No description available.

Thesis (M. App. Sc.)--Carleton University, 2002. / Includes bibliographical references (p. 114-118). Also available in electronic format on the Internet.

Thesis (Ph. D.)--Institute of Technology, Otaniemi. / Bibliography: p. [89]-91.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed June 26, 2009). PDF text: xv, 173 p. : col. ill. ; 23 Mb. UMI publication number: AAT 3350450. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph. D.)--University of Hong Kong, 1996. / Includes bibliographical references (leaf 201-209).

Thesis (Ph.D.)--Brown University, 2005. / Vita. Thesis advisor: Eric Chason. Includes bibliographical references (leaves 21-22, 35, 55-56, 86-87, 119-120, 149). Also available online.

The objective of the research programme has been to investigate the effects of pre-buckling low frequency inelastic cyclic hysteresis upon a range of imperfection sensitive circular hollow section struts. The programme has involved experimental and theoretical studies and computer graphics are widely employed throughout. The subject matter is introduced from a variety of perspectives, phenomenological, historical, theoretical and experimental in Chapter 1, together with an appreciation of therole of the digital computer within the research programme. Experimental factors are initially presented in Chapter 2 whilst the formal testing programme is described in Chapter 3. Original findings are definitively set out in Sections 3.3 and 3.7 wherein the concept of the 'cyclic step' is first introduced, theremaining sections in the chapter providing the necessary supporting data. Theoretical studies are reported in Chapter 4 with the novel moment-thrust-curvature modelling described in Sections 4.2 and 4.3 being of central importance. This modelling enables the formulation of a predictive cyclic strut system effectivelyrequiring of the end user the solution of only a pair of simultaneous equations and yet capable of providing data trends consistent with the experimental findings. Design interpretation together with an overview of the experimental and theoretical studies and their interrelationshipare set out in Chapter 5. A practical design procedure oriented about the effect of a pre-buckling cyclic action phase upon otherwise static strut performance is delineated and anappropriate design chart is provided. Conclusions are drawn with respect to the primary researchfindings in Chapter 6 wherein suggestions are also made regarding possible further studies. An Appendix is included providing the bibliography, nomenclature and respective published work; selected supporting documentation is also presented.

The main purpose of Structural Health Monitoring (SHM) is the assessment of structural conditions in aerospace, mechanical and civil systems. In structural engineering, damage is defined as any permanent change in the structural and geometric properties of a system caused by an external action. Vibration-based damage assessment methods rely on the use of sensors that record the structural dynamic response of a system that is determined by its structural and geometric properties. External disturbances and environmental conditions in which the system operates cause fluctuations of these properties and might hide the change in signature induced by damage. To handle the uncertainties in the determination of the structure’s characteristics, a statistical pattern recognition approach is presented in this thesis. Any statistical approach relies on the statistics of some features that provide a compact representation of the structural properties and that are sensitive to damage. Such features are called damage sensitive features and are extracted from the dynamic response of the structure: their statistical distribution is then analyzed to assess the occurrence of damage. This dissertation focuses on the analysis of the statistical distribution of damage sensitive features which are extracted through parametric and nonparametric algorithms. Cepstral coefficients are features defined in the field of acoustics and, in this thesis, they have been adapted to SHM analyses in order to develop compact damage sensitive features whose extraction requires a low computational effort. In this thesis, cepstral coefficients have been mathematically transformed through a Principal Component Analysis in order to generate damage sensitive features that are barely sensitive to measurement noise, environmental conditions and different excitation sources. In an attempt to develop an automated strategy for structural damage assessment, the search for damage sensitive features has been extended to the estimation of structural mode characteristics obtained through an output-only version of the Inner Product Vector methodology, e.g. considering only the structural response time histories. This new damage assessment procedure requires low computational effort and is capable to identify both the presence of damage and its location. However, one of the critical points of the proposed procedure consists in the manual evaluation of the spectral content of the dynamic responses that requires the user’s intervention. To automatize this procedure, a Bayesian clustering algorithm and a classifier have been successfully implemented and tested. Finally, the robustness of Bayesian regression algorithms to overfitting led us to consider their applicability to the field of system identification in order to provide a reliable estimate of the structural modal parameters that can be used as damage sensitive fea- tures. In fact, one of the main problems of system identification algorithms is that they rely on a regression algorithm that tends to overfit data producing unreliable results. Results provided by the Bayesian regression based system identification algorithm are obtained and compared with the ones coming from standard system identification algorithms.

A simplified procedure that results in a significant reduction of the computation time and effort in the design of single plate framing connections is presented herein. This simplified method is based upon the current design procedure which is applicable to partially restrained shear connections. A total of 140 steel beams with 700 analyses and 500 composite beams were used to develop the simplified method. Tables are provided for the design of most commonly used connections. The simplified single plate design is applicable for fully tightened 3/4, 7/8, and 1. inch A325 or A490 bolts used in either standard round or slotted holes, or snug tight A325 or A490 bolts in standard holes. These studies have led to a single table of the restraint design moments which greatly simplifies the design procedure.

Finite element formulation based on compatible, assumed displacement fields and the principle of stationary potential energy is applied to analyze edge-stiffened plates. Shear deformation is considered in the formulation of the plate bending and beam bending elements by allowing independent interpolation for displacements and rotations. In addition to bending deformation, plane stress action is superposed on the plate element, while torsion and axial deformation are incorporated in the beam element, so that structural interaction between plate and edge beam elements can be facilitated. By enforcing compatible displacements and rotations across the interface between plate and beam elements, the degrees-of-freedom in one element can be related to the degrees-of-freedom of the adjoining element of a different type. Accordingly, the stiffness matrix and equivalent load vector are transformed to correspond to the common degrees-of-freedom as a result of invariance of the potential energy. By means of the direct stiffness method, the global equilibrium equation is thus established and solved by a frontal solution subroutine. Special features are introduced into the solution subroutine in order to handle varying degrees-of-freedom per node in an element and multiple loading cases. In addition, the speed of input-output transfer between in-core and peripheral storage is optimized. Convergence studies on displacements and stresses show that the current formulation with the program is capable of analyzing shear-flexible structures. The formulation allows convergence of shear-rigid solutions as a limiting case by making use of the selective reduced integration scheme when formulating individual elements. Graphs are presented to aid the design of edge-stiffened plates with two adjacent edges clamped and others cast with intersecting edge beams.