University Consortium of Instructional Shake Tables: Final Report to NSF
http://ucist.cive.wustl.edu/
by: R. Tyler Ranf & Shirley J. DykeWashington University in St. Louis
[email protected] 30, 2001
PIs: Shirley J. Dyke, Phillip Gould, and Kevin Z. TrumanNSF-CCLI Program, Grant No. DUE-9950340
A Cooperative Effort Between the Three National Earthquake Centers.Headquartered at Washington University in St. Louis.
1. INTRODUCTION
The University Consortium on Instruction Shake Tables (UCIST) was created in 1998 and isheadquartered at Washington University. Currently, the consortium is composed of 23 institutionswithin three national earthquake centers: Pacific Earthquake Engineering Research Center(PEER), Mid-America Earthquake Center (MAE), and Multidisciplinary Center for EarthquakeResearch (MCEER). A list of participating universities, along with the associated national earth-quake center, is displayed in Table 1.
The purpose of the Consortium is to expose undergraduate students to a hands-on experience ofstructural dynamics and earthquake hazard mitigation. To achieve this goal, a variety of experi-ments and other relevant activities have been developed and implemented into the undergraduatecurriculum for use with the equipment. The equipment consists of an instructional shake table labstation. A photo of the instructional shake table, along with the relevant accessories, is shown inFigure 1.
Table 1: Consortium Member Universities Funds with this Grant.
PEER MAE MCEER
University of California, Berkeley
Washington State University
University of Illinois University of Notre Dame
University of California, Davis
Oregon StateUniversity
Massachusetts Institute of Technology
Pennsylvania State Uni-versity
University of California, Los Angeles
University of Nevada, Las Vegas
Southern Illinois University, Edwardsville
Virginia Tech
University of California, Irvine
University of Nevada, Reno
Washington University in St. Louis
University of California, San Diego
University of Hawaii
California Poly. State University
University of Alaska, Fairbanks
Stanford University University of Utah
San Jose State Univer-sity
Florida A&Ma
a. Florida A&M is a member of UCIST, although it is not affiliated directly with a national earthquake center.
The consortium encourages everyuniversity to implement experi-ments produced by other universi-ties. By involving many schools,the students will have the opportu-nity to gain exposure to severalsubjects, and the experimentsemployed will be developed byexperts in that subject area. Stu-dents will have the full benefit ofthe research and projects that arebeing developed from universitiesacross the country. The consortiumcalls for each university to imple-ment three experiments into theircoursework each school year. Theexperiments developed at eachinstitution are made availablethrough the internet for downloading (see: http://ucist.cive.wustl.edu/). Although the primary focus of the consortium has been to create experiments for undergraduatestudies, there have also been opportunities to establish outreach programs with the public, as wellat to get undergraduates involved in research and the development of experiments. The status ofall of these activities for the member institutions are described herein.
2. OBJECTIVES
The objective of the consortium is to provide the necessary tools for students to learn aboutdynamic response and earthquake hazard mitigation while making the learning a hands-on experi-ence. Specifically, the objectives of the UCIST are: • To assist undergraduate students in understanding
concepts in structural dynamics and earthquake resis-tant design.
• To provide students with hands-on experience to gain an understanding of dynamic structural response.
• To offer opportunities for students to gain experience with experimental equipment for dynamic testing.
• To encourage undergraduate students to get involved in research activities.
A variety of projects have been constructed in order tofulfill these objectives. The types of projects to bedeveloped are described in Figure 2. Several experi-ments and videos have been developed so far. Manymore are planned for the future in order to further real-
Figure 1. UCIST shake table with pendant controller, power module, and two story building.
Primary Activities
Classroom Experiments Videos of ExperimentsStudent CompetitionsCD-ROM of Experiments
Figure 2. UCIST Activities.
Primary Activities
Undergrad. Research ProjectsPublic and K-12 Outreach
Secondary ActivitiesSecondary Activities
ize the objectives set forth. A list of the types of projects under development, along with a generaldescription of what the project encompasses, is displayed in Table 2.
3. OUTCOMES
To accelerate the learning curve associated with using this equipment, several projects and manu-als have been developed for implementation with the shake table. The manuals were written toprovide as a guide for conducting the experiments that were produced, as well as to allow the userto extend their knowledge of the functions of the shake table. Since the consortium is relativelynew, the learning speed of faculty, graduates, and undergraduates has been greatly amplified bythe sharing of these outcomes between the schools. Experiments are in development for classes at all levels. Currently at Washington University thereare four classes that have regularly implemented these experiments in their curriculum including:CE 146: Introduction to Civil Engineering, CE 336: Mechanics of Materials, CE 438/550: Struc-tural Dynamics, and CE 589: Experimental Methods in Structural Dynamics. Each of theseclasses have a different scope on what they are trying to achieve through the shake table experi-ments. For example, Mechanics of Materials will perform an experiment that involves finding thenatural frequencies of different materials while soil mechanics will focus the implications ofdynamic forces on soils, such as soil liquefaction.A couple of initial videos have been developed to allow students, or anyone interested, to observedynamic characteristics of structures on the shake table. These videos are useful to the public
Table 2: Description of Categories of Projects.
Activity Description
Experiment Development Experiments will be developed to cater to engineering students as well as non-engineering students, such as geologists and architects, who will benefit from such an exposure. Along with each experiment, a section on the theory, required exercises, and anticipated results will be provided in order to facili-tate in the educational experience derived from the experiments. The goal is to have these experiments implemented into the classroom corriculum.
Videos Videos will be produced in order to give students who do not have access to a shake table exposure to dynamic response. These videos will also be made available on the internet so that anyone can access them.
CD-ROM In order to compile the experiments in an orderly fashion, a CD-ROM will be developed to group the experiments, as well as laboratory manuals, photo-graphs and videos of the experiments, and software, in an easy to use package. This will be made available to the academic community once it has been com-piled.
Nationwide Competitions The intension of a nation-wide competition is to provide a fun learning experi-ence for both undergraduates and elementary school children. The goal is to make children of all ages aware of dynamic response.
Undergraduate Research Undergraduates will assist in ongoing research projects in order to provide them with a glimpse of possible further research opportunities, as well as to provide them with experience in dynamic response. Undergraduate research is also a helpful tool in completing the planned experiments.
because they are made available online and do not require access to a shake table. The results thathave been completed are described in Table 3.
Table 3: Outcomes To Date.
Title of Project Attributes Project Summary
Sample Experiments and Projects
Introduction to Dynamics of Structures
Institution:
Washington University
Authors: Juan Caicedo, Sinique Betancourt, &Shirley Dyke
The purpose of this experiment is to introduce students to principles in structural dynamics through the use of an instructional shake table. Natural frequencies, mode shapes and damping ratios for a small scale structure will be obtained experimentally through a series of tests. Stu-dents will use a Matlab GUI program to obtain experimen-tal data of the structure and analyze the data.
K-12 Outreach Activi-ties in Earthquake Engineering
Institution:
University of NotreDame
Authors: Bill Spencer
Students will investigate the seismic behavior of buildingsmade from masonry and steel to better understand the wayin which civil engineering structures respond to severeearthquakes. The students will design and construct modelbuildings that will be tested on the bench-scale shakingtables during class visits. Both K'Nex and Lego buildingsystems will be provided.
Relevant Supporting Documents and Media
Shake Table Interactive Manual
Author:Keenan Bull
This manual was created as a tool to help set up and run the shake table. It is an interactive, web based manual that guides the reader through the purpose of the program, the setup of all the necessary connections, and as an introduc-tion to experiments that can be run on the shake table.
Guide to Creating Simulink Models for the UCIST Table
Author: Scott Johnson
This is a manual that was created in order to serve as a tool for creating simulink models that will be run on the shake table. It contains the basic procedures for all of the parts necessary for composing and building a model. It also serves as a step towards more independent techniques in advanced models.
Kobe Earthquake Simulation
Author:Tyler Ranf & Euridice Oware
The Kobe Earthquake Simulation is a video of a building on the shake table that is being excited by a time history of the Kobe Earthquake, which comes with the pendant con-troller of the shake table. This video is used for those who do not have direct access to the shake table.
Increasing Amplitude Sine Function Simulation
Author: Tyler Ranf & Euridice Oware
The increasing amplitude sine function simulation is a video that was produced to show the structural response to a sine function with different amplitudes. It demonstrates a model that was developed through simulink, and run on the shake table through wincon. This video is used for those who do not have direct access to the shake table.
The first item listed in Table 3 is an experi-ment intended for undergraduate use. Thisexperiment fully utilizes the capabilities ofthe shake table, and was developed at Wash-ington University to serve as an example forother investigators. The second item listed isa sample outreach activity developed at theUniversity of Notre Dame. This experimenthas been successfully implemented in theclassroom (see: http://www.nd.edu/~eeri-und). The next three outcomes are manualsthat describe the proper procedure for runningthe shake table and for controlling the shaketable by the shake table through Simulink.These can be accessed through the UCISTweb site. The main page of the interactivemanual that introduces the user to the shaketable, and describes the steps required toproperly set up the table is displayed in Figure 3. The interactive tutorial developed to teach basicconcepts in structural dynamics, experimental methods, and instrumentation is shown in Figure 4.The purpose of this tool is to give students a more widespread and accessible means of perform-ing shake table experiments without the presence of a shake table. Students attending UCISTschools and non-UCIST school alike will use the VSDL program.
Virtual Structural Dynamics Lab
Author:Manolo Soto-Fournier & Juan Caicedo
This is a web based program that serves as a tutorial on experimental methods, data acquisition, and sensors for typical dynamic testing. To aid in explaining these topics, an interactive experiment can be used in order to control a virtual shake table.
Implementation of Transfer Function Iteration Program
Author: Tyler Ranf
This iteration program is used to take a proposed earth-quake signal, run it through the shake table, then change the preliminary signal until the signal that is measured from the shake table matches the desired signal. In order to do this, an iteration procedure was developed in MatLAB. This iteration program uses programs that were previously developed by G. Yang & B.F. Spencer, and later revised by B. Nepote & J. Caicedo.
Table 3: Outcomes To Date.
Title of Project Attributes Project Summary
Figure 3. Interactive manual produced by Keenan Bull. (REU 2000).
Many more experiments have been devel-oped, or are in progress, by other schoolswithin the consortium. These experiments areintended for undergraduate coursework, orfor outreach activities. A complete list of theexperiments from these schools is providedin Table 5 within Appendix A. Note thatthese projects span a wide range of disci-plines within earthquake engineering, includ-ing structural, geotech, and social science.One can foresee them being used at all levelsof the undergraduate curriculum. Several publications and presentations havealso resulted from the efforts of the consor-tium or from projects developed through theconsortium. These are summarized in Table4.
Table 4: UCIST Related Publications and Presentations.
Author/Presenter Title/Association
Presentations
S.J. Dyke, K.Z. Truman, & P.L. Gould
“Current Directions in Earthquake Engineering Education: The University Consor-tium on Instructional Shake Tables,” 7th US National Conference on Earthquake Engineering, Boston, MA, July 2002.
Shirley J. Dyke “Current Directions in Earthquake Engineering Education,” ASCE Engineering Mechanics Conference, Austin, Texas, May 2000
Shirley J. Dyke “Status of the University Consortium on Instructional Shake Tables,” Mid-America Earthquake Center Education Meeting, MIT Campus, March 23, 2000
Shirley J. Dyke “University Consortium on Instructional Shake Tables,” UCIST Coordination Meet-ing, January 27, 2001
R. Tyler Ranf “University Consortium on Instructional Shake Tables: Goals and Results to Date”
Publications
S.J. Dyke, K.Z. Truman, &P.L. Gould
Current Directions in Earthquake Engineering Education: The University Consortium on Instructional Shake Tables, Proceedings of the ASEE Annual Meeting, St. Louis, MO, June 2000
S.J. Dyke Current Directions in Earthquake Engineering Education, Proceedings of the ASCE Engineering Mechanics Conference, Austin, Texas, May 2000
S.J. Dyke, S.M. Johnson, R.T. Ranf, J.M. Caicedo, &Manolo Soto-Fournier
Advancing Earthquake Engineering Education Through a Cooperative Effort Based on Instructional Shake Tables. 7th US National Conference on Earthquake Engineer-ing, Boston, MA, July 2002
Figure 4. Virtual Structural DynamicsLab, developed by Manolo Soto-Fournier.
4. ONGOING ACTIVITIES
The future goal of the UCIST is to continue developing the current projects, as well as to initiateprojects of similar magnitude. In further developing the current research, we anticipate furtherintegrating these programs into the current curriculum, as well as integrating the experiments intonew classes. We plan on making all research involving the shake table that was performed by the23 member institutions fully accessible to each of the other institutions through medias such as aCD-ROM and the internet. Furthermore, we plan on heightening the public’s perception of earth-quake hazard mitigation by performing shake table experiments in public areas such as sciencecenters. As stated before, our primary objective in the future is to educate undergraduates. If we can getthe undergraduate engineering students involved in dynamic response and earthquake hazard mit-igation through mediums such as classroom experiments, videos, and competitions, they will bebetter prepared to make informed decisions in the workplace or research lab regarding reducingdamage caused by earthquakes. We have already developed several experiments to integrate ourfindings into the undergraduate curriculum. Our goal is to further emphasize these methods, aswell as to develop new methods.Our secondary objective for the future is to provide public awareness of earthquake hazards andto inform the public of a safe way to reduce these possible hazards by proper mitigation. Publicinterest in this area tends to peak shortly after an earthquake, and then quickly die down after thememories of the earthquake become less acute. This is particularly true when the damage from theearthquake was not that severe. An example of this is Nisqually earthquake that occurred nearOlympia, Washington on February 28, 2001. After the earthquake, there was a lot of media onproper mitigation for the public. However, because the actual damage from the earthquake wasrelatively mild compared to other recent earthquakes (for instance, those in Kobe, Turkey, Greeceand Colombia), public interest faded. Our goal is to make the public aware of the hazard beforethe hazard actually occurs so that proper mitigation can be used to reduce losses. This can be han-dled through outreach activities. Several recent outreach activities are listed
By focusing on the students and the public, we plan on raising the awareness of possible earth-quake hazards through mediums such as experiments, presentations, and videos. This process willbe expedited by the cooperation of the 23 universities that make up the consortium.
Table 5: Recent outreach activities with instructional shake tables.
• Earthquake Awareness Weekend at the St. Louis Science Center (1998–2001, see Fig. 5)• Women-in-Engineering Day (1999–2000 sponsored by SWE)• April Welcome at Washington University (1999–2000)• Take-Your-Daughter-to-Work Day, Washington University in St. Louis (1999)• Stanley Clark Elementary School Lego competition in 3rd grade, South Bend, Indiana (1998) • Illinois State Fair (2000–2001, see Fig. 5)• Brown and Merit Scholar Tours, Washington University in St. Louis (1999, 2000)• Stanley Clark Elementary School Lego competition in 5th grade, South Bend, Indiana (2000) • Andrew Jackson Middle School Lego competition in 7th grade, South Bend, Indiana (2001)• Gifted Resource Council Introduction to Engineering program (to be held in Fall 2001)
5. CONCLUSION AND FUTURE PLANS
Since the inception of the University Consortium of Instructional Shake Tables (UCIST) in 1998,the goal has been to provide undergraduate students with hands-on experiences in structuraldynamics and earthquake hazard mitigation. In order to pursue this goal, a set of objectives wasagreed upon by the 23 universities that make up the consortium. The members of the consortiumhave already developed many projects to fulfill these objectives. Several manuals and classroomexperiments have already been developed, and several projects are in development. This year theconsortium institutions will be implementing the projects that were developed in their classrooms.Evaluation of the impact of these activities will be performed over the next several years. Weintend to disseminate information on the impact of these activities in the future. Furthermore, weplan to conduct outreach activities to inform the public of the dangers of an earthquake, and howto curb these dangers by proper earthquake hazard mitigation.This consortium is open to all interested universities. The only requirement to joining is that theuniversity incorporate some experiments into its curriculum. Several additional universities havealready obtained the instructional shake table lab station and become involved in the activities.More than 40 shake table experiments have been sold by the manufacturer, including two to Japanand one to Italy. We hope to encourage more members in the consortium and expand these effortsfurther when the activities of UCIST are widely disseminated. Those interested in joining UCIST should contact Prof. Shirley J. Dyke at: [email protected].
Figure 5. Recent outreach activities: (a) St. Louis Science Center Earthquake Awareness Weekend, and (b) Illinois State Fair.
(a) (b)
APPENDIX A: CURRENT PROJECTS
Table 6: Completed and In-Progress Projects.
Title & Attributes Project Summary
Projects That Have Been Completed
Demonstration of Non-Structural SeismicHazards in the Home
Main Investigators:Barbara Luke &Marco Furlan
Institution:
University of Nevada, Las Vegas
A cutaway and see-through model of a home was created for the shake table to dem-onstrate non-structural seismic hazards. The demonstration will be set up so thatheavy objects fall from high shelves, bookcases tip over, pictures fall off walls, and awater heater topples. The purpose of the demonstration is to educate the generalpublic about nonstructural hazards and some simple things they can do to make theirhomes safer during an earthquake. The activity will be useful for undergraduateclasses in engineering and architecture, and for outreach activities to high schoolstudents and the general public.
Liquefaction Demonstration for theUCIST Shake Table
Main Investigator:Brad Cross
Institution:
Southern Illinois University, Edwardsville
This experiment demonstrates to a wide audience the effects of soil liquefaction onstructures. The experiment is designed to be inexpensive and portable to allow easytransportation for demonstrations at schools and museums.
K-12 Outreach Activitiesin Earthquake Engineering
Main Investigator:Bill Spencer
Institution:
University of Notre Dame
Students will investigate the seismic behavior of buildings made from masonry andsteel to better understand the way in which civil engineering structures respond tosevere earthquakes. The students will design and construct model buildings that willbe tested on the bench-scale shaking tables during class visits. Both K'Nex and Legobuilding systems will be provided.
Tuning of a Vibration Absorber on UCIST Shake Table
Main Investigators:Andre Filiatrault &Ahmed Elgamel
Institution:
University of California, San Diego
Vibration absorbers are relatively small mass-spring systems that are calibrated to bein resonance with the structure on which they are installed. These systems, usuallyinstalled on the roof of buildings, have been proven effective to reduce wind-induced vibrations in high-rise buildings, floor vibrations induced by occupantactivity, and the seismic response of buildings. The purpose of this project is to dem-onstrate the effectiveness of vibrations absorbers in reducing the vibration of struc-tures under earthquake-like ground motion input.
Determination of Natural Frequencies &Mode Shapes of Multi-Degree of Freedom Structures
Main Investigator:Makola Abdullah,Marlon Hill, & Claudia Wilson
Institution:Florida A&M
The effect of active and passive control devices will be shown on a two story struc-ture. The students will calculate the natural frequency of the structure and designand construct a suitable passive tuned mass damper. The results from this passivesystem will be compared to the uncontrolled building model and a building modelwith an active mass driver. The demonstrations will benefit the First Year Engineer-ing course and the Civil Engineering Mechanics course. The experiments will beused to complement instruction in the advanced senior and graduate level StructuralDynamics course.
Earthquake-ResistantBridge Competition for Introductory Engineering Students
Main Investigator:Kurt McMullin
Institution:
San Jose State University
This project is intended for entry level engineering students at either the freshman orsophomore level. It is appropriate for all engineering majors and is intended as apotential recruitment tool to attract students to pursue fields related to the seismicdesign of bridges. Student teams design a small truss bridge from balsa wood andthe competition is based upon the ability to support a given gravity load whileexposed to a transverse lateral motion generated by the shake table. The stated goalof the project is to use basic engineering concepts to design and build a bridge thatcan resist the forces induced during an earthquake. The winning bridge is the entrythat supports the highest mass while being shaken by the most severe earthquakemotion.
Small Shake TableExperiments and Comparison to Analytical Predictions
Main Investigator:Thomas Miller & Brenda Shonkweiler
Institution:
Oregon State University
This project describes the necessary steps to run an earthquake simulation on theUCIST Shake Table and to create the corresponding SAP 2000 model. The manualstarts with some basic information about the UCIST equipment and explains how tobuild a 3D model. It goes on to explain how to determine properties of the 3Dmodel, including stiffness and damping. There is also a section on how to determinethe scale used by the UCIST Shake Table for each earthquake. This is followed byexplanations on how to determine accelerations as a function of time for each floorand the maximum relative displacement of the top floor. The manual ends with thesteps for developing the SAP 2000 model.
Table 6: Completed and In-Progress Projects.
Title & Attributes Project Summary
Experimental Identification of Dynamic Properties of Scaled FramesMain Investigators: Ali Memari,Andrew Scanlon, &Young Hak LeeInstitution: Penn State University
Researchers have designed an experiment to be conducted on the instructional shak-ing table to introduce some basic concepts of seismic response of structures. Using the shake table, students can observe how the dynamic response of a simple portal frame changes by doubling the mass and by doubling the stiffness. Students will have the opportunity to compare calculated periods with actual measured periods. Moreover, the experiment allows students to realize how the stiffness of a frame is dependent on the assumption for boundary conditions of the members and how close these assumption are relative to the actual stiffness of a built model.
Introduction to Dynamics of Structures
Main Investigator:Shirley Dyke
Institution:
Washington University
The purpose of this experiment is to introduce students to principles in structural dynamics through the use of an instructional shake table. Natural frequencies, mode shapes and damping ratios for a small scale structure will be obtained experimen-tally through a series of tests. In the first test a sine sweep is applied to the structure to determine the frequency response function of the structure. The frequencies are identified, and a sinusoidal excitation is applied to examine the mode shapes. Next the damping in the system is estimated using two techniques and the results are com-pared. Students will use a Matlab GUI program to obtain experimental data of the structure and analyze the data.
Projects that are in progress
Demonstration of Lateral-Torsional Coupling in Building Structures
Main Investigator:Joel Conte
Institution:
University of California, Los Angeles
The effect of lateral-torsional coupling in building structures due to non-coincident centers of mass and of rigidity will be demonstrated through a small scale one-sto-rey, one bay by one bay building model. The building model will be carefully designed in order to enhance the effects of lateral-torsional coupling on the building mode shapes and its seismic response. The model will allow an adjustable level of mass eccentricity. A mathematical model will be developed for the purpose of ana-lytical-experimental correlation studies. A video of the experiments will also be pre-pared for distribution. This experiment will be designed for undergraduate and graduate engineering students taking analytical courses in structural dynamics and earthquake engineering.
Dynamic Behavior of Simple Soil-Structure Systems
Main Investigators:John Bolander, Tara Hutchinson, &Stefano Berton
Institution:
University of California, Davis
The experiment involves constructing a soil column that supports one or more single degree of freedom (SDOF) structures. The experimental setup will allow for conve-nient, hands-on adjustment of the site and superstructure natural periods by changes of the soil layer thicknesses and column heights of the superstructures. Students will be able to design experiments to explore the interrelated roles of input frequency content, site properties, and structural period. The setup will be used to demonstrate the undesirable effects of having the structural and site periods match. Other combi-nations of soil and structural components that are particularly effective for demon-stration purposes will be identified.
Table 6: Completed and In-Progress Projects.
Title & Attributes Project Summary
Demonstration Experiment of Sloshing Fluid Damper and Tuned Mass Damper
Main Investigator:Greg Deierlein,Ann KiremidjianInstitution:
Stanford University
To develop several devices to demonstrate the physics of two passive damping sys-tems that have applications to building structures. One is a sloshing fluid damper and the second is a tuned mass damper. Our plan is to design and construct these dampers to be installed on the model building structure that will be supplied with the instructional shake tables. In addition to plans for constructing the dampers, the edu-cational module would include a short technical description of the theory related to the dampers and illustrated examples of where they have been applied to control wind-induced vibrations in tall buildings and towers. Among the experiments and principles that can be demonstrated with the dampers are the following: (a) measure-ment of effective damping by monitoring the decay of motion under free vibration, (b) sensitivity of the effective damping to tuning of the device to the vibrational modes of the structure, (c) relative effectiveness of the devices to reduce steady state versus impulsive excitations – e.g., comparing their performance to reduce wind versus earthquake induced effects, and (d) design modifications to the devices (e.g., installation of baffles in the sloshing dampers). Experiments using the dampers should be of interest to students at various levels from undergraduate through begin-ning graduate students.
Capacity Design and Analysis of Frame Behavior
Main Investigator:Mark Aschheim
Institution:
University of Illinois
A module for demonstrating simple concepts in the design and analysis of moment-resistant frames will be developed and distributed to the 23 undergraduate institu-tions. Students will; design frames to have beam hinging or column hinging mecha-nisms using simple concepts, predict response using the nonlinear static procedures of FEMA-273, construct models using simple bar stock capable of developing duc-tile hinging mechanisms, measure response to design ground motions, and post pro-cess measured data to identify modes and their respective amplitudes.
Lateral Stability and Instability of Structural Framing Systems
Main Investigator:Evert Lawton
Institution:
University of Utah
The shake table will be used to demonstrate the stability and instability of different types of structural framing systems. Models that rely on frame action, shear wall action, and bracing will be demonstrated to show how they resist lateral forces. A gravity frame with no moment-connected joints is unstable. By adding moment capacity at selected joints in the structure, the function of the various components in a successful lateral load system will be demonstrated. For the same gravity frame, it will also be demonstrated that the addition of concentric or eccentric braces and/or shear walls will provide the lateral resistance required for stability. Also, these experiments will demonstrate the need to provide symmetry in the bracing systems so as to avoid torsional deformations.
Table 6: Completed and In-Progress Projects.
Title & Attributes Project Summary
Shaking Table Demonstration of Dynamic Response ofBase-Isolated Buildings
Main Investigator:Michael Symans
Institution:
Washington State University
The objective of this experiment is to demonstrate the response of base-isolated buildings subjected to dynamic loading. A three-dimensional, one-story building frame will be designed and constructed for the experiment. The structure will be tested in a conventional configuration in which the building is rigidly attached to the shaking table platform (foundation) and in an alternate configuration in which the building is supported on a base isolation system. Two different isolation systems will be tested; one that incorporates sliding isolation bearings and a second which incorporates elastomeric bearings. The effects of isolating the structure will be explored through system identification tests (free vibration and forced vibration), steady-state harmonic loading tests, and historical earthquake tests. The experimen-tal results will be compared with predictions from numerical analyses. It is expected that the shaking table experiments will be utilized in a junior level Introduction to Structural Engineering course, a senior level Structural Design Laboratory course, and graduate level courses in Structural Dynamics and Earthquake Engineering.
Seismic Testing and Dynamic Behavior of Irregular Buildings
Main Investigator:Sat Rihal
Institution:
Cal Poly. State University
The primary objective is to determine fundamental dynamic characteristics e.g. modal frequencies, mode shapes and damping ratios, through dynamic testing of a two-story model structure with irregularity. Further objectives are to compare the experimental results with those obtained from theory, through analytical modeling of the test structure; as well as study the influence of irregularity on the dynamic behavior of the test structure. The model structure is first subjected to a random (white noise) base excitation or a sine-sweep excitation; and the floor response accelerations are analyzed to determine the frequency response of the structure. Next, the test structure is subjected to sinusoidal base excitation to verify and docu-ment each of the modal frequencies identified in the previous step of the test sequence. The damping of the test structure is estimated in the next step, using a free vibration test and the resulting damped free vibration response. Finally, the test structure will be subjected to one of the earthquake excitation records provided with the UCIST system and the response will be recorded and analyzed.
Effect of Floor Diaphragm Flexibilityon the Dynamic Characteristics and Seismic Response
Main Investigator:Gokhan Pekcan
Institution:
University of Nevada,Reno
Two identical, three-story, small scale building structures will be designed and built. Model structures will be built with thick and relatively thin floor slabs (ply-wood) representing rigid and flexible floor diaphragms, respectively. As part of the project several system identification techniques along with computational models of the building frames will be utilized. The experiments will be used to demonstrate basic principles of structural dynamics at the undergraduate level, and provide a platform to introduce system identification and modeling techniques along with flexible floor diaphragm concept as a special study at the graduate level.
Table 6: Completed and In-Progress Projects.
Title & Attributes Project Summary
Dynamics of Building Structures During Earthquakes and Their Control
Main Investigator:M.P. SinghXing
Institution: Virginia Tech
The table has been set up to conduct free and forced vibration tests. The experi-ments can be conducted to calculate the natural frequencies, inherent damping and mode shapes of the model structure. For damping ratio, both free vibration test and sine-sweep test can be conducted. Experiments can also be conducted to investigate torsional motions that can be caused by eccentricity between the mass and stiffness centers of the model. For this, currently the two degrees of freedom model acquired with the table is installed on the table perpendicular to the axis of the base excitation. The eccentricity is induced by attaching masses to one or both floors eccentrically. The experiments can then be conducted to calculate the frequency and mode shape of the structure. A torsional two-story building model consisting of rigid floor dia-phragms supported on four corner columns is also being prepared to demonstrate the behavior of torsional structures during earthquake induced base motions. The model will have three degrees of freedom per floor. The model will be prepared such that small viscous dampers can be installed in the two stories in different configurations to demonstrate the effect of optimal and non-optimal placement of dampers.
Shake-Table Models for K-12 Outreach Activities
Main Investigator:Gerry Pardoen
Institution: University of California, Irvine
This project contains a series of investigations centered around two 'building' mod-els for students in elementary, middle school and high school. While the strategyand goals for teaching some fundamental concepts of ground motion and structuralresponse varies among the different age groups, several objectives target all audi-ences: a) have the students construct a 'building' to a series of design constraintsusing LEGO or K'NEX ($20 retail price) building blocks, b) have the studentsobserve the response of their structure to a series of tailored table motions to intro-duce the concepts of frequency, amplitude and duration; the students will observetheir 'building's' response when it is parallel and perpendicular to the table's motion,c) have the students iterate their design prior to submitting it to the UCI LEGOEvent in mid-April (an LA area event that draws 75+ models from 800+ students) aspart of California's earthquake awareness month.
Multi-directional Seismic Excitationson Bridges
University of Alaska, Fairbanks
Main Investigator:Leroy Hulsey
Students will mount a small 3-span lexan bridge structure on the shake table. The supports shall all be the same stiffness. The loading will be a sign wave. The vari-ables will be: a). Mass of the deck b). skew of the deck w.r.t. the supports. c). Imposed amplitude and frequency of the sine wave acceleration record. The object will be to show the frequency respones for a structure that is skewed to the earth-quake motion. 4 skewed conditions will be considered including: 0 degrees, 30 degrees, 45 degrees & 90 degrees.
Shake Table WebLab
Main Investigator:Eduardo Kausel
Institution: Massachusetts Institute of Technology
The Shake Table WebLab project will focus on developing a web-based laboratoryfor studying the earthquake and vibration response of buildings. The centerpiece ofthe WebLab will be a sophisticated, commercially built laboratory apparatus, whichcan be used to excite, monitor and control model structures. The proposed effortwould extend the reach of this state-of-the-art research facility so that it is readilyaccessible to students in and beyond the classroom. The equipment will be controlla-ble and observable over the web. Students will then be able to measure the responseof the model and compare it with numerical predictions obtained using MOTIONLAB, a PC-based software system, and the observed behavior of real-life structuresduring actual earthquakes.
Table 6: Completed and In-Progress Projects.
Title & Attributes Project Summary
Natural Frequency:From Single to Multi-Degree of Freedom Structures
Main Investigator:Ian Robertson
Institution: University of Hawaii
This tutorial is designed to introduce students to the concept of natural frequencyand mode shapes. Two shake table models are used to demonstrate single degree offreedom systems with varying mass and stiffness. An understanding of these singledegree of freedom systems is then translated into the shake table performance ofone-story and three-story building models. Students learn how to compute naturalfrequencies and mode shapes for single and multi-degree of freedom systems. Bothstudent and instructor manuals are provided. The instructor's manual includes fullinstructions for fabrication of the four simple models and calibration of the modelsfor use in the tutorial.
Dynamics of a Chalk Model
Main Investigators:Nicos Makris
University of California, Berkeley
The objective of this experiment is to introduce basic principles of structural dynam-ics by testing a simple model on the instructional shake table. The model’s stiffnessand natural frequency, along with its response to various ground motions, will beobtained experimentally. This experiment is based on a study to examined the grav-ity load collapse of reinforced concrete frames. During an earthquake, the columnsof many older reinforced concrete buildings are vulnerable to brittle shear failurebecause of wide column tie spacing. As a column loses the ability to support axialloads, the gravity load it carries must be transferred to surrounding elements. Theaforementioned study investigated how these additional loads can lead to the pro-gressive collapse of the structure. The setup for the study consists of a three columnreinforced concrete frame, the middle column being non-ductile. Upon failure of themiddle column, the axial load was transferred to the outside, ductile columns whichrepresent building elements resisting gravity load collapse.
Table 6: Completed and In-Progress Projects.
Title & Attributes Project Summary
