Experimental characterization, modeling and identification of the NEES‐UCSD shake table mechanical system

Özçelik, Özgür; Luco, J. Enrique; Conte, Joseph Le; Trombetti, Tomaso; Restrepo, José I.

doi:10.1002/eqe.754

Cited by 33 publications

(26 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: Test Building Design Approachmentioning

confidence: 99%

“…Figure 3 shows photos of the NEES-Soft four-story test building built at the NEES@UCSD laboratory just prior to the installation of the CLT rocking walls. The shake table is a 7.6 m (25 ft) × 12.2 m (40 ft) outdoor uni-axial shake table with a maximum gravity payload of 20,000 kN (4496 kips); full details on the shake table performance and capabilities can be found in Ozcelik et al [25]. Although the exterior architecture was important for the aspect ratio and determining the locations and number of openings at the soft and other stories, there were several other features of this particular building era that had to be identified, such as interior wall density, room size, nail schedules, floor diaphragm, and flooring details, and of particular note is the lack of hardware such as metal straps and plates, which were not available in this era.…”

Section: Test Building Design Approachmentioning

confidence: 99%

See 1 more Smart Citation

Mass Timber Rocking Panel Retrofit of a Four-Story Soft-Story Building with Full-Scale Shake Table Validation

et al. 2017

View full text Add to dashboard Cite

Soft-story wood-frame buildings have been recognized as a disaster preparedness problem for decades. There are tens of thousands of these multi-family three-and four-story structures throughout California and other cities in the United States. The majority were constructed between 1920 and 1970, with many being prevalent in the San Francisco Bay Area in California. The NEES-Soft project was a five-university multi-industry effort that culminated in a series of full-scale soft-story wood-frame building tests to validate retrofit philosophies proposed by (1) the Federal Emergency Management Agency (FEMA) P-807 guidelines and (2) a performance-based seismic retrofit (PBSR) approach developed within the project. Four different retrofit designs were developed and validated at full-scale, each with specified performance objectives, which were typically not the same. This paper focuses on the retrofit design using cross laminated timber (CLT) rocking panels and presents the experimental results of the full-scale shake table test of a four-story 370 m 2 (4000 ft 2 ) soft-story test building with that FEMA P-807 focused retrofit in place. The building was subjected to the 1989 Loma Prieta and 1992 Cape Mendocino ground motions scaled to 5% damped spectral accelerations ranging from 0.2 to 0.9 g.

show abstract

Section: Test Building Design Approachmentioning

confidence: 99%

Section: Test Building Design Approachmentioning

confidence: 99%

Mass Timber Rocking Panel Retrofit of a Four-Story Soft-Story Building with Full-Scale Shake Table Validation

et al. 2017

View full text Add to dashboard Cite

show abstract

“…4) can be attributed to the dynamic interaction between the specimen and the table. More details on the mechanical and dynamic characteristics of the shake table can be found in Ozcelik et al (2008). The application of output-only system identification methods to these nominal white-noise base excitation test data would result in large estimation errors in the modal parameters, because of deviation of the input excitations from broadband signals.…”

Section: System Identification Of the Infilled Framementioning

confidence: 99%

Finite-Element Model Updating for Assessment of Progressive Damage in a 3-Story Infilled RC Frame

et al. 2013

View full text Add to dashboard Cite

This paper presents a study on the identification of progressive damage, using an equivalent linear finite-element model updating strategy, in a masonry infilled RC frame that was tested on a shake table. A two-thirds-scale, 3-story, 2-bay, infilled RC frame was tested on the UCSD-NEES shake table to investigate the seismic performance of this type of construction. The shake table tests induced damage in the structure progressively through scaled historical earthquake records of increasing intensity. Between the earthquake tests and at various levels of damage, low-amplitude white-noise base excitations were applied to the infilled RC frame. In this study, the effective modal parameters of the damaged structure have been identified from the white-noise test data with the assumption that it responded in a quasi-linear manner. Modal identification has been performed using a deterministic-stochastic subspace identification method based on the measured input-output data. A sensitivity-based finite-element model updating strategy has been employed to detect, locate, and quantify damage (as a loss of effective local stiffness) based on the changes in the identified effective modal parameters. The results indicate that the method can reliably identify the location and severity of damage observed in the tests.

show abstract

“…As indicated above, it depends on many factors such as the oil compressibility, oil leakage, servovalve dynamics, etc. [1,4] that can be obtained from formulations [4,6] or identifications as shown herein. In order to obtain the best fidelity of the achieved motion, a compensated drive motion can be applied.…”

Section: Shake Table Simulation Of Base Motion For Required Response mentioning

confidence: 99%

“…In general, components of shake tables can be grouped into three sub-systems: mechanical, hydraulic, and electronic. Typically, platform and actuators are included in the mechanical category; pumps, accumulators, and servovalves are included in the hydraulic category; controller and feedback sensors are included in the electronic category [1]. 593 table.…”

Section: Introductionmentioning

confidence: 99%

Simulation of floor response spectra in shake table experiments

Maddaloni

Ryu

Reinhorn

2010

Earthq Engng Struct Dyn

View full text Add to dashboard Cite

Among several different experimental techniques, used to test the response of structures and to verify their seismic performance, the shake table testing allows to reproduce the conditions of true effects of earthquake ground motions in order to challenge complex model structures and systems. However, the reproduction of dynamic signals, due to the dynamics of the shake table and of the specimen, is usually imperfect even though closed-loop control in a shake table system is used to reduce these errors and obtain the best fidelity reproduction. Furthermore, because of the dynamic amplifications in the specimen, the signal recorded at desired locations could be completely different from the expected effect of shake table motion. This paper focuses on the development of practical shake table simulations using additional 'open loop' feedforward compensation in form of inverse transfer functions (i.e. the ratio of the output structural response to an input base motion in the frequency domain) in order to obtain an acceptable reproduction of desired acceleration histories at specific locations in the specimen. As the first step, a well-known global feedforward procedure is reformulated for the compensation of the table motion distortions due to the servo-hydraulic system. Subsequently, the same concept is extended to the table-structure system to adjust the shake table input in order to achieve a desired response spectrum at any floor of the specimen. Implementations show how such a method can be used in any experimental facility.The table (or platform) supports the specimen during the test. It is constructed to provide high stiffness with minimum weight and typically consists of a rectangular-or square-shapes platform able to reproduce up to six degrees of freedom (DOF) by servo-hydraulic actuators.The actuators apply the force necessary to create the desired table movement during seismic testing. Linear variable differential transformers (LVDT), or equivalent, are usually mounted in each actuator to provide an electrical feedback signal and to indicate the actuator piston rod position. The actuators are equipped with servovalves that control the direction and the amount of fluid flow to the actuators to minimize the difference between the desired (programmed) and the achieved (measured) displacement. The servovalve ports the fluid provided by the hydraulic power system into the appropriate side of the actuator chambers. This causes the piston to move the actuator arm in the desired direction.The control system monitors and generates program command and feedback signals for the control of the test system. Generally, the control is the key element of the whole system and one of the most difficult technical challenges for mechanical engineers [2]. The controller provides the servovalve command in order to obtain a specific position of the actuator and finally the motion of the platform to reproduce earthquake accelerograms. However, reproduction of a dynamic signal is known to remain imperfect [3]. The degree of distor...

show abstract

Experimental characterization, modeling and identification of the NEES‐UCSD shake table mechanical system

Cited by 33 publications

References 8 publications

Mass Timber Rocking Panel Retrofit of a Four-Story Soft-Story Building with Full-Scale Shake Table Validation

Mass Timber Rocking Panel Retrofit of a Four-Story Soft-Story Building with Full-Scale Shake Table Validation

Finite-Element Model Updating for Assessment of Progressive Damage in a 3-Story Infilled RC Frame

Simulation of floor response spectra in shake table experiments

Contact Info

Product

Resources

About