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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Lateral Torsional Buckling of Wood Beams

Xiao, Qiuwu 11 June 2014 (has links)
Structural wood design standards recognize lateral torsional buckling as an important failure mode, which tends to govern the capacity of long span laterally unsupported beams. A survey of the literature indicates that only a few experimental programs have been conducted on the lateral torsional buckling of wooden beams. Within this context, the present study reports an experimental and computational study on the elastic lateral torsional buckling resistance of wooden beams. The experimental program consists of conducting material tests to determine the longitudinal modulus of elasticity and rigidity modulus followed by a series of 18 full-scale tests. The buckling loads and mode shapes are documented. The numerical component of the study captures the orthotropic constitutive properties of wood and involves a sensitivity analysis on various orthotropic material constants, models for simulating the full-scale tests conducted, a comparison with experimental results, and a parametric study to expand the experimental database. Based on the comparison between the experimental program, classical solution and FEA models, it can be concluded that the classical solution is able to predict the critical moment of wood beams. By performing the parametric analysis using the FEA models, it was observed that loads applied on the top and bottom face of a beam decrease and increase its critical moment,respectively. The critical moment is not greatly influenced by moving the supports from mid-span to the bottom of the end cross-section.
12

Lateral Torsional Buckling of Wood Beams

Xiao, Qiuwu January 2014 (has links)
Structural wood design standards recognize lateral torsional buckling as an important failure mode, which tends to govern the capacity of long span laterally unsupported beams. A survey of the literature indicates that only a few experimental programs have been conducted on the lateral torsional buckling of wooden beams. Within this context, the present study reports an experimental and computational study on the elastic lateral torsional buckling resistance of wooden beams. The experimental program consists of conducting material tests to determine the longitudinal modulus of elasticity and rigidity modulus followed by a series of 18 full-scale tests. The buckling loads and mode shapes are documented. The numerical component of the study captures the orthotropic constitutive properties of wood and involves a sensitivity analysis on various orthotropic material constants, models for simulating the full-scale tests conducted, a comparison with experimental results, and a parametric study to expand the experimental database. Based on the comparison between the experimental program, classical solution and FEA models, it can be concluded that the classical solution is able to predict the critical moment of wood beams. By performing the parametric analysis using the FEA models, it was observed that loads applied on the top and bottom face of a beam decrease and increase its critical moment,respectively. The critical moment is not greatly influenced by moving the supports from mid-span to the bottom of the end cross-section.
13

Full Scale Experimental Testing of Partially Composite Precast Concrete Sandwich Panels

Cox, Brandon L. 01 May 2018 (has links)
Precast concrete sandwich panels are a structural system consisting of concrete layers with insulation layers in between. The concrete layers are connected through the insulation with specially designed connectors. For engineers to properly design and analyze the strength characteristics of sandwich panels and their connectors, the engineers need to obtain recommendations from the individual connector manufacturers, which can be a very rigorous process. This project tested eight full scale precast concrete sandwich panels with two concrete layers on either side of an insulation layer with connectors concentrated at either end of each panel. The objectives of this project were to evaluate the interaction between the two concrete layers and how well the connectors transferred forces between the layers (percent of composite action) and to validate simplified methods of predicting properties of the panels by comparing the predicted panel properties to the results of the testing series. Additionally, this study evaluated the panel’s different thicknesses and lengths and compared their results.
14

Full-Scale Evaluation Of Matting Systems For Temporary Roads

Rushing, Timothy Wallace 10 December 2010 (has links)
An evaluation of eleven roadway matting systems was conducted to determine their effectiveness in carrying heavy vehicle traffic over loose sand subgrades. Three of the eleven matting systems were also evaluated over soft fine-grained subgrades. Matting products included high-density polyethylene, aluminum, fiberglass, and polyester. System configurations included continuous rolls of material, segmented rolls, and individual panels. The matting products were assembled on test sections and trafficked with a 7-ton, 6-wheeled truck loaded with a 7-ton payload until 20 percent of the mat section was no longer reusable or 2,000 truck passes were achieved. Earth pressure cells were installed under nine of the sand test sections to monitor load distributions provided by the matting systems. Based on the test results, recommendations are given for selecting the best roadway matting system types for use on temporary roads with sand or soft fine-grained subgrades.
15

Arkitekturens tillstånd / The Condition of Architecture

Söderlind, Viktor, Hallström, Gustav January 2018 (has links)
Vi ville, med en fysisk struktur som slutmål, undersöka och reflektera kring vilka svårigheter och möjligheter som byggd arkitektur möter. I ett försök att inledningsvis frigöra oss från en alltför formalistisk arbetsprocess utgick vi från leken som en kreativ katalysator. Leken, och speciellt den lekande människan, kom att informera projektet på era sätt. Exempelvis har det hela tiden funnits en stark känsla av serendipitet under projektutvecklingen som vi bejakat och tagit på allvar. Vi har drivits av ett lätt situationistiskt tankesätt, där handling, speciellt under projektets tidiga faser, tilllåtits gå före rigid logik. Med visst instämmande i Debords resonemang i Skådespelarsamhället har vi velat bryta mot skolans och samhällets passiviserande inverkan. / We wanted to, with a physical structure, investigate and reflect on the difficulties and opportunities that built architecture meets. In an attempt to initially free ourselves from an overly formalistic work process, we saw the art of play as a catalyst for creativity. The play, and especially the playful human, influenced the project in several ways. For example, there has always been a strong sense of serendipity during the project development. We have been driven by a situationist mindset, in which action, especially during the early stages of the project, has prevailed over planning. In agreement with Debord’s reasoning in “The Society of the Spectacle” and Lefebvres “Right to the City”, we saw an opportunity to go against the passivizing influence induced by school and society.
16

A mobile art gallery / Ett mobilt konstgalleri

Wolters, Erika January 2018 (has links)
Most art galleries around the world look the same; a large white room with a few artworks placed far apart. This standard way of designing art spaces together with locating them almost exclusively in the city centers makes them both physically and culturally distant for many people.  This project aims to explore other ways of displaying art to make it accessible to more people through small architectural interventions. It is an exploration about the relation between space the body and the object. A prototype for a mobile art gallery has been built as a testing device.
17

Full-Scale Instrumented Evaluations of Multiple Airfield Matting Systems on Soft Soil to Characterize Permanent Deformation

García Beltrán, Lyan Ivonne 14 August 2015 (has links)
Airfield matting systems are used for the expedient construction of temporary airfields and rapid expansion of existing airfields to provide maneuvering support for military aircraft. They protect the subgrade by distributing the load exerted by aircraft over a larger area. Six airfield matting systems of varying materials and designs were evaluated through the construction of full-scale test sections to determine their effectiveness at reducing the accumulation of subgrade deformation and decreasing the pressure experienced by the subgrade. The matting systems were tested on a California Bearing Ratio (CBR) of 6 and subjected to simulated F-15E aircraft traffic while monitoring mat breakage, deformation, and subgrade earth pressure. The systems were compared in terms of the rate of subgrade permanent deformation. Based on test results, a simplified expression was developed to predict subgrade deformation on a CBR of 6 as a function of F 15E aircraft passes and airfield mat properties.
18

Developing and Validating New Bolted End-Plate Moment Connection Configurations

Jain, Nonish 13 September 2015 (has links)
This research has been aimed to introduce larger moment carrying connections for any type of buildings, in particular the metal building industry. A total of four connection configurations, namely eight-bolt extended four wide, eight-bolt extended stiffened, six bolt flush unstiffened and twelve bolt extended unstiffened, have been investigated. The last two configurations are proposed whereas the first two configurations have been tested before, but the design procedures need to be validated against the test results. Design procedures, namely yield line analysis and bolt force models, were proposed to calculate moment capacity for end-plate yielding, moment capacity at bolt rupture with prying action and moment capacity at bolt rupture without prying action. The calculated values from these procedures were compared with the values obtained from the experimental test data available (whether from the literature or from this testing program). The experimental data from already tested configurations, eight-bolt extended four wide and eight-bolt extended stiffened, was analyzed. It was concluded that for the eight-bolt extended four wide configuration, the experimental values matched with the calculated values. For the eight-bolt extended stiffened configuration reasonable match was found between the experimentally obtained data and theoretically calculated values only for shallower depths. Hence, it was concluded that two deeper tests need to be performed for this configuration. A full-scale testing program was conducted for ten specimens covering three configurations. The two new configurations (six bolt flush unstiffened and twelve bolt multiple row extended unstiffened) were designed for a shallow and deep beam depth and the behavior of each depth observed for a thin end-plate and a thick end-plate respectively (four tests for each configuration). Also, two deep beam tests, one each for thick and thin plate behavior, were done for the eight-bolt extended stiffened configuration. Based on the comparison, it was determined whether the predicted values were in reasonable agreement with the experimental values or not. The design procedures for both the new configurations appear to be validated for a range of design parameters. The calculated moment capacities for bolt rupture, based on the nominal material properties, were found to be safe when compared with the experimentally obtained moments. The calculations for end-plate yield moments was within ±10% of the experimental yield moment. Also, for the deep tests for eight-bolt extended stiffened the yield line analysis seems to be a valid model and the bolt force model appears to be safe in comparison to the experimental values. / Master of Science
19

Performance of geotextile-reinforced bases for paved roads

Saghebfar, Milad January 1900 (has links)
Doctor of Philosophy / Department of Civil Engineering / Mustaque Hossain / Geotextiles have been widely promoted for pavement structure over the past 30 years. However, there is a lack of well-instrumented, full-scale experiments to investigate the effect of geotextile reinforcement on the pavement design. In this study, full–scale accelerated tests were conducted on eight lanes of pavement test sections. Six out of these eight sections had granular bases reinforced with different types of woven geotextiles. The reinforced base sections and the control sections (with unreinforced base) were paved with Superpave hot-mix asphalt. Base and subgrade materials were the same for all sections while the test sections had different asphalt and base layer thicknesses. Each section was instrumented with two pressure cells on top of the subgrade, six strain gages on the geotextile body, six H-bar strain gages at the bottom of the asphalt layer, two thermocouples and one Time Domain Reflectometer (TDR) sensor. The sections were loaded to 250,000 to 500,000 repetitions of an 80-kN single axle load of the accelerated pavement testing machine. The mechanistic response of each section was monitored and analyzed at selected number of wheel passes. Results indicate that properly selected and designed geotextile-reinforced bases improve pavement performance in term of rutting and reduced pressure at the top of the subgrade. Finite element (FE) models were developed and verified using results from the full-scale accelerated pavement tests. The calibrated model was used to investigate the effects of geotextile properties on the pavement responses. FE analysis shows that benefits of reinforcement are more evident when stiffer geotextile is used.
20

ASSESSMENT OF DETERIORATED CORRUGATED STEEL CULVERTS

MAI, VAN THIEN 31 January 2013 (has links)
The goal of this thesis is to develop more effective quantitative procedures to evaluate the stability of deteriorated metal culverts and a better understanding of the deteriorated culverts' behaviour through non-destructive testing, full scale experiments and numerical analyses. First, three design cases were examined using numerical analysis to study the effects of corrosion, burial depth and staged construction on the capacity of deteriorated steel culverts. Then, a method to measure the remaining wall thickness of two 1.8 m diameter corroded metal culverts using ultrasonic device was developed. Both culverts were then buried in the test pit at Queen's University and tested under nominal and working vehicle loads at 0.9m cover and 0.6m cover. The more heavily corroded structure (CSP1) was tested up to its ultimate limit state, inducing local bending across the crown, as well as local buckling of the remnants of the corrugated steel wall between perforations at the haunches. The results suggest that the single axle pads interact to influence the culvert's behaviour despite the shallow cover used in these experiments. CSP1 was able to carry the working load and did not fail until reaching 340 kN, which was equal to 90% of the fully factored load. The experiment suggests that less deteriorated metal culverts (as compared to CSP1) may have the required capacity. Two finite element packages, CANDE and ABAQUS, were used to perform the numerical investigation and the AASHTO and CHBDC approaches were then used to calculate the thrust force in the culverts. Although the numerical analysis produced conservative values for the thrust forces, it failed to capture the non-linear behaviour of both specimens in the experiments. Both the AASHTO and the CHBDC approaches produced unconservative thrust forces compared to experimental results while numerical analysis using Moore's spreading factor produced the most conservative results in terms of thrust. The analysis suggests that CANDE could be used to predict thrust forces in less deteriorated metal culverts. A procedure to assess the stability of deteriorated corrugated metal culverts based on quantitative data was developed using the numerical analysis and experimental results. / Thesis (Master, Civil Engineering) -- Queen's University, 2013-01-30 12:56:17.945

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