An experimental testing program was conducted to determine the compression member performance in post-buckling region. These results are compared with an analytical computer program developed by Portland State University under Bonneville Power Administration Contract 79-80BP 24005. The paper presents the sensitivity of the performance of single angle compression members to various parameters such as length to radius of gyration ratio, eccentricity, end conditions and yield stress. The effect of local buckling on long member performance is also documented.

A36 steel is a commonly used material in civil engineering structures where fatigue damage can lead to catastrophic failure. In this research, nonlinear Rayleigh surface waves are used to characterize damage in A36 steel specimens caused by monotonic tension and low cycle fatigue. Fatigue damage produces the increased acoustic nonlinearity that leads to the generation of measurable higher harmonics in an initially monochromatic Rayleigh wave signal. One specimen is subjected to static tension and four specimens are used for low cycle fatigue tests in the tension-tension mode with a constant stress amplitude. The fatigue tests are interrupted at different numbers of cycles for the nonlinear ultrasonic measurements. Tone burst Rayleigh wave signals are generated and detected using a pair of oil coupled wedge transducers. The amplitudes of the first and second harmonic are measured at varying propagation distances to obtain the nonlinearity parameter for a given damage state. The experimental results show an increase of acoustic nonlinearity in the early stages of fatigue life. Furthermore, a close relationship between plastic deformation and the acoustic nonlinearity is found, which indicates that the acoustic nonlinearity is indeed a measure of microplasticity in this material.

The use of plastered straw bale walls in residential construction is growing as builders and owners seek environmentally friendly alternatives to typical timber construction practices. Straw has excellent insulation properties and is an agricultural bi-product which is annually renewable, and is often considered a waste product of grain production. This thesis presents new models for predicting the compressive strength of plastered straw bale assemblies subjected to concentric and eccentric load. A constitutive model for lime-cement plaster is adapted from a stress-strain model for concrete, available in the literature. Twenty-two cylinder tests on plasters typically used for straw bale construction were used to verify the constitutive model. The models for plastered straw bale assemblies were verified by testing plastered straw bale assemblies under concentric and eccentric compressive loads. An innovative steel frame test jig was designed to facilitate fabrication and testing of the specimens. Using this jig, 18 specimens of height 0.33 m, 0.99 m, 1.05 m or 2.31 m were subjected to concentric or eccentric compressive load until failure. The experimental strengths of the assemblies ranged from 23 kN/m to 61 kN/m, depending on the eccentricity of the load, the plaster strength, and the plaster thickness. Results indicated that the specimen height did not significantly influence the strengths of the specimens. The models predicted the ultimate strength of the assemblies to be, on average, 6% less than the experimentally determined strengths, with a standard deviation of 13%. The models were also used to predict the theoretical ultimate strengths for a number of plastered straw bale wall assemblies described in the literature. The fabrication techniques for these specimens were more representative of conventional straw bale construction techniques, and it was found that the experimental results were 30% of the theoretical strengths for assemblies with plaster strength less than 10 MPa and 6% of the theoretical strengths for assemblies with plaster strength greater than 10 MPa. Thus, to account for construction imperfections and potential alternative failure mechanisms, a reduction factor of no more than 0.3 for plaster less than 10 MPa is suggested in order to predict the strength of plastered straw bale walls constructed using conventional construction techniques. The results presented herein provide support for the use of plastered straw bale walls in residential construction and indicate the applicability of models based on the compressive behaviour of lime-cement plaster for modelling the behaviour of plastered straw bale walls under eccentric and concentric compression. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2009-05-29 13:34:53.867

Solar road panels are a technology that have the ability to revolutionize the way that roads are built and how electricity is generated. Strong incentives towards sustainable solutions in both of these fields have led to the design of innovative, multifaceted solutions, of which solar road panels are one of the most recent entrants. This research presents some initial analysis into the design of solar road panels from the perspective of Canadian pavement engineering. The hypothesis of this research was as follows: A specially designed modular panel can be constructed to withstand the structural and environmental loads on Canadian pavement structures while simultaneously generating electricity through embedded photovoltaic cells. Through a process that covers the design, construction, and analysis of the structural elements of a solar road panel prototype, this research evaluated the impact that solar road panels can have for Canada???s pavement infrastructure. Specific elements researched include the material selection for such a panel, the flexural response of the composite structure, how the panel will interact with traditional pavement and geotechnical materials while in use, and the change in performance of transparent layer materials as they are subjected to freeze-thaw cycling and scaling. The research found that the initial prototype design included a two 10-mm tempered glass pane transparent layers with a 12.7-mm GPO-3 optical layer and 19.1-mm GPO-3 base layer. The concept being that the glass would provide the rigidity required to protect the fragile solar cells while the fiberglass laminate has demonstrated performance as a traffic-supporting material in adverse conditions. Testing of this structure found that the performance was easily duplicated through finite element analysis, given that the material properties were assumed to be more rigid than the averages for tempered glass and GPO-3. Further finite element analysis demonstrated that the prototype solar road panel would not fail through traditional fatiguing methods, and in all cases on concrete, asphalt, granular, and subgrade bases the panels improved the performance characteristics of the structural base. The environmental conditioning of acrylic, glass, and polycarbonate specimens demonstrated that glass is the ideal material choice for the transparent layer for Canadian solar road panels. It proved to have the greatest freeze-thaw and scaling resistance of the three materials, and while the friction characteristic of the flat glass samples would not be suitable for driving on, avenues of research were identified that could improve this characteristic. In summary, the research conducted clearly proved the hypothesis; it is possible to build a structure that can house a photovoltaic system while supporting the structural and environmental loads that Canadian pavement are exposed to. The ideal panel would be constructed with a tempered glass transparent layer, GPO-3 optical and base layers, and the structure would be installed on a concrete structural base. The refinement of this design will be the scope for future research.

This thesis investigates the appropriateness of a simplified, open-source digital image correlation (DIC) software for use in quasi-static, structural testing utilizing two-dimensional (2D) DIC measurements. DIC is a non-contact optical measurement technique that uses computer vision to track unique attributes on the surface of an object. For structural testing, traditional instrumentation such as displacement sensors and strain gages are impractical for full field measurements due their limited ability to capture large amounts of data. However, over the past decade, DIC has proven a successful method for full-field kinematics measurements, making it an appealing tool for collecting high densities of accurate data. This thesis specifically studies the accuracy and limitations of the DIC software, MODEM, for various test specimens and loading conditions. This research work is part of an experimental program comprised of three phases. The first stage was conducted by another investigator on aluminum coupons tested in pure tension. These results were used to calibrate parameters (speckle pattern density, lighting, and camera settings) used with the DIC software. The second stage included pure compression tests on concrete cubes and concrete cylinders to compare the difference in results between: (i) surface curvature, (ii) camera distance, (iii) surface treatment, and (iv) speckle pattern color. The final stage involved analysis of a tension test of a concrete prism completed at the University of Auckland in an effort to assess how MODEM could be utilized to accurately detect onset and propagation of concrete cracking. Results showed the most accurate DIC strains were within 5% error when compared to traditional instrumentation for aluminum loaded in tension and within 6% error for concrete loaded in compression/tension. This level of accuracy is comparable to existing open source and commercial DIC software utilizing 2D DIC analysis. Therefore, MODEM can be used to provide accurate 2D DIC strain measurements for small and medium scale structural test specimens when using the following parameters: (i) the surface of the specimen is planar, (ii) the camera is placed accordingly so the maximum amount of zoom can be used, (iii) the surface of a test specimen is free of debris or imperfections, and (iv) a high contrast and evenly distributed speckle pattern is used. Computational analysis of the results showed that known material properties can be used to calibrate, or remove errors from, the DIC results when traditional instrumentation is not available. Additionally, results showed MODEM strain contours can be used for initial detection of cracks in concrete loaded in tension while MODEM tracking performance can be used to characterize the centerline and orientation of cracks. The experimental tests provide critical information on how to set up, run, and analyze DIC results when using MODEM. The full field measurements are of value in providing accurate data for structural testing to develop a better understanding of material response and structural performance, since large-scale tests are typically limited by a sparse number of data points when using traditional instrumentation.

The main objective of this research is to extend the “Direct strength method” for determining the web crippling strength of cold-formed steel C and Z sections subjected to End one flange loading and Interior one flange loading conditions. Direct strength method is applied for designing the columns and beams earlier. The existing specifications equation for calculating the web crippling strength of cold-formed steels designed by American Institute of Iron and Steel is very old method and it is based on the extensive experimental investigations conducted at different universities. Calculating the web crippling strength of cold-formed steels using direct strength method is a new technique. In the present research the web crippling strength of cold-formed steels were calculated using Direct Strength Method. The experimental data is collected from the tests that were conducted at different universities. The critical buckling strength of the members were calculated using Abaqus. Microsoft excel is used to generate the equations. The safety and resistance factors for the designed equations were calculated using “Load and resistance factor design” and “Allowable strength design” from North American Cold-Formed Steel Specification, 2012 edition book.

This thesis presents experiments and numerical analysis of the cold-formed steel clip angle in three different limit states which are shear, compression, and combination of the screw connection. A previous cold-formed steel clip angle test program (which is Phase 1) developed design methods for clip angle. Therefore, the object of this thesis is to further investigate the behavior and design methods of loading-bearing cold-formed steel clip angles under different screw pattern. For each limit state, a test program was conducted to investigate the behavior, strength, and deflection of the clip angle. The test result were compared with previous CFS clip angle design method. Amending existing CFS clip angle method were developed by each of the four limit states studied in this project.

Hip disarticulations and hemipelvectomies are the highest level of lower limb amputations. As such, these amputations create ambulation difficulties and current prosthetic solutions are limited. Powered prosthetic joints have successfully improved lower limb amputee gait; however, no powered hip joints are available on the market. This thesis presents the design and evaluation of a microprocessor-controlled powered hip joint for hip-level amputees. A rope and pulley system was used to transmit power from an actuator located at the prosthetic thigh to rotate the prosthetic leg around an anteriorly-located prosthetic hip joint. The pulley system features an innovative tensioning system using multiple keyways, allowing the system to be tensioned without external tensioning devices. The powered hip prosthesis passed ISO 15032:2000 mechanical strength tests that simulated 100 kg user loads. The joint was also tested by able-bodied individuals using a hip disarticulation simulator to walk with the powered hip-knee-ankle-foot prosthesis. Though the participants had asymmetrical gait with shorter intact-side swing time, the device successfully allowed the participants to ambulate. The final device weighed 3.9 kg and respected geometric design constraints to fit comfortably under pants. Future work is needed to implement a gait control system, resolve a rope slack issue, and test the device with hip-level amputees.

This thesis presents a novel method for the correlation of FEM results to experimental test results known as the "Load updating method." Specifically, the load updating method uses the math model from the FEM and the strains measured from experimental or flight test data as inputs and then predicts the loads in the FEM which would result in strains that would correlate best to the measured strains in the least squared sense. In this research, the load updating method is applied to the analysis of a complex frame structure whose validation is challenging due to the complex nature of its structural behavior, load distributions, and error derived from residual strains. A FEM created for this structure is used to generate strain data for thirty-two different load cases. These same thirty-two load cases are replicated in an experimental setup consisting of the frame, supporting structure, and thirty actuators which are used to load the frame according to the specifications for each of the thirty-two load conditions. A force-strain matrix is created from the math model in NASTRAN using unit loads which are separately applied to each load point in order to extract strain results for each of the locations of the seventy-four strain gages. The strain data from the structural test and the force-strain matrix is then input into a Matlab code which is created to perform the load updating method. This algorithm delivers a set of coefficients which in turn gives the updated loads. These loads are applied to the FEM and the strain values extracted for correlation to the strains from test data. It is found that the load updating method applied to this structure produces strains which correlate well to the experimental strain data. Although the loads found using the load updating method do not perfectly match those which are applied during the test, this error is primarily attributed to residual strains within the structure. In summary, the load updating method provides a way to predict loads which, when applied to the FEM, would result in strains that correlate best to the experimental strains. Ultimately, this method could prove especially useful for predicting loads in experimental and flight test structures and could aid greatly in the Federal Aviation Administration (FAA) certification process. / Master of Science

WEb Services constituem uma tecnologia emergente utilizada para disponibilização de serviços na Web. Devido aos complexos processos de negócio existentes, esses serviços são combinados para que operem seguindo um fluxo de trabalho. Esse processo é chamado de composição de Web Services. Como no processo de desenvolvimento de um software tradicional, a atividade de teste é fundamental no processo de desenvolvimento da composição de Web Services. Neste trabalho é proposta uma estratégia de teste para a composição de Web Services, em que especificações de composições são transformadas para um modelo de teste de programas paralelos baseados em passagem de mensagens. É proposto o conceito de grupos de elementos requeridos para melhorar a cobertura dos critérios. Uma ferramenta de apoio à estratégia de teste foi desenvolvida. Alguns estudos experimentais para avaliar a aplicabilidade da estratégia proposta também são apresentados. Além disso, é proposto um método que utiliza redes de Petri para eliminar sincronizações não-executáveis no envio e recebimento de mensagens / WEb Services constitute an emerging technology for deploying services in the Web. Due to the complex business processes, these services are combined to operate, following a workflow. This process is named Web Services Composition. As in the development process of a traditional software, the testing activity is fundamental in the development process of Web Services Composition. This work proposes a test strategy for Web Services Composition, in that composition specifications are transformed into a test model of message-passing parallel programs. The concept of required elements groups is proposed to improve the criteria coverage. A tool that supports the test strategy was developed. Some experimental studies for evaluating the applicability of proposed strategy are also presented. Furthermore, it presents a method that uses Petri Nets to eliminate non-executable synchronizations in the sending and receiving of messages