1. Nonlinear Performance and Potential Damage of Degraded Structures Under Different Earthquakes The 5 th Tongji-UBC Symposium on Earthquake Engineering “Facing Earthquake Challenges Together” May 4-8 2015, Tongji University Shanghai, China Case study of ground motion and response spectra comparison of the Wenchuan (2008) and Lushan (2013) earthquakes Yuxin Pan Structural & Earthquake Engineering / Dr. Carlos E Ventura M.Phil | The Hong Kong University of Science and Technology, Hong Kong (2012) PhD Candidate | The University of British Columbia, Canada (2013 - Present) May 7 th, 2015

2.  Background & Objectives  General Seismicity of Selected Stations  Numerical Model of Equivalent SDOF System  Analysis Results & Discussions Inelastic hysteretic response Arias intensity vs. drift limit Elastic & inelastic response spectra  Conclusions & Future Works Outline

3. Research background Crustal EQs Intraplate EQs Interplate EQs Cascadia Seismic Sources Historical Eqs in Canada

4. Crustal Eq. vs Subduction Eq. 1995 Kobe eq. 1985 Chile eq. Research background

5. 5% damping Crustal Eq. vs Subduction Eq. SA spectra SV spectraSD spectra

6. Research background Rule Based Hysteretic Models & Backbone Curves

7. Research background Arias Intensity

8. Research background Directivity is an effect of a fault rupturing whereby earthquake ground motion in the direction of rupture propagation is more severe than that in other directions from the earthquake source. 8 52 49

9. Research background Fig. Intensity map for Wenchuan and Lushan EQs In 2008, there was an big earthquake with Mw of 7.9 occurred in Wenchuan, Sichuan Province of China. Five years later, in 2013, another earthquake with Mw of 7.0 took place at the same region (Lushan, Sichuan Province) along the Long Men Shan fault. Wenchuan Earthquake (2008): Epicenter: 31.000N 103.400E Depth: 14 KM Duration: 350 SEC Lushan Earthquake (2013): Epicenter: 30.299N 103.000E Depth: 13 KM Duration: 80 SEC

10. Objectives This study mainly analyzed the ground motion records at same stations from both earthquakes, and compared the elastic and inelastic response spectra for a typical SDOF in-filled reinforced concrete (RC) structure by considering the stiffness and strength degradation. Response of different capacity levels’ structures (100% Fy, 75% Fy, … 10% Fy) will also be investigated. Four main stations were selected for comparison, both east-west (EW) and north-south (NS) ground motions were analyzed, as seen in Figure. They are 51YAM, 51LSF, 51QLY and 51YAL. These four stations recorded the maximum PGA of Lushan Earthquake.

11. Fig. Elastic spectra comparison Fig. Arias Intensity and significant duration (5%-95%) Elastic spectra & Arias intensity

12. Directivity 12 51LSF Location30.021N 102.895E Site ConditionSoil Distance to Wenchuan Epicenter119.3 KM PGA of Wenchuan EQ124.1 CM/S 2 (EW) Distance to Lushan Epicenter32.6 KM PGA of Lushan EQ387.4 CM/S 2 (EW)

13. 13 51QLY Location30.407N 103.266E Site ConditionSoil Distance to Wenchuan Epicenter67.2 KM PGA of Wenchuan EQ199.8 CM/S 2 (NS) Distance to Lushan Epicenter28.2 KM PGA of Lushan EQ315.5 CM/S 2 (NS) Directivity

14. Equivalent SDOF System Experimental Test  Reinforced Concrete Partially Infilled Frames;  OpenSees modeling: Hysteretic material;  Strength and stiffness degradation;  No pinching effect was considered;  10% collapse drift limit Reference: Anil, Özgür, and Sinan Altin. "An experimental study on reinforced concrete partially infilled frames." Engineering Structures 29.3 (2007): 449-460. Zerolength element Rigid column Mass Numerical model in OpenSees

15. Inelastic hysteretic response  51YAM_Lushan_EW  51YAM_Wenchuan_EW Short Period (T=0.5s)

16.  51YAM_Lushan_EW  51YAM_Wenchuan_EW Medium Period (T=1.0s) Inelastic hysteretic response

17.  51YAM_Lushan_EW  51YAM_Wenchuan_EW Long Period (T=2.0s)

18. Drift limit vs. Significant duration 51YAM_Lushan_EW51YAM_Wenchuan_EW

19. Elastic & inelastic response spectra  For each station, both N-S and E-W directions were studied.  The design earthquake spectra and rare earthquake spectra (2% in 50 years) based on Chinese Code for Seismic Design of Buildings (CCSDB) were also plotted for comparison. CCSDB51YAM51LSF51QLY51YAL Design Intensity7777 Design EQ Acceleration0.10g0.15g0.10g0.15g Rate EQ Acceleration0.50g0.72g0.50g0.72g Characteristic Period0.45s0.40s0.45s Site CategoryII Design EQ Category3 rd 2 nd 3 rd Damping Ratio 5%

20. Elastic & inelastic response spectra  51YAM (N-S)

21. Elastic & inelastic response spectra  51LSF (E-W)

22. Conclusions  For the four selected stations, the Lushan Earthquake has much higher PGA, but larger drift demands resulted from the Wenchuan Earthquake;  Both elastic and inelastic spectra from Lushan Earthquake are higher than the local design spectra, and could be higher than rare earthquake spectra;  Overall, long period structures have larger displacements, but this trend varies with different capacity levels;  For the Wenchuan Earthquake, as expected, elastic system performed better than those weaker systems. However, for the Lushan Earthquake, elastic systems generated larger displacement at different period ranges.

23. Future work Sensitivity Studies Degradation Capacity level Structures Gravity system High-rise building Incremental Dynamic Analysis (IDA) Ground Motion Ground motion characteristics Ground motion Selection & Scaling

24. Thank you Certificate of Structural Engineering Program