ABSTRACT Two different implant impression materials viz. a polyether (Impregum ®) and a plaster (Plastogum ®) impression material were used and compared with respect to the accuracy with which abutment positions were reproduced from a stainless steel master model containing five implant analogues. Ten polyether impressions and ten plaster impressions were taken and cast in stone. The positions of the precision impression copings on the twenty impressions were measured using a Reflex Microscope. The positions of the implant analogues on the twenty casts were also measured and compared to the positions on the stainless steel master model. Statistical analysis indicated significant differences between the polyether impression and the plaster impression for full arch implant supported prostheses. The use of plaster resulted in smaller interabutment error but with less predictable variance in dimensions.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed March 2, 2010). PDF text: 1 v. (ca. 170 p.) : ill. ; 184 K. UMI publication number: AAT 3386553. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 228-241). Also available in electronic version.

Thesis (Ph. D.)--Washington State University, December 2006. / Includes bibliographical references (p. 148-156).

Thesis (Ph. D.)--Drexel University, 2006. / Includes abstract and vita. Includes bibliographical references (leaves 436-440).

Includes bibliographical references (p. 91-94).

Deep-corrugated steel culverts (with a corrugation wavelength of 400mm and amplitude of 150mm) can be used as an effective alternative for short-span bridges. Current design methods are typically based on two-dimensional finite element analysis. This thesis reports results from three-dimensional finite element analysis, with explicit modelling of the geometry of the corrugated plates (called corrugated analyses) and employing the orthotropic shell theory (called orthotropic analyses), for a specific box culvert having a 10 m span and 2.4 m rise. The results were compared to previously reported experimental data where a specific large span box culvert was tested under controlled laboratory conditions. The behaviour of the box culvert under small vertical displacement without any soil support was modelled to isolate the structure response. The box culvert was also modelled when subject to fully loaded dump truck, and when loaded using a tandem axle frame to service and ultimate loads. Both corrugated and orthotropic analyses successfully captured the response of the box culvert when backfilled and loaded using dump truck and axle frame loading. It was found that the orthotropic model overestimated the culvert stiffness at the ultimate limit state, but provided effective estimates of response up to the factored design loads. The corrugated model with geometric nonlinearity was required to capture the real behaviour of the corrugated plates up to the ultimate limit state. New insight into the failure mechanisms of the box culvert were provided by the corrugated model analysis. A parametric study was then performed for 86 different long-span box and arch culverts, examining live load spreading in the axial direction, number of loaded lanes, design truck position, culvert geometry, plate thickness, and the existence of pavement. The results were then compared to the moment and thrust equations in the 2006 Canadian Highway Bridge Design Code (CHBDC) to check the performance of the current design equations. CHBDC equations overestimated the earth and live load bending moments, and did not give the correct trend for different spans. CHBDC thrust equations were found to underestimate the earth and live load thrust values for arch culverts. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-04-26 15:33:45.103

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Experimental and analytical research was conducted to address the vibration properties of Long Span Deck Floor Systems (LSDFS). The research comprised three stages. In the first part, experimental in-situ tests were conducted on thirteen bays of buildings under construction. The natural frequencies and acceleration responses were captured to observe the vibration behavior of the tested floors. In the second part, a laboratory footbridge was constructed to determine the fixity level attained at the supports when a LSDFS is supported by CMU walls. For this purpose, the footbridge was tested with three support conditions, and a number of experiments were carried out to determine the dynamic properties of the structure. Static tests using both point and distributed loadings were conducted to measure the deflections at the footbridge midspan. The static test results were compared to the theoretical deflections for a pinned-end beam and a fixed-end beam. Dynamic tests using experimental modal analysis techniques were conducted to determine the natural frequencies and mode shapes of the structure. The measured fundamental natural frequency of the footbridge was compared to the frequencies calculated for a simply supported beam and a beam with fixed ends, to determine the degree of fixity attained in the connection between the LSDFS and the supporting walls. In the last part of the research, three analytical procedures to predict modal characteristics of long span deck floor systems are studied. Floor frequencies are calculated using finite element analyses. Two design guides for floor vibration analysis were used to calculate natural frequencies and response accelerations. The predicted results obtained from the analytical methods are compared to the experimental results to determine their accuracy. Recommendations for the use of the analytical methods are provided. / Master of Science

Master of Science / Department of Architectural Engineering / Kimberly W. Kramer / Trusses are an efficient way to span long distances with minimal material required. This report is a parametric study of the different design and construction aspects for a 300’-0” span, steel, Warren type truss. The study specifically examines the vertical loading on the truss, including components and cladding wind loading. The engineering variables investigated are panel point location, steel shape size and type, steel grade, member orientation, and connection design. Each of these aspects are studied independently with major results accounted for later in analysis. This allows for the most economical truss by reviewing each alternative possibly not commonly used in steel construction. However, trusses require special consideration in constructability compared to a common steel structure such as an office building. Because of this added complexity, constructability issues are also examined after all parametric studies are completed for engineering variables. Transportation regulations and restrictions, steel erecting (including the construction loading of the ASCE 37-02), and temporary structures are considered for the 300’-0” span steel truss. The results of the engineering design variables are documented showing the benefit of using W-Shape members with higher grades of steel in select members, and the rotation of members for truss stability and simplified connection detailing. Each of the multiple construction considerations are presented, providing the most recent information available at the time of this report.