gtstrudl volume8 chapter 4

GT STRUDL Punching Shear Checks

V 8 4.1 - 1 Rev Q

4.0 Punching Shear Checks

4.1 Introduction

The basis of the Punching Shear Checks implementation is the limit state or stressevaluation of the tubular connection specification of the American Petroleum Institute (API)Recommended practices and of the Norwegian Petroleum Directorate (NPD) Codes.

The three GTSTRUDL commands described in this section present the syntax ofstatements required for inputting chord information to GTSTRUDL and for executing theGTSTRUDL punching shear checks with respect to the chords identified. Chords normally arethe main vertical members of the jacket structure.

Appendix B, Volume 8, GTSTRUDL User’s Reference Manual lists the equations for thestrength checks that GTSTRUDL makes for each chord and brace specified. A punching shearstress check cannot be made before an analysis has been executed and before certainPARAMETERS have been specified. Section 4.2 describes the applicable PARAMETERS.

API Code

The GTSTRUDL Punching Shear Check is based on API Recommended Practicefor Planning, Designing, and Constructing Fixed Offshore Platforms. Punching shear canbe checked based on the LRFD First Edition, WSD Twentieth Edition, SeventeenthEdition, or Fifteenth Edition of the API RP 2A-WSD code.

RP 2A-LRFD First Edition

The punching shear adequacy of a joint is based on Section E of the API RP 2A-LRFD First Edition. The adequacy of the joint may be checked by GTSTRUDL on thebasis of the ultimate strength joint capacity (Section E.3.1.1 of API 1st Edition). SeeTable 4.2-1 for the punching shear code parameters.

Punching Shear Checks GT STRUDL

Rev Q 4.1 - 2 V 8

RP 2A-WSD Twentieth Edition

The punching shear checks are based on Section 4 of the API RP 2A-WSDTwentieth Edition (11). The adequacy of the joint may be checked by GTSTRUDL onthe basis of (a) punching shear (see Section 4.3.1(a) of API 20th Edition, and ParameterBASIS) or (b) nominal loads (see Section 4.3.1(b) of API 20th Edition, and ParameterBASIS) in the brace. See Table 4.2-2 for the punching shear code parameters.

RP 2A Seventeenth Edition

The Punching Shear Checks are performed based on Section 2.5.5a (Equation2.5.5-1) of the Seventeenth Edition. Sections 2.5.5c, parts 1, 2, and 3 of the FifteenthEdition correspond to Sections 2.5.5c, parts 1, 2, and 3 of the Seventeenth Edition. SeeTable E.1-1 of Appendix E for the punching shear code parameters.

RP 2A Fifteenth Edition

The Fifteenth Edition of RP 2A (2) permits the punching shear adequacy of a jointto be evaluated on a stress or load basis. GTSTRUDL parameter BASIS permits theselection of which criteria should be used or if both should be used. The default is a checkbased on stress. See Table E.1-1 of Appendix E for the punching shear code parameters.

NPD83 Code

The NPD83 Code Punching Shear option results in checks being conductedaccording to:

"Regulations for the Structural Design of Fixed Structures on theNorwegian Continental Shelf", Norwegian Petroleum Directorate, 1983(9), Sections 3.3 through 3.6.

The 1983 version of the NPD code is valid for K, T, Y, X, and DOUBLE-Ybrace/chord geometry configurations. If an S joint configuration is attempted, a warningmessage will be printed and GTSTRUDL will proceed to the next joint configuration. SeeTable E.1-2 of Appendix E for the punching shear code parameters.

GT STRUDL Punching Shear Checks

V 8 4.2 - 1 Rev Q

4.2 Properties and Parameters Used by Punching Shear Check

The profile properties for the tubular section are described in Appendix A.2, Volume 3 ofthe GTSTRUDL Reference Manual.

The parameters used by Punching Shear checks are described in the tables itemized in thefollowing schedule:

Applicable Code Table

American Petroleum Institute, LRFD 1st Edition (APILRFD1)

Table 4.2-1

American Petroleum Institute, WSD 20th Edition (APIWSD20)

Table 4.2-2

American Petrolium Institute, WSD, 17th and 15th Editions(APIAPR87 and APIOCT84 respectively)

Table E.1-1

Norwegian Petroleum Directorate, 1983 (NPD83)

Table E.1-2

APILRFD1 Code Parameters GT STRUDL

Rev R 4.2 - 2 V 8

Table 4.2-1

The Punching Shear APILRFD1 Code Parameters

Parameter Default Name Value Meaning

GRPLOAD* 0.0 Specify a load identifier followed by the word LOAD and a list ofload identifiers. The load identified is used to compute the clas-sification. The list of loads following are each assigned theclassification computed. Repeat the GRPLOAD statement as re-quired to group similar load conditions that produce the sameclassification. This parameter is applicable to joint classificationcommands (Sections 4.3.1 and 4.3.2, Volume 8 of the ReferenceManual).

TOLPLANE+ ±10 Plane tolerance. Planes defined by the intersection of brace andchord members that lie within this angular tolerance areconsidered as one plane for joint classification. The tolerancemay be increased up to ± 20 degrees. The ± symbols shall notbe specified. This parameter should be specified for a joint listonly. This parameter is applicable to automatic joint classification(Section 4.3.2, Volume 8 of the Reference Manual).

CHECK50% YES Parameter to request the check for the connections at the ends oftension and compression members that should develop thestrength required by design loads, but not less than 50% of theeffective strength of the member (Section E.1 of the API RP 2A-LRFD 1st Edition). Choices are YES or NO. A value of NO forthis parameter indicates that the Section E.1 of the API RP 2A-LRFD 1st Edition should not be checked.

*Only the LOADS list of the PARAMETER command is applicable to parameter GRPLOAD.+Only the JOINTS list of the PARAMETER command is applicable to parameter TOLPLANE.

GT STRUDL APILRFD1 Code Parameters

V 8 4.2 - 3 Rev R

Table 4.2-1 (Continued)



Material Properties

STEELGRD A36 Identifies the grade of steel from which a member is made. SeeTable 3.3-6, Volume 8 of the Reference Manual for steel gradesand their properties.

FYLD Computed Yield stress of member. Computed from STEELGRD if notgiven.

REDFYLD 1.0 Reduction factor for FYLD. This factor times FYLD gives theFY value used by the code.

APA 0.0 Coincident pile cross-sectional area used in distribution of axialforces between the pile and the chord members.

IPA 0.0 Pile moment of inertia used in distributing bending momentbetween a coincident pile and the chord members.

FCHTK 0.0 Final (or maximum) chord wall thickness to be tested for punchingshear checks. GTSTRUDL will not increment wall thicknessbeyond this value.

ICHTK 0.0 Initial thickness of the chord wall used to determine the cross-sectional area, moments of inertia and section modulus for useduring the punching shear checks of the chord.

INCWT 0.125 The pipe thickness increment value )t used in searching for anadequate profile. The inside diameter is held constant during theincrementing process. The outside diameter is held constant fora negative )t value.

APILRFD1 Code Parameters GT STRUDL

Rev Q 4.2 - 4 V 8




Factors Applied to Allowable Stress Equations

INCR 1.0 Factor used on several allowable stress equations; e.g., bendingtension and compression, interaction of axial and bending, thebending terms of the combined stress equations, and shear stress.

LF* 1.0 A factor used in a manner similar to the parameter INCR toadjust the allowable stresses. LF is defined as a function ofloading condition rather than as a function of member ID.

Output Processing

TRACE 4 Flag indicating when checks of code provisions should be outputduring code checking.3 = all checks4 = controlling Actual/Allowable values

VALUES 1 Flag indicating if parameter or property values are to be outputwhen retrieved. See Appendix A.3.2 for explanation.1 = no output2 = output parameters3 = output properties4 = output parameters and properties.

*Only the LOADS list of the PARAMETER command is applicable to parameter LF.

GT STRUDL APIWSD20, APIAPR87, and APIOCT84 Code Parameters

V 8 4.2 - 5 Rev R

Table 4.2-2

The Punching Shear APIWSD20 Code Parameters


BASIS STRESS Controls whether the punching shear check is performed on astress or load basis, or both. Possible parameter assignments are:STRESS, LOAD, BOTH

GRPLOAD* 0.0 Specify a load identifier followed by the word LOAD and a list ofload identifiers. The load identified is used to compute theclassification. The list of loads following are each assigned theclassification computed. Repeat the GRPLOAD statement as re-quired to group similar load conditions that produce the sameclassification. This parameter is applicable to joint classificationcommands (Sections 4.3.1 and 4.3.2, Volume 8, GTSTRUDLReference Manual).

TOLPLANE+ ±10 Plane tolerance. Planes defined by brace members and the chordthat lie within this degree tolerance of each other are consideredas one plane for classification. You may increase the tolerance upto ± 20 degrees. The ± symbols are not to be specified. Thisparameter should be specified for the joint list only. Thisparameter is applicable to automatic joint classification (Section4.3.2, Volume 8, GTSTRUDL Reference Manual).

*Only the LOADS list of the PARAMETER command is applicable to parameter GRPLOAD.+Only the JOINTS list of the PARAMETER command is applicable to parameter TOLPLANE.

The Punching Shear APIWSD20 Code Parameters GT STRUDL

Rev R 4.2 - 6 V 8


The Punching Shear APIWSD20, APIAPR87, and APIOCT84 Code Parameters


CHECK50% YES Parameter to request the check for the connections at the ends oftension and compression members that should develop thestrength required by design loads, but not less than 50% of theeffective strength of the member (Section 4.1 of the API RP 2A-WSD 20th Edition). Choices are YES or NO. A value of NOfor this parameter indicates that the Section 4.1 of the API RP2A-WSD 20th Edition should not be checked.

Material Properties

FYLD Computed Yield stress of member. Computed from STEELGRD if notgiven.

REDFYLD 1.0 Reduction factor for FYLD. This factor times FYLD gives theFY value used by the code.

APA 0.0 Coincident pile cross-sectional area used in distribution of axialforces between the pile and the chord members.

IPA 0.0 Pile moment of inertia in distributing bending moment between acoincident pile and the chord members.

FCHTK 0.0 Final (or maximum) chord wall thickness to be tested for punchingshear checks. GTSTRUDL will not increment beyond this value.

ICHTK 0.0 Initial thickness of the chord wall used to determine the cross-sectional area, moments of inertia and section modulus for useduring the punching shear checks of the chord.

GT STRUDL APIWSD20, APIAPR87, and APIOCT84 Code Parameters

V 8 4.2 - 7 Rev Q




Material Properties (Continued)

INCWT 0.125 The pipe thickness increment value ) t used in searching for anadequate profile. The inside diameter is held constant duringthe incrementing process. The outside diameter is heldconstant for a negative ) t value.

Factors Applied to the Allowable Stress Equations

INCR 1.0 Factor used on several allowable stress equations; e.g., bendingtension and compression, interaction of axial and bending, thebending terms of the combined stress equations, and shear stress.

LF* 1.0 A factor used in a manner similar to the parameter INCR toadjust the allowable stresses. LF is defined as a function ofloading condition rather than as a function of member ID.

Output Processing

UNITS CODEUNIT Indicate the CHECK FOR PUNCHING SHEAR Commandoutput units. Choices are CODEUNIT, or ACTIVE.

CODEUNIT = Output from CHECK FOR PUNCHINGSHEAR Command in Code units (kip-inch).

*Only the LOADS list of the PARAMETER command is applicable to parameter LF.

The Punching Shear APIWSD20 Code Parameters GT STRUDL

Rev Q 4.2 - 8 V 8

Table 4.2-2 (continued)



Output Processing (Continued)

ACTIVE = Output from CHECK FOR PUNCHINGSHEAR Command in active units.

TRACE 4 Flag indicating when checks of code provisions should be outputduring code checking.3 = all checks4 = controlling Actual/Allowable values

VALUES 1 Flag indicating if parameter or property values are to be outputwhen retrieved. See Appendix A.3.2 for explanation.1 = no output2 = output parameters3 = output properties4 = output parameters and properties.

GT STRUDL Punching Shear Classification

V 8 4.3 - 1 Rev Q

4.3 Punching Shear Classification

The classification of each joint to be checked may be done explicitly or automatically byGTSTRUDL. Section 4.3.1 discusses the explicit joint classification and Section 4.3.2 discussesthe automatic joint classification.

4.3.1 CHORDS FOR PUNCHING SHEAR Command: ExplicitJoint Classification

Simple form:

CHORDS (FOR) (PUNCHING SHEAR)

C C CC C CC C C

END (OF CHORD DATA)

where:

Punching Shear Classification GTSTRUDL

Rev Q 4.3 - 2 V 8

General form:

CHORDS (FOR) (PUNCHING SHEAR)

(CHORD) c1 (JOINT) j1

C C C C C C C C C C C C C C C END (OF CHORD DATA)

*where,


V 8 4.3 - 3 Rev Q

Elements:

ci = integer or alphanumeric id of the member that is designated as a chordmember at joint ji.

ji = integer or alphanumeric id of the joint for which classification data arespecified.

list1 = integer or alphanumeric id of the members designated as bracemembers at joint ji.

bi = integer or alphanumeric id of the member designated as a bracemember at joint ji.

list2 = list of integer/alphanumeric loading names.

v1 = the gap between the two brace members where they intersect thechord applicable to the K joint configuration only.

r1, r2 = fractional factor ranging from 0.0 to 1.0 which defines the percentageof different configurations acting at the joint ji.

v2 = circumference of brace contact with chord, neglecting presence ofoverlap.

v3 = circumference of that portion of the brace which contacts the chord(actual length).

v4 = the projected chord length (one side) of the overlapping weld,measured perpendicular to the chord.

v5 = the lesser of the weld throat thickness or the thickness of the thinnerbrace.

v6 = AISC allowable shear stress for the weld between braces. Defaultvalue is 18.0 ksi.


Rev Q 4.3 - 4 V 8

Explanation:

The user must completely describe the geometry of the braced joints whenusing the explicit method of joint classification. The chord member, the chord joint,and the brace members framing into the joint must be identified. The joints, chords,and the braces framing into the joints must be identified exactly as specified underJOINT COORDINATES and MEMBER INCIDENCES, respectively. Normally,this information is placed before the PARAMETERS command.

GEOMETRY:

The input values r1 and r2 are the ratios (expressed as decimal values) usedto assign the various classes in a partial classification.

The API code classifies joint geometries into three categories: K, T&Y,and CROSS joints (Figure 4.3.1-1). The joint configuration GEOMETRY 'T' or'Y' of CHORDS FOR PUNCHING SHEAR command is the T&Y geometryclassification of the API Code. Valid designations for the 1983 version of theNorwegian Petroleum Directorate code are: K, T or Y, CROSS or X, andDOUBLE-Y.

Example:

BRACE 1 LOAD 1 GEOMETRY PART 'K' 0.5 'Y' 0.3 'CROSS'

The above example under load 1 shows the geometry for brace 1 is 50percent K, 30 percent Y and 20 percent CROSS. GTSTRUDL assigns the ratioequal to 1.0-r1-r2 = 1.0 - 0.5 - 0.3 = 0.2 to the CROSS classification.

OVERLAP:

The OVERLAP designation specifies the minimum spacing between bracemembers where they intersect the chord (Figures 4.3.1-1 and 4.3.1-2). In termsof the API Punching Shear Check, the overlap status of a joint configuration isrelevant for 'K' geometries only. The OVERLAP PARAMETER should beomitted for 'T', 'Y', 'CROSS' or 'X', and 'Double-Y' geometries. The integer -1means that some of the brace members are over-


V 8 4.3 - 5 Rev Q

Figure 4.3.1-1 Examples of Joint Classification


Rev Q 4.3 - 6 V 8

lapped. In this case the 'K' geometry has overlap condition. The factor whichaccounts for the effects of type of loading and geometry (Qq) is assumed equal to1.8, and the allowable axial load component perpendicular to the chord is checked(overlapping joints). A value of 0 indicates the 'K' geometry with a gap. Aninteger 0 initiates a computation of the minimum brace separation distance basedon the input chord/brace geometry. When explicit classification is used and thechord data are input with the general form, the value 0 may not be input. Braceseparation values can be input directly by the user entering a positive decimalnumber. Negative decimal values will result in the joint configuration being treatedas overlapped. The procedure used by GTSTRUDL to compute the minimumbrace separation distance assumes that all brace members and the chord member liein the same plane. For automatic classification, the default tolerance for bracesconsidered in one plane is ±10 degrees by default. Furthermore, the braces areassumed to lie on the same side of the chord. Therefore, if you choose to let thesystem determine the overlap status of a joint and you are classifying jointsexplicitly, be certain to group the brace list so that the above criteria are met.

Example:

The correct user input for the K joint configuration in Figure 4.3.1-3 shownas

Correct: CHORDS FOR PUNCHING SHEARCHORD 1 JOINT 50 OVERLAP 0 BRACES 2 3 4CHORD 1 JOINT 50 OVERLAP 0 BRACES 6 7CHORD 1 JOINT 50 OVERLAP 0 BRACES 5 8CHORD 9 JOINT 50 OVERLAP 0 BRACES 2 3 4CHORD 9 JOINT 50 OVERLAP 0 BRACES 6 7CHORD 9 JOINT 50 OVERLAP 0 BRACES 5 8


V 8 4.3 - 7 Rev Q

Figure 4.3.1-2 The OVERLAP Parameter

Figure 4.3.1-3 Example for Automatic Joint Classification


Rev Q 4.3 - 8 V 8

Incorrect: CHORDS FOR PUNCHING SHEARCHORD 1 JOINT 50 OVERLAP 0 BRACES 2 TO 8CHORD 9 JOINT 50 OVERLAP 0 BRACES ALL

The incorrect coding presumes that all the braces and the chord lie in acommon plane and that the braces are all located on the same side of the chord.The computation of brace separation distance will include any brace membereccentricities specified at the chord joint. The automatic classification will definethe chords as in the correct case and classify the joint according to the brace loads.

DIAPHRAM:

The DIAPHRAM modifier indicates the presence of a stiffening diaphramin the chord for 'CROSS' joints configurations.

L/L1/L2/TW/VW:

The input quantities L, L1, L2, TW and VW describe the weld that connectsthe brace to the chord member. The dimension L is the circumference of the bracecontact with the chord, neglecting the presence of the overlap. L1 and L2 areweld length dimensions shown in the Figure 4.3.1-4

Figure 4.3.1-4 Stiffening Diaphram


V 8 4.3 - 9 Rev Q

TW is the weld thickness and VW is the allowable weld stress in force unitsper square length unit (i.e., psi, ksi). The default values of these weld propertiesare listed in the table on the next page. Welds are assumed as partial to fullpenetration groove welds.


Rev Q 4.3 - 10 V 8

Table 4.3.1-1

Weld Properties

Quantity Symbol Default Value

Single Brace Weld L B × Brace Diameter/Sin 1Length where 1 = brace-chord angle

Actual Weld L1 B × Brace Diameter/Sin 1Length where 1 = brace-chord angle

Brace Offset L2 0.0

Weld Thickness TW Brace wall thickness.

Weld Allowable VW 18.0 ksi

If several brace members form a K joint, conservative results will beobtained from the code check if minimum weld properties are specified.

GT STRUDL Chords for Punching Shear Automatic

V 8 4.3 - 11 Rev Q

4.3.2 CHORDS FOR PUNCHING SHEAR AUTOMATICCommand: Automatic Joint Classification

General form:

( LIST CHORDS ) ( joint configuration )

*

Elements:

list1 = integer or alphanumeric id of the joint which automatic classification isspecified.

list2 = integer or alphanumeric id of the load which computations for classificationis performed.

For joint configuration elements, see Section 4.3.1, Volume 8 of the Users Manual.

Chords for Punching Shear Automatic GT STRUDL

Rev Q 4.3 - 12 V 8

Explanation:

The automatic classification option will automatically identify the chords framing

into the joints given in the list and will classify the joint according to the brace loads for

each active load according to API RP 2A-LRFD 1st, 2A-WSD 20th, 17th, or 15th

Edition. (External loads are ignored thus producing the effect of shear in the chords.)

The chords at a joint are identified and defined according to the following criteria:

C The largest continuous diameter member pair framing into a joint (independent of

wall thickness), or,

C If several members of the same size frame into a common joint, the member that has

the greatest wall thickness.

C If all members are of the same diameter and wall thickness, or the chord cannot be

determined because more than one chord could exist by the preceding, then a

warning message instructing the user to classify the joint using the explicit CHORD

command. No check is performed for this joint.

C Under all circumstances, if the chord is made up of the ends of two connecting

members of equal diameter making the chord continuous through the joint, i.e., two

members form the chord, one from the left and one from the right, they must lie on

the same vector.

Figure 4.3.2-1 Angle between the continuous chords

GT STRUDL Chords for Punching Shear Automatic

V 8 4.3 - 13 Rev Q

C If an angle between the two chord segments continuing through a joint is greater than

a tolerance value, a warning message is given instructing the user to classify the joint

using explicit joint classification and no check is performed for the joint. The

tolerance for members considered continuous or in one plane is ±10 degrees, which

can be overridden by the parameter TOLPLANE up to a maximum of ±20 degrees.

This parameter should be specified before automatic joint classification commands.

The possible automatic joint classifications are K, T, Y, CROSS, PART K

CROSS, PART K T, PART K Y, PART CROSS T, PART CROSS Y, PART K

CROSS T, and PART K CROSS Y. The classification is made by systematically

balancing brace forces of opposite sign in half planes on each side of the chord. The

process begins with the two highest brace forces of opposite sign, continuing the process

in each half plane until no more members are left for balancing. If only one brace is found

in a half plane, the brace is either T or Y, depending solely on geometry. Refer to

Appendix B.2, Volume 8 of the GTSTRUDL User’s Reference Manual for the procedure

description.

As voluminous computations and output could result from the different possible

classifications for different loads, you are cautioned to specify only loads representative

of the different conditions. For example, identify only selected wave loads from the

different directions, rather than all wave loads or all loads.

The parameter GRPLOAD may be used to limit the computations for classification

while still allowing proper checks for all active loads. By your identifying a load case

representative of numerous similar loads, GTSTRUDL computes the classification for the

one load identified and assigns the same classification for all of the loads in the LOAD list.

This parameter should be specified before CHORDS FOR PUNCHING SHEAR

Commands.

Chords for Punching Shear Automatic GT STRUDL

Rev Q 4.3 - 14 V 8

Example:

PARAMETER

GRPLOAD 1 LOADS 20 TO 30

Only the load identified as 1 for parameter GRPLOAD will be used for automaticclassification. All members for LOADS 20 to 30 each will be assigned the same classification asassigned for load 1. Note that load 1 must also be identified in the LOAD portion of the automaticclassification options.

When the automatic classification is used, the chords and braces can be listed byGTSTRUDL by specifying the LIST CHORDS option. The chord output is similar to the explicitidentification for chords and braces. For example, referring to the Figure 4.3.1-3, for joint 50, theGTSTRUDL output listing the chords is as follows:

CHORD 1 JOINT 50BRACE 2 LOAD 1 GEOMETRY 'K' OVERLAP 6.62

BRACE 3 LOAD 1 GEOMETRY PART 'K' 0.6 'T' OVERLAP 6.62

BRACE 4 LOAD 1 GEOMETRY PART 'K' 0.3 'CROSS' -OVERLAP 6.62

BRACE 5 LOAD 1 GEOMETRY 'K' OVERLAP 4.37BRACE 6 LOAD 1 GEOMETRY 'K' OVERLAP 5.18

BRACE 7 LOAD 1 GEOMETRY PART 'K' 0.5 'CROSS' 0.34 -'Y' OVERLAP 5.18

BRACE 8 LOAD 1 GEOMETRY 'K' OVERLAP 4.37

CHORD 9 JOINT 50BRACE 2 LOAD 1 GEOMETRY 'K' OVERLAP 6.62

BRACE 3 LOAD 1 GEOMETRY PART 'K' 0.6 'T' OVERLAP 6.62

BRACE 4 LOAD 1 GEOMETRY PART 'K' 0.3 'CROSS' -OVERLAP 6.62

BRACE 5 LOAD 1 GEOMETRY 'K' OVERLAP 4.37BRACE 6 LOAD 1 GEOMETRY 'K' OVERLAP 5.18

BRACE 7 LOAD 1 GEOMETRY PART 'K' 0.5 'CROSS' 0.34 -'Y' OVERLAP 5.18

BRACE 8 LOAD 1 GEOMETRY 'K' OVERLAP 4.37

GT STRUDL Chords Additions/Deletions Mode

V 8 4.3 - 15 Rev Q

4.3.3 CHORD ADDITIONS/DELETIONS Mode

The ADDITIONS and DELETIONS modes are the only valid options for makingmodifications to CHORD data. To modify the chord data base, you must DELETE the data tobe modified and use the ADDITIONS mode to add the changed data. This changed data mustinclude all the other data previously related to the DELETED data. For example, to modifyexisting data associated with CHORD 5 JOINT 6, you must do the following:

CCC

DELETIONSCHORDS

CHORD 5 JOINT 6ADDITIONS

CHORDS CHORD 5 JOINT 7 BRACES 8 9 10

CCC

The DELETIONS mode will cause all CHORD information related to CHORD 5 to beerased from the CHORD data base. The ADDITIONS mode defines a new chord at joint 7 withbraces 8, 9, and 10 framing into the chord.

A precondition to the above example is the requirement that CHORD 5 JOINT 6 hadbeen previously defined as specified in the DELETIONS mode. New chords may be added tothe CHORD data base at any time using only the ADDITIONS mode.

Chords Additions/Deletions Mode GT STRUDL

Rev Q 4.3 - 16 V 8

This page was intentionally left blank.

GT STRUDL Check Punching Shear Command

V 8 4.4 - 1 Rev Q

4.4 CHECK PUNCHING SHEAR Command

General form:

where

( LIST CHORDS ) ( joint configuration )

*

Check Punching Shear Command GT STRUDL

Rev Q 4.4 - 2 V 8

Elements:

list1 = integer or alphanumeric id of the member which check for punching shear isspecified.

list2 = integer or alphanumeric id of the joint which automatic classification is specified.

list3 = integer or alphanumeric id of the load which computations for classification isperformed.

For joint configuration elements, see Section 4.3.1.

Explanation:

The designations shown in the closed bracket immediately after the CHECKcommand are the valid code names for the punching shear check. Table 4.4-1 lists theavailable GTSTRUDL punching shear codes.

The members given in this command refer to those members identified as chordsin the CHORDS FOR PUNCHING SHEAR command (Section 4.3).

The AUTOMATIC option specifying the joints ALL to be classified refers to alljoints in the structure not classified by explicit chord identifiers. Note that regardless of thecode identified immediately following the CHECK command, the chord/brace classificationis always as defined by APILRFD1, APIWSD20, APIAPR87, or APIOCT84 guidelines.The default classification is for all loads. For efficient computer use, you should utilize theLOAD LIST option or the GRPLOAD parameter to limit the loads used forclassification and checks.

The CHECK PUNCHING SHEAR command follows the PARAMETERScommand; it initiates action on the information previously specified. Consistent with otherGTSTRUDL "design options", you will, upon successful execution, receive the results ofthe checks made without having to ask for any output specifically. The amount and formatof this output is dependent upon the parameter TRACE that is active for the CHORDMEMBERS listed. TRACE equal to 4 produces the default output which summarizes thevalues for the checks made as well as a limited amount of input information related to eachchord.


V 8 4.4 - 3 Rev Q

APILRFD1 and APIWSD20 output:

The default TRACE output for the APIWSD20 punching shear check shows thejoint and the geometry classification name, the partial classification percentages, the chordand the brace name, the load name, SIN(ANG) (the Sin of the angle between the chordand the brace) and the chord area, the outside diameter and the moment of inertia in theY direction of the chord, the thickness and the section modulus in the Y direction of thechord, the brace axial force, shear force in the Y direction, and the shear force in the Zdirection at the chord connection, the brace torsional moment and the bending moment inthe Y and Z direction at the chord connection, the actual punching shear stress due to thebrace axial force and the allowable stress, the actual punching shear stress due to the bracein-plane moment and the allowable stress, the actual punching shear stress due to the braceout-of-plane moment and the allowable stress, the actual axial load componentperpendicular to the chord and the allowable, the highest actual/allowable ratio and theprovision name. The output for APILRFD1 and APIWSD20 Codes is in the active units.

APIAPR87 and APIOCT84 output:

The default TRACE output for the APIAPR87 and APIOCT84 punching shearcheck shows the joint and the geometry classification name, the chord and the brace name,the load name and SIN(ANG) (the SIN of the angle between the chord and the brace),the outside diameter and the thickness of the chord, the chord area and the brace axialforce at the chord connection, the chord moment of inertia in the Y direction and the braceshear force in the Y direction at the chord connection, the chord section modulus in the Ydirection and the shear force in the Z direction at the chord connection, the chord's weightin pound per foot and the brace torsional moment at the chord connection, the bracemoments in the Y and Z directions at the chord connection, the actual punching shearstress due to the brace axial force and the allowable stress, the actual punching shear stressdue to the brace in-plane moment and the allowable stress, the actual punching shear stressdue to the brace out-of-plane moment and the allowable stress, the actual axial loadcomponent perpendicular to the chord and the allowable, the highest unity stress check(actual/allowable) ratio and the provision name.


Rev Q 4.4 - 4 V 8

Table 4.4-1

GTSTRUDL Punching Shear Codes

Code Parameter Name Table Application

APILRFD1 4.2-1 Based on the Recommended Practice for Planning,Designing and Constructing Fixed Offshore Platforms Loadand Resistance Factor Design. API Recommended Practice2A-LRFD (RP 2A-LRFD) First Edition, July 1, 1993.

APIWSD20 4.2-2 Based on the Recommended Practice for Planning,Designing and Constructing Fixed Offshore Platforms -Working Stress Design. API Recommended Practice 2A-WSD (RP 2A-WSD) Twentieth Edition, July 1, 1993 (11).

APIAPR87 E.1-1 Based on the API recommended Practice for Planning,Designing and Constructing Fixed Offshore Platforms,Seventeenth Edition, dated April 1, 1987 (2).

APIOCT84 E.1-1 Based on the API recommended Practice for Planning,Designing and Constructing Fixed Offshore Platforms, Fif-teenth Edition, dated October 22, 1984 (1).

NPD83 E.1-2 Based on the Norwegian Petroleum Directorate (NPD),Guidelines on Design and Analysis of Steel Structures in thePetroleum Activity, dated 1993 (9).


V 8 4.4 - 5 Rev Q

NPD output:

The default TRACE output for the NPD punching shear check shows the joint, thechord name, the outside diameter, the thickness, the chord area, the moment of inertia inthe Y direction at the chord connection and SIN(ANG) (the SIN of the angle between thechord and the brace), the chord section modulus in the Y direction and the brace axialforce at the chord connection, the chord's weight in pound per foot and the brace shearforce in the Y direction at the chord connection, the allowable punching shear stress andthe brace shear force in the Z direction at the chord connection, the actual punching shearstress and the torsional moment, the actual/allowable punching shear stress ratio, the bracename and the moment of inertia in the Y direction, the load name and the moment of inertiain the Z direction.

TRACE 3 provides the user with a full report of the checks made for eachCHORD specified in the TRACE member list. Although TRACE 3 output is valuable toyour understanding and verification of GTSTRUDL checks, TRACE 3 can be veryexpensive and counterproductive when specified indiscriminately. SUMMARIZECommand is not available for PUNCHING SHEAR code check command.


Rev Q 4.4 - 6 V 8

This page intentionally left blank.

GT STRUDL Input Example and Comments

V 8 4.5 - 1 Rev Q

4.5 Input Example and Comments

The flow of punching shear input data is somewhat different from the flow of a typicalGTSTRUDL "design problem". Section 4.3 defines additional data, which is not required for otherGTSTRUDL design options but is required for executing the punching shear checks.

GTSTRUDLCCC

MEMBER PROPERTIES $ for punching shear checks, either$ pipe, table, or prismatic options

C $ may be used. See Sections 2.1.9CC

STIFFNESS ANALYSIS $ See Section 2.1.13.2CCC

CHORDS FOR PUNCHING SHEAR $ See Section 4.3CHORD 1 JOINT 3 BRACE 14, 35 TO 37CHORD 25 JOINT 27 BRACE 6 8CHORD 14 JOINT 11 GEO 'K' OVE 0 L1 19.0 TW 0.25 BRA 15 12

CCC

LOAD LIST 'COMB1' 'COMB2' $ See Section 2.1.3.5 UNITS INCH $ See Section 2.1.2.6 PARAMETERS $ See Section 4.2 'APA' 14.0 MEM 1 'IPA' 500.0 MEM 1 'INCWT' -0.375 MEM 25 'INCWT' 0.25 MEM 1 14 'FCHTK 2.0 MEM 1 'TRACE' 3.0 MEM 1 'LF' 1.33 LOAD 'COMB2'

Input Example and Comments GT STRUDL

Rev Q 4.5 - 2 V 8

CHECK APIWSD20 PUNCHING SHEAR AUT APIWSD20 CLASS - LIST CHORDS $ See Section 4.4

CCC

FINISH

Note that no CODE or SECTION statements are required to execute the punching shearchecks. All checks are made using forces reported at the chord joint identified. The axial forceand the moments reported at the chord joint 3 will be distributed between the chord and a pile,which may be coincident with the chord in the real structure but is not defined in the GTSTRUDLdata. The brace forces used are at the end of each brace at the chord joint. The chord member1 wall thickness will be increased in 0.25 inch increments while holding the inside diameter of themember constant as failures occur. In contrast, the outside diameter of member 25 is held constantwhile incrementing the member wall thickness by 0.375 inch for each trial. The final chord wallthickness to be checked is 2.0 inches for member 1. Chords 1, 14 and 25 at joints 3, 11 and 27are explicitly identified as K joints. Additionally for chord 14, GTSTRUDL computes a minimumbrace separation distance and uses a weld thickness of .25 inches with a weld length equal to 19inches for braces 12 and 15 connected to the chord. With the exception of the user classifiedjoints 3, 11 and 27, all joints in the structure are, where possible, classified with overlapped bracesfor all active loads with their chords identified and listed by GTSTRUDL. By default, all bracesdefining a plane with the chord within ±10 degrees of each other are considered one plane. Theefficiency option instructing GTSTRUDL to assign classifications to a list of loads by way of theGRPLOAD parameter was not used. All identified chords in the structure are checked accordingto the API RP 2A-WSD Twentieth Edition recommended practices using the PARAMETERS asdefined for the respective chords and joints. Refer to Section 4.2 for PARAMETER explanations.A full check report (TRACE 3) will be given for member 1. A shorter check report (TRACE 4)will be given for all other members.

gtstrudl volume8 chapter 4

Documents