Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains xv, 141 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 139-141).

Thesis (M.C.E.)--University of Delaware, 2006. / Principal faculty advisor: Dennis R. Mertz, Dept. of Civil and Environmental Engineering. Includes bibliographical references.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed on Oct. 6, 2006). PDF text:xxiii, 306 p. : ill. ; 15.42Mb. UMI publication number: AAT 3213328. Includes bibliographical references. Also available in microfilm, microfiche and paper format.

Gusset plate connections are commonly used in steel truss bridges to connect individual members together at a node. Many of these bridges are classified as non-load-path-redundant bridges, meaning a failure of a single truss member or connection could lead to collapse. Current gusset plated design philosophy is based upon experimental work from simplified, small-scale connections which are seldom representative of bridge connections. This makes development of a refined methodology for conducting high-fidelity strength capacity evaluations for existing bridge connections a highly desirable goal. The primary goal of this research effort is to develop an analytical model capable of evaluating gusset plate stresses and ultimate strength limit states. A connection-level gusset connection model was developed in parallel with an experimental testing program at Oregon State University. Data was collected on elastic stress distributions and ultimate buckling capacity. The analytical model compared different bolt modeling techniques on their effectiveness in predicting buckling loads and stress distributions. Analytical tensile capacity was compared to the current bridge gusset plate design equations for block shear. Results from the elastic stress analysis showed no significant differences between the bolt modeling techniques examined, and moderate correlation between analytical and experimental values. Results from the analytical model predicted experimental buckling capacity within 10% for most of the bolt modeling techniques examined. Tensile capacity was within 7% of the calculated tensile nominal capacity for all bolt modeling techniques examined. A preliminary parametric study was conducted to investigate the effects of member flexural stiffness and length on gusset plate buckling capacity, and showed an increase in member length or decrease in member flexural stiffness resulted in diminished gusset plate buckling capacity.

In recent years there has been a constant search for better and more economical structures in the field of structural engineering. Within the past ten to twenty years this search has resulted in the introduction of two new structural systems: prestressed concrete and composite design. Each of these new construction methods has advantages and limitations. A new idea of combining these two structural systems into one could result in more economical structures particularly suited for long span bridges. The slab-and-stringer bridge is one of the most common types in highway construction. Such a bridge is composed of two principal load-carrying elements: the steel beams which transfer the loads in the direction along the bridge axis, and the concrete slab which distributes the loads in the transverse direction to the steel beams. If some appropriate mechanical device is used to connect the steel beams end concrete slab together, the concrete slab can act as a cover plate for the beams and assist the beams in carrying the load in the longitudinal direction. Such a structure is known as a Conventional Composite Structure. If such a structure is prestressed with high-strength steel cables, it acquires additional qualities. The principle of prestressing in steel structures is not used to overcome tensile deficiencies of the material, as ls the case for concrete, but to build opposing stresses into members in order to counteract the stresses caused by external forces. When favorable residual stresses have been induced in such structures they will be capable of carrying greater loads than their conventional counterpart. It is the objective of this thesis: (1) to investigate the physical properties of the materials used in prestressed composite structures, (2) to discuss the methods for construction, (3) to develop a usable design technique for simply supported and continuous beams, (4) to discuss the layout of prestressing cables in continuous prestressed composite beams, (5) to show the use of equations for selecting the steel beam cf the prestressed composite structure, and (6) to illustrate the design of prestressed composite structures with typical problems. / Master of Science

Weathering steel has been a primary construction material for bridges in the United States. Notches caused by corrosion are observed on the flange of steel I-beams. These notches reduce the cross section area of the structure and are threats to bridge safety. A606-04 Type 4 cold rolled weathering steel samples were studied in this thesis to understand the effect of notches that caused by corrosion. Weathering steel samples were in the shape of plates, which simulated flange of I-beams. The plate samples were notched across their surfaces by applying electrical current through an electrochemical circuit composed of an anode, a cathode and electrolyte. Sixteen samples were notched and cut into appropriate shape for fatigue testing. S-N (Stress-Number of cycles to failure) diagram established from fatigue data indicated that the fatigue strength decreased below AASHTO category B. Weibull analysis was also performed to understand the reliability distribution. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Thesis (M.S.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains xi, 188 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 111-115).

Thesis (M.C.E.)--University of Delaware, 2006. / Principal faculty advisor: Dennis R. Mertz, Dept. of Civil and Environmental Engineering. Includes bibliographical references.

The collapse of the I-35W Bridge in Minneapolis, MN on August 1, 2007 brought into question the design and inspection of gusset plates in steel truss bridges. The experimental tests performed in this research study the sway-buckling strength and behavior of large-scale steel gusset plates in an isolated truss connection. Parameters studied include plate thickness,combination member loading, initial out-of-plane imperfection, diagonal compression member out-of-plane flexural stiffness, corrosion, and alternative retrofits to increase lateral stiffness. The flexural stiffness of the diagonal compression member and retrofit designs were unique to the testing program. The variables monitored during testing include gusset plate surface stresses and strains, member axial strains, out-of-plane displacement of the gusset plate free edge, and buckling capacity. The results were compared with previously established design models for predicting buckling capacity of gusset plates which include the Whitmore effective width, the Modified-Thornton method, and the FHWA Load Rating Guidelines. A parametric finite element model was developed to determine the lateral stiffness of the gusset plate connection and the additional stiffness provided by the alternative retrofit options. The results showed interaction between the diagonal compression member and gusset plate occurs, which affects sway-buckling capacity. Combination of member loads showed evidence of detrimental effects on sway-buckling capacity. Corrosion of the gusset plates along the top edge of the bottom chord did not lead to significant reduction in sway-buckling capacity. The two retrofit designs showed increases in both lateral stiffness and buckling capacity as well as economic benefits over traditional retrofit methods. Comparison of the results to the current design guidelines showed that the current methods are conservative and do not accurately represent the true behavior of gusset plate connections. The research concludes with two proposed models for future use in design and retrofit of gusset plates. The first is a member-gusset plate interaction model based on a stepped column analogy that takes into account the effects of member flexural stiffness and gusset plate stiffness. The second is a general design guideline developed for retrofit of gusset plate connections dominated by sway-buckling behavior which uses a stiffness based approach to increase the capacity of gusset plate connections. / Graduation date: 2012

No description available.