The Extradosed Prestressed Bridge represents a relatively new bridge type. The first of this type bridge was constructed in Japan in 1994, and Japan has since built at least 29 examples of this bridge type. Throughout the rest of the world, another 34 of this bridge type have been built, with most countries having only one, or at most a few, examples. A broader application of this bridge type has been hampered by lack of design information and in particular lack design criteria for the stay cables. The purpose of this dissertation is to progress the understanding and application of this bridge type by providing (1) a summary and discussion of extradosed bridges constructed worldwide, (2) an assessment and recommendations on proportioning parameters, characteristics and features of extradosed prestressed bridges, and (3) a contribution of a new design approach for the stay-cable design for extradosed prestressed bridges. Also presented is an application of the above to a real-world prototype design to assess and comment on the application of the recommended proportioning parameters, characteristics, features and the new approach to stay cable design criteria.

The main purpose of this study was to investigate and implement a repair design for corrosion damaged bridge bents in order to resist lateral loading, such as wind loads or ship impact. Using the results from a one-third scale bridge bent constructed and tested for a previous study, non-linear modeling was used to simulate the same corrosion damage and load response. The principle variable considered was damage, represented as a percent of effective area loss of prestressing steel within a designated damage zone along the length of piles. Other influencing variables included: prestress transfer length, localized loss in prestress due to corrosion damage, prestress force, and concrete modulus of elasticity. Upon successful convergence of measured and modeled results, carbon fiber repair schemes were then modeled to restore bents to their full capacity. Suitable repairs were judged on the basis of restoration of capacity of the entire pile bent and the interaction diagrams of the individual piles. Results of the modeled repairs suggested that a single layer of a commercially available unidirectional carbon fiber would be sufficient when aligned longitudinally. No benefit from accompanying transverse fibers were considered although such a repair was suggested by the study findings. Analysis indicated that longitudinally bonded carbon fiber reinforced polymer (CFRP) to bridge piles increases a bent’s ability to resist bending moment due to lateral loading at the cap. However, additional capacity to plastic region of the response curve indicated larger capacity gains than by gains to elastic regions.

This diploma thesis deals with problem of design and calculation of membrane structure. Design proces of light and airy structure was demonstrated on conical shaped roof in the finite element analysis program RFEM. The structure was loaded in the virtual wind tunnel in the program RWIND. Results were compared with the values given in the literature. A comprehensive guide for the design of membrane structures has been created. Subsequently, the influence of design stages on the internal forces was demonstrated. Membrane structures are very sensitive to construction stages, because it is not possible to prestress all membrane surfaces at once. Program by DLUBAL software s.r.o. was used for form-finding analysis during construction stages.

This document describes the design of the roof structure for the dimensions of the rink. It was designed and evaluated three roofing solutions – steel truss structure, concrete arch with external prestress and prestress truss roof girder with concrete roof panel. One option was selected – prestress truss girder. This variant has been further developed. In the beginning was drafted several proposals geometry respecting the demands on the type of construction. Within the static calculation was created a mathematical model of the structure of the program Scia Engineer. Using this model were obtained values needed for the assessment of individual elements of construction and design assessment as a whole for the ultimate limit state and usability. According to the proposed geometry and opinions parts of the structure was drawing documentation structure as a whole and individual parts of the structure solved in this thesis. The last proposal was visualized structures together with the phases of the construction by program ArchiCAD and rendered by program Artlantis.

This diploma thesis involves design and assessment of the supporting elements of a two-storey family house ceiling construction. The slab components are pairs of beams and translations. I have choose two variants of solution for a long span elements. The first variant includes reinforced concrete elements only and in the second one prestress is used for beams, because of reducing construction height requirements. The basic model was evaluate by the calculation program Scia Engineer 2013, so I made 2D model of a slab in the program and joined 1D elements to the slab like a ribs. Selected prestress reduces a construction height, so it matches the desired appearance.

Diploma thesis is focused on design of road bridge bearing structure over road in Jihlava. The construction is girder with 3 fields beard by local supports. Calculations were made in the program called Scia Engineer. Appraisals were made by hand.

The ultimate shear capacity of prestressed concrete beams is difficult to predict accurately, especially after being in service for an extended period of time. The Utah Department of Transportation asked researchers at Utah State University to experimentally determine the existing shear capacity of 41-year-old prestressed, decommissioned concrete bridge girders and then provide recommendations on how to increase that ultimate shear capacity. This thesis presents the research findings that relate to the existing shear capacity of the prestressed concrete girders. Eight AASHTO Type II bridge girders were tested up to failure by applying external loads near the supports to determine their ultimate shear capacities. The measured results were then compared to calculated values obtained using the AASHTO LRFD bridge design code, and the ACI 318-08 design code. Prestress losses were also measured by means of a cracking test and then compared to values calculated according to the AASHTO prestress loss equations. Both the ultimate shear capacities and the residual prestress forces were used to evaluate the girders after being in service for more than 40 years.

The Varina-Enon Bridge is a cable-stayed, precast, segmental, post-tensioned box girder bridge located in Richmond, Virginia. Inspectors noticed flexural cracking in July of 2012 that prompted concerns regarding long-term prestress losses in the structure. Prestress losses could impact the future performance, serviceability, and flexural strength of the bridge. Accurately quantifying prestress losses is critical for understanding and maintaining the structure during its remaining service life. Long-term prestress losses are estimated in the Varina-Enon Bridge using two methods. The first utilizes a time-dependent staged-construction analysis in a finite element model of the full structure to obtain predicted prestress losses using the CEB-FIP '90 code expressions for creep and shrinkage. The second method involves collecting data from instrumentation installed in the bridge that is used to back-calculate the effective prestress force. The prestress losses predicted by the finite element model were 44.9 ksi in Span 5, 47.8 ksi in Span 6, and 45.3 ksi in Span 9. The prestress losses estimated from field data were 50.0 ksi in Span 5, 48.0 ksi in Span 6, and 46.7 ksi in Span 9. The field data estimates were consistently greater than the finite element model predictions, but the discrepancies are relatively small. Therefore, the methods used to estimate the effective prestress from field data are validated. In addition, long-term prestress losses in the Varina-Enon Bridge are not significantly greater than expected. / Master of Science / Post-tensioned concrete uses stressed steel strands to apply a precompression force to concrete structures. This popular building technology can be used to create lighter, stiffer structures. Over time, the steel strands experience a reduction in force known as prestress losses. Accurately quantifying prestress losses is critical for understanding and maintaining a structure during its remaining service life. The Varina-Enon Bridge is a cable-stayed, prestressed box girder bridge located in Richmond, Virginia. Inspectors noticed cracking in July of 2012 that prompted concerns regarding long-term prestress losses in the structure. Prestress losses were estimated using two methods. The first method utilized a computer model of the full bridge. The second method used data from sensors installed on the bridge to back calculate prestress losses. It was found that the prestress losses estimated from field data were slightly greater than, but closely aligned with, the computer model results. Therefore, it was concluded that the Varina-Enon Bridge has not experienced significantly more prestress losses than expected.

Cell modulus and prestress are important determinants of cell behavior. This study creates new software tools to compute the modulus and prestress distribution within a living cell. As input, we have a sequence of images of a cell plated on a substrate with fluorescently labeled fibronectin dots. The cell generates focal adhesions with the dots and thus deforms the substrate. A sequence of images of the cell and the fibronectin dots shows their deformation. We tested three different ways to track the movement of the fluorescent fibronectin dots. We demonstrated the accuracy and the adaptability of each method on a sequence of test images with a rigid movement. We found the best method for dot tracking is a combination of successive dot identification and digital image correlation. The dot deformation provides a measure of traction forces acting on the cell. From traction forces thus inferred, we use FEM to compute the stress distribution within a cell. We consider two approaches. The first is based on the assumption that the cell has homogeneous elastic properties. This is straightforward and requires only the cell being meshed and the linear elasticity problem solved on that mesh. Second, we relaxed the homogeneity assumption. We used previously published correlations between prestress and modulus to iteratively update the modulus and prestress distributions within the cell. A novel feature of this work is the implicit reconstruction of the modulus distribution without a measured displacement field, and the reconstruction of the prestress distribution accounting for intracellular inhomogeneity.

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