Seismic response of steel buckling restrained knee braced truss moment frames

Transcription

1 Seismic response of steel buckling restrained knee braced truss moment frames By Yuanjie Li Supervised By Prof. Yang University of British Columbia

2 Buckling restrained knee braces + Truss Structural Fuse

3 Buckling restrained knee braces special truss moment frames (BRKB-TMF)

4 Design Procedure Traditional code design approach? design for the forces check for the drifts Iteration Facing two problems? unpreditable damage locations uncontrollable damage effect

5 Design Procedure 1. Performance based plastic design procedure (PBPD) method 2. Energy equation for BRBs and input earthquake 3. Capacity design for truss and columns (Yang et al. 2013)

6 Rigid diaphragm assumption OpenSees Navigator Model Truss pin connection Fiber section force beam column element Truss element Calibrated BRB (truss element with steel 02 material) Fix support

7 BRB Calibration (Black et al. 2004)

8 EQ scaling (UC Berkely 2 % in 50 yr) The ground motions obtained from PEER (2010) were scaled such that the mean spectrum of the set do not fall below the target spectrum by 10% within the period range from 0.2T to 1.5T.

9 Different BRB Angles for archetype building

10 Design Results based on PBPD BRB Angles Period(s) Floor BRB Strength (kips) Truss 2 Member 411 Sizes Columns Exterior Interior W24x229 W24x279 W24x279 W24x306 W24x229 W24x250 W24x279 W24x279 Floor Chord Diagonal Vertical Ext. Vertical 4 2MC8x18.7 2MC6x12 L3.5x3.5x5/16W24x207 2L3.5x3.5x5/16 W24x MC10x25 2MC6x15.3 L3.5x3.5x5/16 2L3.5x3.5x5/16 W24x250 W24x MC10x28.5 2MC6x15.3 L3.5x3.5x5/16 2L3.5x3.5x5/16 1 2MC10x28.5 2MC8x18.7 L3.5x3.5x5/16W24x162 2L3.5x3.5x5/16 W24x131 W24x192 W24x207 W24x131 W24x117 W24x162 W24x207

11 Floor Floor Floor Floor Structural Behavior 5 Median 5 Coefficient of Variance 4 30 Deg 3 45 Deg 63 Deg 2 80 Deg 1 90 Deg Acceleration (g) Median 4 30 Deg 3 45 Deg 63 Deg 2 80 Deg 90 Deg Acceleration (g) 4 Coefficient of Variance % 2.00% 4.00% Inter-story Drift 30 Deg 45 Deg 63 Deg 80 Deg 90 Deg Inter-story Drift 30 Deg 45 Deg 63 Deg 80 Deg 90 Deg

12 BRB impact from Angle α BRB Strain (%) θp=0.5% θp=1.5% θp=2.5% θp=3.5% BRB Angles (Degree) ( D0 l1/ tan( )) l d p sin l 2 0

13 Total Repair Cost Study Define performance group (structural or nonstructural component) P(DS<=DSi) Fragility Curves for BRBs Defined potential damaged items and obtain corresponding fragility curves and unit cost Calculate Engineering Demand Parameter (Interstory drift and floor accleration) EDP - du1 Calculate life cycle repair cost Referred to Yang et al. 2009

14 Cumulative Distributed Function P(Total Repair Cost <= $C) o 80 o o o 30 o $C (dollar) x 10 6

15 4 30'=120' 3@15.5'=46.5' 16.5' Parameter study 2 - Comparison Study for Spans E 6 30'=180' 6 30'=180' N 30 ft. Span: Typical office building 60 ft. Span: Conference room or dining hall D C B Pin Connection Moment Connection -Truss Moment Frame -Traditional Moment Frame A 30 Gravity Truss/Beam TMF/MF 60 Gravity Truss TMF/MF 3@13'=39' 14' 6 30'=180' 3 60'=180'

16 4 30'=120' 3@14'=42' 15' 3@13'=39' 14' Parameter study 2 - Comparison Study for Spans E 6 30'=180' 6 30'=180' N 30 ft. Span: Typical office building 60 ft. Span: Conference room or dining hall D C B Pin Connection Moment Connection -Truss Moment Frame -Traditional Moment Frame A 30 Gravity Truss/Beam TMF/MF 60 Gravity Truss TMF/MF W24X68 W 30X99 W27X94 W40X215 W36X150 W 33X169 W 40X215 W 40X183 W30X108 W40X215 W36X150 W 36X135 W 40X215 W 40X183 W30X116 W44X290 W40X215 W 36X135 W 40X503 W 40X431 W44X290 W40X215 W 40X503 W 40X '=180' 3 60'=180'

17 16.5' 15' 14' Parameter study 2 - Comparison Study for Spans 3@13'=39' 14' 6 30'=180' 3 60'=180' W24X68 W 30X99 W27X94 W40X215 W36X150 W 33X169 W 40X215 W 40X183 W30X108 W40X215 W36X150 W 36X135 W 40X215 W 40X183 W30X116 W44X290 W40X215 W 36X135 W 40X503 W 40X431 W44X290 W40X215 W 40X503 W 40X '=180' 3 60'=180'

18 Floor Floor Structural Behavior ft Truss MF 3 30 ft Truss MF 60 ft Truss MF 3 60 ft Truss MF 2 30 ft Typical MF 60 ft Typical MF 2 30 ft Typical MF 60 ft Typical MF % 2.00% 3.00% Interstory Drift 4.00% Acceleration (g)

19 Initial Structural Cost Repair Cost Cost Comparison $8,000,000 $6,000,000 $7,000,000 $5,000,000 Equipment $6,000,000 $5,000,000 $4,000,000 $3,000,000 $2,000,000 $1,000,000 $- 30 ft. TMF 60 ft. TMF 30 ft. MF 60 ft. MF Slab Gravity Columns Gravity Truss/Beams Seismic Columns Seismic Truss/Beams BRB $4,000,000 $3,000,000 $2,000,000 $1,000,000 $0 30 ft. TMF 60 ft. TMF 30 ft. MF 60 ft. MF Contents Int. Non-Structural Acc. Sensitive Int. Non-Structural Drift Sensitive Ext. Non-Structural Structural Lateral Comp. * Initial Structural Cost Life Cycle Repair Cost

20 Conclusion From angle parameter study: 1) The proposed PBPD procedure is an efficient and straight forward design procedure to select the member sizes. 2) The structural response was not significantly affected by the orientation of the BRB. 3) As the orientation of the BRB became more horizontal, the BRBs were able to tolerate higher drift demand, hence produced lower repair cost during the maximum credible earthquake shaking. From span parameter study: 1) The larger truss span could create more flexible and attractive architectural usage for the BRKBTMF and it costs less compared with traditional moment frame. 2) The structural behavior with different span systems is similar in BRKBTMF, quite different in traditional moment frame.

21 Acknowledgement: Prof. T. Y. Yang from University of British Columbia Prof. S.C. Goel from University of Michigan Prof. S. Leelataviwat from King Mongkut s University of Technology Mr. John D. Hooper from MKA Mr. David MacKinnon from SSEF Funding from Natural Sciences and Engineering Research Council of Canada (NSERC) and Steel Strcutres Education Foundation (SSEF) Thank you for your invitation and attention. Contact information: Yuanjie Li yuanjieli01@gmail.com

22 Appendix

23 Depth Depth Optimal Truss Depth for Gravity Truss and BRB Truss G G G G G G G G G G Span BRB Span BRB 1.2D 1. 6L D L Limit L / 240 ( )D (1 )D 3 ) Steel Usage (ft BRB = 200 kips BRB = 300 kips BRB = 400 kips Depth (ft)