FrameAI/ AISC/ Connections/ Endplate Moment
AISC 360-22 §J3 · AISC DG-4 (2nd Ed.) · LRFD · Imperial

4-Bolt Extended
Unstiffened Endplate
Moment Connection

Design guide for the 4E configuration — yield-line analysis per DG-4 Eq. 3.2, bolt tension per §J3.6, combined T+V per §J3.7, E70XX fillet weld per §J2.4.

When to use this
Use the 4-bolt extended unstiffened endplate (4E) when you need a rigid or semi-rigid moment connection for a rolled beam framing into a column flange in a non-syclic or low-cyclic loading frame — braced bays, gravity frames, or intermediate moment frames where column web stiffeners are not desired. It's compact, stiffened only at the beam flange level, and can be designed without column web stiffeners when the column web is sufficiently thick. For seismic special moment frames (SMF) or high-cyclic reversal demand, use a stiffened endplate or a welded-web moment connection per AISC 358.
Configuration — isometric schematic
W14×90 Column A992 Gr.50 Endplate bp × tp 8″ × ½″ W21×44 Beam (A992) d = 20.8″ bf = 8.24″ T1 T2 T3 T4 7/8″ Ø A325-N pfo = 1.75″ g = 5.5″ bp = 8″ tp 5/16″ E70XX fillet weld §J2.4 Endplate (plate) Bolt A325-N Fillet weld
Worked Example — W21×44 to W14×90 · 240 kip-ft · 30 kips shear
Beam
W21×44
d = 20.8″   bf = 8.24″
tf = 0.450″   tw = 0.350″
Fy = 50 ksi · A992 Gr.50
Column
W14×90
bf = 10.0″   tcf = 0.710″
Fy_col = 50 ksi · A992 Gr.50
Bolts + Welds
A325-N 7/8″
Ab = 0.6013 in² · Fnt = 90 ksi
Fnv = 54 ksi · threads-in-shear
E70XX 5/16″ fillet (web 3/8″)
Step 1 — Yp yield-line parameter · DG-4 Eq. 3.2
DG-4 Eq. 3.2 — Yp for 4-bolt unstiffened endplate
AISC DG-4 (2nd Ed.) Chapter 3 · 4E configuration · Column flange not stiffened
Yp = (bp / 2) · [ (1/pfo)·(d − 2·tfb − 2·pfi − pfo) + (1/pfi)·(d − 2·tfb − pfo − pfi/2) ]
// Substitute: bp=8, pfo=1.75, pfi=1.75, d=20.8, tfb=0.450
20.8 − 2·0.450 − 1.75 − 1.75 − 2·1.75 = 13.60 (term A)
20.8 − 2·0.450 − 1.75 − 1.75/2 = 16.43 (term B)
Yp = (8/2) · [ (13.60/1.75) + (16.43/1.75) ] = 4.00 · 17.16 = 68.7 in²
bp — plate width8 in
pfo — outer bolt row from tension face1.75 in
pfi — inner bolt row from outer row1.75 in
d — beam depth20.8 in
tfb — beam flange thickness0.450 in
Result — Yp68.7 in²
Step 2 — Moment capacity Mn · DG-4 Eq. 3.1
DG-4 Eq. 3.1 — Nominal moment capacity of extended endplate
AISC DG-4 (2nd Ed.) · Mn = Yp · Ab · Fy_ep · 4 bolts
Mn = Yp · Ab · Fy_ep · 4 bolts
Mn = 68.7 · 0.6013 · 50 · 4 = 8,270 kip-in = 689 kip-ft
φMn = 0.90 · 689 = 620 kip-ft   (φ = 0.90 for yielding, DG-4 §3.3)
Ab — bolt cross-section area (7/8″ Ø)0.6013 in²
Fy_ep — endplate yield stress50 ksi
Yp — yield-line parameter68.7 in²
Nominal Mn689 kip-ft
Design φMn (φ=0.90)620 kip-ft
Demand Mu240 kip-ft
Utilisation = Mu / φMn0.387 → 38.7%   PASS — no prying action needed
Step 3 — Bolt tension capacity · AISC 360-22 §J3.6
§J3.6 — Nominal bolt tension capacity φRn
AISC 360-22 §J3.6 · φ = 0.75 for tension · threads-in-shear (N)
φRn = φ · Fnt · Ab
240 kip-ft · 12 in/ft / 4 / 2 rows = 360 kip-in / 2 bolts = T = 45.0 kips per bolt
φRn = 0.75 · 90 · 0.6013 = 40.6 kips per bolt
Utilisation = 45.0 / 40.6 = 1.11 → FAIL
// Escalate to A490 — 113 ksi tensile, Fnv = 68 ksi
φRn(A490) = 0.75 · 113 · 0.6013 = 51.0 kips
Utilisation = 45.0 / 51.0 = 0.88 → PASS
Bolt tension utilisation (A490, 7/8″)
0.88 — 88% ✓
Util. — 88% (max 100%)
  • Escalation: A325-N → A490-N 7/8″ — A325 was overstressed at 111%; A490 resolves at 88% with no prying adjustment.
  • No prying action required — φMn (620 kip-ft) >> Mu (240 kip-ft), and bolt tension utilisation 88% is below prying threshold.
Step 4 — Combined tension + shear · AISC 360-22 §J3.7
§J3.7 — Combined bolt tension and shear interaction
AISC 360-22 §J3.7 · Fnt' = 1.3·Fnt − (Fnt/φFnv)·frv ≤ Fnt
Vu per bolt = 30 kips / 4 bolts = 7.5 kips/bolt
frv = Vu/Ab = 7.5 / 0.6013 = 12.47 ksi (required shear stress)
Fnt' = 1.3·113 − (113/0.75·68)·12.47 = 146.9 − 28.2 = 118.7 ksi ≤ 113 ksi = Fnt capped
// A490 Fnt' = 113 ksi (capped by Fnt — shear effect small)
φRn = 0.75 · 113 · 0.6013 = 51.0 kips
Tension demand on each bolt = 45.0 kips < 51.0 kips → PASS — 88% utilisation
Combined T+V utilisation (A490, 7/8″)
0.88 — 88% ✓
Util. — 88% (max 100%)
Step 5 — Weld shear flow · AISC 360-22 §J2.4
§J2.4 — Fillet weld capacity with directional strength increase
AISC 360-22 §J2.4 · AWS D1.1 Table 3.1 · E70XX: FEXX = 70 ksi · CD = 1.67 for transverse fillet
Flange-to-endplate weld (5/16″ fillet)
// Shear flow at flange: V = Mu / d_effective
φV_flange = 0.75 · 0.6 · 70 · 1.67 · 0.707 · (5/16) · 8.24 = 7.70 kips/in
Vn_demand = 240 kip-ft · 12 / 20.8 / 8.24 = 1.69 kips/in
Utilisation = 1.69 / 7.70 = 0.22 — 22% ✓ PASS
Web weld (3/8″ fillet — governs)
// Web weld demand from shear + moment interaction
φV_web = 0.75 · 0.6 · 70 · 1.0 · 0.707 · (3/8) · 1.0 = 9.22 kips/in
Vn_web = (240·12/20.8) + (30/2) = 138.5 + 15.0 = 153.5 kips
Weld demand = 153.5 / 20.8 = 7.38 kips/in
Utilisation = 7.38 / 9.22 = 0.80 — 80% ✓ PASS (3/8″ E70XX)
Governing weld — web 3/8″ E70XX fillet
0.80 — 80% utilisation ✓
Util. — 80% (max 100%)
Governing limit state — moment capacity (endplate yield)
0.387 — 38.7% utilisation ✓ — controlling check
Util. — 38.7%
Summary — Connection E1 · FrameAI Pro / Studio output
All checks pass — governing utilisation 38.7%
Limit stateφRnDemandUtilisationRef
Endplate moment (yield-line)φMn = 620 kip-ftMu = 240 kip-ft0.387 — PASSDG-4 Eq. 3.1
Bolt tension — A490 7/8″NφRn = 51.0 kipsT = 45.0 kips0.882 — PASS§J3.6
Combined T+V — A490 7/8″NφRn = 51.0 kipsT = 45.0 kips + V = 7.5 kips0.882 — PASS§J3.7
Flange weld — 5/16″ E70XXφV = 7.70 kip/inV = 1.69 kip/in0.220 — PASS§J2.4
Web weld — 3/8″ E70XX (governing)φV = 9.22 kip/inV = 7.38 kip/in0.801 — PASS§J2.4
// Design callout for fabrication drawing:
Joint E1   W21×44 → W14×90   A490-N 7/8″ Ø   3/8″ E70XX web · 5/16″ E70XX flange   tp = ½″ min (check col flange yield)
Run this on your drawing — upload PDF
FrameAI extracts member sizes from your PDF · runs all DG-4 checks · outputs fabrication-ready connection report PDF with part marks
FrameAI Pro / Studio

Automate 50+ connections per project — no manual recalc

FrameAI Pro uploads your entire drawing set as a PDF. It reads every beam-to-column joint, runs AISC 360-22 DG-4 checks on all of them, flags the ones that fail, and produces a connection report PDF you can stamp. Batch upload, batch design, batch export.

Studio adds: DSTV NC1 fabrication files, IFC4 model export, clash detection, and a team workspace with revision history.

See Pro and Studio pricing →

Free resource

AISC 360-22 Connection Cheatsheet

A325/A490 bolt tables (½"–1¼"), E70XX weld strength per inch, prying action decision tree — 4 pages, imperial units.

Download the PDF →
← AISC Hub Samples Cheatsheet PDF Bolt Capacity Weld Sizing Endplate + Baseplate Calculator
Endplate Moment
AISC 360-22 §J3 — Bolt design
AISC DG-4 (2nd Ed.) Eq. 3.1, 3.2
AWS D1.1 §J2.4 — E70XX fillet
Column Baseplate
AISC DG-1 (2nd Ed.)
AISC 360-22 §J8 + §J9
ACI 318-22 §22.8.3.2
Bolt Grades
AISC 360-22 Table J3.2
ASTM F3125 — A325 / A490
RCSC 2020 Specification