Tubular Joints in Offshore Structures As Per API RP2A (WSD) Spreadsheet

Tubular Joints in Offshore Structures As Per API RP2A (WSD) Spreadsheet

 

This spreadsheet defines the principle terms and ratios used in tubular joint design. It presents the classifications for T, Y, X, N, K and KT joints and the details of joint arrangements. It describes design methods for static strength.

The main structure of a topside consists of either an integrated deck or a module support frame and modules. Commonly tubular lattice frames are present, however a significant amount of rolled and built up sections are also used. This calculation sheet refers to the design of tubular joints. These are used extensively offshore, particularly for jacket structures.

Only static check is performed here, fatigue check shall be added in further revisions.

Calculation Reference
Tubular Steel Construction

 

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Design Of Concentrically Loaded Isolated Footing Spreadsheet

Design Of Concentrically Loaded Isolated Footing Spreadsheet

 

The footings were proportioned so that the bearing pressure does not exceed the safe bearing capacity of the soil. The bending moments and shears are determined at critical sections. The calculation follows methods set out in ACI 318-08.

Calculation Reference
Reinforced Concrete Design

 

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Angle Section Properties Calculation Spreadsheet

Angle Section Properties Calculation Spreadsheet

 

If you are like me you may have found out the hard way that the values published in the 13th Edition AISC manual for the principle axis section modulus for angles are incorrect. Although the values for principle axes moment of inertia are correct, an incorrect value of “c” was consistently used to obtain the section modulus. In addition to the principle axis properties and orientation of the principle axes with respect to the geometric axes, Version 2.0 now includes the following:

1. The ability to specify orientation of the angle legs and to subsequently calculate the section properties about the modified axis orientation. The following are addressed SLVD Unequal leg – short leg vertically SLVU Unequal leg – short leg vertically up LLVD Unequal leg-long leg vertically down LLVU Unequal leg – long leg vertically up EQVLD Equal leg – long leg vertical down EQVLU Equal leg – long leg vertically up

2. Calculation of the Beta w factor which is utilized in the 13th Edition AISC Manual – equation F10-6 for calculation of allowable moments about the major principle axis for unequal length angles. The proper sign of Beta w is also calculated which is dependent upon whether the shear center is in flexural compression or tension.

3. Calculation of the torsional resistance factor J

4. Calculation of the extreme fiber distances from neutral axis to all angle tip points. The worksheet is protected but without a password

Calculation Reference
AISC 13th Edition

 

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Flexible Seat Angle Reaction Analysis Spreadsheet

Flexible Seat Angle Reaction Analysis Spreadsheet

 

This spreadsheet is a program written in MS-Excel for the purpose of determining the capacity of a flexible seat angle connection and determine the allowable beam end reaction, the allowable end moment for the purpose of end connection design and the weld capacity of the angle to a steel connection.

Design References:

1. AISC Steel Construction Manual, 13th Ed.
2. AISC spreadsheet, “AISC_ShapesDatabase_v13.0-Current.xls”
3. Handbook of Structural Steel Connection Design and Details; Tamboli, Akbar R.; The McGraw-Hill Companies, Inc.; 1999

This program is a workbook consisting of two (2) worksheets, described as follows:

Doc – documentation sheet
ANGLEFLEXSEAT – Allowable End Reaction for Angle Seat Connection Design

1. Revision 1.2 (5/31/10) Limited the angle width, ‘b’, to prevent erroneous output and limit angle bending stress.

Program Assumptions and Limitations:

1.   This program uses the database of member dimensions and section properties from the “AISC Shapes Database”, Version 13.0 (2005) as well as the AISC 13th Edition (ASD) Manual (2005).

2.   The user may select a beam from W, S, M, C, and MC shapes and angles from all AISC listed shapes.

3.  This program determines the appropriate minimum angle thickness from design procedures of the Handbook of Stuctural Steel Connection Design and Detail, p. 154-156.

4.   This program utilizes the procedure which a steel fabricator would typically use to determine end connection design loads when end reaction values are not specified on the design and construction drawings by the engineer.  This procedure is based on the AISC 13th Edition (ASD) Manual (2005) Maximum Total Uniform Load Tables on pages 3-33 to 3-95 and AISC Specification Chapter J10, pages 16.1-116 and 16.1-117.

5.   The welding capacity, found in this program, is from the AISC 13th Edition (ASD) Manual (2005) Coefficients C for Eccentrically Loaded Weld Groups (Table 8-4) and AISC Specificiations Chapter J2, pages 16.1-93 to 16.1-102.

6.  This program does not check the column or angle supporting member’s web or flange as there are too many variables for connection.

7.  This program contains “comment boxes” which contain a wide variety of information including explanations of input or output items, equations used, data tables, etc.  (Note:  presence of a “comment box” is denoted by a “red triangle” in the upper right-hand corner of a cell.  Merely move the mouse pointer to the desired cell to view the contents of that particular “comment box”.)

Calculation Reference
AISC Steel Construction Manual, 13th Ed.

 

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Steel Column Base Plate Analysis Spreadsheet

Steel Column Base Plate Analysis Spreadsheet

 

This spreadsheet is a program written in MS-Excel for the purpose of analysis of steel column base plates.  Specifically, wide flange column base plates may be subjected to axial loads (compression or tension), with or without major-axis column bending, plus major-axis shear.

Base plate bearing pressure is checked as well as bolt tension, if applicable.  If shear is present, bolt shear as well as interaction of bolt tension and shear, if applicable, are calculated.

Finally, the required base plate thickness is calculated.  There is a separate worksheet for base plate shear lug design, when shear load is high and cannot be effectively handled by bolts.

This program is a workbook consisting of four (4) worksheets, described as follows:

Worksheet Name Description
Doc This documentation sheet
Base Plate Steel column base plate analysis
Shear Lug Steel column base – shear lug analysis
Base Plate (Table) Multiple steel column base plate analysis (table format)

Program Assumptions and Limitations:

1.   This program follows the procedures and guidelines of the AISC 9th Edition Allowable Stress (ASD) Manual (2nd Revision, 1995) for wide flange column base plates subjected to axial compressive load only.

2.   This program uses a “cubic equation” method of solution for column base plates subjected to axial compression or tension load with major axis column bending as presented in the reference:
“Design of Welded Structures” – by Omer W. Blodgett (James F. Lincoln Arc Welding Foundation)

3.   For interaction of anchor bolt tension and shear, this program follows the article:
“Design Aid: Anchor Bolt Interaction of Shear and Tension Loads”, by Mario N. Scacco
AISC Engineering Journal, 4th Quarter – 1992.

4.   User has option to take out some of the total shear though friction between column base and grout based on column dead load and coefficient of friction, thus reducing amount of shear to be taken by anchor bolts.

5.   This program uses the database of member dimensions and section properties from the “AISC Shapes
Database”, Version 3.0 (2001) as well as the AISC 9th Edition (ASD) Manual (1989).

6.   This program assumes that the base plate is sufficiently rigid to assume linear distribution of load to the base plate and/or anchor bolts.  (Note: adequate base plate rigidity is most likely assured if the distance  from the face of the column to the edge of the base plate is <= 4*tp.  See “General Anchorage to Concrete”, TVA Civil Design Standard DS-C1.7.1 (Rev. 1984), page 25.)

7.   Additional assumptions used in this program are as follows:
a.  The column is centered on the base plate in both directions.
b.  Axial column load, ‘P’, can be = 0  for the case with moment.
c.  The minimum area of concrete support is:  A2(min) = N*B.
d.  For a base plate supported on a slab or mat, use  A2 = 4*(N*B).
e.  Two (2) total rows of anchor bolts are allowed, one row outside of each column flange.
f.  There must be an equal number of anchor bolts in each of the two (2) rows.

8.   For cases with anchor bolt tension and base plate bearing, this program calculates the bending moment in the base plate at two locations.  One, at the column flange in compression using the bearing pressure distribution, and the other at the column flange in tension using the tension in one bolt distributed over an assumed width effective plate width based on edge distances and bolt spacing.

At both locations, the moment and resulting base plate thickness are calculated using a “cantilever” length equal to the calculated “m” distance from the AISC code.  Then, the larger of the two calculated thickness values is used for the required base plate thickness.  (Note:  this program assumes that the anchor bolts are not located in plan significantly beyond the ends of the column flange, so that corner-type plate bending does not control.)

9.   The “Shear Lug” worksheet follows the AISC “Steel Design Guide Series #7 – Industrial Buildings – Roofs to Column Anchorage” (page 33 and pages 38-40).

10. The “Base Plate (Table)” worksheet enables the user to analyze/design virtually any number of individual column bases or column load combinations.  Refer to that worksheet for list of specific assumptions used.

11.  This program contains numerous “comment boxes” which contain a wide variety of information including explanations of input or output items, equations used, data tables, etc.  (Note:  presence of a “comment box” is denoted by a “red triangle” in the upper right-hand corner of a cell.  Merely move the mouse pointer to the desired cell to view the contents of that particular “comment box”.)

Calculation Reference
AISC

 

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Steel Beam Web Stiffener Analysis Spreadsheet

Steel Beam Web Stiffener Analysis Spreadsheet

 

This spreadsheet is a program written in MS-Excel for the purpose of analysis of steel beams subject to concentrated loads.  Specifically, web yielding, web crippling, and web buckling criteria are checked to determine if web stiffeners are required to resist the concentrated load.  If stiffeners are required, the stiffener size and weld requirements are determined.

This program is a workbook consisting of three (3) worksheets, described as follows:

  • Doc – Documentation sheet
  • Beam Stiffeners – Steel beam web stiffener analysis for concentrated loads
  • Beam Stiffeners (Table) – Steel beam web stiffener analysis for concentrated loads (table version)

All the worksheets are independent and self contained, so that you can move them from one workbook to another. All the worksheets are protected, but not with a password.

Program Assumptions and Limitations:

1.  This program follows the procedures and guidelines of the AISC 9th Edition Allowable Stress (ASD) Manual for wide flange beams subjected to concentrated compressive loads per Chapter K, pages 5-80 to 5-83.

2.  This program uses the database of member dimensions and section properties from the “AISC Shapes Database”, Version 3.0 (2001) as well as the AISC 9th Edition (ASD) Manual (1989).

3.  For the purpose of determining the total composite section to be considered for resisting the compressive load, the program assumes a spacing of 3″ center-to-center between the stiffener pairs.  Thus the total effective strips of web to be included in the composite section along with the stiffeners are as follows:
For interior condition (P or R > d/2):
1-pair:25*tw
2-pairs:  25*tw+3″
3-pairs:  25*tw+6″
For end condition (P or R <= d/2):
1-pair:12*tw
2-pairs:  12*tw+3″
3-pairs:  12*tw+6″

4.  This program contains numerous “comment boxes” which contain a wide variety of information including explanations of input or output items, equations used, data tables, etc.  (Note:  presence of a “comment box” is denoted by a “red triangle” in the upper right-hand corner of a cell.  Merely move the mouse pointer to the desired cell to view the contents of that particular “comment box”.)

Calculation Reference
AISC

 

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Steel Beam and Column Analysis Spreadsheet

Steel Beam and Column Analysis Spreadsheet

 

This spreadsheet is a program written in MS-Excel for the purpose of analysis and code checking of steel beams and columns.  Specifically, beams and columns are analyzed / code checked per the AISC 9th Edition Allowable Stress Design (ASD) Manual.  Both actual and allowable stresses are computed, with the final result being a computed “stress ratio” of actual stress/allowable stress.  Also, a list of the lightest weight members which satisfy the code check is displayed for convenience.

This program is a workbook consisting of six (6) worksheets, described as follows:

  • Doc – Documentation sheet
  • BeamCol(I) – Analysis / Code Check for W, S, M, and HP Shapes
  • BeamCol(Built-Up) – Analysis / Code Check for Non-Database and Built-Up Shapes
  • BeamCol(C) – Analysis / Code Check for Channel Shapes
  • BeamCol(Tube) – Analysis / Code Check for Rectangular HSS (Tube) Shapes
  • BeamCol(Pipe) – Analysis / Code Check for Round HSS and Pipe Shapes

All the worksheets are independent and self contained, so that you can move them from one workbook to another. All the worksheets are protected, but not with a password.

Program Assumptions and Limitations:

1.   This program follows the procedures and guidelines of the AISC 9th Edition Allowable Stress (ASD) Manual (1989).

2.   This program uses the database of member dimensions and section properties from the “AISC Shapes Database”, Version 3.0 (2001) as well as the AISC 9th Edition (ASD) Manual (1989).

3.   The “BeamCol(Built-Up)” worksheet is valid for AISC W, S, M, and HP shapes NOT contained in the AISC 9th Edition Manual, as well as for non-hybird and doubly-symmetrical (“I” shaped) built-up members which have their flanges continuously welded to the web and which DO NOT quailify as plate girders.(Note: the AISC Code limiting value on the web for built-up beams not to qualify as plate girders is as follows:
(d-2*tf)/tw <= 760/SQRT(0.60*Fy)

4.   This program is NOT valid for tees (WT shapes) and angles.

5.   In this program for members subjected to known loadings consisting of axial load (compression or tension) and/or uniaxial or biaxial bending, both the actual and allowable stress are computed, with the final result being a computed “stress ratio” of actual stress/allowable stress.

6.   The “BeamCol(Built-Up)” worksheet will require the input for the total depth, web thickness, flange width, and flange thickness.  Then, all the remaining section properties are automatically calculated, assuming straight,non-sloping flanges.

7.  This program utilizes an “Allowable Stress Increase Factor” (ASIF) which is a multiplier of any of the calculated allowable stresses Fa, Fbx, and Fby and also the Euler column buckling stresses F’ex and F’ey. It is used and appears ONLY in the stress ratio calculation.  Typically a value of 1.0 may be used.  However, a value of 1.333 may be used for load combinations which include wind or seismic loads.

8.  If an axially loaded compression member has a value of the maximum slenderness ratio K*L*12/r >200, then a message will appear.  However, this program DOES NOT consider or deem a particular member as “inadequate” based on the slenderness ratio of 200 being exceeded.

9.  For the case of combined axial compression with bending, if the calculated value of fa >=F’e (which is not allowed) then a warning (error!) message will appear.

10. When the values of either ‘Lx’, ‘Ly’, or ‘Lb’ are input = 0′ (or actually <= 1.0′), this program will use a value = 1.0′.

11. When a stiffened element (web) of a member subjected to axial compression is classified as a “slender” element (exceeding non-compact limits) based on local buckling criteria, then the program complies with AISC Appendix B.

12. In the “BeamCol(C)” worksheet for channels subjected to Y-axis bending, the properties database uses the minimum value of ‘Sy’.  However, it is desired to calculate the bending stress at the back of the channel instead of at the tips of the flanges, this may be done by computing a “reduced effective” Y-axis bending moment,  Mye = My*Sy*(xbar)/Iy , for member loading input.

13. The values of ‘Cb’, ‘Cmx’, ‘Cmy’, ‘Kx, and ‘Ky’ may be calculated (if applicable) by accessing the additional input data to the right of the main page in each of the calculation worksheets.  Then, these calculated values can be input under the member design parameters on the main page.  (Note: there are equations which very closely approximate the solutions for ‘Kx’ and ‘Ky’ obtained using the AISC Code Alignment Charts.)

14. This program does not calculate or check shear or deflection in member

15. This program does not consider torsion on member.

16. This program does not consider deduction for holes in members subjected to tension.

17. This program contains numerous “comment boxes” which contain a wide variety of information including explanations of input or output items, equations used, data tables, etc.  (Note:  presence of a “comment box” is denoted by a “red triangle” in the upper right-hand corner of a cell.  Merely move the mouse pointer to the desired cell to view the contents of that particular “comment box”.)

Calculation Reference
AISC

 

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Stair Stringer Design Spreadsheet

Stair Stringer Design Spreadsheet

 

This worksheet is written in order to design uniformly loaded simple stair steel stringers in accordance with the AISC 13th Edition requirements – Section F. It can also be used as a check or to investigate an existing stringer steel section.

The design is based upon user selected limits on stringer depth and the allowable deflections. For those cases where it is necessary to verify a railing connection to the top of the stringer the user can define upper and lower limits on width of the stringer flange as well. Stringer types are limited to C channel, MC channel and rectangular tubes.

Based upon all of the user defined selection criteria in conjunction with the applied loads, a maximum of 16 selections are automatically made from the AISC steel shape database and are tabulated along with their relevant section properties.

The following  apply
1. Channel  stringers are assumed to be simply supported on each end and continuously laterally braced along their length by the stair pan.
2. All current ASTM A6 C, MC and tubes are compact
3. Stringers are assumed to be pinned top & bottom such that vertical loads are distributed equally to top & bottom supports.

Input
1. The user defines the uniform loads as well as the allowable deflection criteria and the upper and lower bounds on stringer depth.
2.  One can check an existing stringer section simply by inputing the appropriate limits on the section properties so they match the section on question. If the section shows up in the results table then it is an appropriate selection.

 

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