS )D + 0.7ρQ E + P + T ASD 8 ( S DS )D + 0.7ρQ E + P +T LRFD 1 1.4D + P + T LRFD 5 ( S DS )D + {Ω}Q E + P + T LRFD 7 ( S DS )D + {Ω}Q E + P + T Table 3.3: ASD/LRFD Design Combinations The valve panel anchors are designed for tension and shear loads using ASD combinations to facilitate ease of computation for the fasteners. Since ASD combination 8 results in the highest overturning moment effect, it is the most critical case for the skid frame anchorage. External forces and moments from piping systems must also be considered as forces on the frame as well as required forces to be developed by the anchoring system. By combining the external forces/moments of the external piping systems with the inertial loads of the frame itself, the required loads are calculated. The resultant design loads for the skid frame anchors are shown in Table 3.4. The corresponding acceleration/inertial loads for the ANSYS analysis are also computed and listed in Table 3.5. ANSYS Inertial Loads Name Symbol Value Unit Note Acceleration X Ax in/s 2 ASD 8 Acceleration Y Ay in/s 2 Acceleration Z Az in/s 2 Table 3.5: ANSYS Inertial Loads from Seismic Event CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 7

8 Author(s): Connor Kaufmann Page 8 of 16 System/Fluid Design Pressure (psig) Nominal Pipe Size GV-512 Vacuum 15 1 HE-511 Helium IA-513 Air CW-528 Water CW-527 Water Force at Bolt Center Moment at Bolt Center Total Anchorage Loads Symbol Inertial Loads Piping Loads Total Load Unit Note Fx 380 1,500 1,880 lbf Fy 1, ,811 lbf Fz lbf Mx -51,153-13,221-64,374 lbf-in My ,977 18,215 lbf-in Mz ,397 17,018 lbf-in Table 3.4: Anchorage Design Loads From the design forces/moments/accelerations calculated within Section 3, the analysis of the anchorage system and the structural frame is undertaken. CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 8

9 4.0 Anchorage Analysis for Bolts Fastened to Platform CSA Documentation-Calculations Author(s): Connor Kaufmann Page 9 of 16 As described in Section 2, the 2K cold box valve panel is anchored to the structural platform with 5/8 structural steel grade bolts. From the design loads for the anchorage system calculated in Section 3, the anchorage system is analyzed assuming these bolts take the entire valve panel tensile and shear loads. The anchorage system is analyzed as a group using the elastic center method outlined in [10]. In this method, the reaction forces for each bolt in the group are calculated, and the shear and tensile stresses are compared to allowables determined by [9]. As shown in Figure 4.1, the stresses in the bolts are acceptable for the calculated seismic load combinations. As the structural bolts require a through hole in the flanges of the I-beam lateral supports, the resultant strength of the structural member is also verified. In this analysis, two failure modes are investigated. 1. Excessive bearing/ contact stress of the bolt surface on the flange hole 2. Tear-out (Shear plane) failure in the flange Both failure modes are addressed in [9] simultaneously and calculated as shown in Figure 4.1. The bearing/tear-out stresses in the structural I-beam flange are acceptable. 5.0 Anchorage Analysis for Bolts Fastened to Grating The grating bolts fasten the 2K cold box valve panel to the platform grating (not the platform beams), due to space constraints. The purpose of this connection is to provide additional load sharing components to the anchorage system, and to prevent any heeling action that can occur in the frame s feet, as one side of the foot is rigidly attached to the platform beams. The platform grating is fastened to the structural lateral beams using clips, as per Smith Group Drawing Detail C6. In a similar fashion, a bolted plate assembly is also used to fasten the valve panel to the grating. The valve panel design and analysis does not assume to carry any additional load from the platform grating itself, and the grating bolts for the valve panel do not resist these loads. As the platform load is nominally designed for a 100 lbf/ft 2 live load, and the valve panel represents roughly a 53 lbf/ft 2 load, the valve panel is not an undue burden for the platform and grating. An identical bolting analysis is repeated for the bolts fastened to the grating with the exception that the I-beam tear-out calculation is replaced by the flat steel plate. This calculation is provided in Figure 5.1. CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 9

10 Author(s): Connor Kaufmann Page 10 of 16 Figure 4.1: I-Beam Bolt Group Analysis CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 10

11 Author(s): Connor Kaufmann Page 11 of 16 Figure 5.1: Grating Bolt Group Analysis CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 11

12 Author(s): Connor Kaufmann Page 12 of Analysis of Structural Frame In addition to the evaluation of the anchorage of the 2K cold box valve panel, a structural assessment was also undertaken to assess the skid under seismic loads. The structural frame is comprised of double and quadruple 12 gauge steel Unistrut channels, as shown in Table 6.1. Gusseted Unistrut fitting attachments serve as additional reinforcements at connection locations. 2K Coldbox Valve Panel Frame Members Name Symbol Unistrut P1001-HG Unistrut P1001C41-HG Unit Description - Unistrut Double Combination Unistrut Quadruple Combination - Material Specification - ASTM A1011 Gr. 33 ASTM A1011 Gr Yield Strength Fy ksi Ultimate Strength Fu ksi Table 6.1: Valve Panel Frame Members By inspection of the low magnitude of the loads, compared to the resiliency of the Unistrut frame, the design capacity should be sufficient. However, to verify the frame is compliant with AISC/ASCE code, a finite element analysis was performed. Due to the intricate geometric cross section of the Unistrut channels, and the small load profile on the frame, geometric modelling abstractions were taken to simplify the analysis model. The Unistrut frame was modelled using 1-D beam elements, instead of using traditional solid prismatic or tetrahedron element types. Figure 6.1 shows this process. For additional conservatism, the stiffening and load sharing effects of the gussets at each connection were left out, making a worst case load scenario for the frame members. The external piping forces and moments on the frame were modelled as loads at a point. The frame itself weighed about 250 lbm in the model, so an additional point mass was added to the model at the center of gravity in order to capture the dead weight of the valves, gauges and piping. To account for the dead weight of piping, gages, etc, a point mass was assigned at the upper frame center of gravity to capture the full 530 lbm assembly. CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 12

13 Author(s): Connor Kaufmann Page 13 of 16 Figure 6.1: Geometric Abstraction of Frame into Beam Elements From the load analysis of the frame, the shear and moment diagram of each of the members was computed. The shear and moment diagram is shown in Figure 6.2. From the peak bending moment of the member, and the peak axial force in each member, the loads in the analysis are compared to allowable loads per [8]. As the frame s capacity exceeds the demand, the frame is sufficiently designed to carry both seismic inertial loads and piping external forces/moments. It should also be noted that, as the strengthening effects of gussets were not included in the analysis, additional load capacity is expected in the structure. The process of calculating the tensile, compressive and flexural capacities for the frame Unistrut members under combined loading conditions is captured in Figure 6.3. As each gusset is rated roughly for 10,000 lbf pull-out on the channel nuts, the fittings are able to handle the load demands of the frame, with this conservative analysis approach. As further reinforcement to the structure, judicious use of welds are used in addition to the Unistrut gussets. One rigid and one semi-rigid attachment of bolts to the platform are sufficient to prevent heeling in the frame feet from overturning moments. CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 13

14 Lateral Member Column Member CSA Documentation-Calculations Author(s): Connor Kaufmann Page 14 of 16 Paths for Calculation of Shear and Moment Diagrams Column Member Path Lateral Member Path Figure 6.2: Shear and Moment Diagrams for Member Paths Shown CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 14

15 Author(s): Connor Kaufmann Page 15 of 16 Figure 6.3: Analysis of 2K Coldbox Valve Panel Frame CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 15

16 Author(s): Connor Kaufmann Page 16 of Conclusion and Summary In conclusion, the anchorage and structural systems of the 2K cold box valve panel have designs exceeding required load capacity. The assembly has sufficient strength to withstand the required seismic design loads for the LCLS-II cryoplant. 8.0 References [1] California Building Code, 2013 [2] Minimum Design Loads for Buildings and Other Structures. ASCE/SEI 7-10, 2010 [3] Final Report Geotechnical Investigation LCLS II Cryogenic Building and Infrastructure SLAC National Accelerator Laboratory, Rutherford+Chekene # G [4] Cryogenic Plant Seismic Design Criteria, LCLSII-4.8-EN-0227-R2 [5] LCLS-II Control Valve Panel Assembly, JLAB [6] LCLS-II Cryogenic Building and Infrastructure IFC Submittal, ID [7] LCLS-II Cryogenic Building and Infrastructure IFC Submittal, Project Manual [8] AISC Steel Construction Manual 14 th Ed. [9] AISC Research Council on Structural Connections: Specifications for Structural Joints 2009 Table B5.2 [10] AISC Manual of Steel Construction 9 th Ed. ASD Section 4-59 Eccentric Loads on Fastener Groups: Alternative Method 1: Elastic Appendix A The calculations and supporting files for this technical report are located at: Name Excel Calculations, Hilti Model, Etc. ANSYS Files Location M:\cryo\LCLS II ANALYSIS FOLDER\SCB Valve Panel Y:\connork\ANSYS work\2k CBX Valve Panel CSA Documentation - 2K Cold Box Valve Panel Structural Calculations Page 16