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Weian Liu

3. Research Interest Soil Structure Interaction Seismic Analysis and Design of Bridge Structures Earthquake Engineering and Structural Dynamics. Weian Liu. 1. Educational Background UC San Diego (CA), PhD Student, 2009- Syracuse University (NY), PhD Student, 2007-2009

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Weian Liu

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  1. 3. Research Interest Soil Structure Interaction Seismic Analysis and Design of Bridge Structures Earthquake Engineering and Structural Dynamics Weian Liu • 1. Educational Background • UC San Diego (CA), PhD Student, 2009- • Syracuse University (NY), PhD Student, 2007-2009 • Tongji University (CHN), Master of Engineering (Bridge Engineering), 2004-2007 • Wuhan Univ. of Tech. (CHN), Bachelor of Engineering (Civil Engineering), 2000-2004 • 2. Research Activities • Design of soil and structure compatible yielding to improve system performance (NEES) • Seismic response analysis and design of long-span bridges (State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji Univ., Shanghai CHN) • Seismic response analysis of High-Rise pile foundation (SLDRCE, Tongji Univ., Shanghai, CHN)

  2. Concepts for designing small scale realistic buildings & Task 2 NEESR-CoSSY 3-Story Model October 14, 2009 Project Kick-off Meeting @ UC Davis PEER-Shallow Foundations (Chang et al.) 1-Story Model NEESR-City Blocks (Bray et al.)

  3. Complementary systems? Structural fuses Chang et al. tests Foundations

  4. Complementary? (more research questions – sorry Sashi) • What measures are most important to control (and predict) such that complementary yielding between foundation & structural elements is achieved (e.g. structure: Mcap, elimit, global parameters; foundation: Smax, qmax, Mcap)? • What are key (desirable) characteristics of structural fuses? Bilinear M-q behavior, elastic shear & axial, simplicity – same question applies to footings… • Do we have a preference re: complementary nature of system performance eg (i) series vs parallel, (ii) can we achieve (in reality) series behavior, what defines/controls yielding in the next element, which one yields first?

  5. Question for TTT • Has practice embraced rocking concept – or do we need to do more work in this area convincing practitioners? • How much our effort should be concentrated here?

  6. 2 key papers 1) Gajan et al. (2009, Earthquake Spectra, in press) – summarizes modeling efforts of PEER-supported study 2) Alavi & Krawinkler (2004); strength & story drift distributions in wall-frame systems (including hinged wall) 3) Foundation modeling review paper (e.g. Dutta & Roy, 2002) 4) Centrifuge modeling/background paper; (e.g. BLK, 1995) 5) Building performance limit states (e.g. latest code literature) – TTT?

  7. Subject Bruce asked me to talk about

  8. Building design concepts • Start simple • Links with prototypical buildings, via basic parameters? • System: Period, yield strength, yield drift ratio • Foundation: Type, degree of precompression, bearing stress • Do we want rocking systems to have the same range of prototypical (fixed-base) structures? • Incorporate compatible mechanisms of yielding at strategic locations in superstructure • Goal: protect superstructure from damage & foundation from excessive deformation

  9. Prototypical Building Characteristics • ATC-63: ArchType structures • Ganuza & Gupta/Krawinkler studies • Three base lateral load systems: (i) steel eccentrically braced frame (EBF), (ii) steel special moment resisting frame (SRMF), (iii) reinforced concrete shear walls. • 3-story (39’ plan dimensions 120’ x 180’), 5-story (65’ plan dimensions 150’ x 150’), and 9-story (122’ plan dimensions 150’ x 150’). • T1FB spans 0.18 → 2.64 seconds • Yield drift ratio spans 0.06 → 1.37% • Yield strength Vy spans 0.14 → 0.55 x seismic weight

  10. System with same yield drift ratio can have different yield strength

  11. Model & testing considerations • 2D versus 3D buildings? • N? (all tests same?) • Replaceable structural fuses? Locking fuses? • What are the performance objectives of the building-foundation system? • When should the structural fuses yield (what is acceptable at the foundation level)? • Identify most important variables in Test-1 model – [simulation can help guide this] • Motion protocol – selection, sequencing, etc.?

  12. Task 2: Implementation & Validation of Analysis Tools • OpenSees • FE models for soil-footing interface • Continued development & validation of Gajan & Raychowdhury models • Soil-foundation-building systems • Integration of soil-footing models w/ structural system • Ground motions for parametric studies

  13. References • Ganuza, E. (2006). Seismic behavior of hybrid lateral force resisting systems. MS Thesis, SUNY-Buffalo. • Gupta, A. and Krawinkler, H. (1999) “Seismic Demands for Performance Evaluation of Steel Moment Resisting Frame Structures”. John A. Blume Earthquake Engineering Center, Report No. 132, Dept. of Civil Engineering, Stanford University, Stanford, CA • ATC-63 report

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