Joist Models in Standard Structural Software September 24, 2015 Dave Samuelson, P.E. Nucor New Product & Market Development Joe Pote, P.E. New Millennium Building Systems
Learning Objectives What are the advantages and disadvantages to using classic tools to select conventional standard joists and Joist Girder designations? What are a Virtual Joist and Virtual Joist Girder and how are they used? In what situation might it be advantageous for a Structural Engineer to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When a Virtual Joist or Virtual Joist Girder is used in the building design model, how should it be specified on the contract structural drawings? 2
Joist Models in Standard Structural Software Joists and Joist Girders in a RAM-Steel Rendering 3
Learning Objectives What are the advantages and disadvantages to using classic tools to select conventional standard joists and Joist Girder designations? 4
Learning Objectives What are the advantages and disadvantages to using classic tools to select conventional standard joists and Joist Girder designations? What are a Virtual Joist and Virtual Joist Girder and how are they used? 5
Learning Objectives What are the advantages and disadvantages to using classic tools to select conventional standard joists and Joist Girder designations? What are a Virtual Joist and Virtual Joist Girder and how are they used? In what situation might it be advantageous for a Structural Engineer to use the SJI Virtual Joist Table or Virtual Joist Girder Table? 6
Learning Objectives What are the advantages and disadvantages to using classic tools to select conventional standard joists and Joist Girder designations? What are a Virtual Joist and Virtual Joist Girder and how are they used? In what situation might it be advantageous for a Structural Engineer to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When a Virtual Joist or Virtual Joist Girder is used in the building design model, how should it be specified on the contract structural drawings? 7
Advantages and Disadvantages to using Classic Tools to select Standard Joists and Joist Girders Classic Roof and Floor Framing Optimizers such as RAM-Steel or RISA- Floor General Structural Analysis Software such as STAAD, RISA or STRUDL 8
Classic Roof and Floor Framing Optimizers such as RAM-Steel or RISA-Floor Excellent job of selecting optimum Standard joists (Pro) 9
Standard Joists Selected based on Span and Loading RAM-Steel Partial Framing Plan 10
Classic Roof and Floor Framing Optimizers such as RAM-Steel or Risa-Floor Excellent job of selecting optimum Standard joists (Pro) Cannot actually select Joist Girders, as there are no standard Joist Girders to select from. Joist Girder Designation is specified based on loading and user-provided depth. (Con) 11
Joist Girder Designations Assigned based on Loading and User-Provided Depth RAM-Steel Partial Framing Plan without User-Provided Depth 12
Classic Roof and Floor Framing Optimizers such as RAM-Steel Excellent job of selecting optimum Standard joists (Pro) Cannot actually select Joist Girders, as there are no standard Joist Girders to select from. Joist Girder Designation is specified based on loading and user-provided depth. (Con) Joists and Joist Girders automatically appear on the Structural Drawings with correct designation needed by the Joist Manufacturer for quoting, designing and manufacturing. (Pro) 13
Joist and Girder Designations displayed in Conventional Format RAM-Steel Partial Framing Plan 14
Joist and Girder Designations transferred to CAD in Conventional Format AutoCAD Partial Framing Plan 15
Classic Roof and Floor Framing Optimizers such as RAM-Steel Excellent job of selecting optimum Standard joists (Pro) Cannot actually select Joist Girders, as there are no standard Joist Girders to select from. Joist Girder Designation is specified based on loading and user-provided depth. (Con) Joists and Joist Girders automatically appear on the Structural Drawings with correct designation needed by the Joist Manufacturer for quoting, designing and manufacturing. (Pro) Joists can only be managed as simple-span infill joists supporting vertical gravity loads. Standard joist designations and definition do not address negative moments, end moments, or axial loads. (Con) 16
Advantages and Disadvantages to using Classic Tools to select Standard Joists and Joist Girders Classic Roof and Floor Framing Optimizers such as RAM-Steel General Structural Analysis Software such as STAAD, RISA or STRUDL 17
General Structural Analysis Software such as STAAD, RISA, or STRUDL No Section Properties available for standard joists and girders. Therefore, the joists and girders cannot be included in the stiffness matrix model. (Con) 18
Steel Joist and Joist Girder Stiffness are not included in the Structural Model Quote from STAAD-Pro Technical Reference Manual 19
General Structural Analysis Software such as STAAD, RISA, or STRUDL No Section Properties available for standard joists and girders. Therefore, the joists and girders cannot be included in the stiffness matrix model. (Con) Some general analysis software does include tools for selecting joists and treats the joist as a load distribution link an infinitely rigid simply supported infill component between supporting members. (Pro) 20
Joists Treated as Links with Simple Selection Tools Screen Shot of STAAD-Pro Joist Database Table Tool 21
Learning Objectives What are the advantages and disadvantages to using classic tools to select conventional standard joists and Joist Girder designations? What are a Virtual Joist and Virtual Joist Girder and how are they used? In what situation might it be advantageous for a Structural Engineer to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When a Virtual Joist or Virtual Joist Girder is used in the building design model, how should it be specified on the contract structural drawings? 22
What are a Virtual Joist and Virtual Joist Girder? Virtual Joists and Virtual Joist Girders are a set of pseudo section properties based on commonly available joist chord pairs. 23
What are a Virtual Joist and Virtual Joist Girder? Excerpt from Virtual Joist Girder Table 24
What are a Virtual Joist and Virtual Joist Girder? Virtual Joists and Virtual Joist Girders are a set of pseudo section properties based on commonly available joist chord pairs. The major axis moment of inertia (I Z ) is based directly on the pair of double angle joist chords and pre-adjusted for approximate deflection contribution from web strain. The Area is likewise based directly on the pair of double angle joist chords. 25
What are a Virtual Joist and Virtual Joist Girder? Virtual Joist Girder Section Properties: A x : Total Area of Top and Bottom Chords Sum of top and bottom chord areas D: Total VJG Depth I z : VJG Strong-Axis Effective Moment of Inertia Classically calculated Moment of Inertia of the Chords divided by 1.15 to account for deflection effects from the joist web members. 26
Virtual Joist Section Properties, I z From SJI 43 rd Edition Joist Catalog, Page 14: 27
Virtual Joist Section Properties, Izz From SJI Technical Digest 11, Design of Lateral Load Resisting Frames using Steel Joists and Joist Girders : 28
What are a Virtual Joist and Virtual Joist Girder? Virtual Joists and Virtual Joist Girders are a set of pseudo section properties based on commonly available joist chord pairs. The major axis moment of inertia (I Z ) is based directly on the pair of double angle joist chords and pre-adjusted for approximate deflection contribution from web strain. The Area is likewise based directly on the pair of double angle joist chords. All other section properties are equivalent wide-flange beam properties manipulated to encourage selection of the appropriate Virtual Joist and/ or Virtual Joist Girder when checked against a Wide-Flange Beam selection routine. 29
What are a Virtual Joist and Virtual Joist Girder? Sample VJ & VJG Section Properties: TD: Web Thickness Total Depth/30; Ensures that the sec7on is treated as "compact" when considering web shear. B: Flange Width 2*Chord Angle Leg + 1" Chord Gap TB: Flange Thickness (Chord angle thickness)/(chord angle leg) * B/2; This value results in the correct width/thickness ra7o when STAAD checks (B/2)/TB. 30
What are a Virtual Joist and Virtual Joist Girder? Virtual Joists and Virtual Joist Girders are a set of pseudo section properties based on commonly available joist chord pairs. The major axis moment of inertia (I Z ) is based directly on the pair of double angle joist chords and pre-adjusted for approximate deflection contribution from web strain. The Area is likewise based directly on the pair of double angle joist chords. All other section properties are equivalent wide-flange beam properties manipulated to encourage selection of the appropriate Virtual Joist and/ or Virtual Joist Girder when checked against a Wide-Flange Beam selection routine. The Virtual Joist and Virtual Joist Girder tables provide approximate section properties suitable for use in a stiffness based structural analysis program. Testing at South Dakota School of Mine and Technology has verified that Virtual Joists and Virtual Joist Girders selected via STAAD and/or RAM using a broad range of loading scenarios result in section properties reasonably close to those in the final joist and Joist Girder designs. 31
SDSM&T Comparison Study of VJ and VJG K-Series Span/Load Test Matrix 32
SDSM&T Comparison Study of VJ and VJG Moment of Inertia Variance vs- Depth for Simply Supported K-Series Tests 33
SDSM&T Comparison Study of VJ and VJG LH-Series Span/Load Test Matrix 34
SDSM&T Comparison Study of VJ and VJG Moment of Inertia Variance vs- Depth for Simply Supported LH-Series Tests 35
Learning Objectives What are the advantages and disadvantages to using classic tools to select conventional standard joists and Joist Girder designations? What are a Virtual Joist and Virtual Joist Girder and how are they used? In what situation might it be advantageous for a Structural Engineer to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When a Virtual Joist or Virtual Joist Girder is used in the building design model, how should it be specified on the contract structural drawings? 36
When might it be advantageous to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When sizing joists for special loads (anything other than full-length uniform design loads) 37
Not all Design Loads are Uniformly Distributed Sample Special Load Diagram from SJI COSP 38
When might it be advantageous to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When sizing joists for special loads (anything other than full-length uniform design loads) A more accurate estimate of appropriate joist and/or Joist Girder depth and weight can be found using the Virtual Joist and Virtual Joist Girder tables than by using equivalent uniform loads and standard joist load tables. 39
When might it be advantageous to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When sizing joists for special loads (anything other than full-length uniform design loads) When sizing joists for conditions with negative moments, such as cantilevered joists and/or joists with intermediate supports (multi-span conditions). 40
Not all Joists are Simply Supported Cantilevered Joist Diagram from SJI 43 rd ed Catalog 41
When might it be advantageous to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When sizing joists for special loads (anything other than full-length uniform design loads) When sizing joists for conditions with negative moments, such as cantilevered joists and/or joists with intermediate supports (multi-span conditions). Anytime it is desirable to include the joists and/or Joist Girders directly in the structural model with appropriate approximate section properties. 42
When might it be advantageous to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When sizing joists for special loads (anything other than full-length uniform design loads) When sizing joists for conditions with negative moments, such as cantilevered joists and/or joists with intermediate supports (multi-span conditions). Anytime it is desirable to include the joists and/or Joist Girders directly in the structural model with appropriate approximate section properties. Particularly when joists and/or Joist Girders are used as part of a lateral load resisting frame. The VJ and VJG tables allow easy selection of appropriate depths with appropriate approximate section properties for use in the structural model. 43
Not all Joists are Simply Supported Frame Model with Joist Girders 24 @ 5'-0" = 120'-0" P P P WIND = 1000 plf 23'-6" 5 6 7 G3 G4 P : DL = 2.4 kips G3 LL = 4.0 kips TL = 6.4 kips 1 2 WL = 7.0 kips 3 4 WIND = 1000 plf FRAME MODEL @ GRID LINE B & E 44
Not all Joists are Simply Supported Mark Target Ix [in 4 ] Joist Girder End Moment Schedule Fixed-End Moments (Pos. is Counter-Clockwise) Couples between Top & Bottom Chord Left Ext r Col. Dead [ft-k] Live [ft-k] Wind [ft-k] Acting to Right Right Int r Col. Left Ext r Col. Right Int r Col. Left Ext r Col. Right Int r Col. Wind [ft-k] Acting To Left Left Ext r Col. Right Int r Col. G1 931 G2 931 24.5-24.5 38.2-38.2-204.9-71.2 71.2 204.9 G3 1347 11.2-51.5 17.8-81.8-55.5-106.6-5.8 396.0 G4 1521 G5 1521 G6 1236 44.0-44.0 70.2-70.2-398.9-153.3 153.3 398.9 45
Learning Objectives What are the advantages and disadvantages to using classic tools to select conventional standard joists and Joist Girder designations? What are a Virtual Joist and Virtual Joist Girder and how are they used? In what situation might it be advantageous for a Structural Engineer to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When a Virtual Joist or Virtual Joist Girder is used in the building design model, how should it be specified on the contract structural drawings? 46
How should a Virtual Joist or Virtual Joist Girder be Specified on the Structural Drawings? It is important to specify all joists and Joist Girders using conventional SJI designation nomenclature. 47
ASD 28K7 Joist 185/100 Uniform Load (PLF) 50 Span 28 Joist Depth Standard Joist Designation ASD Allowable 28 Joist Depth K Joist 7 Chord Strength In Inches Series Size Design 48
ASD 28K Load/Load Joist 185/100 Uniform Load (PLF) 50 Span 28 Joist Depth ASD 28K 185/100 185 = Total safe uniformly distributed load carrying capacity in PLF of ASD K-Series Steel Joists 100 = Nominal LIVE loads per lineal foot of joist. Load/Load Joist Designation ASD Allowable 28 Joist Depth K Joist 185 Total Load 100 Live Load Strength In Inches Series Capacity Capacity Design PLF PLF 49
Standard Joist Girder Joist Space 11.9K 11.9K 11.9K 11.9K 11.9K 11.9K 11.9K Joist Girder Span (C.L. of Column to C.L. of Column) 44 Depth Standard Joist Girder Designation ASD Allowable Strength Design 44G Depth of Girder in Inches 8N Number of Joist Spaces 11.9K Load in Kips at Each Panel Point 50
How should a Virtual Joist or Virtual Joist Girder be Specified on the Structural Drawings? It is important to specify all joists and Joist Girders using conventional SJI designation nomenclature. The VJ and/or VJG selections cannot be used as a substitute for the joist and Joist Girder designations. It may, at times, be helpful to include these as additional information. However, they do not provide the information needed by the joist manufacturer to design and manufacture the joists and joist girders required for the project. 51
Virtual Joist Girder Designation An Example from a set of Structural Drawings Standard Designation Above VJG Designation Below 52
How should a Virtual Joist or Virtual Joist Girder be Specified on the Structural Drawings? It is important to specify all joists and Joist Girders using conventional SJI designation nomenclature. The VJ and/or VJG selections cannot be used as a substitute for the joist and Joist Girder designations. It may, at times, be helpful to include these as additional information. However, they do not provide the information needed by the joist manufacturer to design and manufacture the joists and joist girders required for the project. For Joist Girders, specify the designation based on depth, number of joist spaces, and joist reaction. If the loading is unequal, unequally spaced, or includes special loads, use a load diagram and/or load schedule. 53
Virtual Joist Girder Reporting Loads Mark Designation Panel Point Loads Axial (Pos. causes Tens.) Split between Top & Bottom Chord Dead [kips] Live [kips] Total (D+L) Wind [kips] Dead [kips] Live [kips] Wind [kips] [kips] G1 36G8N 1.2 2.0 3.2 ±3.5 ±5.88 G2 36G8N 1.2 2.0 3.2 ±3.5 1.04 1.63 ±2.84 G3 36G8N 2.4 4.0 6.4 ±7.0 0.48 0.76 ±9.39 G4 36G8N 2.4 4.0 6.4 ±7.0 1.71 2.72 ±4.85 G5 36G8N 2.4 4.0 6.4 ±7.0 ±11.75 G6 36G8N 2.4 4.0 6.4 ±7.0 1.87 2.99 ±5.23 54
Virtual Joist Girder Reporting Loads Mark Target Ix [in 4 ] Fixed-End Moments (Pos. is Counter-Clockwise) couples Between Top & Bottom Chord Left Ext r Col. Dead [ft-k] Live [ft-k] Wind [ft-k] Acting to Right Right Int r Col. Left Ext r Col. Right Int r Col. Left Ext r Col. Right Int r Col. Wind [ft-k] Acting To Left Left Ext r Col. Right Int r Col. G1 931 G2 931 24.5-24.5 38.2-38.2-204.9-71.2 71.2 204.9 G3 1347 11.2-51.5 17.8-81.8-55.5-106.6-5.8 396.0 G4 1521 G5 1521 G6 1236 44.0-44.0 70.2-70.2-398.9-153.3 153.3 398.9 55
How should a Virtual Joist or Virtual Joist Girder be Specified on the Structural Drawings? It is important to specify all joists and Joist Girders using conventional SJI designation nomenclature. The VJ and/or VJG selections cannot be used as a substitute for the joist and Joist Girder designations. It may, at times, be helpful to include these as additional information. However, they do not provide the information needed by the joist manufacturer to design and manufacture the joists and joist girders required for the project. For Joist Girders, specify the designation based on depth, number of joist spaces, and joist reaction. If the loading is unequal, unequally spaced, or includes special loads, use a load diagram and/or load schedule. For joists, specify the designation using either a standard joist designation or a load/load joist designation. For special loading conditions, show all loads on the framing plan, in load diagrams and/or a load schedule. 56
How should a Virtual Joist or Virtual Joist Girder be Specified on the Structural Drawings? It is important to specify all joists and Joist Girders using conventional SJI designation nomenclature. The VJ and/or VJG selections cannot be used as a substitute for the joist and Joist Girder designations. It may, at times, be helpful to include these as additional information. However, they do not provide the information needed by the joist manufacturer to design and manufacture the joists and joist girders required for the project. For Joist Girders, specify the designation based on depth, number of joist spaces, and joist reaction. If the loading is unequal, unequally spaced, or includes special loads, use a load diagram and/or load schedule. For joists, specify the designation using either a standard joist designation or a load/ load joist designation. For special loading conditions, show all loads on the framing plan, in load diagrams and/or a load schedule. For joists and/or Joist Girders used as part of a lateral load resisting frame, provide the Joist Moment of Inertia used in the structural model (from the VJ and/or VJG tables) as a target value for the Joist Manufacturer. It is recommended to specify that the Joist Manufacturer is to contact the Structural Engineer of Record regarding moments of inertia that deviate from the target values by more than 10%. 57
Virtual Joist Girder Reporting Loads Mark Target Effective Ix [in 4 ] Fixed-End Moments (Pos. is Counter-Clockwise) couples Between Top & Bottom Chord Left Ext r Col. Dead [ft-k] Live [ft-k] Wind [ft-k] Acting to Right Right Int r Col. Left Ext r Col. Right Int r Col. Left Ext r Col. Right Int r Col. Wind [ft-k] Acting To Left Left Ext r Col. Right Int r Col. G1 931 G2 931 24.5-24.5 38.2-38.2-204.9-71.2 71.2 204.9 G3 1347 11.2-51.5 17.8-81.8-55.5-106.6-5.8 396.0 G4 1521 G5 1521 G6 1236 44.0-44.0 70.2-70.2-398.9-153.3 153.3 398.9 Note: Please contact the Project Structural Engineer of Record if the final effective Joist Girder Moment of Inertia (Ix) varies from the tabulated target value by more than 10% 58
Current Access to VJ and VJG in Structural Software STAAD / STAAD-Pro VJG Table available as a built-in VJ Table available as a User Defined Table which can be downloaded from the SJI website RAM / RAM-Structural VJG Table available as a built-in RISA and RISA-Floor VJG Table available as a built-in Scia Engineer (scheduled for October release) VJG Table available as built-in Uses VJG Depth for Conventional Girder Designation VJ Table available as built in Uses VJ Depth for Load/Load Joist Designation 59
Current Access to VJ and VJG in Structural Software STAAD / STAAD-Pro VJG Table available as a built-in VJ Table available as a User Defined Table which can be downloaded from the SJI website RAM / RAM-Structural VJG Table available as a built-in RISA and RISA-Floor VJG Table available as a built-in Scia Engineer (scheduled for October release) VJG Table available as built-in Uses VJG Depth for Conventional Girder Designation VJ Table available as built in Uses VJ Depth for Load/Load Joist Designation 60
Virtual Joist Girder RAM-Steel Screen Shot with VJG Designations 61
Current Access to VJ and VJG in Structural Software STAAD / STAAD-Pro VJG Table available as a built-in VJ Table available as a User Defined Table which can be downloaded from the SJI website RAM / RAM-Structural VJG Table available as a built-in RISA and RISA-Floor VJG Table available as a built-in Scia Engineer (scheduled for October release) VJG Table available as built-in Uses VJG Depth for Conventional Girder Designation VJ Table available as built in Uses VJ Depth for Load/Load Joist Designation 62
Virtual Joist Girder RISA-Floor Screen Shot with VJG Designations 63
Virtual Joist Girder RISA-3D Screen Shot with VJG Designations 64
Current Access to VJ and VJG in Structural Software STAAD / STAAD-Pro VJG Table available as a built-in VJ Table available as a User Defined Table which can be downloaded from the SJI website RAM / RAM-Structural VJG Table available as a built-in RISA and RISA-Floor VJG Table available as a built-in Scia Engineer (scheduled for October release) VJG Table available as built-in Uses VJG Depth for Conventional Girder Designation VJ Table available as built in Uses VJ Depth for Load/Load Joist Designation 65
Virtual Joist and Virtual Joist Girder Scia uses VJ & VJG Designations for Stiffness Modeling 66
Virtual Joist and Virtual Joist Girder Scia overlays the VJ/VJG Designations with Conventional Designations 67
Virtual Joist and Virtual Joist Girder Scia uses the VJ/VJG Depths in Defining Special Joist and Joist Girder Designations 68
Learning Objectives What are the advantages and disadvantages to using classic tools to select conventional standard joists and Joist Girder designations? What are a Virtual Joist and Virtual Joist Girder and how are they used? In what situation might it be advantageous for a Structural Engineer to use the SJI Virtual Joist Table or Virtual Joist Girder Table? When a Virtual Joist or Virtual Joist Girder is used in the building design model, how should it be specified on the contract structural drawings? 69
Conclusions The classic tools, though limited, provide a very effective means of selecting standard joists with appropriate designations. Popular structural design packages are beginning to incorporate Virtual Joists and Virtual Joist Girders, thereby allowing more modeling flexibility. For simple-span uniformly loaded conditions, the classic tools are simple, accurate and easy to use. For complex loading and/or complex support conditions, the VJ and VJG tables provide a good tool for incorporation in the structural model. Current use of VJ and VJG requires the user to manually follow up with their own standard format designation for use on Structural Framing Plan. Some structural software packages are now working toward incorporating VJ and VJG in such a way as to automate the accompanying standard format designation. 70
Conclusions The classic tools, though limited, provide a very effective means of selecting standard joists with appropriate designations. Popular structural design packages are beginning to incorporate Virtual Joists and Virtual Joist Girders, thereby allowing more modeling flexibility. For simple-span uniformly loaded conditions, the classic tools are simple, accurate and easy to use. For complex loading and/or complex support conditions, the VJ and VJG tables provide a good tool for incorporation in the structural model. Current use of VJ and VJG requires the user to manually follow up with their own standard format designation for use on Structural Framing Plan. Some structural software packages are now working toward incorporating VJ and VJG in such a way as to automate the accompanying standard format designation. 71
Conclusions The classic tools, though limited, provide a very effective means of selecting standard joists with appropriate designations. Popular structural design packages are beginning to incorporate Virtual Joists and Virtual Joist Girders, thereby allowing more modeling flexibility. For simple-span uniformly loaded conditions, the classic tools are simple, accurate and easy to use. For complex loading and/or complex support conditions, the VJ and VJG tables provide a good tool for incorporation in the structural model. Current use of VJ and VJG requires the user to manually follow up with their own standard format designation for use on Structural Framing Plan. Some structural software packages are now working toward incorporating VJ and VJG in such a way as to automate the accompanying standard format designation. 72
Conclusions The classic tools, though limited, provide a very effective means of selecting standard joists with appropriate designations. Popular structural design packages are beginning to incorporate Virtual Joists and Virtual Joist Girders, thereby allowing more modeling flexibility. For simple-span uniformly loaded conditions, the classic tools are simple, accurate and easy to use. For complex loading and/or complex support conditions, the VJ and VJG tables provide a good tool for incorporation in the structural model. Current use of VJ and VJG requires the user to manually follow up with their own standard format designation for use on Structural Framing Plan. Some structural software packages are now working toward incorporating VJ and VJG in such a way as to automate the accompanying standard format designation. 73
Conclusions The classic tools, though limited, provide a very effective means of selecting standard joists with appropriate designations. Popular structural design packages are beginning to incorporate Virtual Joists and Virtual Joist Girders, thereby allowing more modeling flexibility. For simple-span uniformly loaded conditions, the classic tools are simple, accurate and easy to use. For complex loading and/or complex support conditions, the VJ and VJG tables provide a good tool for incorporation in the structural model. Current use of VJ and VJG requires the user to manually follow up with their own standard format designation for use on Structural Framing Plan. Some structural software packages are now working toward incorporating VJ and VJG in such a way as to automate the accompanying standard format designation. 74
Conclusions The classic tools, though limited, provide a very effective means of selecting standard joists with appropriate designations. Popular structural design packages are beginning to incorporate Virtual Joists and Virtual Joist Girders, thereby allowing more modeling flexibility. For simple-span uniformly loaded conditions, the classic tools are simple, accurate and easy to use. For complex loading and/or complex support conditions, the VJ and VJG tables provide a good tool for incorporation in the structural model. Current use of VJ and VJG requires the user to manually follow up with their own standard format designation for use on Structural Framing Plan. Some structural software packages are now working toward incorporating VJ and VJG in such a way as to automate the accompanying standard format designation. 75