Seismic Analysis of Reinforced Concrete Non-planar Walls and Buildings using Three-dimensional Beam-truss Models

Transcription

1 Seismic Analysis of Reinforced Concrete Non-planar Walls and Buildings using Three-dimensional Beam-truss Models Yuan Lu Marios Panagiotou Department of Civil and Environmental Engineering University of California, Berkeley Sixth Kwang-Hua Forum December 12-14, 2014 Shanghai, China

2 Tall RC Wall Buildings in High Seismicity Regions RC core walls for earthquake lateral force resistance Reinforcement of a RC core wall One Rincon Hill, 60-stories San Francisco, USA Notes of Professor J. Moehle Construction of Seattle Art Museum, WA, USA Maffei and Yen (2007) 2

3 Earthquake Damage of RC Walls Maffei and Yuen (2007) Boroschek et al. (2014) Dazio et al. (2009) 1995 Kobe Japan earthquake M6.8 Courtesy of J. Restrepo 2010 Chile earthquake M L'Aquila earthquake M6.3 3

4 Three-dimensional Beam-truss Model for RC Walls Diagonal shear failure of non-planar walls are determined by multi-axial stress and strain states Explicitly account for shear-flexure interaction 4

5 Three-dimensional Beam-truss Model for RC Walls 5

6 Three-dimensional Beam-truss Model for RC Walls Section discretization, concrete and steel areas determination 6

7 Three-dimensional Beam-truss Model for RC Walls Nonlinear fiber-section beam-column elements (out-of-plane flexural rigidity only) 7

8 Three-dimensional Beam-truss Model for RC Walls Section discretization, concrete and steel areas determination 8

9 Three-dimensional Beam-truss Model for RC Walls Nonlinear fiber-section beam-column elements (out-of-plane flexural rigidity only) 9

10 Three-dimensional Beam-truss Model for RC Walls Nonlinear truss modeling diagonal compression field of concrete accounting for bi-axial effects truss 10

11 Three-dimensional Beam-truss Model for RC Walls Diagonal angle (θ d ) corresponds to the inclination of the compressive concrete struts formed at V max Determined based on: shear force demand shear reinforcement geometry of the wall V N For walls uniform over their height: ft V max θ d = tan 1 ( ) 65 o f y,t ρ t A v 11

12 4470 Shear-dominated Barbell-shaped Wall Subject to Static Cyclic Loading Longitudinal steel ratio: ρ l = 2.3% (average) Transverse steel ratio: ρ t = 0.62% Axial load ratio: N/f c A g = 13.4% Oesterle, R. G., Aristizabal-Ochoa, J. D., Fiorato, A. E., Russell, H. G., and Corley, W. G. (1979). Earthquake Resistant Structural Walls Test of Isolated Walls Phase II, Report to the National Science Foundation, Construction Technology Laboratories, Portland Cement Association, Skokie, IL. 12

13 Shear-dominated Barbell-shaped Wall Subject to Static Cyclic Loading Longitudinal steel ratio: ρ l = 2.3% (average) Transverse steel ratio: ρ t = 0.62% Axial load ratio: N/f c A g = 13.4% Oesterle, R. G., Aristizabal-Ochoa, J. D., Fiorato, A. E., Russell, H. G., and Corley, W. G. (1979). Earthquake Resistant Structural Walls Test of Isolated Walls Phase II, Report to the National Science Foundation, Construction Technology Laboratories, Portland Cement Association, Skokie, IL. 13

14 Shear-dominated Barbell-shaped Wall Subject to Static Cyclic Loading 14

15 Shear-dominated Barbell-shaped Wall Subject to Static Cyclic Loading 15

16 Shear-dominated Barbell-shaped Wall Subject to Static Cyclic Loading 16

17 U-shaped Wall Subject to Multi-axial Static Cyclic Loading 17

18 U-shaped Wall Subject to Multi-axial Static Cyclic Loading 18

19 U-shaped Wall Subject to Multi-axial Static Cyclic Loading 19

20 NS Lateral force (kn) (2.95 m from base) EW Lateral force (kn) (3.35 m from base) U-shaped Wall Subject to Multi-axial Static Cyclic Loading 500 N-S cycles 400 DIAG cycles 500 SWEEP cycles NS drift ratio (%) E-W cycles first diagonal softening first diagonal crushing NS drift ratio (%) DIAG cycles NS drift ratio (%) SWEEP cycles EW drift ratio (%) -250 Experimental Cyclic Monotonic EW drift ratio (%) EW drift ratio (%) 20

21 Shake-table test of 5-story coupled wall, Specimen SLO (Coelho et al. 2006), subject to triaxial excitation

22 Shake-table test of 5-story coupled wall subject to triaxial base excitation

23 Shake-table test of 5-story coupled wall subject to triaxial base excitation

24 Base shear / W Roof drift ratio (%) Shake-table test of 5-story coupled wall subject to triaxial base excitation parallel to web Experimental Numerically computed parallel to flange first diagonal softening first diagonal crushing horizontal strain 1.5% time (s) time (s)

25 base shear / W Shake-table test of 5-story coupled wall subject to triaxial base excitation 1 parallel to web 1 parallel to flange first diagonal softening first diagonal crushing horizontal strain 1.5% roof drift ratio (%) -0.5 experimental computed roof drift ratio (%)

26 3D Analysis of a 20-story RC core wall building subject to biaxial ground motions 1 m x 1 m columns 26

27 Sa (g) Sd (m) acceleration (g) Sa (g) 3D Analysis of a 20-story RC core wall building subject to biaxial ground motions Ground motion record TCU052 Ground from Acceleration M Chi-chi, Taiwan EQ eleration time (s) Spectral Acceleration Spectral Displacement DE (ASCE 7-10) MCE (ASCE 7-10) TCU052 - N direction TCU052 - E direction s) period (s) period (s) 27

28 3D Analysis of a 20-story RC core wall building subject to biaxial ground motions 28

29 3D Analysis of a 20-story RC core wall building subject to biaxial ground motions diagonal compression failure of the core wall with normal tensile strain of 0.8% 29

30 3D Analysis of a 20-story RC core wall building subject to biaxial ground motions At 3% roof drift ratio: Widespread diagonal compression failure of the core wall 30

31 3D Analysis of a 20-story RC core wall building subject to biaxial ground motions The BTM is shown to have good results for RC walls and buildings under cyclic static or dynamic seismic excitation. Diagonal shear failures are modeled. We study of the behavior of a conventionally designed fixed-based 20-story core wall building for a strong near-fault ground motion Diagonal crushing failure, especially in the unconfined region of the wall, occur at 2.3% roof drift ratio. 31

32 Questions?