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LecturesModule 12

Bolted Connections

Bolt shear, bearing, tearout, slip-critical (Chapter J).

AISC Reference Box
  • AISC 360-22 §J3 — Bolts and Threaded Parts

Lecture Notes

This module introduces bolted connections. Lecture content here covers the governing physics, LRFD philosophy, and how the relevant AISC 360-22 chapter organizes the limit states.

Instructors can replace this text in Admin Mode. Each section is structured around: (1) behavior, (2) failure modes, (3) AISC limit-state equations, (4) design workflow, (5) detailing requirements.

A short comparison to ASD is included only where the resistance factor / safety factor relationship clarifies the LRFD design check.

Project case study — Cardinal Square — 4-story braced-frame office

Every chapter's worked example is one step in the design of the same building: Plan: 4 bays N–S × 3 bays E–W, each 30 ft × 30 ft. Stories: 4 @ 13 ft (52 ft roof). Composite floor: 4.5 in NW concrete on 3 VLI20 deck. Roof: 1.5 in B-deck + insulation + membrane. Materials: Wide-flange members A992 (Fy = 50 ksi, Fu = 65 ksi). Plates A572 Gr. 50. HSS bracing A500 Gr. C. Bolts A325-N 7/8 in dia. Welds E70XX. Concrete f'c = 4 ksi. Anchor rods F1554 Gr. 36.

Chapter 12 — Bolted shear-tab connection
Filler-to-girder shear tab — 3 bolts, A325-N 7/8 in
Demand carried forward
From Chapter 7: Vu = 25.5 k per bolt group.
This chapter contributes
Checks bolt shear (φRn = 0.75 · Fnv · Ab), plate bearing and tearout per §J3.7 / §J3.11. Verifies plate edge distance and bolt spacing.
PuLap splice in single shear
Bolted lap splice — limit states: bolt shear (§J3.7), bearing (§J3.11), tearout, slip (§J3.9).

Formula Sheet

NameEquationAISC Ref
Bolt shearφRn = 0.75 · Fnv · AbAISC §J3.7
BearingφRn = 0.75 · 2.4 · db · t · FuAISC §J3.11
TearoutφRn = 0.75 · 1.5 · lc · t · FuAISC §J3.11

Worked Example

Bolted Connections

Given
Replace with project-specific given data (loads, geometry, material).
Load combination
Controlling LRFD load combination from ASCE 7.
Required strength
Compute required strength Ru from the controlling combination.
Limit states
  • Limit state 1
  • Limit state 2
AISC reference
AISC 360-22 — applicable chapter
Solution steps
  1. 1. Required strength
    Compute Ru.
  2. 2. Trial section
    Pick a trial from AISC shape tables Instructor should verify with official AISC Manual.
  3. 3. Check each limit state
    Apply φ Rn ≥ Ru for every governing limit state.
  4. 4. Iterate
    Resize until the most economical section satisfies all checks.
Final design decision
Select the lightest section that satisfies all LRFD limit states.
Common mistakes in this example
  • Skipping a limit state
  • Using the wrong φ factor
  • Forgetting serviceability checks

FE-Style Worked Examples (7)

Each example mirrors the NCEES FE Civil Reference Handbook style: brief givens, a labeled figure, AISC section reference, step-by-step numeric solution, and a single boxed answer.

Given
3/4" A325-N bolt, Fnv=54 ksi, Ab=0.442 in².
AISC Reference
AISC §J3.7 Table J3.2
Step-by-step solution
  1. φRn
    0.75 × 54 × 0.442 = 17.9 k per shear plane
Answer φRn = 17.9 k.
PuLap splice in single shear

Textbook — Aghayere & Vigil (2009)(5 worked examples with figures + numerical answers)

Worked examples scanned directly from the CEGR 436 course textbook. Each card shows the original page (figure + full step-by-step solution) and adds an FE-style numerical multiple-choice prompt with answer key.

Chapter summary

Chapter 9 develops bolt mechanics. A bolt may fail in (a) shear of the bolt body, (b) bearing of the plate against the bolt, (c) tearout of plate material to the edge, (d) tension of the bolt body, or (e) slip in a slip-critical joint. AISC §J3 governs.

  • Bolt shear strength: φRn = 0.75·Fnv·Ab; Fnv = 54 ksi (A325 N), 68 (A325 X), 68 (A490 N), 84 (A490 X).
  • Bearing on plate: φRn = 0.75·2.4·db·t·Fu (deformation OK at service).
  • Tearout: φRn = 0.75·1.5·lc·t·Fu where lc = clear edge/spacing distance.
  • Min spacing s ≥ 2 2/3·db (preferred 3·db); min edge per Table J3.4.
  • Slip-critical (Class A): φRn = 1.00·μ·Du·hf·Tb·ns (μ = 0.30 Class A).
  • Combined shear + tension: use elliptical interaction (§J3.7).
Setup
3/4" A325-N bolt (Fnv = 54 ksi, Ab = 0.442 in²) in single shear.
AISC Reference
AISC §J3.7
Numerical practice
φrn per bolt?
Textbook page 434 — Shear capacity of A325-N bolt
Aghayere & Vigil (2009), p. 434 — full worked solution & sketch.

FE Practice Bank (1)

Multiple-choice problems pulled from the instructor's CEGR 492 FE Review packet (EasyFEExam © 2025, Steve Efe, PhD). Pick an answer, then click Reveal solution.

P37F. Block Shear L4×4×⅜EasyFEExam Structural Design – Problem 37
L4×4×⅜ A36, 5/8-in bolts in one line, 3 bolts @ 3 in, edge 1.5 in. φRn?

Interactive Calculator

Bolt Shear / Bearing / Tearout

AISC §J3.7, §J3.11
Ab0.601 in²
φ Rn (shear, all bolts)97.4 kips
φ Rn (bearing, all bolts)182.7 kips
φ Rn (tearout, all bolts)195.8 kips
Governing φ Rn97.4 kips

Practice Problems

  1. [E] State φ for bolt shear (0.75).
  2. [E] Compute Ab for a 7/8 in. bolt.
  3. [E] State Fnv for A325-N (54 ksi) and A325-X (68 ksi).
  4. [E] State bearing equation φRn = 0.75·2.4·db·t·Fu.
  5. [E] Compute dh for a 1 in. bolt in a standard hole.
  6. [M] 3/4 in. A325-N in single shear. Compute φRn shear.
  7. [M] Bearing on 1/2 in. A36 plate at 7/8 in. bolt with edge dist. 1.5 in. Compute bearing + tearout.
  8. [M] Connection of 6 bolts 3/4 A325-N in double shear. Compute design strength.
  9. [M] Eccentric shear in a 6-bolt group, e = 4 in. — use Table 7-7 IC method.
  10. [M] Slip-critical: 3/4 A325, Class A μ = 0.30. Compute φRn per §J3.9.
  11. [H] Design beam-to-column shear-tab connection for Vu = 80 k using 3/4 A325-N bolts.
  12. [H] Combined shear + tension on a single 7/8 A325-N bolt: Vu = 12 k, Tu = 18 k. Check §J3.7.
  13. [H] Pretensioned 1 in. A490 with calibrated wrench. Verify per Table J3.1.
  14. [H] Design an oversized-hole connection (1/4 in. larger) and state when slip-critical is REQUIRED.
  15. [H] Investigate a 6-bolt single-shear lap splice that fails at 0.75 expected capacity. Identify likely cause.
Structured Clues
  • Bearing controls only when edge distance or pitch is tight.
  • Slip-critical required for oversized/short-slotted holes loaded perpendicular to slot.
  • Combined V+T: use Eq. J3-3a/3b.
Code References
  • AISC 360-22 §J3
  • AISC Manual Tables 7-1 to 7-7

Quiz (1 FE-bank + 2 concept)

1. [P37] L4×4×⅜ A36, 5/8-in bolts in one line, 3 bolts @ 3 in, edge 1.5 in. φRn?
2. Which AISC 360-22 chapter primarily governs bolted connections?
3. In LRFD, the basic design inequality is:

Common Student Mistakes

  • Mixing ASD and LRFD load combinations in the same problem.
  • Using nominal strength Rn instead of design strength φRn.
  • Forgetting to check every limit state listed in the AISC chapter.

"Professor Explains" Script

Today we're talking about bolted connections. Think of this topic as one step in the LRFD workflow: identify the demand, identify the limit states from the relevant AISC chapter, then check that φ·Rn is at least equal to Ru. We'll walk through the failure modes, the equations, and a worked example. Pay close attention to where the resistance factor changes — that's where students lose points on exams.