Thesis (M.S.)--Ohio University, November, 2003. / Title from PDF t.p. Includes bibliographical references (leaves 189-191).

No description available.

This dissertation is concerned with controlling the motion of a semisubmersible structure induced by high-frequency waves. The structure consists of a rigid platform and a flexible superstructure. Motion of a structure in fluids generates forces depending on the motion itself. The added mass and damping terms stemming from this motion depend on the frequency of motion. It is well known that for a given wave height, the wave energy is distributed according to a Rayleigh distribution. Because mass and damping terms vary with the frequency of the wave motion, there is an infinite number of sets of dynamical equations, one for each frequency in the Rayleigh distribution. Practical considerations make it necessary to discretize the frequency spectrum, so that there are as many dynamical equations as frequency increments. The center frequency in each increment is computed by equipartitioning of the wave energy distribution represented by a Bretschneider spectrum. The excitation forces are estimated for each increment and the design of optimal control is carried out by the Independent Modal-Space Control (IMSC) method. The net control forces can be found by summing the forces associated with each increment. The technique is demonstrated by means of a numerical example in which the wave-induced vibration of a cylindrical platform with a flexible cantilever beam is suppressed. / Ph. D. / incomplete_metadata

Chan Cho Wa, Carlos. / "Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2010-2011, design report." / Chapter 0 --- Abstract --- p.2 / Chapter 0.1 --- Objective / Chapter 0.2 --- Focus and Study / Chapter 1 --- Theory --- p.6 / Chapter 1.1 --- Aldo Rossi / Chapter 1.2 --- Enric Miralles / Chapter 1.3 --- Etienne Louis / Chapter 1.4 --- Arata Isozaki / Chapter 2 --- HK Situation --- p.8 / Chapter 2.1 --- Supply and Demands in HK / Chapter 2.2 --- Architectural Treatment / Chapter 2.3 --- Locations / Chapter 2.4 --- "Government, Policy" / Chapter 2.5 --- Social Concern / Chapter 2.6 --- Religious / Chapter 2.7 --- Summary / Chapter 3 --- Typology Study --- p.14 / Chapter 3.1 --- Traditional Hill / Chapter 3.2 --- Flat Land / Chapter 3.3 --- Slab Block / Chapter 3.4 --- High Rise / Chapter 4 --- Detailed Case Studies --- p.16 / Chapter 4.1 --- Igualada Cemetery / Chapter 4.2 --- "Diamond Hill ^sff ""<;." / Chapter "4,3" --- Others / Chapter 4.4 --- First Summary / Chapter 5 --- Rock Study --- p.24 / Chapter 5.1 --- "Countryside, Town, Urban Edge" / Chapter 5.2 --- Type of Rock / Chapter 5.3 --- Method of Excavation & Tunnel / Chapter 6 --- Site Investigation --- p.26 / Chapter 6.1 --- Why the site / Chapter 6.1.1 --- Urban Edge / Chapter 6.1.2 --- Natural elements / Chapter 6.1.3 --- Traditional and New Type / Chapter 6.1.4 --- "Site nature, old cemetery and countryside" / Chapter 6.2 --- History of sites / Chapter 6.2.1 --- History of Lee Yue Mun / Chapter 6.2.2 --- History of Devil Hill / Chapter 6.3 --- Important elements in sites / Chapter 6.4 --- Zoning and Site Response / Chapter 7 --- Design Strategies --- p.32 / Chapter 7.1 --- Caved Landscape / Chapter 7.2 --- Double Layering System / Chapter 7.3 --- Mix program / Chapter 7.4 --- Linkage and Revitalizing the size / Chapter 7.5 --- Narrative Route and Program / Chapter 7.6 --- Circulation of Darkness and Light / Chapter 8 --- Design Research --- p.40 / Chapter 8.1 --- Atmospheric Drawings / Chapter 8.2 --- System Studies / Chapter 8.3 --- 8.3 Parti Models / Chapter 9 --- Design Process --- p.46 / Chapter 10 --- Lighting Study --- p.52 / Chapter 10.1 --- Single Source / Chapter 10.2 --- Combination / Chapter 10.3 --- Sequence Study / Chapter 10.4 --- Unit Study / Chapter 10.5 --- Unit of sunken niche / Chapter 10.6 --- Sequence in niche / Chapter 10.7 --- Overall Sequence / Chapter 10.8 --- Sequence of Darkness / Chapter 11 --- Final Design --- p.58 / Chapter 11.1 --- Design Summary / Chapter 11.2 --- Key Drawings / Chapter 11.3 --- Sequence / Chapter 11.4 --- Models

Submitted in fulfillment of the requirements of the Degree of Magister Technologiae: Civil Engineering, Durban University of Technology, 2013. / The urgent need to rehabilitate or replace ageing deteriorated buried potable water pipeline networks is one of the many critical service utility provision challenges faced within the municipalities in South Africa. The majority of these unreliable deteriorated pipeline networks consist of un-dipped (not coated with bitumen) AC piping which have long passed their planned economic and technical lifespan. Traditionally, the open trenching method has been utilised for the replacement of aged and deteriorated piping. However, this traditional open trenching method has shown to be expensive and difficult to implement, particularly in congested high traffic use urban areas. The need to rehabilitate or replace the ageing deteriorated buried potable water pipelines in South Africa, taking into account the above mentioned expensive factors has a solution. This solution is termed ‘trenchless technology’ and sometimes also termed ‘no dig’. Recent advancements in trenchless technologies now include innovative methods such as pipe bursting, close-fit lining and sliplining. Close-fit compact pipe manufactured by Wavin Overseas B.V. was newly introduced in South Africa in 2010 for the rehabilitation of deteriorated pipelines. These trenchless methods require further research into their technical application merits, drawbacks and costs in relation to the traditional open trenching method in order to determine which method is more expensive and also least suitable. Traditionally, the ‘total cost’ associated with pipe rehabilitation or replacement projects consisted only of the direct costs. The indirect and socio-economic inconvenience costs were often ignored and resulted in costly expenses to the municipalities. However, this research will show that these indirect and socio-economic inconvenience costs must form part of the total cost of a project as it assists with the successful completion of the project without expensive unforeseen costs to the municipalities. In addition, this research will provide insight as to which indirect and socio-economic inconveniences are dominantly experienced by the public. To achieve this, a quantitative socio-economic survey questionnaire was developed. This questionnaire was aimed at residents and business owners who were affected during a project of this nature. This research study will serve as a support tool to municipalities of South Africa when selecting a pipe rehabilitation or replacement method. This support tool will provide key technical merits and drawbacks of the traditional open trenching method, pipe bursting method, close-fit compact pipe method and sliplining method. In addition, this research study will compare the ‘total cost’ of the traditional open trenching method against the trenchless pipe bursting method. The decision making process lies in the hands of the municipal technical managers. Therefore, their knowledge and experience of up to date information on trenchless methods (as well as the traditional open trenching method) is vitally important. This research provides insight as to the knowledge and experience of technical municipal staff on trenchless methods, its application and use in South Africa. A quantitative survey questionnaire was developed by the researcher. This questionnaire was aimed at technical staff in the water departments of district and local municipalities of South Africa. The results of the above questionnaire surveys formed part of the eThekwini Water and Sanitation (EWS) Feasibility study funded by the Dutch Government. When comparing the costs of the trenchless pipe bursting method against the traditional open trenching method, the results revealed that trenchless methods are undoubtedly cheaper and far less disruptive to the public. The results of the socio-economic survey revealed that trenchless methods were preferred by the public since it was less disturbing and the hindrances experienced were also far less than the traditional open trenching method. The results of the technical municipal survey questionnaire revealed that at least 50% of municipal technical staff of South Africa are not adequately informed about trenchless methods, its application and technical merits and drawbacks respectively. This survey questionnaire revealed that South Africa may be advancing over the years on the use of trenchless methods, however, more educating in the form of training, seminars and other methods of marketing must be undertaken starting at a municipal level.

Insufficient information on the host medium can cause serious problems, even collapse, during construction in a tunnel. This study focuses on understanding the reasons behind the collapse of the Tunnel BT24 to be opened within the framework of Ankara-Istanbul High Speed Railway Project. The tunnel is located near Boz&uuml / y&uuml / k in the Bilecik Province. The collapsed section of the tunnel was driven into a highly weathered, weak to medium rock mass. Unanticipated geological/geotechnical circumstances caused excessive deformations at the section on which the primary support system was applied, leading eventually to collapse. To understand the response of the tunnel and the collapse mechanism, the construction sequence is simulated using two-dimensional plane-strain and axisymmetric finite element models. The analyses were carried out for the section with and without invert closure of the shotcrete liner. To implement the effects of likely unfavorable ground conditions on the tunnel response, a number of fault scenarios and possible creep effects were also considered with those two alternatives. Displacements in the tunnel periphery, forces and moments in the primary liner as well as the plastic deformation zones in the surrounding ground were determined for each case and comprasions were made accordingly. It is concluded that the unforseen ground circumstances might have substantially aggravated the deformations in the section and that the lack of ring closure of the primary liner at invert played the key role in the collapse.

Weakening and liquefaction of sands with increasing excess pore water pressures under repeated loads is well-known. Occurrence of extensive damage to the built environment also at the sites underlain by fine soils during earthquakes have led the researchers to focus on the seismic response of such soils more recently. The primary objective of this study is to investigate the factors affecting cyclic behavior of saturated low-plastic fine soils through laboratory testing. An extensive laboratory testing program including conventional soil mechanics tests, consolidation tests, reconstituted sample preparation, monotonic and cyclic triaxial tests was carried out for this purpose. Laboratory program was conducted within two parts, one of which includes the tests performed with the silt specimens reconstituted in the laboratory and the other consisting of the tests performed with the undisturbed soil samples retrieved from Adapazari. The effects of the inherent soil properties and the effects of loading characteristics on the cyclic response of saturated low plastic silty soils were examined separately. Based on the test results, models were introduced (i) to predict the relationship between excess pore pressure ratio (ru), number of cycles (N) and cyclic stress ratio (CSRtx), (ii) to estimate the effect of initial shear stress on cyclic response, and (iii) to show the effects of initial void ratio (ei), initial shear stress ratio (

published_or_final_version / Civil Engineering / Master / Master of Philosophy

No description available.

The design of support systems, comprising rock bolt reinforcement and fabric containment components for tunnels in deep level mining environments does not currently cater well for adverse rock mass conditions. This often results in periodic failure of the support system, particularly under dynamic (rockburst) conditions with the potential for total collapse of the excavation. The design of support systems is currently based either on empirical design guidelines often not applicable to this environment or simple mechanistic models. This thesis details a methodology for the rational design of tunnel support systems based on a mechanistic evaluation of the interaction between the components of a support system and a highly discontinuous rock mass structure. This analysis is conducted under both static and dynamic loading conditions. Due to the highly complex and variable nature of the rock mass structure and the dynamic loading environment, a large component of the practical work on the evaluation of the mechanisms of rock mass deformation and support interaction is based on rockburst case studies. The understanding gained from these investigations is further evaluated by means of laboratory testing of the performance of the components of the support systems and numerical modelling of the interaction of the components of the support system with the rock mass. Due to the complex nature of this design environment the methodology developed in this thesis is but a step towards our greater understanding of the behaviour of the rock mass, and the interaction of support systems in the stabilisation of tunnel excavations. However, in comparison to the current design, this methodology now allows the design engineer to make better estimations of the anticipated demand on the different components of the support systems, under a defined rock mass environment on engineering principles. This understanding will give the design engineer greater flexibility, and confidence to design the appropriate tunnel support system for a specific rock mass and loading condition based on the often limited availability of different support units in the underground mining environment. / Thesis (Ph.D.)-University of Natal, Durban, 1999.