Connection Design Standard-Document

CONNECTION DESIGN STANDARD

DOC NO: CDS-1

CONNECTION DESIGN STANDARDSDOCUMENT NO: CDS-1 SECOND EDITION DATE: DECEMBER 9, 2005


DOC NO: CDS-1

TABLE OF CONTENTS Section 1 2 3 4 Description Connection Components Allowable Loads Connection Types Shear Connections Double Clip-Angle Connections Single-Plate Connections Seated Beam Connections Beam Copes and Cope Reinforcement Figures 4.1 thru 4.27 Moment Connections Directly welded flanges Flange plate connection Figures 5.1 thru 5.6 Truss and Vertical Bracing Connection Single Brace Connections Double Brace Connections Chevron Bracing Connections Brace connection at column base X-brace connection Figures 6.1 thru 6.26 Horizontal Bracing Connection Shear-tab Connections Clip-Angle Connections Figures 7.1 thru 7.6 Splices Connection Capacity Tables Calculation Summary Table Templates Design Software and Worksheets Page No 1-1 thru 1-3 2-1 thru 2-8 3-1 thru 3-2 4-1 thru 4-50 Release Date

5

5-1 thru 5-7 8/12/05 6-1 thru 6-27

6

7

7-1 thru 7-7

8 Appendix A Appendix B Appendix C

8-1 thru 8-5 A-1 thru A-7 B-1 thru B-36 C-1 thru C-33

12/9/05

Page i


DOC NO: CDS-1

REFERENCES AISC Manual of Steel Construction, Allowable Stress Design, 9th Edition, Vol I AISC Manual of Steel Construction, Allowable Stress Design, 9th Edition, Vol II Connections Steel Structures, Design and Behavior, by Charles G. Salmon and John E. Johnson. Design of Welded Structures, A Publication of The James F. Lincoln Arc Welding Foundation, June 1996 5. Hollow Structural Sections, Connections Manual, 1st Edition, 1997 1. 2. 3. 4.

Page ii

CONNECTION DESIGN STANDARD1.0 Connection Components

DOC NO: CDS-1 Prep by: JVJ Chkd by: MNG

Members are connected by means of welding or bolting. Structural framing members of a building are usually connected using high strength bolts. The different components of a connection are as follows. A connection can have some or all of the components listed below. 1. Beam/Column Web 2. Beam/Column Flange 3. Bracing Member 4. Bolts, Nuts and Washers 5. Welds 6. Clip Angle (Used for connecting beam webs to column or other beams) 7. Gusset Plate (Typically the plates at the ends of bracing members) 8. Seat Plate 9. Seat Angle 10. Stiffener Plate Used to stiffen another plate against yielding, crippling, buckling, bending etc. Typically these are provided at column or beam webs, seat plate, etc. 11. Web Doubler Plate 12. Bearing Plate 13. Cap Plate Each of the components of the connection is checked for their limit states or failure modes. In addition to checking these components of the connection, local checks of the beam and column have to be done. The local checks include the beam copes, beam web, column web and column flange. The limit states for the connection components are as follows. 1. 2. 3. 4. 5. 6. 7. 8. Bolt failure due to shear or tension Weld failure Shear yielding (of beam web, of clip angle, etc) on gross area Shear rupture (of beam web, of clip angle, etc) on net area Tension yielding on gross area Tension rupture on effective net area Block shear (failure by shear and tension) of a block of material Bolt bearing (failure caused by excessive deformation at bolt holes or limited by proximity to a loaded edge) 9. Flexural yielding 10. Web yielding 11. Web crippling 12. Web buckling 13. Flange local bending 14. Prying action (causes additional tension in bolts based on the flexural stiffness of the connecting elements) 15. Whitmore section yielding or buckling of gusset plate at the ends of the bracing members



1.1 Material Requirement Bolts: The two common types of high-strength bolts are A325 and A490. A325 bolts are heat treated, while A490 bolts are heat treated and are of alloy steel. High-strength bolts are installed with a pre-tension. The pre-tension loads are given in Table J3.7 of AISC Manual, Specification Section J3. For structures that are not part of the main or critical load carrying system of a building, A307 carbonsteel bolts that are not heat-treated may be specified. High-strength bolts are pre-tensioned using one of the three methods, which are the calibrated wrench method, the turn-of-the-nut method and direct tension indicator method. The Specification for Structural Joints Using ASTM A325 or A490 Bolts provided in the AISC Manual discusses these methods in detail. The calibrated wrench method uses a manual or power wrench that stalls at a specified torque. The specified torque is calculated to obtain the desired tension in the bolt. The turn-of-the-nut method develops the pretension in the bolt by turning the nut through a specified rotation past the snug condition. The turn-of-the-nut method is more reliable than calibrated wrench method. The direct tension indicator method uses a hardened washer with protrusions on one face. When bolts are tensioned, the protrusions are flattened. The amount of gap remaining will indicate the amount of tension in the bolt. Recent development is the tension control (TC) bolts, which are torqued until the tip snaps off the threaded portion of the bolt indicating that the desired tension has been obtained. The TC bolts are covered by ASTM F1852. Washers: Shall be per ASTM F436. For A325 bolts, generally one hardened washer is provided under the turned element. For A490 bolts, hardened washer under the bolt head and the nut is provided. When long slotted holes are used in an outer ply, a plate washer at least 5/16 thick with a standard hole could be used. These washers shall be sized to cover the slot after installation. For A490 bolts a hardened washer 5/16 thick minimum shall be used. Nuts: For ASTM A325 bolts, nuts shall be per ASTM A563, grades C, C3, D, DH or DH3 or A194 grade 2H. For galvanized bolts, nuts shall be per ASTM A563 grade DH or A194 grade 2H. Nuts for A490 bolts shall be A563 grade DH or DH3 or A194 grade 2H.. Welding Material Common weld electrode used for joing carbon steel elements is the E70 weld electrode having a tensile strength of 70 ksi. E60 may also be specified but is not used extensively.



Table 1-1: Material Properties Connection Components (Commonly Specified) (Note 1) Component Beam/Column Members Brace/Truss Members Shapes/Plates/Misc Wide Flange Wide Flange Square or Rectangular HSS Wide Flange Wide Flange Angle Tee (Cut from W Shapes) Round HSS Square or Rectangular HSS to 1 dia 1 1/8 to 1 dia to 1 dia to 1 dia 1 1/8 dia Plate ASTM Designation A992 A36 A500 Grade B A992 A36 A36 A992 A36 A53 Type E, Grade B A500 Grade B A325 A325 A490 F1852 (TC bolts) F1852 (TC bolts) A307 A36 A572 Grade 50 A36 Min Yield Strength 50 ksi 36 ksi 46 ksi 50 ksi 36 ksi 36 ksi 50 ksi 36 ksi 35 ksi 46 ksi 92 ksi 81 ksi 92 ksi 81 ksi 36 ksi Min Tensile Strength 65 ksi 58 ksi 58 ksi 65 ksi 58 ksi 58 ksi 65 ksi 58 ksi 60 ksi 58 ksi 120 ksi 105 ksi 150 ksi 120 ksi 105 ksi 60 ksi 58 ksi AISC Manual Ref Page Pg. 1-7 Pg. 1-92 Pg. 1-7 Pg. 1-7 Pg. 1-7 Pg. 1-92 Pg. 1-92 Pg. 4-4

High-Strength Bolts

Common Bolts Gusset/Stiffener/B earing/Seat/Web Doubler/Cap Plates Clip/Seat/Claw Angles

Pg. 4-4 Pg. 1-7

Angle

36 ksi

58 ksi

Pg. 1-7

Note 1: For additional material properties not covered in the table, see the AISC Manual Reference pages.

CONNECTION DESIGN STANDARD2.0 Allowable Loads for Bolts and Welds


2.1 Bolts The Allowable Loads for bolts in tension is given in Table I-A of AISC Manual, Vol I. The Allowable Loads for bolts in shear is given in Table I-D of AISC Manual, Vol I. When slipcritical bolts are used in a connection, the resistance to slip is provided by the clamping force across the faying surface. The resistance is calculated as the clamping force times a coefficient of friction. The coefficient of friction varies depending on the type of surface preparation and the coating specified for the steel. Generally, the design is based on a Class A surface. When steel is galvanized, the Class C friction coefficient can be used. The friction coefficient for various class of surface is provided in Specification for Structural Joints Using ASTM A325 or A490 Bolts. The allowable shear given in Table I-D is based on a Class A surface. These allowable can be revised (increased) if the faying surface is Class B or Class C. The Allowable Loads for bolts in bearing on different material thicknesses is given in Table I-E of AISC Manual, Vol I. Bolt allowables shall be reduced when using oversized or slotted holes. Short slotted holes can be used in any or all plies of the connection. Long slotted holes are generally provided in only one ply of the connection. In bearing-type connection, the bolts shall not be considered to share the load with the weld. However, in slip-critical connections, bolts and welds shall be considered to share the load. However, it is preferable to avoid such situations. Bolt and weld group subjected to shear load with an eccentricity can be designed using either elastic method or the ultimate strength method, also called the instantaneous center of rotation method. AISC Manual provides coefficients for both bolt and weld groups based on the instantaneous center of rotation method. These Tables are conservative for slip-critical bolts and when used for ASTM A490 bolts. When the eccentric shear load is at an angle to the vertical, AISC Manual provides a procedure for using the instantaneous center of rotation method. See Alternate Method 2, pgs. 4-59 thru 4-61 in the AISC Manual. In lieu of this alternate method, the elastic method can always be used. The load obtained by elastic method is about 10% less than what is obtained by the ultimate load method. However, when bolt groups do not conform to the pattern given in the AISC Tables XI through XVIII, the elastic method shall be used.



2.1.a Elastic Method of Bolt Analysis for bolts subjected to loads in the plane of the connection Let the assumed plane of the connection be X and Y Loads: Px, Py and Mz Where Px = Load along X-direction Py = Load along Y-direction Mz = Torsional moment caused due to eccentricity of Px and Py load about the centroid of bolt group Number of bolts = n Determine the Moment of Inertia Ix and Iy Determine the Moment of Inertia Ix = y Where y is the distance of each bolt in the y-direction from the neutral axis.2

x Determine the Moment of Inertia Iy = Where x is the distance of each bolt in the y-direction from the neutral axis.2

Determine Polar Moment of Inertia Ip = Ix + Iy Let distance of the farthest bolt along X-Axis = Cx Let distance of the farthest bolt along Y-Axis = Cy Bolt Stress (X-Dir) = fx = ( Px n) + Mz * Cy Ip Bolt Stress (Y-Dir) = fy = ( Py n) + Mz * Cx Ip Resultant Bolt stress =fr = fx 2 + fy 2

should be less than allowable bolt shear.

2.1. b Elastic Method of Bolt Analysis for bolts subjected to shear and tension due to bending Let the assumed plane of the connection be X and Y Loads: Py and Mx Where Py = Load along Y-direction Mx = Moment caused due to eccentricity of Py load about the X-axis Number of bolts = n Let distance of the farthest bolt along Y-Axis = Cy



Bolt shear Stress (y-dir) = Bolt tensile Stress (z-dir) =

fy = ( Py n) fz = ( Mx Ix ) Cy

See Section 2.1.c for checking bolts subjected to tension and shear simultaneously. 2.1. c Bolts subjected to Tension and Shear When bolts are subjected to both tension and shear, the interaction of tension and shear stresses has to be performed. In calculating the applied tension, the applied tension shall be the sum of the external load and any tension resulting from prying action produced by deformation of connected parts. Prying action is discussed at the end of this section. For Slip-Critical Bolts The interaction of tension and shear is done only if there is a net direct tension on the joint. As discussed earlier, the slip-critical joints obtain their resistance through the clamping force across the faying surface. When a moment is applied across a faying surface that causes some portion to go into tension and some into compression, there is no change in the net clamping force across the joint. Hence, although some bolts in the joint may experience tension and others do not, the bolts under tension need not be evaluated for the tension load since there is no net tension on the joint. Therefore, when there is a net direct tension on the joint, The allowable bolt shear shall be reduced by the factor (1 ft Ab Tb ) Where ft is the average tensile stress on a bolt caused by direct tension load And Ab is the nominal tensile area of the bolt given in Table I-A and Tb is the bolt pretension as given in Table J3.7 of the AISC Specification For Bearing Type Bolts For bearing type bolts, whether the tension is caused through direct tension or through a moment, the interaction of tension and shear is done. For bearing type connections, the allowable tension stress is altered based on the equations provided in Table J3.3 for A325 and A490 bolts depending on whether threads are included in the shear plane or not. Prying Action Prying action is the deformation of the connected part, for example the clip angle of a shear connection subjected to tension or transfer loads, split-beam tee moment connection where the flanges of the tee deform and dig into the column causing extra tensile force in bolts or hanger type connections where the bending of the outstanding leg of angles or flanges of Tee cause prying forces.



Hence prying action involves not only the bolts but also the flange or angle thickness, bolt pitch and gage. AISC, ASD Manual, Part 4 provides the Analysis and Design Methodology to determine the prying force, the thickness of the flange or angle leg required to develop the full tensile capacity without additional prying loads, the thickness of the angle or flange required to develop the moment due to prying. Note that shear connections subjected to axial loads usually require much thicker angles to resist the moment developed in the connection angle. Hence, shear connections subjected to axial loads shall be evaluated on a case by case basis. 2.2 Welds Welding is a process for joining similar metals. Welding joins metals by melting and/or fusing the base metals being joined with or without a filler metal. Welding is done using localized heat input. Most welding involves ferrous-based metals such as steel and stainless steel. Weld joints are usually stronger or as strong as the base metals being joined. Most of the commonly used welding techniques employ an electric arc to generate the heat necessary for welding. These processes are covered under the general term Arc Welding. The different arc welding techniques are the following. 1. 2. 3. 4. Shielded Metal Arc Welding (SMAW) Submerged Arc Welding (SAW) Gas Metal Arc Welding (GMAW) Flux Cored Arc Welding (FCAW)

Another unique arc welding technique is Stud Welding. In this process the stud itself acts as the electrode. The stud is placed in a stud gun that contains a ceramic ferrule, which acts as the shield for the weld. The gun is placed in position and an electric arc is created to melt the end of the stud. The molten metal is contained within a ceramic ferrule. The stud is then driven into the molten metal by the gun creating a full penetration weld across the shank along with a small fillet around the stud. Welds shall be designed per the requirements of AWS D1.1 - Structural Welding Code Steel For Carbon steels used in the design, the E70XX electrode is the matching electrode commonly used. This has similar or greater mechanical properties than the connected materials. Allowable Stress for E70XX electrode and effective throat of welds shall be as provided in Table 2-1.



Table 2-1: Effective Throat of Weld and Allowable Stress of E70XX Weld Weld Type Effective Throat Stress Type Allowable Stress Fillet Weld Shortest distance Shear on effective 0.3 x 70 ksi from root of joint to area the face of the weld, Tension or Same as base Typically equal to Compression parallel metal 0.707 x weld size to axis of weld Complete1) Thickness of the Tension/compression Same as base Penetration thinner part joined normal to effective metal Groove Weld 2) For Flare groove area weld, 5/16 R where R Tension/compression Same as base = 2t, t being the parallel to axis of the metal thickness of the weld material with the Shear on effective 0.3 x 70 ksi rounded corner area PartialPenetration Groove Weld 1) Depth of chamfer (for J or U joint or for bevel >= 60 deg) 2) For bevel < 60 deg and >=45 deg it is depth of chamfer 1/8 Shear parallel to axis of weld Tension normal to effective area Compression to effective area Tension/compression parallel to axis of the weld 0.3 x 70 ksi 0.3 x 70 ksi Same as base metal Same as base metal



2.2.a

Weld Analysis and Design

Weld group subjected to shear load with an eccentricity can be designed using either elastic method or the ultimate strength method, also called the instantaneous center of rotation method. AISC Manual, Tables XIX through XXVI provide coefficients for weld groups based on the instantaneous center of rotation method. When the eccentric shear load is at an angle to the vertical, AISC Manual provides a procedure for using the instantaneous center of rotation method. See Alternate Method 2, pgs. 4-73 thru 4-74 in the AISC Manual. In lieu of this alternate method, the elastic method can always be used. The load obtained by elastic method is about 5% less than what is obtained by the ultimate load method. However, when bolt groups do not conform to the pattern given in the AISC Tables XI through XVIII, the elastic method shall be used. 2.2.b Elastic Method of Weld Analysis for welds subjected to shear, torsion and moment Welds can be subjected to a combination of shear, torsion and bending moment loads. To investigate the weld, the following steps shall be taken. 1. Assume a unit thickness of weld and draw the effective cross-section of the weld group. 2. Establish a coordinate system and determine the centroid of weld group. Calculate the properties of weld treated as lines. Properties of most commonly used weld groups are provided in Table 2-2. For example: Let the assumed plane of the connection be X and Y Properties required are Centroid Length Moment of Inertia Ix Moment of Inertia Iy Polar Moment of Inertia Ip Distance of the extreme weld point to the weld centroid along x-axis (cx) Distance of the extreme weld point to the weld centroid along y-axis (cy) 3. Determine the forces on the weld group. Loads: Px, Py, Pz, Mx, My and Mz Where Px and Py = Shear Loads Pz = tension Load Mx = Moment about the X-axis My = Moment about the Y-axis Mz Torsional Moment



4. Determine the individual weld stresses (in each principal axis) due to shear, moment and torsion. Weld stress along x-axis due to Px = fx1 = Px / L Weld stress along y-axis due to Py = fy1 = Py / L Weld stress along z-axis due to Pz = fz1 = Pz / L Weld stress along x-axis due to Mz = Weld stress along y-axis due to Mz = Weld stress along z-axis due to Mx = Weld stress along z-axis due to My =fx 2 = ( Mz Ip ) cy fxy 2 = ( Mz Ip ) cx fz 2 = ( Mx Ix ) cy fz 3 = ( My Iy ) cx

Total weld stress in x-direction: fxtot = fx1 + fx 2 Total weld stress in y-direction: fytot = fy1 + fy 2 Total weld stress in z-direction: fztot = fz1 + fz 2 + fz 3 5. Combine the stresses vectorially. Resultant Weld Stress: fr _ weld =

fxtot

2

+ fytot

2

+ fztot

2

in kips/inch

6. Determine the weld size required for the computed weld stress. Resultant Weld stress shall be less than the weld allowable. Weld Allowable = Effective Throat Thickness x Allowable Weld Stress in kips/inch 7. Check to ensure that the weld size does not exceed the maximum allowed per AISC Manual, Specifications, Section J2. 8. Weld sizes shall also meet the AISC minimum weld size provided in Tables J2.3 and J2.4.



Table 2-2: Properties of Welds Treated as Lines (Courtesy Ref. [4])

CONNECTION DESIGN STANDARDConnection Types


Structural steel connections can be classified into the following broad categories. 1. Shear Connections a. Framed Beam Connections (Double-Clip Angle Connections) b. Seated Connections c. End Plate Connection d. Single-Plate Connection 2. Moment Connections a. Directly welded flange type to column flange (flanges are field welded to the column flange and the beam web is field bolted to a shear plate). b. Welded Flange Plate Connection (top flange plate is field welded to the column flange, bottom flange plate is shop welded to the column flange and beam is field welded to the flange plates). c. Shop Welded-Field Bolted Flange Plate Connection (flange plates are shop welded to the column flange and the beam web is field bolted to a shear plate). d. End-Plate Connection (end plate is welded to the beam and field bolted to the column flange). e. Directly welded flange type to column web (flanges are field welded to extension plates welded to the column flange and web and the beam web is field bolted to an extended shear plate). f. Shop Welded-Field Bolted Flange Plate Connection (flange plates are shop welded to the column web and flange flange and the beam web is field bolted to an extended shear plate). g. Moment connections using WT or angles. h. Beam to Beam moment connections (directly welded or using flange plates). i. Other variations of the above listed moment connections 3. Horizontal Bracing Connections 4. Vertical Bracing Connections a. Brace connections at column base b. Chevron Brace connection (Inverted-V brace connection) c. Single and Double brace connections at beam/column intersection d. K-Brace connection e. X-Brace connection 5. HSS Connections a. WF beam to HSS column shear connections b. WF beam to HSS column moment connections c. HSS to HSS shear connections d. HSS to WF beam moment connection 6. Hanger and Post Connections 7. Truss Connections (all bolted, all welded or a combination) a. Angle diagonal and strut to WF chord b. Angle diagonal and strut to WT chord

CONNECTION DESIGN STANDARDc. WF diagonal and strut to WF chord d. HSS to HSS truss connections (T, K and N type)


Several variations of the above mentioned connection types are typically encountered in the real world. For example, the framed beam connection for skew beams will have to be designed using bent plates instead of clip angles. Also, parameters such as bolt eccentricity will change depending on the amount of skew and such information shall be considered in the design. Similarly, connections of sloping beams and connections to sloping beams will require additional considerations in design, such as fit up, larger than usual copes, reduced number of bolts, etc. However, these are variations of the basic connection types listed above.

CONNECTION DESIGN STANDARDShear Connections


Framed Beam connections are generally made with a pair of clip angles. Single angle connections can also be used for lightly loaded members and where the beam is not subjected to loads that could cause twisting on it. Single angle connections would require the consideration of eccentricity of the load with respect to the bolt line on the outstanding leg. For evaluation of this eccentricity effect, the procedure given in AISC Manual Part 4, pg. 4-83 is useful. Other framed beam connections involve using bent plates for skew connections, shear plate and extended shear plates. For details of various typical shear connections see Figures 4.1 thru 4.24. 4.1 Double Clip-Angle Connections These are the standard clip angle connections. When supported on column flange, this detail can be used as a Knifed connection (where the beam is lowered into position between the clip angles). For a knifed connection, allowance must be made for erection clearance between the clip angles. This is accommodated by providing slotted holes on the outstanding leg of the clip angles that bolt to the supporting column flange. Four variants using bolts and/or welds can be formulated.

CONNECTION DESIGN STANDARD4.1.a Shop Bolted / Field Bolted Connection (Detail DCA-BB)


Formulation for developing load capacity table for Double Bolted Clip Angle Connection using SlipCritical Bolts Step 1: Establish the Design Inputs: Bolt Type, Bolt Diameter (d), Bolt Hole Dia (dh) No. of Bolts (n), Clip-Angle Length (L), Clip-Angle thickness (t), Clip-Angle Yield Strength (Fy_angle) Clip-Angle Tensile Strength (Fu_angle) Beam Yield Strength (Fy), Beam Tensile Strength (Fu), Beam web thickness (tw) Vertical Edge Distance for the top bolt (for coped beams) (lv) Distance from center of bolt hole to beam end (lh) Spacing of bolts (s) Cope depth (dc) Reduced beam depth (ho) Cope length (c) Reduced Section Modulus of the coped beam section (Sn) Supporting member web or flange thickness (t_supt) Step 2: Determine Allowable Bolt Shear in Kips: Use Table II-A, AISC Manual Part 4 (or) Allowable Bolt Shear = n x (double shear capacity of bolt from Table I-D) Step 3: Determine Net Shear on the Angle: Use Table II-C, AISC Manual Part 4 (or) Allowable Net Shear = 2 x [L-n(dh)] x t x 0.3 x Fu_angle Step 4: Determine Beam Web Bearing: Allowable Beam Web bearing load = 1.2 x Fu x d x tw x n Step 5: Determine Beam Block Shear (if beam is coped on top): Determine Coefficients C1 and C2 from Table I-G, AISC Manual Part 4 Block Shear = (C1 + C2) x Fu x tw (or) Block Shear = {(0.3 x lv + 0.5 x lh) + 0.3 [(n-1)(s-dh)-dh/2] dh/4} x Fu x tw Step 6: Check cope based on AISC, Manual of Steel Construction, Vol. II, Appendix B,



For checking the beam copes and obtaining the allowable reaction see the procedure outlined in Section 5.3.a.1 and 5.3.a.2. If only a bottom cope is present conservatively assume it as top cope for design. Step 7: Determine Supporting member (web or flange) bearing: For One-Sided Connection: Allowable supporting member (web or flange) bearing load = 1.2 x Fu x d x t_supt x n x 2 For Two-Sided Connection: Conservatively take 50% of the one-sided conn. load Allowable supporting member (web or flange) bearing load = 1.2 x Fu x d x t_supt x n Conclusion: Maximum Allowable Beam End Reaction = Minimum of Loads obtained from Steps 2 through 7. If Actual Reaction exceeds the Allowable, then the following can be done: a. If the governing allowable is due to bolt shear : Either increase number of bolts or increase bolt diameter b. If the governing allowable is due to net shear on the angle, increase angle thickness. c. If the governing allowable is due to beam web bearing : Either increase number of bolts or increase bolt diameter or add web doubler plates d. If the governing allowable is due to block shear : Either increase number of bolts or add web doubler plates e. If the governing allowable is due to beam cope : Reinforce the cope with web doubler plates or horizontal stiffeners f. If the governing allowable is due to supporting member web or flange thickness: Increase the connection depth, or reinforce the support member. Capacity of this connection type for various beam sections is provided in Table CDS 4.1 and Table CDS 4.2 for bearing type and slip-critical type connections. Excel worksheet no. DCA-1 is applicable for evaluating this connection.

The ideal engineer is a composite ... He is not a scientist, he is not a mathematician, he is not a sociologist or a writer; but he may use the knowledge and techniques of any or all of these disciplines in solving engineering problems.



4.1.b Shop Welded / Field Bolted Connection (Detail DCA-WB) Formulation for developing load capacity table for Double Clip Angle Connection (shop welded to beam web and field bolted to column or beam) using Slip-Critical Bolts Step 1: Establish the Design Inputs: Bolt Type, Bolt Diameter (d), Bolt Hole Dia (dh) No. of Bolts (n), Clip-Angle Length (L), Clip-Angle thickness (t), Clip-Angle In-Standing Leg dimension (ISL) Clip-Angle Yield Strength (Fy_angle) Clip-Angle Tensile Strength (Fu_angle) Beam Yield Strength (Fy), Beam Tensile Strength (Fu), Beam web thickness (tw) Cope depth (dc) Reduced beam depth (ho) Cope length (c) Reduced Section Modulus of the coped beam section (Sn) Weld Electrode E70XX, Fu = 70 ksi Distance from top of clip angle to edge of beam cope (a) Supporting member web or flange thickness (t_supt) Step 2: Determine Allowable Bolt Shear in Kips: Use Table II-A, AISC Manual Part 4 (or) Allowable Bolt Shear = 2 x n x (single shear capacity of bolt from Table I-D) Step 3: Determine Net Shear on the Angle: Use Table II-C, AISC Manual Part 4 (or) Allowable Net Shear = 2 x [L-n(dh)] x t x 0.3 x Fu_angle Step 4: Determine Weld Capacity: Use Table III, AISC Manual Part 4, Weld A Capacity Based on angle length and weld size (limited by the beam web size) obtain Weld Capacity. If the actual web thickness is less than the minimum required web thickness provided in the Table, then Revised Allowable = tw x Weld Allowable per Table / Min. web thickness per Table Step 5: Determine Beam Block Shear (if beam is coped on top): Block Shear = 0.4 x Fy x (L + a) x tw + 0.5 x Fu x (ISL setback) x tw Step 6: Check cope based on AISC, Manual of Steel Construction, Vol. II, Appendix B,



For checking the beam copes and obtaining the allowable reaction see the procedure outlined in Section 5.3.a.1 and 5.3.a.2. If only a bottom cope is present conservatively assume it as top cope for design. Step 7: Determine Supporting member (web or flange) bearing: For One-Sided Connection: Allowable supporting member (web or flange) bearing load = 1.2 x Fu x d x t_supt x n x 2 For Two-Sided Connection: Conservatively take 50% of the one-sided conn. load Allowable supporting member (web or flange) bearing load = 1.2 x Fu x d x t_supt x n Conclusion: Maximum Allowable Beam End Reaction = Minimum of Loads obtained from Steps 2 through 7. If Actual Reaction exceeds the Allowable, then the following can be done: a. If the governing allowable is due to bolt shear : Either increase number of bolts or increase bolt diameter b. If the governing allowable is due to net shear on the angle, increase angle thickness. c. If the governing allowable is due to Weld capacity : Either increase weld size or increase weld length by increasing clip angle length, if possible. d. If the governing allowable is due to block shear : Add web doubler plates e. If the governing allowable is due to beam cope : Reinforce the cope with web doubler plates or horizontal stiffeners. f. If the governing allowable is due to supporting member web or flange thickness: Increase the connection depth, or reinforce the support member. Capacity of this connection type for various beam sections is provided in Table CDS 4.3 through Table CDS 4.6 for bearing type and slip-critical type connections. Excel worksheet no. DCA-2 is applicable for evaluating this connection.



4.1.c Shop Bolted / Field Welded Connection (Detail DCA-BW) Formulation for developing load capacity table for Double Clip Angle Connection (Shop Bolted / Field Welded Connection) using Slip-Critical Bolts Step 1: Establish the Design Inputs: Bolt Type, Bolt Diameter (d), Bolt Hole Dia (dh) No. of Bolts (n), Clip-Angle Length (L), Clip-Angle thickness (t), Clip-Angle Yield Strength (Fy_angle) Clip-Angle Tensile Strength (Fu_angle) Beam Yield Strength (Fy), Beam Tensile Strength (Fu), Beam web thickness (tw) Vertical Edge Distance for the top bolt (for coped beams) (lv) Distance from center of bolt hole to beam end (lh) Spacing of bolts (s) Cope depth (dc) Reduced beam depth (ho) Cope length (c) Reduced Section Modulus of the coped beam section (Sn) Weld Electrode E70XX, Fu = 70 ksi Supporting member web or flange thickness (t_supt) Supporting Member Yield Strength (Fy_Supt), Step 2: Determine Allowable Bolt Shear in Kips: Use Table II-A, AISC Manual Part 4 (or) Allowable Bolt Shear = n x (double shear capacity of bolt from Table I-D) Step 3: Determine Net Shear on the Angle: Use Table II-C, AISC Manual Part 4 (or) Allowable Net Shear = 2 x [L-n(dh)] x t x 0.3 x Fu_angle Step 4: Determine Beam Web Bearing: Allowable Beam Web bearing load = 1.2 x Fu x d x tw x n Step 5: Determine Beam Block Shear (if beam is coped on top): Determine Coefficients C1 and C2 from Table I-G, AISC Manual Part 4 Block Shear = (C1 + C2) x Fu x tw (or) Block Shear = {(0.3 x lv + 0.5 x lh) + 0.3 [(n-1)(s-dh)-dh/2] dh/4} x Fu x tw



Step 6: Check cope based on AISC, Manual of Steel Construction, Vol. II, Appendix B, For checking the beam copes and obtaining the allowable reaction see the procedure outlined in Section 5.3.a.1 and 5.3.a.2. If only a bottom cope is present conservatively assume it as top cope for design. Step 7: Check Weld on the Outstanding leg of the clip angle: Use Table III, AISC Manual Part 4, Weld B Capacity Based on angle length and Required weld capacity obtain the weld size. Note: Connection capacity may be limited by the shear capacity of the supporting member. Hence check the following: For One-Sided Connection: For Fy_Supt = 36 ksi, weld size shall be

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