Nonlinear Analysis of Reinforced Masonry Shear Walls with ASCE 41

Transcription

1 Nonlinear Analysis of Reinforced Masonry Shear Walls with ASCE 41 Noveber 4, 2017 P. Benson Shing University of California, San Diego The Masonry Society AIA Provider: Reinforced Masonry Wall Systes NIST GCR Seisic Design of Special Reinforced Masonry Shear Walls A Guide for Practicing Engineers 2 1

2 Nonlinear Behavior of RM Walls Flexure-Doinated Behavior Shear-Doinated Behavior Flexure-Doinated Behavior Wall tested by Sheran (2011) Relatively gentle Daage includes: Toe crushing Vertical bar buckling Vertical bar fracture Lap splice failure Strength and ductility depend on: Aount of vertical steel Aount of axial copressive load Effective aspect ratio (h eff /l w or M/Vd) 4 2

3 ASCE 41-1 Flexure-Doinated Walls Deforation-Controlled In-Plane RM Walls Axial Stress f ae / f e 1/Aspect Ratio l / h w eff Reinforceent Index ρ f / f g ye e k For cantilever walls, 1 k = h h + E (0.5I ) A G g v Less drift capacity 5 Shear-Doinated Behavior Wall tested by Ahadi (2011) Severe load drop Daage involves: Diagonal cracking Masonry crushing Horizontal bar fracture /anchorage failure Strength and ductility depend on: Aount of horizontal steel Aount of vertical steel Aount of axial copressive load Presence/absence of wall flanges 6

4 ASCE 41-1 Shear-Doinated Walls k For cantilever walls, 1 k = h h + E (0.5I ) A G g v TMS 402: Q = ( V + V ) γ y n ns g M ' Vn = An f P Vlw V 0.5 v ns = A f ydv s 7 Coparison with Experiental Data Flexure-Doinated Wall Shear-Doinated Wall ASCE 7-1 pushover curves: Too stiff Too brittle 8 4

5 Proposed Changes Chapter 9 Reinforced Masonry Walls 9 Flexure-Doinated RM Walls Q Experiental Data + Rational Analysis Cantilever Wall for Exaple 1 k = h h + E I 0.5A G Ie e v = 0.15I Considering cracking based on wall test data 10 5

6 Envelope Deterined by Moent-Curvature Analysis Moent-Curvature Relation Cantilever Wall for Exaple: = f + v M h ax ax p Δ f = + φ Lp ( h ) EIe EIe 2 h v = Q ax 0.20A G Sae for p v 75and L = 0.20h eff Flexure + Shear c M L 11 Material Models Masonry Steel function of α and β Bar Buckling f y α = ρv f P β = f A n Accounts for Buckling Low-cycle fatigue 12 6

7 Nondiensionalized Moent-Curvature Relation for a Rectangular Wall Section Function of: f y α = ρv f P β = f A n σ / f - ε relation σ / f - ε relation s y 1 Nondiensionalized M-ϕ Values for Fully Grouted Rectangular Wall Sections under Cyclic Loading Reinforceent α = (f y /f' )ρ v Axial Copression Ratio β = P/(f' A n ) ϕ u l w ϕ 75 l w ϕ c l w M/(f' A n l w )

8 10/0/2017 Coparison with Test Data ρ v = 0.% ρ v = 0.16% Axial Load = 0 Axial Load Ratio = 6.25% Axial Load = 0 h/lw= 1 ρ v = 0.% h/lw= 2 15 Coparison with Test Data Axial Load Ratio = 5% ρv = 0.72% Lap-splice failure not well represented h/lw= Axial Load Ratio = 5% ρv = 0.72% h/lw= 4.5 Too ductile for a slender wall Need to ipose 4% Drift Liit 16 8

9 Coparison with 2 Wall Tests Calculated/Experiental Q ax Δ y Δ Δ c Mean Median SD COV Cyclic Analyses Bea-Colun Eleent in OpenSEES Hysteretic Material Model for Steel 18 9

10 Monotonic vs. Cyclic Loading α + β = α + β = Lateral Force(kips) Lateral Force(kips) Lateral Force(kips) α + β = f y α = ρv f P β = f A n 19 Lap Splices at Base of Walls w/o lap splice w/ lap splice w/ lap splice Slender wall w/ extensive toe crushing leading to loss of two extree vertical bars 20 10

11 Shear-Doinated Fully Grouted Walls Based on Experiental Data For cantilever walls, 1 k = h h + E I 0.5A G Ie e v = 0.15I TMS 402: Qax = Vn = Vn + Vns Sae as ASCE 41-1 M ' Vn = An f P Vlw V 0.5 v ns = A f ydv s Q r = V ns 21 Coparison with Test Data M / Vl w = 0.5 M / Vl w = 1.0 M / Vl w = Wall Tests 2% ultiate drift liit is a bit ore than that indicated by wall coponent tests 22 11

12 2-Story RM Building Tested on Shaking Table Positive direction Shaking direction Shear failure in piers Wall syste appeared to be ore ductile than wall coponents. Maxiu Local Drift Ratio of Piers:.8% in positive direction 2.% in the negative direction Additional displaceent capability contributed by Wall flange Out-of-plane walls 2 Shear-Doinated Partially Grouted Walls Based on Experiental Data For cantilever walls, 1 k = h h + E I 0.5A G e v 0.2% 0.4% 0.8% TMS 402: ( ) Qax = Vn = Vn + Vns 0.75 Qr = Vns 0.75 M ' Vn = An f P Vlw V 0.5 v ns = A f ydv s Ie = 0.15I 24 12

13 Wall Syste Analysis Special attention: Ability of bea-colun eleents to odel shear behavior is liited. One ay add a nonlinear shear spring to a bea eleent. Predefined shear behavior will not account for the variation of axial loads induced by lateral forces. Behavior of partially grouted walls can be coplicated resebling an infilled frae. 25 This concludes The Aerican Institute of Architects Continuing Education Systes Course Contact Inforation: The Masonry Society pshing@ucsd.edu 1