CEE Earthquake Resistant Design. General Information

Transcription

1 University of California at Berkeley Civil and Environmental Engineering Instructor: Stephen A. Mahin Spring Semester 2007 CEE Earthquake Resistant Design General Information Course Objectives This course integrates information from various engineering and scientific disciplines in order to provide a rational basis for the design of earthquake-resistant structures. As such, the course touches upon pertinent information from engineering seismology, geotechnical engineering, economic, risk and reliability theory, and architecture in addition to advanced topics related to structural dynamics, analysis and design. The focus of the course is on buildings, bridges, industrial facilities and other types of structures that may in the event of a major earthquake be allowed to respond in the inelastic range. The course emphasizes understanding the fundamental factors that influence and control the response of such structures, establishing a performance-based framework with which to assess seismic response, and developing effective, but simplified, design procedures capable of reliably achieving specified performance goals. Course Outline 1. Introduction. -- Basis of earthquake engineering design philosophies: role of uncertainty and the management of risk, an 'ideal' approach and some practical simplifications, limit state approaches, approaches adopted in current and emerging building code provisions. Special design considerations when permitting inelastic structural response are highlighted; limitations of historic analysis-based design approaches and introduction to "capacity design" concepts. Establishing a basis for performance-based earthquake engineering. Earthquake engineering issues relevant to sustainable development. 2. Engineering Characterization of Earthquake Ground Motions. -- Sources of earthquake ground motions; measures of earthquake intensity and damage potential; effects of local soil conditions on ground shaking; engineering estimation of ground motion characteristics based on deterministic and probabilistic approaches. 3. Response of Simple Structural Systems to Different Types of Ground Motion. -- Assessment of the effect of structural system and ground motions on the response of simple single- and multiple-degree-of-freedom systems. Emphasis on identifying desirable characteristics of structures for various types of ground shaking, and on developing simplified procedures suitable for estimating seismic response during the preliminary design process.

2 4. Development of Design Earthquakes for Linear Structural Response. -- Identification of critical parameters -- influence of local soil conditions and structural damping; development of design spectrum. 5. Development of Design Earthquakes for Nonlinear Structural Response. - Identification of critical parameters -- influence of local soil conditions, viscous damping, duration of shaking, nonlinear mechanical characteristics of the structure, and geometric nonlinearities; development of design spectra from ground motion and structural characteristics; displacement estimates; alternative spectra formats; extension of design spectra to multi-degree of freedom systems. 6. Analytical Procedures for Preliminary/Conceptual Design and Proportioning of Structural Systems. Review of simple plastic theory; estimation of the maximum strength and deformation capacities of structural systems; simplifications for design of multistory structures; application of capacity design methods. Emphasis on ductile moment-resisting frames and braced frames. Methods discussed to control displacements and other response parameters of structural interest. 7. Code Related Issues. -- Basis and limitations of current code provisions for structural analysis and design. Future trends. Nonlinear static pushover procedures for evaluation of new and existing structures, development of target displacements. 8. Basic Performance-based Evaluation and Design Issues. -- Lessons from past earthquakes; quantification of performance objectives and levels for seismic resistant design; Selection of analysis procedures; numerical modeling of structural systems. Estimation of fragility functions and quantifying the confidence of a structure s ability to achieve a targeted performance objective. Current and emerging guidelines for the evaluation of existing and new structures. 9. Applications. -- Steel (and to a lessor extent reinforced concrete) details to insure member and connection ductility; basic design considerations for moment-resisting frames and concentrically braced frames. Application of concepts to structures employing seismic isolation or utilizing supplemental energy dissipation devises. Prerequisites Students are expected to have a background in structural analysis and structural dynamics. A basic understanding of inelastic structural analysis is required. Courses such as CEE 220 and CEE 225, or their substantial equivalent, satisfy this requirement. Students uncertain about the adequacy of their preparation should contact the instructor.

3 Required Course Materials Extensive course notes will available on-line for the first half of the class. Copies of handout materials, problem sets, review questions and some papers will also be available from the web. Students are expected to regularly read papers and sections of reports to complete homework assignments and the class project. Copies of the papers will be distributed in class, made available for copying in the engineering library on campus, or available for download from the National Information Service for Earthquake Engineering ( or elsewhere. In addition, specific supplemental reading assignments will be made from the following sources: 1. Introduction to Structural Dynamics and Earthquake Engineering by Anil Chopra, Prentice Hall, Improvement of Nonlinear Static Seismic Analysis Procedures (FEMA 440), FEMA, Washington DC. Download from 3. ASCE/SEI Standard Seismic Rehabilitation of Existing Buildings, ASCE, 2006 (available early 2007), or NEHRP Guidelines for the Seismic Rehabilitation of Buildings (FEMA 356), FEMA/ASCE, Washington DC, Download from: 4. The 2003 NEHRP Recommended Provisions For New Buildings And Other Structures (FEMA 450) FEMA, Washington DC, Download from 5. Seismic Evaluation and Upgrade Criteria for Existing Welded Steel Moment- Frame Buildings (FEMA 351), FEMA, Washington DC, July Copies of the FEMA documents can be obtained for free by calling Copies of several SAC/FEMA state of the art reports will be available for down load from the class website. Of special interest to this class are: 1. FEMA 355F, State of the Art Report on Performance Prediction and Evaluation of Steel Moment-Frame Structures. 2. FEMA 355C, State of the Art Report on Systems Performance of Steel Moment Frames Subject to Earthquake Ground Shaking 3. FEMA 355E, State of the Art Report on Past Performance of Steel Moment- Frame Buildings in Earthquakes.

4 Hardcopies of these and similar SAC reports on steel construction in seismic areas can be obtained for a fee from: Several computer programs will be utilized in the course to illustrate concepts and to complete homework assignments. These include: 1. WWW Applets Attenuate and ModSpec for computing attenuation relationships and design response spectrum ( ) 2. WWW applet Pre-D for preliminary design of moment frame structures considering force and displacement criteria (also available from ) 3. The program BiSpec, used for computing the response of single degree of freedom subjected to one or two horizontal components of excitation. This program will be extensively used and should be downloaded from: Program manuals (online and downloadable PDF files) can be obtained from the same site. 4. Students will complete a number of assignments related to the nonlinear static and dynamic analysis of simple 2D framed structures. The computer program to be used is left to the student. Various computer programs are available: a. OpenSEES Navigator - Available for download from: This program is a Matlab-based application and requires Matlab 6.1 or higher, in addition to a copy of OpenSEES computational framework (see A tutorial on installing and using these programs will be given in the discussion sections). b. Fedeas Lab Available at: This program is very powerful and simpler to use than OpenSees. It is also used as the primary analytical platform in CE 221. c. CSI Perform, SAP, ETABS, etc various versions of Perform, SAP and ETABS (and other commercial programs) may be on the department computer system and otherwise available to students. Reference Material A wide variety of reference material is available. For example, several good (but expensive) textbooks exist. These may provide useful information on a number of topics not covered by course notes. These books include: 1. Earthquake Engineering: From Engineering Seismology to Performance- Based Engineering, Yousef Borzorgnia and Vitelmo Bertero, Eds., CRC Press, 2004 (available on line from 2. Earthquake Engineering Handbook, W-F. Chen, C. Scawthorn, CRC Press, 2002.

5 3. The Seismic Design Handbook, F. Naeim, Ed., Kluwer Academic Publishers, Geotechnical Earthquake Engineering, Steven Kramer, Prentice Hall, Earthquake Engineering, Hu, Y-X, Liu, S-C and Dong, W, E&FN Spon, London, Design of Earthquake Resistant Buildings, Wakabayashi, M., McGraw-Hill, New York, NY, Earthquake Resistant Design, Dorwick, D., Wiley, New York, NY, Fundamentals of Earthquake Engineering, Newmark, N. and Rosenblueth, E., Prentice Hall, New York, NY, Introduction to Structural Motion Control, Connor, J. J. Prentice Hall, August Design of Ductile Steel Structures, Bruneau, M., Uang, C-M, and Whittaker, A., McGraw-Hill, Steel Structures: Controlling Behavior Through Design, Robert Englekirk, Wiley, Seismic Design of Reinforced Concrete and Masonry Buildings, Paulay, T. and Priestley, N., John Wiley & Sons, Some other useful, code-related documents include: 1. Recommended Seismic Design Criteria for New Steel Moment-Frame Buildings, FEMA 350, Federal Emergency Management Agency, Washington DC, July Recommended Post-Earthquake Evaluation and Repair Criteria for Welded Steel Moment-Frame Buildings (FEMA 352), FEMA, Washington DC, July Specifications and Quality Assurance Guidelines for Steel Moment-Frame Construction for Seismic Applications (FEMA 353), FEMA, Washington DC, 4. SEAOC, Recommended Lateral Force Requirements and Commentary (the Blue Book ), Sacramento, CA, 1999 (see 5. California Building Code, Title 24, California Administrative Code, 2001 edition (see 6. HAZUS, a natural hazard loss estimation methodology, FEMA in partnership with the National Institute of Building Sciences, Washington DC. Note that hardcopies of FEMA documents may be generally obtained for free by calling

6 Some important sources of information include: 1. The National Information Service for Earthquake Engineering (NISEE) has its offices at the Richmond Field Station. It has the worlds largest library related to earthquake engineering. The WWW site for NISEE has a variety of user features, including an on-line search feature, library of earthquake damage photos, downloadable computer programs, and so on. The homepage for NISEE is 2. The Pacific Earthquake Engineering Research (PEER) Center at the Richmond Field Station. It can be reached at Course Organization Lectures: Discussion Session: Tu-Th 11 AM -12:30 PM; 534 Davis Hall Wednesday, 12-1 PM; 534 Davis Hall The weekly discussion session will be devoted to discussion of the conceptual and analytical approaches presented in the class and for help in solving homework assignments. Make up lectures will be, to the extend possible, held in the time slot assigned to the discussion section. The time of the discussion session may be changed to make it more convenient for students to attend. Exams: There will be two 80 minute long midterms. There will be no final exam, but a final term project will be required. Course Project: The term project may be done individually, or in groups of two. The intent of the term project is for the student to undertake a significant, but short project related to the design or analysis of structures, development of software to assist in the seismic resistant design of structures, or other application of the material learned in the course. The choice of topic is left to the student, but instructor approval is required. A separate handout will describe the scope and requirements for the term project. Larger groups are possible, but require special prior approval by the instructor. Grades: Grades will be based on performance on homework assignments, several midterm quizzes, and a final term project, according to the following approximate weights: 25%, 40% and 35%. Contact Information Instructor: Prof. Stephen Mahin Teaching Assistant: Michalis Vassiliou Office: 777 Davis Hall 504 Davis Hall Phone: (Mobile) mahin@berkeley.edu vassiliou@berkeley.edu Office Hours: M 2:15-3 & T1-2 TBD