1. Design of Beam-Column Connections in Steel Moment Frames

2. Observed Damage to Steel Moment Frames in the 1994 Northridge Earthquake

3. Observed Damage to Steel Moment Frames in the 1994 Northridge Earthquake

4. Typical Moment Frame Connection Detail Prior to 1994

5. The SAC Steel Project www.sacsteel.org
Funded by FEMA
Over 6 years to 2000
$12m research funding
Participated by 100s of practicing engineers, university researchers, contractors, materials suppliers, inspectors and building officials

6. Output of the SAC Steel Project

7. Prequalified Connection Detail by FEMA 350

8. Welded Unreinforced Flanges, Welded Web Connection (WUF-W)

9. Welded Unreinforced Flanges, Bolted Web Connection (WUF-B)

10. Recommended Weld Access Hole Detail

11. Typical Details of the Joint Panel Zone - Continuity Plate and Column Web Doubler Plate

12. Design Procedure of the WUF-B Connections

13. Beam-Colum Connection Recommended in GB50011-2001: WUF-B Connection – Beam Parallel to Column Web
Column through, joint panel zone in the column
The 2 welds between the beam flanges and the columns flange must be CJP groove welds
The beam web to column flange connection by high strength friction grip bolts via a column connection plate
The weld between the column flange and the column connection plate shall be fillet weld both sides, >=5mm, and to develop the full shear strength of the connection plate. If the plate exceeds 16mm in thickness, use double bevel CJP groove welds
Continuity plates and beam flanges equal thickness and equal strength

14. Beam-Colum Connection Recommended in GB : WUF-B Connection – Beam Perpendicular to Column Web

15. Design Process – Step 1 Design Connection for Bending
Mu >= 1.3Mp
Mp = full plastic moment capacity of the plastic hinge of the beam (column through), or of the column (beam through)
Mu = Bending moment resistance capacity of the joint connection provided by the flange connections and based on the design strength of connection
If column through and if CJP groove welds are used to connect the beam flanges to the column, this overtrength requirement is considered met

16. Eurocode 8 Provisions

17. Design Process – Step 2 Design Connection for Shear
Vu >= 1.2(2Mp/ln)+VGb
Mp = full plastic moment capacity of the plastic hinge of the beam (column through), or of the column (beam through)
ln = clear span of beam
VGb=(seismic weight UDL)ln/2, shear force at beam ends, determined by considering static equilibrium of the isolated beam under the seismic weight UDL
Vu = Shear resistance capacity of the joint connection provided by the web connection and based on the design strength of connection

18. Design Process – Step 3 Calculate the Required Panel Zone Thickness and Determine if a Doubler Plate is Needed
The shear stress in the panel zone bounded by the flanges of the column and the continuity plates shall meet t = y(Mpb1 + Mpb2)/Vp<=4fyv/3, as well as t = (Mb1 + Mb2)/Vp<=(4/3)fv/gRE
Vp = hbhctp is the volume of the panel zone, tp is the panel zone thickness >=(hb + hc)/90
y = 0.6 for Seismic Resistance Class 3 and 4, 0.7 for Seismic Resistance Class 1 and 2
Mb1 and Mb2 = the factored bending moments of beams at the two sides of the joint panel
gRE=0.75
fv = design shear strength of steel
fyv = 0.58fy, is the yielding stress in shear of steel material
Beam-Column Joint Panel Zone
Doubler Plate if Required

19. Design Process – Step 4 Design the Shear Tab and the HSFG Bolts
To resist the connection shear force demand 1.3(2Mp/l)
FEMA 350 recommends that the bolts should be designed for bearing
Chinese code recommends the following for checking the shear resistance of HSFG bolts: Nvb = 0.75nAnbfub
Nvb = shear resistance provided by one HSFG bolt
n = number of cross sections resisting shear in the bolt
Anb= net cross section area of bolt
fub = tensile strength of bolt material