13-08 Dome venting- 5th floor walkway structural capacity

Transcription

1 13-08 Dome venting- 5th floor walkway structural capacity Analyzed File: Walkway framing section from iam Autodesk Inventor Version: 2012 SP2 (Build , 219) Creation Date: Simulation Author: Summary: 7/30/2013, 4:25 PM S.Bauman A Structural Analysis of the 5th floor walkway to determine load capacity. Request from outside vendor performing contract work to use man-lift on walkway platform for installation and assembly of dome vent units. Reference drawings: The drawing below gives dimensions for the location of the elevation 13,784 73/4, the individual segments that make up the walkway, and specifics on structural members. The designed live load defined in the drawing is 100PSF.

2

3 Figure 1: _CFHT Dome walkway framing section and details by SNC After verifying the drawing above with the as built configuration and construction of the dome inconsistencies were found. The callouts for the structural members that make up each walkway segment were incorrect, C4 x 5.4 TYP underlined in yellow below, was not used for the construction of the walkway. How the as-built details differ from the drawing will be identified below in actual photos, the remaining details in figure 2 below seem consistent.

4 Figure 2: Close-up view of walkway framing plan Section B-B enlarged from the above drawing: The section below shows a detail of the 5 th floor walkway. Each segment is arrayed around the inside of the dome at 7.5 degrees (typical).

5

6 Figure 3: Section B-B After verifying the drawings above with the as built configuration and construction of the dome the following inconsistencies were found. In Figure 5 below one can see that the support beams for the walkway are W4 x 13 not C4 x 5.4 TYP as identified in the drawings. W4 x 13 Figure 4: Walkway main support beam, W4 X 13 (typical) The member highlighted below in yellow shows a support for the walkway. It is welded at an angle from the bottom of the W4 x 13 wide flange beam to the vertical rib member of the dome skeletal structure. The callout in the drawing is incorrect, instead a hollow tube, indentified in the yellow highlighted oval, shows the 2 STD pipe with.158 wall thickness, instead of the called out L 2 ½ x 2 ½ x ¼ angle bar.

7 Figure 5: Section A-A and detail 7, 8, 9 The support beam that spans the width of the platform segment between the Wide flange beams is a L4 x 4 x ¼ L angle and not a C4 x 5.4 TYP as depicted in the drawing. There also is not a structural beam at the termination of the platform where the railing is located.

8 L4 x 4 x ¼ 2 STD round tube,.158 wall Figure 4: Walkway plate support beam, L4 X 4 X 1/4 (typical) The photo below shows the ¼ steel checkered plate which is positioned on top of the wide flange beams, not show in the drawing is the 4 lip (toe kicks) on each side of the walkway plate. There is not s C4 x 5.4 beam positioned between the wide flange beams.

9 ¼ checkered plate TYP Figure 5: Walkway platform surface plate, ¼ thick plate all around (typ) Project Info (iproperties) Summary Title Subject Dome Venting 5ht floor structural walkway capacity

10 Author S.Bauman Manager D.Salmon Company CFHT Category Engineering verification Project Part Number Walkway framing section from Description Project Designer Engineer S.Bauman Status Design Status WorkInProgress Physical Mass Area Volume Center of Gravity lbmass in^ in^3 x= in y= in z= in Note: Physical values could be different from Physical values used by FEA reported below. Simulation:1 General objective and settings: Design Objective Single Point Simulation Type Static Analysis Last Modification Date 7/30/2013, 4:16 PM Detect and Eliminate Rigid Body Modes No Separate Stresses Across Contact Surfaces No Motion Loads Analysis No Advanced settings: Avg. Element Size (fraction of model diameter) 0.1

11 Min. Element Size (fraction of avg. size) 0.2 Grading Factor 1.5 Max. Turn Angle Create Curved Mesh Elements Use part based measure for Assembly mesh Material(s) Name General Stress Steel Mass Density Yield Strength 60 deg No Yes lbmass/in^ psi Ultimate Tensile Strength psi Young's Modulus Poisson's Ratio Shear Modulus Expansion Coefficient ksi 0.3 ul 0 ksi ul/f Stress Thermal Thermal Conductivity btu/( ft hr f ) Part Name(s) Specific Heat btu/( lbmass f ) AISC - W 4x ipt AISC - W 4x ipt Walking surface.ipt AISC - L 4 x 4 x 1_4-70 JLG 1930ES wheel footprint.ipt JLG 1930ES half wheel footprint.ipt Operating conditions Summary: The two highlighted areas below show the pressure applied to the walkway platform model from the wheels of the JLG 1930ES scissor lift. The load below is the worst case where the lift is placed on two portions of the walkway, directly at the center of the segment where the most bending and deflection takes place due to the load of the lift. The details for the JLG 1930ES lift can be found in the appendix. The following information was used for the analysis: JLG 1930ES weight: Lbs Personal weight (max platform weight capacity): 500lbs Total weight of lift: 3, Load per wheel: 812.4lbs Wheel size: 12.5 O.D. x 4 wide

12 Area of wheel on steel platform: 4 wide wheel x 2 effective wheel contact surface = 8 in^2 Pressure:1 Load Type Pressure Magnitude psi Selected Face(s) Gravity Load Type Gravity Magnitude in/s^2

13 Vector X Vector Y Vector Z in/s^ in/s^ in/s^2 Selected Face(s) Fixed Constraint:1 Constraint Type Fixed Constraint The platform is constrained at the end of the wide flange beam where it ties into the vertical rib structure of the dome skeletal structure.

14 Selected Face(s) Contacts (Bonded) Name Bonded:1 Bonded:2 Bonded:4 Bonded:5 Part Name(s) AISC - W 4x :1 Walking surface:1 AISC - W 4x :2 Walking surface:1 Walking surface:1 JLG 1930ES wheel footprint:1 Walking surface:1 JLG 1930ES wheel footprint:1

15 Bonded:6 Bonded:10 Bonded:11 Bonded:13 Bonded:14 Bonded:15 Bonded:16 Results Walking surface:1 JLG 1930ES wheel footprint:1 Walking surface:1 JLG 1930ES half wheel footprint:1 Walking surface:1 JLG 1930ES half wheel footprint:1 AISC - W 4x :1 AISC - L 2.5 x 2.5 x 1_4-70:1 AISC - W 4x :2 AISC - L 4 x 4 x 1_4-70:1 Walking surface:1 AISC - L 4 x 4 x 1_4-70:1 Walking surface:1 AISC - L 4 x 4 x 1_4-70:1 Reaction Force and Moment on Constraints Reaction Force Reaction Moment Constraint Name Magnitude Component (X,Y,Z) Magnitude Component (X,Y,Z) 0 lbforce lbforce ft Fixed Constraint: lbforce lbforce lbforce ft 0 lbforce ft Result Summary Name Minimum Maximum Volume Mass Von Mises Stress in^ lbmass 1st Principal Stress ksi 3rd Principal Stress ksi ksi ksi 0 lbforce 0 lbforce ft ksi ksi Displacement 0 in in Safety Factor ul 15 ul X Displacement Y Displacement Z Displacement in in in in in in Contact Pressure 0 ksi ksi Contact Pressure X ksi Contact Pressure Y ksi Contact Pressure Z ksi ksi ksi ksi

16 Figures The greatest stress found was at the center of the platform at the wheel loading location closest to the railing. This makes sense since it is the furthest supported edge in the platform. Von Mises Stress 1st Principal Stress

17 3rd Principal Stress

18 Displacement The largest displacement the platform sees from loading of the lift is 0.24 inches of deflection downward.

19 Safety Factor

20 X Displacement

21 Y Displacement

22 Z Displacement

23 Contact Pressure

24 Contact Pressure X

25 Contact Pressure Y

26 Contact Pressure Z

27 C:\VaultProdWorkspace\CFHT DESIGNS\10-19 OBSERVATORY BUILDING\11 ARCHITECTURAL AND STRUCTURAL\11-04 FLOORING\Walkway framing section from iam