codes

GT STRUDL BS5950 Code

V2A BS5950.0 - 1 Rev Q

BS5950.0 BS5950 Code

The BS5950 Code of GTSTRUDL may be used to select or check any of thefollowing shapes:

I shapes Round barChannel PipeSingle angle Square bar Tee Rectangular barDouble angle Structural tubing

The term I shapes is used to mean ROLLED I beams and columns, universal beams andcolumns, joists, W, S, M, and HP profiles.

The code is primarily based on the BS 5950: Part 1: 1990 "British Standard Structuraluse of Steelwork in Building, Part 1. Code of practice for design in simple and continuousconstruction: hot rolled sections" adopted July 31, 1990 (79). The BS5950 code utilizes thelimit state design techniques of the BSI (British Standard Institution) specification.

The following assumptions are made throughout the BS5950 Code.

1. The member under consideration is made of one grade of steel.2. Torsional stresses are usually small when compared to axial and bending

stresses, and may be neglected. No checks are made for torsion. Thedesigner is reminded to check the torsional stresses whenever they becomesignificant.

3. Web stiffeners are not considered.4. Double angles contain an adequate number of intermediate connectors (stitch

plates) which make the two angles act as one, Tee-like section.

The sections of the BS 5950: Part 1: 1990 specifications which are considered by theGTSTRUDL BS5950 code are summarized below:

BS5950 Code GT STRUDL

Rev Q BS5950.0 - 2 V2A

SectionTitle

3 Properties of materials and section properties

3.1 General

3.1.1 Strength of steel.Table 6. Design strengths, py, for steel BS 4360.

3.5 Limiting proportions of cross sections

3.5.2 Classification of cross sections.Table 7. Limiting width to thickness ratios.

3.6 Slender cross sections

Table 8. Strength reduction factors for slender elements.

4 Design of structural elements

4.2.3 Shear

4.2.5 Moment capacity with low shear load.

4.3 Lateral torsional buckling

4.3.4 Destabilizing load.

4.3.5 Effective lengths of beams.Table 9. Effective lengths of beams.

4.3.7.6 Factors m and n, whereN is a parameter with a value of 1.0 as a default, and M is a parameter which as a default is computed according to Table 18. Equivalent uniform moment factor, m.

4.3.8 Buckling resistance moment for single angles.


V2A BS5950.0 - 3 Rev Q

SectionTitle

Shear buckling resistance of thin webs.

4.4.5 Shear buckling resistance of thin webs. See Section 4.4.5.4.1

4.4.5.4.1 General. Design using tension field action.

4.6 Axially loaded tension members

4.6.1 Tension capacity.

4.7 Compression members

4.7.2 Effective lengths.Table 24. Nominal effective length, LE, for a strut.

4.7.3.2 Maximum slenderness.(a) For members resisting loads other than wind loads.

4.7.4 Compression resistance.

4.7.7 Columns in simple construction.

4.8 Axially loaded members with moments

4.8.2 Tension members with moments.

4.8.3.2 Local capacity check.

4.8.3.3.1 Simplified approach.Overall buckling check.

4.8.3.3.2 More exact approach.Overall buckling check.

4.9 Members with biaxial moments.


Rev Q BS5950.0 - 4 V2A

SectionTitle

Appendix B Lateral torsional buckling of members subject to bending

B.2.1 General.Buckling resistance moment.

B.2.2 Elastic critical moment.

B.2.3 Perry coefficient.

B.2.4 Limiting equivalent slenderness.

B.2.5 Determination of equivalent slenderness.(a) n, see parameter n.(b) u, the buckling parameter. The u value may be

in the GTSTRUDL Table, if not, it is com-puted based on the equation in this section.

(c) J, the torsion constant.H, the warping constant.These section properties (IX for J, and H orCW) must be in the GTSTRUDL Tables. Inthe GTSTRUDL AISC Tables (i.eWSHAPES9), H is stored with a AISC nameof CW. In GTSTRUDL Tables H or CW hasto be available.

(d) v, the slenderness factor.

B.2.6.1 �LT computation.Box sections (including RHS)

Appendix C Compression strength: Perry strut formula

C.1 Basis.

C.2 Perry factor.


V2A BS5950.0 - 5 Rev Q

SectionTitle

Appendix H Web buckling

H.1 Shear buckling without utilizing tension field action.

Tensile or compressive axial stresses, bi-axial bending, shear stresses, and combinedstresses are considered by BS5950. Provisions for columns in simple construction areincluded. Parameters allowing for the changes which occur in structural steel at hightemperatures have been included and may be invoked at the user's discretion.

The properties used for each shape are defined separately under Section BS5950.1.The parameters used by BS5950 are discussed in detail in Section BS5950.2.


Rev Q BS5950.0 - 6 V2A

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GT STRUDL Properties Used by BS5950

V2A BS5950.1 - 1 Rev Q

BS5950.1 Properties Used by BS5950

This section describes the profile properties used by the BS5950 Code. Since eachshape has different properties that are required by the design code, the properties of eachshape are listed separately. The tables supplied with GTSTRUDL contain these propertiesrequired for design in addition to the properties required for analysis. New tables created bythe user should include the same properties if the BS5950 Code is to be used. Theorientation of the principle axes (Z and Y) for each shape is shown in Figure BS5950.1-1.

Properties Used by BS5950 GT STRUDL

Rev Q BS5950.1 - 2 V2A

Figure BS5950.1-1 Local Axes for Design with BS5950


V2A BS5950.1 - 3 Rev Q

Figure BS5950.1-1 Local Axes for Design with BS5950 (Continued)


Rev Q BS5950.1 - 4 V2A

I Shapes:

For W shapes and other doubly symmetric I beams, the following propertiesare required:

AX = the cross-sectional area,AY = the Y axis shear area computed as the profile depth times the

web thickness,AZ = the Z axis shear area computed as 2/3 of the total flange area,IX = the torsional moment of inertia,IY = the moment of inertia about the Y axis,IZ = the moment of inertia about the Z axis,RY = the radius of gyration about the Y axis,RZ = the radius of gyration about the Z axis,SY = the section modulus about the Y axis,SZ = the section modulus about the Z axis,FLTK = the flange thickness,WBTK = the web thickness,YD = the profile depth,YC = the positive Y direction distance from the Z axis to the extreme

fiber along the Y axis (half of the profile depth),ZD = the flange width,ZC = the positive Z direction distance from the Y axis to the extreme

fiber along the Z axis (half of the flange width),INTYD = the clear depth of the web computed as the profile depth minus

twice the flange thickness,EY = distance from centroid to shear center parallel to the Y axis,EZ = distance from centroid to shear center parallel to the Z axis,H or CW = the warping constant,ND = the nominal depth,WEIGHT = the weight per unit length,GRPNUM = 1.0SHAPE = a number that indicates the profile shape,

= 1.0, I shapes,= 1.2, H shapes,

ZY = the plastic modulus about the local Y axis,ZZ = the plastic modulus about the local Z axis,


V2A BS5950.1 - 5 Rev Q

X = the torsional index, (corresponds to x in BS5950: Part 1: 1990).If not specified, the torsional index is computed based on theequation given in the Appendix B.2.5 of BS 5950: Part 1: 1990,

U = the buckling parameter, (corresponds to u in BS5950: Part 1:1990). If not specified, the buckling parameter is computedbased on the equation given in the Appendix B.2.5 of BS 5950:Part 1: 1990.


Rev Q BS5950.1 - 6 V2A

Channels:

For channels, the following properties are required:

AX = the cross-sectional area,AY = the Y axis shear area computed as the profile depth times the

web thickness,AZ = the Z axis shear area computed as 2/3 of the total flange area,IX = the torsional moment of inertia,IY = the moment of inertia about the Y axis,IZ = the moment of inertia about the Z axis,RY = the radius of gyration about the Y axis,RZ = the radius of gyration about the Z axis,SY = the negative direction section modulus about the Y axis

(IY/(ZD�ZC)),SYS = the positive direction section modulus about the Y axis

(IY/ZC),SZ = the section modulus about the Z axis,FLTK = the flange thickness,WBTK = the web thickness,YD = the profile depth,YC = the positive Y direction distance from the Z axis to the extreme

fiber along the Y axis (half of the profile depth),ZD = the flange width,ZC = the positive Z direction distance from the Y axis to the extreme

fiber along the Z axis (from Y axis to the web extreme fiber),INTYD = the clear depth of the web computed as the profile depth minus

twice the flange thickness,EY = distance from centroid to shear center parallel to the Y axis,EZ = distance from centroid to shear center parallel to the Z axis,H or CW = the warping constant,ND = the nominal depth,WEIGHT = the weight per unit length,GRPNUM = 1.0SHAPE = a number that indicates the profile shape,

= 2.0, Channels,ZY = the plastic modulus about the local Y axis,ZZ = the plastic modulus about the local Z axis,


V2A BS5950.1 - 7 Rev Q

X = the torsional index, (corresponds to x in BS5950: Part 1: 1990).If not specified, the torsional index is computed based on theequation given in the Appendix B.2.5 of BS 5950: Part 1: 1990,



Rev Q BS5950.1 - 8 V2A

Single Angles:

For single angles, the properties are defined with respect to the principleaxes, the following properties are required:

AX = the cross-sectional area,AY = the Y-shear area along the Y-principle axis. AY is taken as a

value that will produce the maximum transverse shear from theequation FY/AY, where FY is the Y-shear force in the Y-principle axis direction. In this case, AY is taken as the term(IZ×THICK/QZ), where QZ is the first moment of the areaabove the Z-principle axis about the Z-principle axis. See S.P.Timoshekno and J.M. Gere, Mechanics of Materials, D. VonNostrand, New York, 1972.

AZ = the Z-shear area along the Z-principle axis. AZ is taken as avalue that will produce the maximum transverse shear from theequation FZ/AZ, where FZ is the Z-shear force in the Z-principle axis direction. In this case, AZ is taken as the term(IY×THICK/QY), where QY is the first moment of the areaabove the Y-principle axis about the Y-principle axis. See S.P.Timoshenko and J.M. Gere, Mechanics of Materials, D. VonNostrand, New York, 1972.

IX = the torsional moment of inertia,IY = the moment of inertia about the Y axis,IZ = the moment of inertia about the Z axis,RY = the radius of gyration about the Y axis,RZ = the radius of gyration about the Z axis,SY = the positive direction section modulus about the Y axis

(IY/ZC),SYS = the negative direction section modulus about the Y axis

(IY/(ZD-ZC)), (note, if both legs are equal, LEG1 = LEG2, thenSY = SYS)

SZ = the positive direction section modulus about the Z axis (IZ/YC),SZS = the negative direction section modulus about the Z axis

(IZ/(YD-YC)),THICK = the thickness of the single angle,LEG1 = the length of the longer leg,LEG2 = the length of the shorter leg,


V2A BS5950.1 - 9 Rev Q

YD = depth parallel to the Y axis,= LEG2×cos (ALPHA)+THICK×sin (ALPHA),

YC = the positive Y direction distance from the Z axis to the extremefiber along the Y axis,

ZD = depth parallel to principle Z axis,= LEG1×cos (ALPHA) + LEG2×sin (ALPHA)

ZC = the positive Z direction distance from the Y axis to the extremefiber along the Z axis,

ALPHA = the angle between the longer leg of the angle and the principleZ axis,

EY = distance from centroid to shear center parallel to the principleY axis,

EZ = distance from centroid to shear Center parallel to the principleZ axis,

WEIGHT = the weight per unit length,GRPNUM = 1.0SHAPE = a number that indicates the profile shape,

= 3.0, single angles.


Rev Q BS5950.1 - 10 V2A

Tees:

For tees, the following properties are required:

AX = the cross-sectional area,AY = the Y axis shear area computed as 2/3 of the profile depth times

web thickness,AZ = the Z axis shear area computed as 2/3 of the total flange area,IX = the torsional moment of inertia,IY = the moment of inertia about the Y axis,IZ = the moment of inertia about the Z axis,RY = the radius of gyration about the Y axis,RZ = the radius of gyration about the Z axis,SY = the section modulus about the Y axis,SZ = the negative direction section modulus about the Z axis

(IZ/(ZD�ZC)),SZS = the positive direction section modulus about the Z axis (IZ/ZC),FLTK = the flange thickness,WBTK = the web thickness,YD = the profile depth,YC = the positive Y direction distance from the Z axis to the extreme

fiber along the Y axis (from Z axis to top-of-flange),ZD = the flange width,ZC = the positive Z direction distance from the Y axis to the extreme

fiber along the Z axis (half of the flange width),INTYD = the clear depth of the web computed as the profile depth minus

the flange thickness,EY = distance from centroid to shear center parallel to the Y axis,EZ = distance from centroid to shear center parallel to the Z axis,ND = the nominal depth,WEIGHT = the weight per unit length,GRPNUM = 1.0SHAPE = a number that indicates the profile shape,

= 4.0, Tee,ZY = the plastic modulus about the local Y axis,ZZ = the plastic modulus about the local Z axis,X = the torsional index, (corresponds to x in BS5950: Part 1: 1990).

If not specified, the torsional index is computed based on theequation given in the Appendix B.2.5 of BS 5950: Part 1: 1990,


V2A BS5950.1 - 11 Rev Q



Rev Q BS5950.1 - 12 V2A

Double Angles:

For double angles, the following properties are required:

AX = the cross section area,AY = the Y-axis shear area computed as 2/3 of the profile depth times

twice the leg thickness,AZ = the Z-axis shear area computed as 2/3 of the total flange area,IX = the torsional moment of inertia,IY = the moment of inertia about the Y axis,IZ = the moment of inertia about the Z axis,RY = the radius of gyration about the Y axis, RZ = the radius of gyration about the Z axis, SY = the section modulus about Y axis, SZ = the negative direction section modulus about Z axis

(IZ/(ZD�ZC)), SZS = the positive direction section modulus about Z axis (IZ/ZC),THICK = the thickness of the flange (note: the thickness of both single

angles is assumed to be the same and uniform),LEGl = the length of the longer leg of each single angle which makes

up the double angle,LEG2 = the length of the shorter leg of each single angle which makes

up the double angle,SPACING = the spacing between the single angles. When each angle is in

contact, SPACING equals zero, YD = depth parallel to Y axis,YC = the positive Y direction distance from the Z axis to the extreme

fiber along the Y axis,ZD = depth parallel to Z axis,ZC = the positive Z direction distance from the Y axis to the extreme

fiber along the Z axis,EY = distance from centroid to shear center parallel to the Y axis,EZ = distance from centroid to shear center parallel to the Z axis,GRPNUM = 1.0SHAPE = a number that indicates the profile shape,

= 4.4, equal legs back-to-back double angles,= 4.5, long legs back-to-back double angles,= 4.6, short legs back-to-back double angles,

ZY = the plastic modulus about the local Y axis,


V2A BS5950.1 - 13 Rev Q

ZZ = the plastic modulus about the local Z axis,X = the torsional index, (corresponds to x in BS5950: Part 1: 1990).

If not specified, the torsional index is computed based on theequation given in the Appendix B.2.5 of BS 5950: Part 1: 1990,



Rev Q BS5950.1 - 14 V2A

Solid Round Bars:

For solid round bars, the following properties are required:

AX = the cross-sectional area,AY = the Y axis shear area computed as 3/4 of AX,AZ = the Z axis shear area computed as 3/4 of AX,IX = the torsional moment of inertia,IY = the moment of inertia about the Y axis,IZ = the moment of inertia about the Z axis,RY = the radius of gyration about the Y axis,RZ = the radius of gyration about the Z axis,SY = the section modulus about the Y axis,SZ = the section modulus about the Z axis,YD = depth parallel to Y axis (diameter of bar),YC = distance to extreme fiber in positive Y direction (radius of bar),ZD = depth parallel to Z axis (diameter of bar),ZC = distance to extreme fiber in positive Z direction (radius of bar),GRPNUM = 1.0SHAPE = a number that indicates the profile shape,

= 5.0, solid round bars,ZY = the plastic modulus about the local Y axis. If not specified, it is

computed,ZZ = the plastic modulus about the local Z axis. If not specified, it

is computed.


V2A BS5950.1 - 15 Rev Q

Pipes:

For pipes, the following properties are required:

AX = the cross-sectional area, AY = the Y axis shear area computed as 1/2 of AX, AZ = the Z axis shear area computed as 1/2 of AX, IX = the torsional moment of inertia,IY = the moment of inertia about the Y axis,IZ = the moment of inertia about the Z axis,RY = the radius of gyration about the Y axis, RZ = the radius of gyration about the Z axis,SY = the section modulus about the Y axis, SZ = the section modulus about the Z axis, OD = the outside diameter of the pipe, ID = the inside diameter of the pipe,THICK = the thickness of the pipe, YD = depth parallel to Y axis (OD),YC = distance to extreme fiber in positive Y direction (OD/2.0),ZD = depth parallel to Z axis (OD),ZC = distance to extreme fiber in positive Z direction (OD/2.0),ND = the nominal depth,GRPNUM = 1.0SHAPE = a number that indicates the profile shape,

= 5.1, pipes,ZY = the plastic modulus about the local Y axis,ZZ = the plastic modulus about the local Z axis.


Rev Q BS5950.1 - 16 V2A

Square and Rectangular Bars:

For square and rectangular bars. Both the square and rectangular bars requirethe following properties:

AX = the cross-sectional area, AY = the Y axis shear area computed as 2/3 of AX, AZ = The Z axis shear area computed as 2/3 of AX, IX = the torsional moment of inertia,IY = the moment of inertia about the Y axis,IZ = the moment of inertia about the Z axis,RY = The radius of gyration about the Y axis, RZ = the radius of gyration about the Z axis, SY = the section modulus about the Y axis,SZ = the section modulus about the Z axis,YD = depth parallel to Y axis,YC = distance to extreme fiber in positive Y direction (YD/2),ZD = depth parallel to Z axis,ZC = distance to extreme fiber in positive Z direction (ZD/2),GRPNUM = 1.0SHAPE = a number that indicates the profile shape,

= 6.0, square bars,= 6.1, rectangular bars,

ZY = the plastic modulus about the local Y axis. If not specified, itis computed,

ZZ = the plastic modulus about the local Z axis. If not specified, itis computed.


V2A BS5950.1 - 17 Rev Q

Structural Tubing:

For structural tubing, the following properties are required:

AX = the cross-sectional area, AY = the Y axis shear area computed as twice the web thickness

times the flat width of the web,AZ = the Z axis shear area computed as twice the flange thickness

times the flat width of the flange, IX = the torsional moment of inertia,IY = the moment of inertia about the Y axis,IZ = the moment of inertia about the Z axis,RY = the radius of gyration about Y axis,RZ = the radius of gyration about Z axis,SY = the section modulus about Y axis,SZ = the section modulus about Z axis,FLTK = the flange thickness,WBTK = the web thickness, YD = the profile depth, YC = the positive Y direction distance from the Z axis to the extreme

fiber along the Y axis (YD/2),ZD = the profile width, ZC = the positive Z direction distance from the Y axis to the extreme

fiber along the Z axis (ZD/2),INTYD = the flat width of the web (YD�2×FLTK�2×radius),INTZD = the flat width of the flange (ZD�2×WBTK�2×radius),EY = distance from centroid to shear center parallel to the Y axis,EZ = distance from centroid to shear center parallel to Z axis,ND = the nominal depth,GRPNUM = 1.0SHAPE = a number that indicates the profile shape,

= 6.2, structural tubing,ZY = the plastic modulus about the local Y axis,ZZ = the plastic modulus about the local Z axis.


Rev Q BS5950.1 - 18 V2A

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