CE 591 Fall 2013 Lecture 21: Beam-Column Connections

Transcription

1 CE 591 Fall 2013 Lecture 21: Beam-Column Connections Connection Types Connection Classification Schemes Preview of Beam-Column Connections Limit States

2 AISC B3.6 Types of Connections Categorized by amount of restraint Fully-restrained (FR) Moment connection a.k.a. Rigid connection Transfers moment with negligible rotation (rotational restraint ~90% or more) May assume no relative rotation Shall have sufficient strength and stiffness to maintain angle at strength limit states

3 AISC B3.6 Types of Connections Partially-Restrained (PR) Moment Connections Rotation between connected members is not negligible Insufficient stiffness to maintain the angles between connecting members Use of PR connections requires consideration of strength, stiffness, ductility characteristics into analysis and design

4 AISC B3.6 Types of Connections Simple Connections a.k.a. unrestrained, pinned support Original angle changes 80% or more of that of a theoretical frictionless hinge Transfer of shear forces only; negligible moment resistance q

5 AISC B3.6 Simple Connections Requirements Unrestrained relative rotation between framing elements may be assumed Connections shall have sufficient rotation capacity to accommodate the required rotation determined by the analysis of the structure

6 Flexible Moment Connections AISC Part 11 Special case in PR connection section Simplified approach to PR connection design Good for preliminary design Beam and web connections designed as simple framing Consider gravity loads only Beam flange-to-column connections and beams designed for lateral loads Designed as fully restrained Economical and valid for frames <10 stories high

7 Flexible Moment Connections AISC Part 11 Shakedown - this PR connection does not achieve its final moment capacity until it has been subjected to full gravity and lateral loading Shakedown moment = plastic moment of the connection Note: specific requirements for stability analysis

8 FMC/PR Connection Shakedown Flange Angle Connection

9 FMC/PR Connection Shakedown RBS (FR) Connection

10 Moment (M) Classification Rigid - FR Semi-Rigid - PR Simple Rotation (q)

11 Classification w L q M q wl 2 12 wl 3 24EI

12 Moment (M) Classification wl 100% 12 2 FR 20 EI L PR 2 EI L AISC C-B3.6 20% wl % 3 wl 24EI EI 2L Rotation (q) SIMPLE 80% 3 wl 24EI

13 Moment (M) Classification Full Strength Partial Strength Rotation (q)

14 Beam-Line Analysis Based on slope-deflection equations Gravity Loading w a L b M a q a 2EI M a M Fa qa q b M b L

15 Moment (M) Beam-Line Analysis wl 2 12 Connection M-q response (M,q) for your beam and connection Rotation (q) 3 wl 24EI

16 Moment (M) Beam-Line Analysis (Non-linear) wl 2 12 Rotation (q) 3 wl 24EI

17 Load (kips) Example Beam-Line Analysis Shear Tab (6A) With Seat Angle (8A) Drift (radians) 6-bolt Shear Tab + Seat Angle

18 Beam-Line Example M 2 wl kip in wl 24EI rad W24x55 I = 1360 in 4 L = 25 ft w=2 kips/ft Simple q

19 Beam-Line Example M 2 wl kip in wl 24EI rad W24x55 I = 1360 in 4 L = 40 ft w=2 kips/ft Simple q

20 Beam-Line Example M 2 wl kip in wl 24EI rad W24x104 I = 3100 in 4 L = 40 ft w=2 kips/ft Simple q

21 Connections Single Plate / Shear Tab

22 Double Angle (all-bolted)

23 Welded-Bolted Seat (Unstiffened)

24 Field-Welded Moment Connection

25 End Plate Moment Connection

26 Bolted Flange Plate Moment Connection

27 Welded Flange Plate Moment Connection

28 Limit States Tension Fracture Tension Yielding Buckling Swanson & Leon, Georgia Tech

29 Limit States Block Shear Rupture Swanson & Leon, Georgia Tech

30 Limit States Flexural Yielding / Rupture Shear Yielding Shear Rupture Nader & Astaneh, U.C. Berkeley

31 Limit States Prying Action Angle Deformation (flexural yielding / shear yielding) Swanson & Leon, Georgia Tech Yang,et al.

32 Limit States Angle Deformation Garlock et al., 2003 (Lehigh Univ.)

33 Limit States Bolt Bearing Bolt Shear Bolt Tension Fracture Weld Shear Green, U. Florida Swanson & Leon, Georgia Tech

34 Limit States Concentrated Forces Flange Local Bending Web Compression Buckling Local Web Crippling (LWC) Local Web Yielding (LWY) Murray, Virginia Tech