Prediction of the Lateral Load Displacement Curves for RC Squat Walls Failing in Shear

Transcription

1 PESDES 2017 International Workshop on Performance-Based Seismic Design of Structures Prediction of the Lateral Load Displacement Curves for RC Squat Walls Failing in Shear Shyh-Jiann Hang Director National Center for Research on Earthquake Engineering October 14, 2017 Professor National Taian University

2 Mission of NCREE Established at National Taian University in 1990 Mission: Pre-quake preparation Disaster prevention Emergency response Disaster reduction Post-quake recovery Disaster relief 2

3 Outline Introduction Proposed Load Deflection Curve Test Verification Conclusions

4 Outline Introduction Proposed Load Deflection Curve Test Verification Conclusions

5 Seismicity in Taian ( ) 5

6 Vulnerable Lo-rise RC Buildings Collapse of School Building Collapse of Street Tonhouse Most Vulnerable Buildings under Chi-Chi Earthquake

7 Lo-rise Reinforced Concrete Buildings Tax Information of Taian (2011) Total: 54 million buildings,1,651million m 2 RC Buildings ith 7 stories and belo : 61.4% Total Floor Area RC Steel Brick Else

8 Performance Based Engineering

9 Seismic Evaluation Pushover Analysis Capacity Spectrum Method Ap Performance-Target Ground Acceleration Ap

10 Skeleton Curves RC Short Column Shear Wall Column

11 Damage of RC Walls 2016 Meinong Earthquake 2010 Chile Earthquake

12 Damage of Short Columns 1999 Chi-Chi Earthquake

13 Objective Propose the lateral-load displacement curves of shear all and short column subjected to shear failures Considering: cracking strength shear deformation collapse

14 Outline Introduction Proposed Load Deflection Curve Test Verification Conclusions

15 Test Observation on Short Column 1.Shear cracking 2.Shear deformation 3. Strut-and-tie action 4. gradual process Li, Y. A., Huang, Y. T., and Hang, S. J., (2014) Seismic Response of Reinforced Concrete Short Columns Failed in Shear, ACI Structural Journal, V. 111, No. 4, July-August, pp

16 Proposed Curve Weng, P. W., Li, Y. A., Tu, Y. S., and Hang, S. J., (2017) Prediction of Lateral Load Displacement Curves for Reinforced Concrete Squat Walls Failed in Shear, Journal of Structural Engineering, ASCE, 143(10), DOI: /(ASCE)ST X ,

17 (ACI Code) eb shear cracking flexural shear cracking Cracking Point c cr Nd d t f V d t V M t N f f V c c cr

18 Cracking Point cr f, cr s, cr slip, cr Flexure f, cr V cr 12E h c 3 I eff Shear, s cr V cr 0.4E h c t d Slip slip, cr V V cr y d b f 8uE 2 y s d 1 kd h

19 Proposed Curve

20 Softened Strut-and-Tie Model Diagonal Compression Equilibrium Compatibility Softening Shear Strain 2 d d v v h 2 Cylinder r h Normal Strain d Diagonal Comp. Failure d f c f c d o o Hognestad Parabola d d Cracked reinforced concrete f v d r d f h Hang, S. J., and Lee, H. J., (2002) Strength Prediction for Discontinuity Regions by Softened Strut-and-Tie Model, Journal of Structural Engineering, ASCE, Vol. 128, No. 12, pp

21 Strength Point Softened Strut-and-Tie model V n Kf A cos c str A K tan cot B A 1.64 f y A 12 1 f c B f y 30 1 f c f c 3.35 MPa 0.52 Hang, S. J., Tsai, R. J., Lam, W. K., and Moehle, J. P., (2017) Simplification of Softened Strut-and- Tie Model for Strength Prediction of Discontinuity Regions, ACI Structural Journal, V. 114, No. 5, pp kd A kd str t N t f c

22 Formulation of Strut-and-Tie Mechanism Shear Deformation due to Strain Field of Shear Element v 1DL - 1.5% 1DH 0.75% r d h Tests of Short Columns

23 Characteristics of Strength Point V max : : divergent Approximation V max is preferred.

24 Approximation of Strain Field h y v y v d h r d d h v r r 0.005

25 Shear Deformation r (Mohr s Compatibility) sin 2 vh r d 0.006sin 2 vh d h 0.006sin 2 s vh h

26 Lateral Displacement n f s slip Flexure f V cr 12E h c 3 I eff Shear sin 2 s h Slip slip V V cr y d b f 8uE 2 y s d 1 kd h

27 Proposed Curve

28 Collapse Point Condition Strength ratio ( V ) a V n Drift ratio ( a h ) A A s s A s t A s t f y N 0.05 f c f y N 0.05 f c % % (Referred to ASCE Table 10-20)

29 Outline Introduction Proposed Load Deflection Curve Test Verification Conclusions

30 Test Data of Shear Walls Hidalgo et al. (2002) Weng, P. W., Li, Y. A., Tu, Y. S., and Hang, S. J., (2017) Prediction of Lateral Load Displacement Curves for Reinforced Concrete Squat Walls Failed in Shear, Journal of Structural Engineering, ASCE, 143(10), DOI: /(ASCE)ST X ,

31 Verification h v 0 0

32 Verification v 0 H 1.38 h 0 H 1.00 H 0.70

33 Statistics AVG : 1.34 COV : 0.16 AVG : 0.77 COV : 0.37

34 Test Data of Shear Walls Hidalgo et al. (2002)

35 Comparison of Failure Mechanisms Proposed V C cos Kf A cos n, SST d c str Crushing of concrete steel contribution concrete contribution % ACI V, f t f t 0.83 f c t n ASCE c c y Widening of Diagonal crack steel contribution concrete contribution % 0.25

36 Comparison ith ACI Code ACI Proposed

37 Test of Short Columns Speci. 1DL Li, Y. A., and Hang, S. J., (2017) Prediction of Lateral Load Displacement Curves for Reinforced Concrete Short Columns Failed in Shear, Journal of Structural Engineering, ASCE, 143(2), DOI: /(ASCE)ST X , H/h [MPa] DH NL NH DL DH NL NH N A g f c f c s f yt [MPa] 1.27% % % % % % % 300

38 Compared ith Test Results

39 Statistics AVG : 1.21 COV : 0.15 AVG : 1.33 COV : 0.29

40 Outline Introduction Proposed Load Deflection Curve Test Verification Conclusions

41 Conclusions 1. Proposed curve is trilinear, consisting of shear cracking, shear strength and collapse point 2. Proposed curve is suitable for shear alls and short columns 3. Approximation of strain field to calculate shear deformation is feasible

42 Acknoledgement p Funded by Ministry of Science and Technology and National Center for Research on Earthquake Engineering (NCREE)

43 Thanks for Your Attention