Thesis (MS)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Douglas S. Cairns. Includes bibliographical references (leaves 106-110).

Thesis (M.S. in Civil Engineering)--Washington State University. / Includes bibliographical references.

Thesis (Ph. D.)--University of California, San Diego, 2000. / Vita. Includes bibliographical references.

Thesis (M.S. in mechanical engineering)--Washington State University, August 2006. / Includes bibliographical references (p. 77-81).

This thesis is divided in two parts. The first part is devoted to the micro-macro modeling of the behavior of concrete under cyclic loading. Correlations between microscopic (frictional sliding of mesocracks) and macroscopic (energy dissipation) properties are investigated. The second part focuses on the description of a series of uniaxial cyclic tests on concrete and concrete-like materials performed in the "Rock Mechanics Laboratory" of Virginia Polytechnic Institute and State University, Virginia, USA. Data deriving from these experiments are analyzed on the basis of the micro-macro identification theory. Interesting predictions of the real mechanical behavior of concrete can be found by means of the aforementioned theory and are presented in the last part of the thesis. / Master of Science

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). Includes bibliographical references (p. 259-263). Also available via the World Wide Web.

It is not economical, nor practical, to design structures to remain elastic following a major earthquake event. Therefore, traditional seismic design methodologies require structures to respond inelastically by detailing members to accommodate significant plasticity (“plastic hinge zones”). It can be appreciated that, while life-safety of the occupants is ensured, structures conforming to this traditional design philosophy will be subjected to excessive physical damage following an earthquake. Thus, the direct costs associated with repair and the indirect costs associated with business interruption are expected to be great. Adding to this, structures located within a near-field region, close to a surface rupture, can be subjected to large velocity pulses due to a ground motion characteristic known as forward directivity in which a majority of the earthquake’s energy arrives within a very short period of time. Conventionally constructed systems are, in general, unable to efficiently deal with this ground motion. In the last two decades, advanced solutions have been developed to mitigate structural damage utilising unbonded post-tensioning within jointed, ductile connections, typically combined with hysteretic damping. While there is a growing interest amongst the engineering fraternity towards more advanced systems, their implementation into mainstream practice is slow due to the lack of understanding of unfamiliar technology and the perceived large construction cost. However, even considering such emerging construction technology, these systems are still susceptible to excessive displacement and acceleration demands following a major velocity-pulse earthquake event. In this research, the behaviour of advanced post-tensioned, dissipating lateral-resisting systems is experimentally and analytically investigated. The information learned is used to develop a robust post-tensioned system for the seismic protection of structures located in zones of high seismicity within near-field or far-field regions. A series of uniaxial and biaxial cyclic tests are performed on 1/3 scale, post-tensioned rocking bridge piers, followed by high-speed cyclic and dynamic testing of five 1/3 scale, post-tensioned rocking walls with viscous and hysteretic dampers. The experimental testing is carried out to develop and test feasible connection typologies for post-tensioned rocking systems and to improve the understanding of their behaviour under cyclic and dynamic loading. Insights gained from the experimental testing are use to extensively refine existing analytical modelling techniques. In particular, an existing section analysis for post-tensioned rocking connections is extended to assess the response of post-tensioned viscous systems and post-tensioned connections under biaxial loading. The accuracy of existing macro-models is further improved and a damping model is included to account for contact damping during dynamic loading. A Direct-Displacement Based Design (DDBD) framework is developed for post-tensioned viscous-hysteretic systems located in near-field and far-field seismic regions. The single-degree-of-freedom (SDOF) procedure is generic and has applications in new design and retrofit, while the multi-degree-of-freedom (MDOF) procedure is developed specifically for continuous bridge systems. Detailed design guidelines and flow-charts are illustrated to encourage the knowledge transfer from this report and to promote the use of emerging technology. Combining the information gathered from experimental testing, modelling and design, a probabilistic seismic hazard analysis is performed on three post-tensioned viscous-hysteretic bridge systems. In all cases, the post-tensioned bridge systems are shown to be more feasible than a traditional monolithic ductile bridge. Furthermore, while a post-tensioned hysteretic bridge is shown to be the most economic solution, the viscous-hysteretic system becomes more advantageous as the cost of fluid-viscous-dampers reduces.

Different types of breakwaters have been developed in the past for the protection of valuable coastal property, commercial activity and beach morphology. Among these, gravity-type breakwaters are the most common and provide good surface wave attenuation. However, these breakwaters are not always suitable due to their adverse impact on the coastal environment. To alleviate the problem, free surface breakwaters with a variety of caisson designs have been proposed and developed. The main advantages of such breakwaters are low capital cost, freedom from silting and scouring, short construction period, circulation of water beneath the breakwater and exertion of relatively low hydrodynamic forces on the structure as compared to conventional breakwaters. However, complete tranquillity on the lee side is not likely to occur due to wave energy transfer through the permeable parts of the breakwater. The degree of wave attenuation primarily depends on the configuration of the breakwater, the water depth and the incident wave conditions. The hydrodynamic performance of such free surface breakwaters is the subject of this thesis. Semicircular breakwaters mounted on a low-crested rubble mound structure were successfully built for harbour protection in Japan and China. However, the concept of having semicircular structures as free surface breakwaters has not yet been explored by the research community. As a result, this research is initiated with the aim of developing a free surface semicircular breakwater (SCB) that would serve as an anti-reflection barrier and provide reasonably good wave protection to coastal and marine infrastructures. To meet this research goal, a free surface SCB models were constructed and tested in a wave flume under various wave conditions. The experiments were conducted in three stages. For the first stage, the SCB model was initially tested without any perforations on the curved surface (i.e. a solid SCB) for different depths of immersion from the still water level in the wave flume. For the second stage, the front curved wall of the model was subsequently perforated with rectangular openings of different dimensions, producing front wall porosity of 9, 18 and 27%. Following this, two rows of rectangular openings near the crest of the rear curved wall were provided so as to facilitate water infiltration and escape of the run-up waves. For the third stage, additional effort was made to extend the draft of the breakwater by adding a wave screen at the front or/and rear. The screen porosity was 25, 40 and 50%. The hydrodynamic characteristics of the SCB models were investigated in both regular and irregular seas through a series of systematic experimental programme. The water surface elevations were measured at different locations upstream and downstream of the models to determine the coefficients of wave transmission (CT), reflection (CR) and energy dissipation (CL) as well as the wave climate coefficients in front and inside the breakwater chamber. The horizontal wave forces exerted on the SCB models and the wave screen(s) were also measured and subsequently normalised to yield the force coefficients in the analysis. These hydrodynamic coefficients for the respective test cases are presented and discussed in this thesis. The experimental results revealed that even though the solid SCB was a better wave attenuator than the perforated ones, it produced a considerable amount of wave reflection. The perforated SCB with 9% porosity of the front wall (denoted as SCB9) outperformed the other perforated breakwater models; however, it produced high wave transmission when the draft was limited and subjected to longer period waves. Hence, wave screens were added to further enhance the performance of the SCB9. The SCB9 with double screens of 25% porosity was found to provide the highest hydraulic performance. Empirical equations were developed using a multiple regression technique to provide design formulae for wave transmission, wave reflection and horizontal wave forces. The proposed empirical equations showed good agreement with the experimental data. These equations are intended to be of direct use to engineers in predicting the hydrodynamic performance of free surface SCBs. However, sensible engineering judgement must be taken while using these equations as they are based on small scale laboratory tests.

Today scale models are used to design spillway structures for hydropower stations. These are expensive and time-consuming to build and alter. This study investigates the possibilities of using numerical simulations in order to facilitate the spillway design process. It would be possible to save time and resources by altering the spillway parameters in the numerical model and thus find an optimal design, which can be further investigated with a scale model. However, it is complicated to simulate turbulent flows. Therefore the simulated flows in this study are compared to experimental measurements in order to investigate the accuracy of the numerical model. Ansys software Fluent uses Computational Fluid Dynamics (CFD) to calculate turbulent flows and is used as the simulation tool in this study. The simulations were performed on the spillway system of Shuibuya hydropower station. There are five spillway channels with flip bucket terminals and high head. In order to investigate the risk of erosion during large flows the jet throw distance was examined in experiments on a scale model. The same parameter was investigated in this simulation study. The acceptable error margin was set 30 % for the comparison between simulated and experimental measurements. All performed simulations met this criterion. It was therefore concluded that Fluent could be used as a sufficiently good approximation tool when it comes to turbulent flows in spillways.

Extensive use of stirred vessels in the process industries for various operations has attracted researchers to study the mixing mechanisms and its effects on the processes. Among the various flow-measuring methods, Particle Image Velocimetry (PlV) technique has become more popular in comparison to LDA and HW A methods because of its ability to provide instantaneous velocity fields. The present study uses this technique to investigate the flowfields and turbulent properties in a 290mm vessel stirred by Rushton Disc turbine (RDT) and Pitched blade turbine (PBT) impellers. Angle-resolved instantaneous flow-fields were obtained using 2-D and 3-D PlV technique. Flows in the RDT were examined. The distribution of out-of-plane vorticity and turbulent properties such as rms velocities, Reynolds stresses and turbulent kinetic energy was discussed. The flow number and power number of the RDT impeller were obtained as 0.83 and 5.16 respectively. Flows generated by the PBT impeller were examined in more detail. For this purpose, a multiblock approach was developed which allowed analysing larger fields of view with reasonably higher resolution. Whole vessel was thus mapped and various turbulent properties were examined. The mean flow-fields, out-of-plane vorticity and turbulent properties such as Reynolds stresses, turbulent kinetic energy and turbulent energy dissipation rates were estimated at different angle of blade rotation. The variation of the trailing vortex axis was obtained. The pumping number and power number ofPBT impeller was obtained as 0.86 and 1.52 respectively. Using this information, an integral length scales were estimated using 2-D FFT autocorrelation, which showed that these length scales vary significantly through out the vessel. It is demonstrated that assuming constant length scale through out the vessel could underestimate dissipation rate up to 25% in the impeller discharge. A kinetic energy balance was carried out around the PBT blades. It is shown that around 44% of the total power consumed by the impeller is dissipated within the impeller. The average rate of dissipation of kinetic energy was 39 times higher in the impeller region than the average dissipation rate in the vessel. Using LDA and PIV techniques, macro-instabilities (Ml) were studied. Spectral analysis was done using LOMB algorithm, which showed the presence of a dimensionless frequency of O.013-0.0174N in the RDT and PBT impellers. The frequency of Ml varied linearly with the impeller speed. The maximum broadening of turbulence levels due to the presence of Ml was around 20% for the PBT and 18% for the RDT impeller. The effect of mixing on the feed locations was studied using PlV measurements. Results showed that there is no direct effect of feed coming out of the feed pipe on the flow distribution, however, due to feed pipe, there was a wake formation close to the feed pipe. The low Reynolds number in the wake can affect local mixing conditions close to the feed pipe. At the end, angle-resolved Reynolds stresses were calculated and was noticed that flows in the vessel were isotropic in the bulk of the vessel however, anisotropic flow was noticed in the impeller stream.