Thesis (Ph. D.)--Texas A&M University, 2005. / Vita. Includes bibliographical references (p. 150-156). Also available online via the Texas A&M Digital Repository website (https://txspace.tamu.edu/).

Base isolated buildings are well known to provide enhanced performance due to minimized accelerations and decreased interstory drifts. However, the reduced demands are obtained at the expense of large displacements at the isolation layer. This study investigates an innovative system, termed ‘dual isolation’, which applies two layers of isolation, one at the base and one mid-story to resolve this issue. An analytical solution for the equation of motion of the proposed system is developed based on linear isolation theory. This creates a foundation to assess the behavior of various types of seismic protection systems and to select the damping, mass and frequency ratio that leads to an optimal dual isolation design. Time history responses of the dual isolation system with viscous damping are compared to those of a conventional isolation counterpart to examine the effectiveness of the system. The system reduces first floor displacements by 40% on average, while the roof displacement is increased by roughly 15%. This results in reduced design forces for the structure. In addition, accelerations, especially above the second isolation layer, are significantly decreased. By reducing story shears and accelerations, the dual isolation system limits damage to both structural and nonstructural systems and components, thereby increasing global system performance. / Thesis / Master of Applied Science (MASc)

No description available.

The 7th German-Japanese Bridge Symposium, July 30-August 1, 2007 Osaka, JAPAN (GJBS07), full paper + extended abstract (p.84-85)

Ground-borne vibration has existed ever since the development of urban road and rail networks. Vibration generated by the moving traffic propagates through the ground and into buildings, resulting in unacceptable levels of internal noise and vibration. A common solution to this increasingly significant problem is the base-isolation of buildings by incorporating vibration isolation bearings between the buildings and their foundations. This technique has been employed for over forty years but the exact performance of base isolation remains uncertain. This dissertation is concerned with the development of a generic computational model; generic in that it accounts for the essential dynamic behaviour of a typical base-isolated building in order to make predictions of isolation performance. The model is a linear one, formulated in the frequency domain, and consists of a two-dimensional portal-frame model of a building coupled to a three-dimensional boundary-element model of a piled-foundation. Both components of the model achieve computational efficiency by assuming they are infinitely long and using periodic structure theory. The development of the model is described systematically, from the modelling of a building and its isolation bearings to that of its foundation. The majority of the work is concerned with the piled-foundation model, which is comprehensive in that it accounts for the vertical, horizontal and rotational motion of the pile heads due to both direct pile-head loading and interaction through wave propagation in the surrounding soil. It is shown that this level of detail is important in the prediction of base isolation efficiency. A key question facing designers is not only how but on what basis base isolation should be assessed, since fundamental problems exist with the existing measures of isolation performance. Power flow analysis is explored and the concept of power flow insertion gain, based on the total mean vibrational power flow entering a building, is introduced as a useful measure of isolation performance. This is shown to offer clear benefits by providing a single measure of performance that is suitable for design purposes. Finally, the development of a prototype force-sensitive vibration isolation bearing is described as a contribution to verifying base-isolation theory with experiments.

El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / his paper proposes a Lean Green model for increasing profitability in small and medium-sized businesses operating within the plastics sector. This model will use the 5S methodology, KanBan for inventory control and TPM to standardize new corrective and preventive maintenance processes. As an added contribution, a Circular Economy process will be included to reuse products, thus reducing consumption and generating less solid waste. In this way, companies will not only prevent damaging the environment but will also guarantee their compliance with regulatory standards. As a result, an 11% reduction was observed in the acquisition of supplies and spare parts for machine maintenance along with a 4% reduction in the number of machine breakdowns.

The long-term operational safety of nuclear power plants is of utmost importance. Seismic isolation has been shown to be effective in reducing the demands on structures in many applications, including nuclear power plants (NPP). Many designs for Generation III+ NPP include a large passive cooling tank as a measure of safety that can be used during power failure. In a large seismic event, the fluid in the tank may be excited, and while the phenomenon of fluid-structure interaction (FSI) has also been studied in the context of base isolated liquid storage tanks, the effect on seismically isolated NPP has not yet been explored. This thesis presents a two-part study on a base isolated NPP with friction pendulum bearings. The first part of the study compares the usage of a linear fluid model to a nonlinear fluid model in determining tank and structural demand parameters. The linear fluid model was found to represent the nonlinear fluid model well for preliminary analysis apart from peak sloshing height, which it consistently underestimated. The second part of the study uses a linear fluid model, an empty tank model and a rigid fluid model to investigate the influence of FSI on the structural response of an isolated NPP compared to a fixed base NPP. In general, the response of a fixed base NPP considering FSI using a linear fluid model can typically be bound by the results assuming an empty tank and assuming a full tank with rigid fluid mass. However, this does not hold for the base isolated NPP, as the peak isolation displacement for an NPP with a linear fluid model at design depth is greater than the peak isolation displacement than the same NPP with an empty tank and with a rigid fluid model. / Thesis / Master of Applied Science (MASc)

We extend the application of the substructure synthesis method to more complex structures, and establish a design methodology for base isolation and active control in a distributed model of a building under seismic excitation. Our objective is to show that passive and active control complement each other in such an advantageous manner for the case at hand, that simple devices for both types of control are sufficient to achieve excellent response characteristics with very low control forces. The Rayleigh-Ritz based substructure synthesis method proved to be highly successful in analyzing a structure more complex than the ones previously analyzed with it. Comparing the responses of the hybridly controlled building and the conventional fixed building under El Centro excitation, we conclude that the stresses are reduced by 99.6 %, the base displacement is reduced by 91.7 % and the required control force to achieve this is 1.1 % of the building weight. / Ph. D.

No description available.

This thesis focuses on the experimental studies conducted on the development of low-cost seismic base isolation pads using scrap automobile tires. Seismic base isolation is a well-defined building protection system against earthquakes, on which numerous studies have been conducted. The majority of the previous studies focus on the performance improvement of the base isolation systems. However, this study aims at cost and weight reduction of seismic base isolation pads by recycling otherwise useless material: scrap tires. Elastomer-based isolators have been heavily studied and used for the last 25 years. Steel or fiber reinforcement inside the elastomer isolators provides high vertical stiffness, whereas rubber segments between reinforcement layers provide low horizontal stiffness for the seismic base isolation. Since 1960&rsquo / s, automobile tires have been produced by means of vulcanizing rubber with steel mesh in different forms which have a similar effect as the steel plates or fibers inside the conventional elastomer-based isolators. Therefore, rectangular shaped layers cut from tread sections of used tires and then piled on top of each other can function as an elastomeric bearing. Since the tires are being designed for friction, load transfer between scrap tire layers would be large enough to keep all layers intact. A minimal slip generated between the piled layers at high strain rates may even help to dissipate some extra energy. Axial compression, dynamic free vibration, static shear and shaking table tests have been conducted on Scrap Tire Pads (STP) prepared by using different tire brands for different number of layers and orientations. The results have shown that the average shear modulus of STPs change between 0.9MPa and 1.85MPa. At the end of the dynamic tests it has been noticed that the lateral stiffness of STPs can be simply adjusted by changing the number of tread layers placed on top of each other. The amount of wire mesh inside the tire tread layers is relatively low compared to the steel plates in regular elastomeric pads / consequently, axial load capacity of STPs has been found to be around 8.0MPa. Static large deformation shear experiments have been performed to obtain the horizontal stiffness and shear modulus values at high strains and the results are tabulated in the manuscript. Steel and rubber layers are produced separately and just put on top of each other without any adhesive to form the &frac14 / scaled versions of STPs which were used to isolate a &frac14 / scaled masonry house on the shaking table available in METU Structural Laboratory. The experiment showed that non-vulcanized rubber-steel layers put on top of each other can also be used to isolate structures. In conclusion, STPs may be used as a low-cost alternative to conventional elastomer-based pads for seismic isolation of massive structures (e.g. stone wall rural masonry) or for temperature induced deformation compensation of rural bridges. STP usage is demonstrated using three hypothetical design examples in the manuscript.