REFERENCE MANUAL

AND

SPREADSHEET USERS

GUIDE

Joist Girder Moment Connections to HSS Columns- Top Plate

Version 1.0

Steel Joist Institute 234 W. Cheves Street Florence, SC 29501

Phone: (843) 407-4091 www.steeljoist.org

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Joist Girder Moment Connections to HSS Columns- Top

Plate

The detail for a Joist Girder framing to one side of the HSS column is shown in Figure 1. The condition where the girders frame to both sides of the column is shown in Figure 2.

The vertical reaction from the Joist Girder(s) is supported by a stiffened seat welded to the column face. If the Joist Girder is modeled as a truss the chord forces are obtained directly from the model; however, if the Joist Girder is modeled as a beam element the chord forces are determined by resolving the end moments into force couples. The top chord force is transferred to the column by using a top plate field welded to the Joist Girder top chord and to the column cap plate. For Joist Girders framing to both sides of the column the top plate is also used to transfer continuity forces from one Joist Girder to the other. The bottom chord force is transferred to the column from the stabilizer plates. Numerous limit states must be examined. These limit states are discussed below.

Limits of Applicability- Joist Girders to HSS:

The AISC Specifications provide Limits of Applicability (AISC Table K1.2A) for the use of HSS connections. The following requirements must be met for the HSS. If they are not met a different HSS must be selected.

B/t or H/t 40 (B-3t)/t or (H-3t)/t 1.4SQRT (E/Fy)

Material Strength and HSS Thickness:

The strength of HSS connections not only depends on the yield strength and tensile strength of HSS, but it also depends on the design thickness and material type specified. For ASTM A500 and A501 the design thickness is 0.93 times the nominal thickness. For ASTM A1065 and A1085 the design thickness may be taken as the nominal thickness. Shown in Table 1 are the common specifications for HSS.

American Manufacturing Standards for HSS with Mechanical Properties of Common Grades

Product Specification Grade Fy, ksi Fu, ksi

Cold-formed HSS ASTM A500

B 46 58

C 50 62

Hot-formed HSS ASTM A501* B 50 70

Cold-formed HSS ASTM A1065 - 50 60

Cold-formed HSS ASTM A1085 - 50 65 *Not produced in North America

Table 1. Specifications for HSS

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Other Specifications included in the SPREADSHEET:

HSS with Mechanical Properties

Product Specification Grade Fy, ksi Fu, ksi

Hot-formed HSS ASTM A501 A 36 58

Hot-formed HSS ASTM A618 1 50 70

Hot-formed HSS ASTM A618 2 50 70

Hot-formed HSS ASTM A618 3 50 65

Cold-formed HSS ASTM A847 50 70

Table 2. Additional Specifications for HSS

Design Requirements:

For brevity, this Manual is presented in LRFD format. ASD design procedures follow in a parallel nature. Before using the SPREADSHEET the user should perform a structural analysis to determine that the column has the available strength to resist the applied loads. The user should also have a working knowledge of the AISC connection design requirements.

A. Top Chord Connection:

The required strength of the top plate is determined from the axial force in the top chord of the Joist Girder, Pu = Mr/de. Where, Mr is the required end moment of the Joist Girder, and de is taken as the distance from the top of the Joist Girder to the

half depth of the bottom chord leg. The required top plate area = Pu/Fy, where = 0.90. The length of the plate is determined based on the required length of fillet welds used to attach the plate to the column cap plate and the top chord. Shear lag must be checked per the 2010 AISC Specification Table D3.1 Shear Lag Factors for Connections to Tension Members. The SPREADSHEET requires the weld length to be a minimum of two times the width of the top plate for the connection of the plate to the Joist Girder top chord. Based on Case 4 in the AISC Manual Table D3.1, U =1.0 for this condition. For the Top Plate connection to the column cap the strength of the plate is reduced for shear lag. The Joist Girder Manufacturer has the responsibility to check the top chord angles for shear lag. Case 2 from Table D3.1 is applicable for this check. For reference, the shear lag factor is calculated for the top chord based on the INPUT of the angle size. Shear lag factors greater than 0.92 do not have an effect on the Joist Girders. Providing longer length fillet welds will reduce shear lag effects.

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Figure 1: Joist Girder Framing to one side of the HSS

5

Figure 2: Joist Girders Framing to both sides of the HSS

6

The following checks are made in the SPREADSHEET for the Top Plate Connection, Cap Plate and Cap Plate Weld:

1. Yielding Strength of Plate ( = 0.9) Top Plate - Yielding

Rn = FyAplate, kips AISC D2-1

2. Tensile Rupture Strength of Plate ( =0.75) Top Plate - Tensile Rupture

Shear lag at the cap plate per Case 4 AISC Table D3.1

xU 1

where equals the weld length on each side of the plate. Rn = UFuAplate, kips AISC D2-2

3. Shear Yielding Strength of the Column ( = 0.9) Column.- Shear Yielding The AISC Specifications require that the nominal shear strength, Vn, of rectangular

HSS shall be determined using the provisions of AISC Section G5 ( = 0.9).

Vn = 0.6FyAwCv, kips AISC G2-1

where: Aw = 2htw, in.2

When w v y

h / t 1.10 k E / F Cv = 1.0 AISC G2-3

When v y w v y

1.10 k E / F < h / t 1.37 k E / F v y

v

w

1.10 k E / FC =

h / t AISC G2-4

When w v y

h / t >1.37 k E / F

vv 2

w y

1.51k EC =

h / t F

AISC G2-5

Note: There are no HSS that have w v y

h / t >1.37 k E / F

where:

h = width resisting the shear force. If the corner radius is not known, h shall be taken as the corresponding outside dimension minus 3 times the thickness. t = design wall thickness, equals 0.93 times the nominal wall thickness for A500 and A501 material and equals the nominal wall thickness for A1065 and A1085 material. kv= 5

7

NOTE: If the HSS sidewalls do not have the available strength for shear it is generally more economical to select a column with thicker walls or one with longer walls.

4. Joist Girder top chord shear lag factor Joist Girder - Shear Lag Case 2 AISC Table D3.1

xU 1

5. Weld strength between the Joist Girder and the top chord ( = 0.75) Weld - Top Plate to Joist Girder Top Chord

rn = (0.6)(FEXX)(0.707)w tc kips/in.

Rn = (2)( rn)(L tc) kips AISC J2-3

6. Weld strength between the top plate and the column cap ( = 0.75) Weld - Top Plate to Column Cap Plate

rn = (0.6)(FEXX)(0.707)wcp kips/in.

Rn = (2)( rn)(L cp) kips AISC J2-3

7. Weld strength between the column cap plate and the column walls ( = 0.75) Column Cap Plate - Weld to Column Walls

Rn = (0.707)(wccp)(0.60)(FEXX)[(2)(D - 3tw)], kips AISC J2-3

The SPREADSHEET bases the weld length design on the flat width of the column wall. On occasion the base metal strength may be less than the weld strength. If this occurs the user can select a deeper column or one with thicker walls. Note on Interior HSS Columns: Where Joist Girders frame to both sides of a column (Moment Interior HSS Column), the minimum weld requirement to each Joist Girder top chord is checked. The column shear yielding, cap plate thickness, and the weld required from the cap plate to the column walls are checked for the force delivered by the Joist Girder on each side of the column. These results are found under the heading, SUMMARY RESULTS for MOMENT CONNECTION. The minimum requirements for column shear yielding, cap plate thickness, and the weld required from the cap plate to the column walls are based on the algebraic sum of the top chord forces in the top plate. These results are found under the heading COMBINED LEFT & RIGHT JOIST GIRDER RESULTS.

B. Stiffened Seat Connection:

There are a few differences for the design of stiffened seats for Joist Girders supported by HSS columns as compared to stiffened seats for wide flange beams.

8

Most fabricators prefer to fabricate the tee from plates rather than using a WT section. If the stiffened seat connection cannot be designed to carry the required loads due to strength or geometrical requirements then the Through-Plate connection or the Knife-Plate connection can be used. For the stiffened seat connection the stiffener shall be finished to bear under the seat (AISC Manual Table 10-8) discussion. The seat width for beam reactions is based on the required bearing for the beam to prevent local web yielding and web crippling (different for Joist Girders). For Joist Girders the seat width can be determined from the minimum bearing length of 4 in. from the SJI Standard Specifications for Joist Girders Section 1004.4 (b) Steel (SJI 2010)1. The reaction is located N/2 from the interior edge of the seat.

1. AISC provisions indicate that when supporting beams, the stiffener thickness, ts

should be equal to or greater than the thickness, tw of the supported beam web (different for Joist Girders). Since Joist Girder seats are composed of two angles with typically a 1 in. gap between the angles this requirement does not apply. In lieu of this requirement a minimum stiffener and seat plate thickness of 1/2 in. is recommended.

2. For HSS stiffened seats the maximum stiffener thickness (Punching shear):

up maxyp

F tt

F, in. AISC K1-3

where t = tdes for the HSS

where: Fu is the tensile strength of the HSS and Fyp is the yield strength of the stiffener plate.

3. Strength of seat plate and stiffener for local buckling

Seat Plate & Stiffener - Local Buckling

py

p

p

y

Eb / t = 0.38 AISC Table B4.1b - Case 10 Flange

F

b = W / 2

bmin t = in.

E0.38

F

,

1 Consult the SJI 2015 Specifications for revised minimum bearing lengths

9

,

s

y

s p

s

y

Ed / t = 0.84 AISC Table B4.1b - Case 14 Tee stem

F

d = L + t

dmin t = in.

E0.84

F

The maximum length of the stiffener, Ls equals:

The Joist Girder Depth - the seat height - the stiffener cap thickness - the stabilizer plate height - 6 inch clearance.

Lmax = d - 7.5 - t s - W st - 6, in.

4. Bearing strength on the stiffener contact area ( = 0.75) Stiffener - Bearing Strength on Contact Area

The design bearing strength, Rn, on the contact area of stiffener must satisfy Equation from the 2010 AISC Specification Chapter J, Section J7(a).

pbyn AF8.1R , kips AISC J7-1

where:

Apb = projected bearing area, in.2 (mm2)

Fy = specified minimum yield stress, ksi (MPa)

For Structural and Fabricated Tees using a 0.5 in. set back:

us

s

Pt

1.8 W 0.5 in. Eq. 5-112

where: Ws is the seat plate width, in.

5. Seat Plate Shear Yielding Strength (=1.0) Seat Plate - Shear Yielding

Rn = (2)(N)(0.6Fy)(tp), kips AISC G2-1

min

up

y

Rt = , in.

2 N 0.6F Eq. 5-162

2 Equation from the SJI Technical Digest 11, Design of Lateral Load Resisting Frames Using Joist and Joist Girders

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6. Stiffener shear yielding strength (=1.0) Stiffener - Shear Yielding

Rn = (0.6)(Fy)(Ls)(ts), kips AISC G2-1

min

us

y

Rt = , in.

0.6F Ls

Eq. 5-172

7. Local yielding strength of the HSS from the seat plate ( = 0.95) Seat Plate - Local Yielding at HSS

n y p yp p p

p

u u n s

p

u n s

10R = F tW F t W kips AISC Eq. K1- 7

B / t

t2Maximum R : R e = R L + kips

3 2

t2 1R = R L + , kips

3 2 e

where : e = W - N / 2, in.s

,

,

8. Eccentric loading on the stiffener

Stiffener - Eccentric Loading

u s s

s 2sy

P 6e -2Wt =

1.8F W, in. Eq. 5-123

where, es is the eccentricity to the column face = Ws - one half of the bearing length (N), in., es = Ws - N/2

9. Uplift strength of the seat plate ( = 1.0) Seat Plate - Uplift Loading The seat plate must also be checked for bending and shear from uplift reactions. The effective width of plate (beff) is determined by using a 45 degree projection from the bolt line to the face of the stiffener. beff cannot be greater than N. The available bolt uplift strength must be determined by the Engineer of Record or the Specifying Professional. Uplift bolt strength should be based on the Steel Joist Institutes Technical Digest 6, Design of Steel Joist Roofs to Resist Uplift Loads. Based on a bolt gage (g) of 5 in. and using a 45 degree projection, the effective

width in bending for the seat plate equals:

beff = 2(g - ts)/2 N = g - ts N, in.

3 Equation from the SJI Technical Digest 11, Design of Lateral Load Resisting Frames Using Joist and Joist Girders

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The nominal flexural strength Mn = FyZ 1.6My, kip-in.

Mn = Fybefftp2/4 1.6Fybefftp

2/6, kip-in AISC F11-1 Lever arm = (g - ts)/2, in.

Rn = 2Mn/Lever arm, kips The SPREADSHEET performs this calculation even if no uplift load case exists.

10. Minimum stiffener thickness to develop fillet welds ( = 0.75) Stiffener - Thickness to develop Fillet welds

tpmin = 6.19D/Fu, in. AISC Manual , Part 9( Eq. 9 - 2)

11. Weld strength at the column ( = 0.75) Stiffener - Eccentric Weld Group to Column

Strength provided: rn = (0.707)(ws)(0.6)(70), kips / in.

The resultant stress equals:

2 2

u u

v

v s s

2

e s ss s

3

y

e p p s s

yp p

R R eR = + kips / in

l S

where :

l = 2L - w in.

Section Modulus :

l w w4 L - + L -

2 2 2S = in.

3

F t10l = min W and W - t - w in

B / t F t

, .

,

,

, .

R rn Only the vertical legs are assumed effective for providing shear strength.

12. Weld strength between the seat plate and the stiffener ( = 0.75) Weld - Seat Plate to Stiffener Plate

Rn =(2)(0.6)(70)(0.707)wp, kips/in.

If Ru 0 (tension) then:

12

22

u u

eff

R Q RR = +

I b, kips/in.

otherwise:

uR Q

R = , kips / inI

.

where: Q and I are calculated based on strength of materials (See cells R32 and R29).

13. HSS wall strength ( = 0.9) HSS - Wall Yield Line4

TL

n

p

p p

p

des

2

y

s

R = kmL / e, kips

T - W2 7k = 1 T - W 7T + W + T + 2L + T 7

2T - W 4 4L

where :

T = B - 3t , in.

F tm = , kip - in

4

e = W - N / 2, in.

14. Shear yielding strength of the HSS at the seat plate ( = 0.95) HSS - Shear Yielding (Punching)

If 0.85B Wp B 2t then Rn = 0.6Fyt(2tp + 2Bep), kips AISC Eq. K1-8 where:

.

p

ep p

10WB = min and W , in

Bt

otherwise, Rn = 0.0

4 Based on Bending Under Seated Connections, Abolitz and Warner, 1965 AISC Engineering Journal, Vol. 2, No. 1

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C. Bottom Chord, Stabilizer and HSS Wall Checks:

Bottom Chord Connection:

The bottom chord of the Joist Girder must be attached to the stabilizer plate to resist the same force as the top plate. In addition the stabilizer plate must transfer this same force to the column. Stabilizer plates are normally sized based on a 3/4 in. thickness of plate. Using a 3/4 in. plate allows the plate to fit between the bottom chord angles allowing fillet welds to be made to the heels and toes of the chord angles. For economy the stabilizer plates can usually be connected to the column using only fillet welds. The Specifying Professional must specify that the Joist Girder bottom chords be a minimum thickness to accommodate the required weld size. As is required for the top chord, the Joist Girder Manufacturer has the responsibility to check the bottom chord angles for shear lag. Case 2 from Table D3.1 is applicable for this check. For reference, the shear lag factor is calculated for the bottom chord based on the INPUT of the angle size. Shear lag factors greater than 0.92 do not have an effect on the Joist Girders. Providing longer length fillet welds will reduce shear lag effects. Stabilizer Checks:

1. Determine the weld between the bottom chord and the stabilizer Weld - Joist Girder Bottom Chord to Stabilizer Plate There four welds:

Rn = (4)(1.392)D = kips/ in.

Required length = Pu/Rn, in. The welds must be two times the bottom chord leg height to avoid a shear lag reduction for the stabilizer.

2. Stabilizer yielding ( =0.90). Stabilizer Plate - Yielding

Pu Rn AISC D2-1

Rn = tshsFy, kips

Where: ts = stabilizer thickness, hs = stabilizer effective width based on the Whitmore

width.

Whitmore width for stabilizer (AISC Manual Section 9-3): If the bottom chord weld starts at the end of the stabilizer the Whitmore length

equals (2)(tan30o)(Weld Length) + the bottom chord leg height.

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3. Stabilizer block shear rupture strength ( = 0.75). AISC J4.3 Stabilizer Plate - Block Shear Rupture Strength

(a) Block shear plane 1: Rn = 0.60FuAnv + UbsFuAnt 0.60FyAgv + UbsFuAnt, kips

Anv = net area subject to shear, in.2

Ant = net area subject to tension, in.2

Ubs = 1.0

(b) Block shear plane 2: Checked as in (a)

4. Weld strength between the stabilizer and the column

Weld - Stabilizer Plate to HSS Wall There two welds:

Rn = (2)(1.392)D = kips/ in.

Required length = Pu/Rn, in. The SPREADSHEET uses the Joist Girder bottom chord forces to determine the weld requirements. Some designers prefer to provide enough weld to develop the full strength of the stabilizer. The directional weld strength increase is not allowed as indicated in AISC Equations K4-1, K4-2 and K4-3.

5. Joist Girder bottom chord shear lag factor Joist Girder - Shear Lag Case 2 AISC Table D3.1

1x

U

HSS Wall Checks:

1. Strength of the HSS wall for the limit state of wall plastification ( =1.0) HSS - Plastification The stabilizer plate strength is limited by the yielding of the HSS wall due to the

stabilizer pushing or pulling against the wall. This limit state is referred to as HSS

Plastification. The strength is determined using AISC Eq.K1-12.

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2F t t2ly pbR sin = + 4 1- Q

tn fB Bp

1-B

, kips AISC K1-12

tp = the stabilizer thickness (t st), in.

lb = the stabilizer width (W st), in.

B = the HSS wall dimension, in.

t = the HSS design wall thickness, in.

sin=1.0

For HSS (connecting surface) in tension Qf = 1

For HSS (connecting surface) in compression, for longitudinal plate and longitudinal

through plate connections:

f

2Q = 1- U AISC K1-17

P Mro ro

U= + , F A F Sc g c

AISC K1-6

The AISC Specification states that, Pro and Mro refer to required strengths in the HSS,

where Pro and Mro are determined on the side of the joint that has the lower

compression stress. The compressive stress used in the SPREADSHEET is

calculated from the axial load, the bending from the Joist Girder moment, and the

bending from the eccentric load on the stiffened seat.

Pro = Pu for LRFD; Pa for ASD. Mro = Mu for LRFD; Ma for ASD. Fc = Fy for LRFD, 0.6Fy for ASD

Note on Interior HSS Columns: Where Joist Girders frame to both sides of a column, all loads in a given load

combination are conservatively considered additive, regardless of their sign for the

calculation of the utilization ratio in Eq. K1-6. The stress is always assumed

compressive.

If the left and right bottom chord connections overlap the connection is treated as a

cross-connection, and an additional sidewall crippling check is performed for load

combinations when both bottom chord forces are compressive. The equation is

identical to that for web compression buckling of wide flange members per AISC Eq.

J10-8.

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In many cases the walls will not have sufficient strength for the compressive or tensile

forces delivered by the stabilizer. The strength can be increased by:

Increasing the HSS wall thickness.

Increasing the width of the stabilizer plate. When increasing the width of the stabilizer plate the length of the stabilizer may need to be increased (Whitmore Section).

Adding a reinforcing side plate to the column face as shown in Figure 1.

Using a Through Plate (AISC Eq. K1-13) which doubles the strength.

The limit states of Sidewall Local Yielding and Sidewall Local Crippling technically apply; however, unless reinforcing plates are added to the HSS wall they will never control. See Wall Reinforcing below. Wall Reinforcing

1. Strength of the reinforcing plate in flexure ( = 0.9) Reinforcing Plate - Thickness The reinforcing plate is analyzed as a simple beam with a span of B - tdes

Mr = PbcL/4 kip-in.

2M = F Z = F W t kip - inpl y y eff min

Mrt = in.

min F Wy eff

, .

The SPREADSHEET rounds tmin up to the nearest 1/8 in.; however the designer should select a plate with an available thickness.

2. Strength of the reinforcing plate in shear ( = 1.0) Reinforcing Plate - Shear Yield

Rn = (2)(0.6)FyWeff tmin kips AISC G2-1

3. Strength of flare bevel groove welds of the reinforcing plate to HSS

Flare - Bevel Groove Weld ( =0.8):

Effective throat = 5/8tdes, in. AISC Table J2.2 Rn = (2)(0.6)(70)(5/8)(tdes)(Weff), kips

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4. HSS Base Metal Strength ( = 0.90) HSS - Base Metal Strength

Rn = 2(Fy)(tdes)(Weff) kips

5. Local yielding strength of HSS sidewalls ( =1.0) Local Yielding of Chord Sidewalls

AISC local yielding of chord side walls, when = 1.0 and branch is in compression, for T- or Y-connections.

P sin = 2F t 5k +ly bn , kips AISC K2-9

where: lb = the reinforcing plate height = Wst, in. k = 1.5tdes, in.

6. Local crippling strength of HSS sidewalls ( = 0.75) Local crippling of Sidewalls

AISC local crippling of chord side walls, when = 1.0 and branch is in compression, for Plate-to Rectangular HSS.

2 bn y f

3lR =1.6t 1+ EF Q kips AISC K1-10

H- 3t,

lb = Weff, in.

f

UQ =1.3 - 0.4 1.3 - 0.4U

Minimum Member Thicknesses (Weld Compatibility):

Throughout the SPREADSHEET, checks are made for the minimum thicknesses of

base metal to match the weld strength. From the AISC Specification, Section J2.4,

The design strength, Rn and the allowable strength, Rn/ of welded joints shall be

the lower value of the base material strength determined according to the limit states

of tensile rupture and shear rupture and the weld metal strength determined

according to the limit state of rupture as follows:

For the base metal: Rn = FnBMABM, kips AISC J2-2

FnBM = nominal stress of the base metal (0.6Fu), ksi ABM = cross-sectional area of the base metal, in

2. Rn = 0.6FuAnv, kips AISC J4-4

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Anv = net area subject to shear, in2.

= 0.75 (LRFD), = 2.00 (ASD)

For the weld metal: Rn = 0.6FEXXAw, kips

Aw = Area of the weld, in2.

= 0.75 (LRFD), = 2.00 (ASD)

The compatibility check is done by comparing the weld strength (kips/in.) to the base metal strength (kips/in.). In LRFD terms:

n weld n base metal

weld

base metal

cap u

0 75

0 75

1.39D kips / in 0.75 0.6 t F kips / in.

R R

.

.

From Part 9 of the AISC Manual: For fillet welds on one side of the connection:

min

u

3.09D t =

F, in.

For fillet welds on both sides of the connection:

min

u

6.19D t =

F, in.

19

EXAMPLE:

Given: HSS: Material: A500 Gr. B Joist Girder Data: 12x12x1/2 in. M = 183 kip-ft. = 2196 kip-in. (tension in top chord) Fy = 46 ksi Pv = 100 kips, Ph = 2196/(36-2) = 64.6 kips

Fu = 58 ksi Joist Girder Depth = 36 in.

B = 12 in. Assume 4x4x1/4 in. chords, gap = 1.0 in.

tdes=0.465 in. Column Cap Plate t = in. A36

A = 20.9 in2 Seat Plate: 5/8X8X5 in. A36

S = 76.2 in3 Stabilizer Plate: 3/4x8x10 in. A36

Top Plate Fy = 50 ksi

Preliminary Design:

Determine if the stiffener length will fit above the stabilizer plate. If it cannot then the

Through - Plate connection, or the Knife - Plate connection can be used, or a thicker

walled HSS can be selected with a shallower seat.

The maximum length of the stiffener equals: The Joist Girder depth - the seat height -

the stiffener cap thickness - the stabilizer height - 6 in. clearance.

Lmax = 36 - 7.5 - 0.75 - 4 - 6 = 17.75 in.

Required Top Plate, Column Cap Plate and Column Cap Plate Weld:

Required top plate area = Pu/Fy = 64.6/(0.9)(50) = 1.44 in.2 using Fy = 50 ksi for the

plate, and = 0.9. Based on the 4.0 in. chord angles the width of the top chord is 9 in. Try a plate, 4 in. x 1/2 in. The length of the plate can be determined based on the required length of fillet welds used to attach the plate to the column cap plate and the top chord.

1. Check yielding ( = 0.9) Top Plate - Yielding Rn = FyAplate = (50)(0.5)(4) = 100 kips

Rn = (0.9)(100) = 90.0 kips > 64.6 kips ok 2. Check tensile rupture

Top Plate - Tensile Rupture Plate shear lag at Joist Girder, U = 1.0 (Forced by the Spreadsheet) Shear lag at the cap plate: lcp = 8 in., Wtp = 4.0 in., lcp 2Wtp therefore U= 1.0

20

Rn = UFuAplate = (1.0)(65)(0.5)(4) = 130.0 kips

Rn = (0.75)(130.0) = 97.5 kips > 64.6 kips ok

3. Determine the shear yielding strength of the column ( = 0.9) Column - Shear Yielding

h/tdes = (12.0 - 3tdes)/tdes = 10.60/0.465 = 22.8 Aw = 2htdes = (2)[(12.0 - (3)(0.465)](0.465) = 9.86 in

2

When des v yh / t 1.10 k E / F =1.10 (5)29000 / 46 = 61.8 Cv = 1.0

Vn = 0.6FyAwCv =(0.6)(46)(9.86)(1.0) = 272.1 kips

Vn = (0.9)(272.1) = 245 kips > 64.6 ok 4. Determine the Joist Girder top chord shear lag factor

Joist Girder - Shear Lag

1 08

1 1 0 868

x .U .

Increase the weld length so that shear lag does not control the Joist Girder chord size. Try l = 14 in., U = 0.92 ok

5. Determine the weld strength between the Joist Girder and the top chord ( = 0.75) Weld - Top Plate to Joist Girder Top Chord Try 14 inches of in. fillet weld on each side of the plate. Rn = (0.6)(FEXX)(0.707)wtc = (0.6)(70)(0.707)(0.25) = 7.42 kips/in.

Rn = (0.75)(7.42) = 5.56 kips/in

Strength = Rn = (2)( Rn)(Ltc) = (2)(5.56)(14) = 156 kips 64.6 ok

6. Determine the weld strength between the top plate and the column cap ( = 0.75) Weld - Top Plate to Column Cap Plate

Strength = Rn = (2)( Rn)(Lcp) = (2)(5.56)(16) = 178 kips 64.6 ok Minimum cap plate thickness = tmin = (0.6)(FEXX)(0.707)(wcp)/(0.6Fu) = (0.6)(70)(0.707)(0.25)/[(0.6)(58)] = 0.213 in. in. ok

7. Weld strength between the column cap plate and the column walls ( = 0.75) Column Cap Plate - Weld to Column Walls

Rn = (0.707)(wccp)(0.6)(FEXX)[(2)(D 4.5tnom)] = (0.707)(0.25)(.6)(70)[(2)(12.0 - (4.5)(0.5)] = 144.8 kips

Rn = (0.75)(144.8) = 108.6 kips 64.6 kips ok

Minimum cap plate thickness = tmin = 0.6)(FEXX)(0.707)(wccp)/0.6Fu = (0.6)(70)(0.707)(0.25)/[(0.6)(58)] = 0.213 in. in. ok

21

Stiffened Seat Design

Design the stiffened seat for the 100 kip vertical reaction. 1. Recommended Minimum seat plate thickness = 0.50 in.

2. Maximum stiffener thickness equals:

des.

F t 58 0.465ut = = 0.749 inp max F 36

yp

3. Strength of seat plate and stiffener for local buckling Seat Plate & Stiffener - Local Buckling:

AISC Table B4.1b - Case 10 (Flange)

y

p

p

E 29000b / t = 0.38 = 0.38 = 10.78

F 36

b = W / 2 = 8 / 2 = 4, in.

min t = 4 / 10.78 = 0.371 0.500 in.

AISC Table B4.1b - Case 14 (Stem):

Try Ls = 16 in.

s

y

s p

s

E 29000d / t = 0.84 = 0.84 = 23.84

F 36

d = L + t = 16 + 0.625 = 16.625 in.

min t = 16.625 / 23.84 = 0.697 0.500 in.

Try 3/4 in. stiffener

4. Bearing strength on the stiffener contact area ( = 0.75) Stiffener - Bearing Strength on Contact Area

n y pbR = 0.75 1.8F A = 0.75 1.8 36 4 0.75 =145.8 kips 100 kips ok.

5. Seat plate shear yielding strength (=1.0) Seat Plate - Shear Yielding

min.

up

y

R 100t = = = 0.58 in.

1.0 2 4 0.6 362 N 0.6F

where, = 1.0 and N = 4 in.

22

Rn = (2)(N)(0.6Fy)(tp) = (1.0)(2)(4)(0.6)(36)(0.625) = 108 kips

6. Stiffener shear yielding strength (=1.0) Stiffener - Shear Yielding

min

us

y

R 100t = = = 0.29 in.

1.0 0.6 36 160.6F L

Rn = (1.0)(0.6)(36)(16)(0.75) = 259.2 kips 100 kips ok.

7. Local yielding strength of the HSS from the seat plate ( = 0.95) Seat Plate - Local Yielding at HSS

n y p yp p p

n

p

u u n s

p

u n s

10 10R = F tW F t W 46 0 465 8 0 46 0 465 0 625 8 0

B / t 12 / 0.465

66 3 46 0 465 8 0 107 kips

R = 66.3 kips

t2Maximum R : R e = R L +

3 2

t2 1 2 0.625 1R = R L + = 0 95 66.3 16 + = 2

3 2 e 3 2 3

. . . . .

. . .

. 28 kips

228 64.6 kips ok

8. Eccentric loading on the stiffener ( = 0.75) Stiffener - Eccentric Loading

u s

s 2 2

y

100 6 3 0 - 2 5 0R 6e -2wt = = = 0.658 0.75 0.749 ok

1.8F w 0.75 1.8 36 5 0

. .

.

Use in. stiffener

9. Uplift strength of the seat plate ( = 1.0) Seat Plate - Uplift Loading

beff = (g - ts) N = 5.0 - 0.75 = 4.25 > 4.00, beff = 4.00 in. Mn = FyZ 1.6My, kip-in.

Mn = Fybefftp2/4 1.6Fybefftp

2/6 = (36)(4)(0.625)2/4 < (1.6)(36)(4)(0.625)2/6 = 14.06 15.0 kip-in. Mn = 14.06 kip-in. per side

23

Mn = (0.9)(14.06) = 12.65 kip-in. per side Lever arm = (Bolt gage ts)/2 = (5.0 - 0.75)/2 = 2.125 in.

Rn = 2Mn/Lever arm = (2)(12.65)/2.125 = 11.9 kips

10. Minimum stiffener thickness to develop fillet welds ( = 0.75) Stiffener - Thickness to develop Fillet welds tpmin = 6.19D/Fu = (6.19)(5)/58 = 0.534 in.

11. Weld strength at the column ( = 0.75) Stiffener - Eccentric Weld Group to Column

Using a 5/16 fillet weld:

rn = (0.707)(0.3125)(0.6)(70) = 9.279 kips / in.

rn = (0.75)(9.279) = 6.96 kips/in.

The resultant stress, kips/in.:

24

22 2 2

u u

v

v s s

2

e s ss s

100 3R R e 100R = + + 4 097 kips / in

l S 31 687 114 8

where :

l = 2L - w 2 16 0 3125 31 687 in.

Section Modulus :

l w w4 L - + L -

2 2 2S =

3

2 9874 16

2

. .. .

. .

.

2

3

y

e p p s s

yp p

p s s

0 3125 0 3125- + 16 -

2 2114 8 in

3

F t10l = min W and W - t - w

B / t F t

46 0 46510min 8 0 2 947 in.

12 / 0.465 36 0 625

W - t - w 8 0 0 75 0 3125

. .

.

.. .

.

. . . 6 937 in..

R rn, 4.097 6.96 ok

12. Weld strength between the seat plate and the stiffener ( = 0.75) Weld - Seat Plate to Stiffener Plate Rn =(2) (0.6)(70)(0.707)wp = (2)(0.6)(70)(0.707)(0.3125) = 18.56 kips/in.

Rn = (0.75)(18.56) = 13.92 kips/in. If Ru 0 then:

22

u u

eff

R Q RR = +

I b, kips/in.

otherwise:

25

u100 29 338R Q

R = = = 5.87 kips / inI 500.04

..

where: Q and I are calculated based on strength of materials (See cells R32 and R29) = 29.338 in3 and 500.04 in4 respectively. beff = 4.0 in.

R rn, 5.87 13.92 ok

13. HSS wall strength ( = 0.9) HSS - Wall Yield Line

T

L

.

p

p p

p

des

p

T - W2 7k = 1 T - W 7T + W + T + 2L + T 7

2T - W 4 4L

where :

T = B - 3t = 12 - 3 0.465 = 10.605 in.

W = 8.0 in.

L = 16 in.

10 605 71 10.605 - 8.0 7 10.605 + 8.0

4 162k =

2 10.605 - 8.0+1

.

.

22

y

n

s

12 35

10.605 - 8.00.605 + 2 16 +10.605 7

4 16

46 0.465F tm = = = 2.486 kip - in

4 4

R = kmL / e = 12 35 2.486 16 / 3 = 163.7 kips

e = W - N / 2 = 5 - 4 / 2 = 3 in.

Rn = (0.90)(163.7) = 147.3 kips 100 kips ok

14. Shear yielding strength of the HSS ( = 0.95) HSS- Shear Yielding (Punching) If 0.85B Wp B 2tdes then Rn = 0.6Fytdes(2tp + 2Bep) = (0.6)(46)(0.465)[(2)(0.625) + (2)(8.0)] = 221.4 kips where:

26

p

ep p

des

10 8.010WB = min and W = min and 8.0 = 8.0 in

Bt 12 0.465.

otherwise Rn = 0.0 0.85B Wp B 2tdes = (0.85)(12) = 10.2 8.0, 8.0 12 (2)(0.465), 8.0 11.07, in. Rn = 0.0

HSS Wall Checks from Stabilizer Force:

1. Strength of the HSS wall for the limit state of wall plastification ( =1.0) HSS - Plastification:

The strength is determined using AISC Eq.K1-12, =1.0.

2F t t2ly pbR sin = + 4 1- Q , kips AISC K1-12

tn fB Bp

1-B

BH NbcM = Top Chord Force d - +R + W -

ro u s2 2 2

4 12 4.0 = 64.6 36 - +100 + 5.0 -

2 2 2

f

= 3096 kip - in.

P Mro ro 100 3096

U= + = + = 0.987 AISC K1- 6F A F S 46 20.9 46 76.2c g c

22Q = 1- U = 1- 0.987 = 0.161 AISC K1-12

246 0.465

R =0.75n

1-

2 8 0.75+ 4 1- 0.161 R = 20.7kips

n12 12

12

Since Rn 64.6 kips wall reinforcement is necessary.

Add a wall reinforcing plate tminx8x12 in.

Use flare bevel welds to the HSS wall

1. Strength of the reinforcing plate in flexure ( = 0.9) Reinforcing Plate - Thickness

27

The reinforcing plate is analyzed as a simple beam with a span of B - tdes = 12.0 - 0.465 = 11.54 in. Mr = PbcL/4 = 64.6(11.54)/4 = 186.4 kip-in.

20.9 36 8 t2 2minM = F Z = F W t = = 64.8t kip - in

pl y y eff min min4

M 186.3rt = = = 1.70 in.min 64.8 64.8

, .

Rounded up tplate = 1.75 in.

Use tplate = 1.75 in.

2. Strength of the reinforcing plate in shear ( = 1.0) Reinforcing Plate - Shear Yield

Rn = (2)(0.6)FyWefftplate = (1.0)(2)(0.6)(36)(8)(1.75) = 604.8 kips 64.6 kips ok

3. Strength of flare bevel groove welds of the reinforcing plate to HSS

Flare - Bevel Grove Weld ( = 0.8) Effective throat = 5/8tdes, in. Rn = (2)(0.6)(70)(5/8)(tdes)(Weff) = (2)(0.6)(70)(5/8)(0.465)(8) = 195.3 kips

Rn = (0.8)(195.3) = 156.2 kips 64.6 kips ok

4. HSS Base Metal Strength ( = 0.90) HSS - Base Metal Strength

Rn = 2(Fy)(tdes)(Weff) = (0.9)(2)(46)(0.465)(8) = 308 kips 64.6 kips ok

5. Local yielding strength of HSS sidewalls ( =1.0) HSS - Sidewall Local Yielding

AISC local yielding of chord side walls, when = 1.0 and branch is in compression, for T- or Y-connections.

. . . P sin = 2F t 5k +ly bn 2 46 0 465 5 1 5 0 465 8 491 kips

Pn = 491 kips 64.6 kips ok.

28

6. Local crippling strength of HSS sidewalls ( = 0.75) HSS - Sidewall Local Crippling

AISC local crippling of chord side walls, when = 1.0 and branch is in compression, for Plate-to Rectangular HSS.

2 bn y f

2

3lR = 1.6t 1+ EF Q

H - 3t

3 8.0 = 1.6 0.465 1+ 29000 46 0.905 = 1,179 kips

12 - 3 0.465

lb = Weff = 8.0

fU

Q =1.3 - 0.4 1.3 - 0.4 0.987 = 0.905

From the previous calculation:

.

P Mro ro

U= + 0 987F A F Sc g c

Rn = 884 kips > 64.6 kips ok.

Bottom Chord Checks:

1. Determine the weld between the bottom chord and the stabilizer Weld - Joist Girder Bottom Chord to Stabilizer Plate

Try 3/16 in. fillet welds: Rn = (4)(1.392)(3) = 16.7 kips/ in. Required length = 64.6/16.7 = 3.9 in. The welds must be 8 in. long (2 times the bottom chord leg height) to avoid a shear lag reduction for the stabilizer. Use 4-3/16 in. fillet welds 8 in. long

Rn = 16.7(8) = 133.6 kips

The Specifying Professional must request that the Joist Girder bottom chords be a minimum of 1/4 in. thickness to accommodate the required weld size.

29

2. Check stabilizer yielding ( =0.90) Stabilizer Plate - Yielding

Rn = tshsFy, kips

Where: ts = stabilizer thickness, hs = stabilizer effective width (Whitmore width).

Check the Whitmore width for stabilizer: Assuming the bottom chord weld starts at the end of the stabilizer the Whitmore

length equals (2)(tan30o)(8) = 9.24 in. plus the bottom chord leg length. Thus the

Whitmore length = 9.24 + 4 = 13.24 in. > 8 in. ok

Effective width = 8.0 in.

Rn = (0.9)(3/4)(8)(36) = 194.4 kips > 64.6 kips ok

3. Check stabilizer block shear rupture strength ( = 0.75) Stabilizer Plate - Block Shear Rupture Strength These calculations are shown only as an example. They are not applicable for the load case given since the bottom chord is in compression.

Block shear plane 1:

Rn = 0.60FuAnv + UbsFuAnt 0.60FyAgv + UbsFuAnt, kips

Anv = Agv = (2)(8)(0.75) = 12 in.2

Ant = (4)(0.75) = 3.0 in.2

Rn = (0.60)(58)(12) + (1.0)(58)(3.0) (0.6)(36)(12) + (1.0)(58)(3.0) =

542 433 kips, Rn =433 kips

Block shear plane 2: Anv = Agv = (8)(0.75) = 6.0 in

2

Ant = [Angle leg length + (Wst - Angle leg length)/2]tst =[4 + (8 - 4)/2](0.75) = 4.5 in2

Rn = (0.60)(58)(6.0)+(1.0)(58)(4.5) (0.6)(36)(6.0)+(1.0)(58)(4.5) = 470 391 kips, Rn =391 kips

Rn = (0.75)(391) = 294 64.6 kips ok

30

4. Determine the weld between the stabilizer and the column Weld - Stabilizer Plate to Column

The weld force per inch equals 64.6/16 = 4.04 kips/in.

Try 1/4 in. fillet welds: Rn = (1.392)(4) = 5.57 kips/ in. > 4.04 kips ok Use 2-1/4 in. fillet welds 8 in. long

5. Joist Girder bottom chord shear lag factor Joist Girder - Shear Lag Case 2 AISC Table D3.1

1 08

1 1 0 868

x .U .

31

PROGRAM USAGE GUIDE Joist Girder Connections to HSS Columns

SPREADSHEET Philosophy:

The SPREADSHEET is structured to allow the user to input all data rather than forcing

computer generated values. This allows the user to select values or to use office

standards. This is especially useful when a multitude of designs are being considered

so that calculations can be provided for lumping common values.

SPREADSHEET Description: The SPREADSHEET has seven sheet tabs consisting of General Information,

Formatting, Sidewall HSS Column Diagram, Moment Sidewall HSS Column, Interior

HSS Column Diagram, Moment Interior HSS Column, and AISC Database v14.

General Information List of design references, explanation of LFRD and

ASD color coding.

Formatting Information on the printing formatting setup for the

SPREADSHEET.

Sidewall HSS Column Diagram A diagram of the connection being

designed for a Joist Girder to a sidewall HSS column (with nomenclature).

Moment-Sidewall HSS Column Design input and output sheet for the

moment connection for a Joist Girder to a sidewall HSS column.

Interior HSS Column Diagram A diagram of the connection being

designed for Joist Girder to an interior HSS column (with nomenclature).

Moment-Interior HSS Column Design Input and Output sheet for the

moment connection for two Joist Girders to an interior HSS column.

ASIC Database v14 AISC shape data for use in the connection design.

The actual design input and output sheets have been formatted to print all required

information for the design calculations of the connections.

SPREADSHEET Usage:

Before using the SPREADSHEET you should have in your possession: 1. The Steel Joist Institutes Technical Digest 11, Design of Lateral Load Resisting

Frames Using Steel Joists and Joist Girders. 2. The Steel Joist Institutes Technical Digest 6, Design of Steel Joist Roofs to

Resist Uplift Loads. 3. ANSI/AISC 360- 10, Specification for Structural Steel Buildings. 4. The Steel Joist Institutes Standard Specification for Joist Girders, 2010. 5. Frame analysis results, such as Joist Girder end reactions, connection moments,

and column axial loads.

First read the General Information Tab and the Formatting Tab.

32

Print out the diagrams: Sidewall HSS Column Diagram and the Interior HSS Column

Diagram. These will assist you with input requirements. For proper printing of the

SPREADSHEET you may have to reset the margins.

PRELIMINARY DESIGN WORK:

The user can use trial and error to obtain an adequate connection design; however, it is

generally beneficial to do some preliminary sizing of certain input values. An example is

provided at the end of this section as a reference.

Joist Girder Data:

Typically at the early stage of the design the actual Joist Girder design is not known by

the user. The user can either estimate the Joist Girder chords, weights and seat sizes,

or they can contact a SJI member company for the information. If the Joist Girder data

is unknown the following information can be estimated:

The chord sizes can be estimated as described in Chapter 2 of the SJI Technical

Digest 11.

The Joist Girder weight can be estimated using the SJI tabulated values in the published catalog, or by multiplying the chord weight by 2.5. See the PRELIMINARY SIZING EXAMPLE.

The seat size can be estimated using the standards set forth by SJI Standard

Code of practice suggested sizes based on Joist Girder weight.

Top Plate Preliminary Sizing:

The maximum width of the top plate, W tp, is 2 times the chord angle leg size plus the 1

in. gap minus the shelf dimension for the welds.

Minimum Weld Shelf Dimensions

Field Weld Size, in. Minimum Shelf Dimension, in

3/16 7/16

1/4 1/2

5/16 9/16

3/8 5/8

7/16 11/16

1/2 3/4

Table 1 Minimum Weld Shelf Dimensions

The preliminary thickness of the top plate, t tp, can be calculated by:

1. First determining the chord force in the Joist Girder. The chord force is obtained by dividing the end moment of the Joist Girder by the effective depth (Joist Girder depth of the chord angle size).

2. Then adding any additional axial chord load. 3. The plate thickness is then determined by dividing the chord force by the desired

width of the top plate and Fy (LRFD) or 0.6Fy (ASD).

33

Stabilizer Plate Preliminary Sizing:

An initial thickness of the stabilizer plate, t st, is based on the 1 in. standard gap between

the Joist Girder chord angles. Typically a 3/4 in. thickness is used to allow tolerance for

field erection and still allow for fillet welds from the chord angles to the plate.

The width of the stabilizer plate (W st) is estimated by dividing the required axial force

(see Top Plate Preliminary Sizing) by the thickness of the stabilizer plate and Fy

(LRFD) or 0.6Fy (ASD). The stabilizer width must be a minimum of the chord angle leg

size plus the weld shelf dimensions.

Seat Connection:

Determining the maximum length of the stiffener eliminates checking during the design

process. The maximum Stiffener Length (L s) is approximately equal to the Joist Girder

depth minus the (Joist Girder seat depth + seat plate thickness + 1/2 the stabilizer plate

width). The Joist Girder seat depth is 7 1/2 in. on Joist Girders weighing 50 plf or less

and 10 in. for Joist Girders having a weight over 50 plf. The Seat Plate Thickness (t p)

can be estimated at 1 in. for this calculation.

INPUT:

Use the Tabs to select a Moment- Sidewall HSS Column Design, or a Moment-

Interior HSS Column Design. If an interior column only has one side with a moment

connection, use the Moment-Sidewall HSS Column Tab.

All yellow filled cells are required input.

There are two pull down Tabs, one used to select whether you want an LRFD or an

ASD Design and the second to choose the size of the HSS column for the design.

The CLEAR buttons can be used to clear all of the input cells in the group. There is

one button for connection input and one for the loading input. This CLEAR button does

not clear the project information, i.e., project name, number or engineer.

COLUMN DATA:

The ASTM designation for the HSS being used must be specified since it affects the

material thickness of the HSS. Column data is automatically obtained from a file of the

AISC HSS-Shapes after using the drop down tab, or by typing in the column size.

JOIST GIRDER DATA:

For preliminary design, if the Joist Girder properties are not known, the chord sizes can

be estimated as described in Chapter 2 of the SJI Technical Digest 11. If you have

conducted your analysis using the SJI Virtual Joist Girder Tables, you can also obtain

the Joist Girder weight from your analysis,

34

JOIST GIRDER & COLUMN DESIGN LOAD DATA: Fill in the values indicated in the Table. Values must be consistent with the type of

design you have selected, i.e. LRFD or ASD. Up to six load cases are permitted per

design. The column axial load is the total axial load on the column and must include the

reaction(s) of the Joist Girder(s).

REMARKS INDICATED ON THE INPUT DATA: (1) See SJI Specifications for minimum: Applies to the Bearing Seat Length (N) and

Bearing Seat Width (W s). The 2010 SJI Specifications, Section 1004.4(b), indicate

that, the minimum bearing length is 4 inches, and the 2010 SJI Code of Standard

Practice indicates that, Joist Girder bearing seat widths vary depending on the Joist

Girder size and shall be permitted to be up to 13" wide. It is recommended that the

minimum Bearing Seat Length be increased to 6" for Joist Girders weighing more

than 50 pounds per foot, and that the Bearing Seat Width be 9" for Joist Girders

weighing less than 50 pounds per foot and be 13" for Joist Girders weighing more

than 50 pounds per foot. The Joist Girder weight can be estimated from the SJI

Catalog values or by multiplying the chord weight by 2.5.

(2) Not to exceed column flange width:

The Seat Plate Width (W p) should not extend beyond the column flange. (3) Not to encroach on stabilizer:

The Stiffener Length (L s) cannot encroach on the stabilizer plate. Encroachment is not checked in the SPREADSHEET and must be manually determined. For example, for a Joist Girder seat of 7.5 in., the maximum length would be approximately equal to the Joist Girder Depth - 7.5 in. - the Seat Plate Thickness - of the Stabilizer Plate Width. (4) Less than JG TC width minus weld shelf dimension:

The Joist Girder (JG) Top Plate Width (W tp) must be less than the top chord (TC) width plus the shelf dimension for the fillet welds connecting the Top Plate to the Top Chord, i.e. 2 times the chord angle size plus the 1 in. gap minus the shelf dimension.

(5) Includes Joist Girder end reactions:

The Column Axial Load, Pu (LRFD) or Pa (ASD), is to include the end reaction(s) of the Joist Girder(s). DESIGN REVIEW: Examine the SUMMARY RESULTS for MOMENT CONNECTION to determine if the

design criteria are satisfied, or if undo conservatism exists relative to any of the input

data. The DETAILED RESULTS for MOMENT CONNECTION provides minimum

design criteria, the nominal strength, and the Design Strength (LRFD) or the Allowable

Strength (ASD) for the input data. These values can be studied to determine input

refinements. You can then make any necessary input changes.

35

PRELIMINARY SIZING EXAMPLE: For a 48G8N18F Joist Girder spanning 40 ft., with an end moment of 500 kip-ft. and an

end reaction of 100 kips estimate the chord size.

Assume a stabilizer width (W st) of 6 in. , Pchord = (12)(500)/(48-3) = 133 kips

From TD 11 Table 2-1 (LRFD), Fy = 50 ksi, = 0.90):

Table 2-1 (Partial)

The table yields a chord angle size of 3 x 3 x 5/16.

Estimate the Joist Girder weight: From the SJI Catalog 47 plf (partial view shown).

From the chord size, the Joist Girder weight = (2.5)(3.4)(4.21) = 36 plf

So conservatively assume the Joist Girder weight = 47 plf

Estimate the STIFFENED SEAT CONNECTION dimensions based on SJI standards:

Weight = 47 plf; therefore, the Seat Plate Width (W p) = 9 in. The Stiffener Width (W s) =

5 in. to accommodate an erection clearance of in. and a Joist Girder bearing length

(N) of 4 in. Assuming a 5/16 in. fillet weld is used to attach the Top Plate, a 9/16 in. weld

self dimension is required. Use A36 material for the plate.

Angle Size Unbraced Length Area

L = 5 ft. in.2

2L 4 x 4 x 3/4 406 10.9

2L 4 x 4 x 5/8 345 9.21

2L 4 x 4 x 1/2 281 7.49

2L 4 x 4 x 7/16 249 6.61

2L 4 x 4 x 3/8 211 5.71

2L 4 x 4 x 5/16 143 4.80

2L 4 x 4 x 1/4 92 3.87

2L 3-1/2 x 3-1/2 x 1/2 231 6.53

2L 3-1/2 x 3-1/2 x 7/16 205 5.77

2L 3-1/2 x 3-1/2 x 3/8 178 5.50

2L 3-1/2 x 3-1/2 x 5/16 139 4.21

2L 3-1/2 x 3-1/2 x 1/4 92 3.41

36

Preliminary Top Plate size: W tp = 1+2(3.5-9/16) = 6.88 in. maximum width.

Try W tp = 6 in.

t tp = (133)/[(6)(0.9)(36)] = 0.68, Use 3/4 in.

Preliminary Stabilizer Plate size: t st = 3/4 in. for a 1 in. gap between chords

W st = (133)/[(0.75)(0.9)(36)] [3.5+(2)(9/16)]

= 5.47 4.63, Use a 6 in. plate

Determine the Maximum Stiffener Length (L s) for the Stiffened Seat Connection:

L s = 48 - (7.5+1 + (6/2)) = 36.5 in so maximum stiffener length is 36 in.

AISC TABLE J2.4 Minimum Size of Fillet Welds

For convenient reference, the AISC Table J2.4 is shown below (Metric not shown)

Material Thickness of Thinner Part Joined, in.

Minimum Size of Fillet Weld,[a] in.

To 1/4 inclusive 1/8

Over 1/4 to 1/2 3/16

Over 1/2 to 1/4

Over 3/4 5/16 [a]

Leg dimension of fillet welds. Single pass welds must be used. See AISC Section J2.2b for maximum size of fillet welds.