New Trends for Seismic Engineering of Steel and Composite Structures - PowerPoint PPT Presentation

New Trends for Seismic Engineering of Steel and Composite Structures Jerome F. Hajjar, Ph.D., P.E. Professor and Chair Department of Civil and Environmental Engineering Northeastern University Mark D. Denavit Department of Civil and Environmental Engineering University of Illinois at Urbana-Champaign Third International Symposium on Innovative Design of Steel Structures June 28 & 30, 2011

Articulated Fuse Self- Centering Systems Composite Steel/Concrete Systems OUTLINE This image cannot currently be displayed.

AISC Specification and Seismic Provisions 2005 2010 Rewritten from scratch: 2005 AISC Specification for Structural Steel Buildings 2010 AISC Seismic Provisions for Structural Steel Buildings Available from http://www.aisc.org

Possible configurations in composite columns a) SRC b) Circular and Rectangular CFT c) Combinations between SRC and CFT

AISC 2005 Provisions for Composite Columns New Limitations • Material strengths: � Concrete 10 ksi (70 MPa) � Steel 75 ksi (525 MPa) • Steel area: 0.01 A g min

AISC 2005 Provisions for Composite Columns • Typically use Plastic Stress Distribution Method � Plastic Strength Equations • For axial compression: � Square, rectangular, round HSS are in tables in AISC Manual for CFTs � Tabulated versus KL (effective length) � f’ c = 4, 5 ksi concrete

AISC 2005 Provisions for Composite Columns P-M Interaction Diagram A φ P n (kips) C D B φ M n (kip-ft) Axial force-bending moment interaction diagram Slides from L. Griffis, Walter P. Moore & Assoc.

AISC 2005 Provisions for Composite Columns P-M Interaction Diagram A F y 0.85 f’ c φ P n (kips) P A = A s F y + 0 .8 5 f’ c A c M A = 0 A s = area of steel shape A c = A g - A s φ M n (kip-ft)

AISC 2005 Provisions for Composite Columns P-M Interaction Diagram F y 0 .8 5 f’ c P B = 0 12Z = − − M M Z F (0.85f' ) PNA φ P n (kips) B D sn y cn c h n = 2 Z 2t h sn w C L n = 2 Z h h cn 1 n 0.85f' A h = ≤ c c 2 [ ] h n + 2 2 0.85f' h 4t F c 1 w y B φ M n (kip-ft)

AISC 2005 Provisions for Composite Columns P C = 0 .8 5 f’ c A c M C = M B C P-M Interaction Diagram PNA C L φ M n (kip-ft) F y 0 .8 5 f’ c φ P n (kips) h n

AISC 2005 Provisions for Composite Columns P-M Interaction Diagram F y 0 .8 5 f’ c 0.85f' A = c c P D 2 φ P n (kips) 12Z (0.85f' ) = + M Z F D s y c c s = C L Z full y- axis plastic D PNA section modulus of steel shape 2 h h = 2 − 1 3 Z 0.192r c i 4 φ M n (kip-ft)

AISC 2005 Provisions for Composite Columns P-M Interaction Diagram Stability reduction (schematic) A φ P n (kips) C D AISC interaction B φ M n (kip-ft) Unsafe design

AISC 2010 Provisions for Composite Columns (a) Rectangular Filled Section Axial Strength as a Function of Wall Slenderness (b) Circular Filled Section Axial Strength as a Function of Wall Slenderness P o = A s F y + c 2 A c ′ f P o = A s F y + c 2 A c ′ f c c E s E s P o = A s F y + 0 . 7 ′ c × (A c + A sr f ) P o = A s F y + 0 . 7 ′ c × (A c + A sr f ) Section Axial Strength E c Section Axial Strength E c 9 E s E s (b / t) 2 + 0 . 7 ′ P o = A s × c × (A c + A sr f ) 0 . 7 E s (P o ) P o = A s F y × 0 . 2 + 0 . 7 ′ c × (A c + A sr E c (P o ) f ) ⎛ ⎞ E c F y D ⎜ t × ⎟ ⎜ ⎟ E ⎝ ⎠ Slenderness (b/t) Slenderness (b/t) E E 0 . 78 E E λ p = 0 . 15 E λ r = 0 . 19 E λ p = 2 . 26 λ r = 3 . 00 7 . 00 F y F y F y F y F y F y (d) Axial Strength – Flexural Strength Interaction for Filled Columns with Wall Slenderness Greater than λ p (c) Rectangular Filled Section Flexural Strength as a Function of Wall Slenderness σ y 0.85 f’ c P o is function of wall slenderness obtained from Fig.(a) EI eff = E s I s + E s I sr + c 3 E c I c σ 1 ≤ σ y 0.70 f’ c φ c P n Axial Strength with Slenderness Effects P e = π 2 (EI eff )/(KL) 2 When P e < 0 . 44 P o ; P n = 0 . 877 / P e σ y Section Flexural Strength (M n ) When P e ≥ 0 . 44 P o ; P n = P o × 0 . 658 P o P e σ y Linear Interpolation ⎛ ⎞ M ry P r + 8 M rx ⎜ ⎟ + ⎟ ≤ 1 . 0 ⎜ φ c P n φ b M nx φ b M ny 9 ⎝ ⎠ σ cr 0.70 f’ c 0.2 φ c P n Slenderness (b/t) σ y ⎛ ⎞ M ry E E P r M rx E ⎜ ⎟ λ r = 3 . 00 + + ⎟ ≤ 1 . 0 λ p = 2 . 26 7 . 00 ⎜ 2 ×φ c P n φ b M nx φ b M ny F y F y F y ⎝ ⎠ M n Flexural Strength with Slenderness Effects (obtained from Fig. (c))

AISC 2010 Load Transfer Provisions Unified provisions for load transfer: � Direct bearing (CFT, SRC, Composite Components) � Bond interaction (CFT, Composite Components) � Steel anchors (CFT, SRC, Composite Components), with adequate spacing and avoidance of concrete breakout failure

AISC 2005 Provisions for CFT Slip AISC 2010 Provisions: Bond Transfer = 2 V b C F Rectangular CFTs in in in 2 = π Circular CFTs V 0.25 D C F in in in V in = Nominal bond strength < V u / φ C in = 2 if CFT extend only above or below; C in = 1 if CFT extend only above or below; 2 otherwise 4 otherwise F in = Nominal bond stress = 0.06 ksi (0.4 MPa) b = width of rectangular HSS face transferring load D = diameter of circular HSS φ = 0.45 (large scatter in results)

AISC 2010 Provisions: Steel Anchors NON-SEISMIC PROVISIONS � Shear: h/d (height/depth of stud anchor) > 5 and: = φ = φ = β = Q C A F with C 0 . 65 and 1 . 0 and 4 . 0 s v v s u v v � Tension: h/d >8 and: = φ = φ = β = Q C A F with C 0 . 75 and 1 . 0 and 4 . 0 s v v s u v v � Interaction: h/d >8 and: ⎡ ⎤ 5 5 ⎛ ⎞ ⎛ ⎞ 3 3 Q Q ⎢ ⎥ φ = φ = + ≤ 0.75; 0.65 t v 1.0 ⎜ ⎟ ⎜ ⎟ t v ⎢ φ φ ⎥ Q Q ⎝ ⎠ ⎝ ⎠ ⎣ ⎦ t nt v nv � If dimensional limits are not met, use proper detailing or use ACI 318-08 SEISMIC PROVISIONS � Use the AISC formulas but reduce the shear connector strength by 25%

New Organization in AISC 341 ‐ 10: Composite integrated into provisions A. General Requirements B. General Design Requirements C. Analysis D. General Member and Connection Requirements E. Moment Frame Systems F. Braced ‐ Frame and Shear ‐ Wall Systems G. Composite Moment Frame Systems H. Composite Braced ‐ Frame and Shear ‐ Wall Systems I. Fabrication and Erection J. Quality Assurance and Quality Control K. Prequalification and Cyclic Qualification Testing

AISC 341 ‐ 10 2010 Composite Seismic Systems • Composite Moment Frames • Composite Ordinary Moment Frames • Composite Intermediate Moment Frames • Composite Special Moment Frames • Composite Partially ‐ Restrained Moment Frames • Composite Braced Frames • Composite Ordinary Braced Frames • Composite Special Concentrically Braced Frames • Composite Eccentrically Braced Frames • Composite Walls (including coupling beams) • Composite Ordinary Shear Walls • Composite Special Shear Walls • Composite Plate Shear Walls

Ongoing Research Design Recommendations • Design recommendations: – Effective flexural ( EI eff ) and torsional rigidity ( GJ eff ) for 3D analysis – Critical load ( P n ) and column curves ( P n ‐ λ ) for slender CFTs – P ‐ M interaction for slender CFTs – System behavior factors for composite systems ( R , C d , Ω o ) – Direct analysis for composite systems P/P o AISC Fiber Analysis

Non ‐ Seismic and Seismic Design of Composite Beam ‐ Columns and Composite Systems Mark D. Denavit Tiziano Perea University of Illinois at Urbana ‐ Champaign Universidad Autónoma Metropolitana Urbana, Illinois Mexico DF, Mexico Jerome F. Hajjar Roberto T. Leon Northeastern University Georgia Institute of Technology Boston, Massachusetts Atlanta, Georgia Sponsors: National Science Foundation American Institute of Steel Construction Georgia Institute of Technology University of Illinois at Urbana ‐ Champaign

Introduction • Experimental assessment of Composite limit surface Column – Slender CFT beam ‐ column tests Steel Girders • Finite element formulation – Mixed beam ‐ column element – Steel and concrete uniaxial cyclic materials CCFT RCFT – Localization and plastic hinge length • Computational assessment of composite system behavior

Specimens designed for CFT Test Matrix Closing databases gaps in: Specimen L Steel section Fy f c ’ D/t • L, λ , D/t, f c ’ name (ft) HSS D x t (ksi) (ksi) 1-C5-18-5 18 HSS5.563x0.134 42 5 45 Maximize MAST capabilities: 2-C12-18-5 18 HSS12.75X0.25 42 5 55 • P z = 1320 kip 3-C20-18-5 18 HSS20x0.25 42 5 86 • U x =U y =+/ ‐ 16” 4-Rw-18-5 18 HSS20x12x0.25 46 5 67 • 18’ < L < 26’ 5-Rs-18-5 18 HSS20x12x0.25 46 5 67 • Other constraints 6-C12-18-12 18 HSS12.75X0.25 42 12 55 MAST Lab 7-C20-18-12 18 HSS20x0.25 42 12 86 8-Rw-18-12 18 HSS20x12x0.25 46 12 67 9-Rs-18-12 18 HSS20x12x0.25 46 12 67 10-C12-26-5 26 HSS12.75X0.25 42 5 55 11-C20-26-5 26 HSS20x0.25 42 5 86 12-Rw-26-5 26 HSS20x12x0.25 46 5 67 13-Rs-26-5 26 HSS20x12x0.25 46 5 67 14-C12-26-12 26 HSS12.75X0.25 42 12 55 15-C20-26-12 26 HSS20x0.25 42 12 86 16-Rw-26-12 26 HSS20x12x0.25 46 12 67 17-Rs-26-12 26 HSS20x12x0.25 46 12 67 18-C5-26-12 26 HSS5.563x0.134 42 12 45