A full-depth precast concrete deck system presents several safety, timeline, and cost benefits to the process of constructing a bridge, however the relevant professional codes do not provide dependable design models due to the limited amount of research conducted on the subject. One area lacking design direction is the development of a shear connection between the full-depth precast deck and a precast concrete girder via a pocket-haunch-connector system. Push-off tests are performed to investigate the effects of various pre- and post-installed shear connectors, haunch height, surface roughness, grouping effects, and grout composition as compared to cast-in-place specimens. The experimental results are presented along with a method for normalizing the variations of results by connection yield strength. This method is used to evaluate each connector type and connection parameter investigated. Ensuring sufficient shear reinforcement within the beam near the shear connector anchorage is found to be a vital aspect of holistic design. A simplified design procedure is outlined, the design connection forcedisplacement behavior is shown, and an example problem is solved. Recommendations for additions and modifications to current code and practice are prescribed.

Master of Science / Department of Architectural Engineering / Kimberly W. Kramer / In structural steel connection design, simple shear connections are one of the most common connection types utilized. The industry, especially from the side of the engineer, tends to lean toward using Double Clip Angle Connections as the default standard for simple shear connections. A double clip angle connection is a connection consisting of two angles transferring the shear forces from one member to the next either through bolts or welds. The design of Double Clip Angle Connections is efficient and the connections themselves are easy to fabricate. However, benefits to utilizing other types of shear connections exist. Many of these benefits are seen in the fabrication shop or during erection and construction. This is especially true of single shear plate or shear tab connections when applied to open structure design. Shear tab connections consist of a single plate that transfers the shear forces from one member to the next with bolts or with welds. The design of shear tab connections can be a more involved process than the design of double clip angles. Sometimes the shear plate or shear tab has to be longer than is typical. This is called an extended shear plate connection. These extended shear plates can bring other variables into the design that typically don’t occur with Double Clip Angle Connections such as bending of the plate or the need for multiple bolt columns. However, with proper planning and detailing, the benefits and savings experienced in the fabrication or construction phase may outweigh what can be seen as a more laborious design task. The purpose of this report is to identify the possible benefits achieved in using each of these connections, highlight the differences in the design approach for each, and use a study model to compare the outcome of using one connection over another in the design of a typical open structure. Double clip angles are typically the most efficient approach when speed of design and simplicity of fabrication are the desired outcomes. However, shear plate or shear tab connections have the potential to provide safer erection alternatives and materials savings if used in appropriate ways and with the right applications.

No description available.

Yes / For composite beams with low degrees of shear connection, additional deflections occur due to slip in the shear connectors, which can be significant for beams with low degrees of shear connection. A design formula is presented for the effective stiffness of composite beams taking account of the stiffness of the shear connectors, which is compared to measured deflections of 6 symmetric beams and an 11m span composite beam of asymmetric profile. It is shown that the comparison is good when using a shear connector stiffness of 70 kN/mm for single shear connectors and 100 kN/mm for pairs of shear connectors per deck rib. Results of push tests on a range of deck profiles confirm these initial elastic stiffnesses. To ensure that the slip at the serviceability limit state does not lead to permanent deformations of the beam, it is proposed that the minimum degree of shear connection should not fall below 30% for un-propped beams and 40% for propped beams of symmetric cross-section. / European Commission

"The fire resistance of structural building elements has become an increasing concern after the terrorist attacks on September 11th, 2001. This concern has pushed for changes in the building codes and standards to incorporate a performance-based approach to design. Performance-based design is a process where fire safety solutions are determined using a representation of the actual fire stages that may occur in a structure during a fire event. The American Institute of Steel Construction (AISC) has added Appendix 4 in the Specification for Structural Steel Buildings to the current edition of the Steel Construction Manual to provide engineers with guidance in designing steel structures and components for fire conditions. The performance-based approach outlined in Appendix 4 is designed to prevent loss of life, structural collapse, and the outbreak of fires through elimination of ignition sources. Adopting this approach, requires structural engineers to have a better understanding of the behavior of steel connections under fire conditions as well as the tools, techniques and judgment for analysis. The focus of this thesis is to study the strength behavior of steel connections under fire conditions with the assistance of the finite element software, ALGOR. Connections of varying thickness and bolt patterns are constructed using the ALGOR pre-processing software. A time-temperature fire curve is combined with external loads, applied to the models and then analyzed in the program. Stress-strain diagrams are created using the results and yield loads are determined for the various connections at normal and elevated temperatures. These yield loads are compared to values found from a mathematical analysis of the limit state equations in Chapter J of the Specifications. The elevated models are created with temperature-dependent material properties, therefore the yield loads are associated with critical temperatures within the connection models. It is found that the capacity and governing temperature of the connections is determined by the limit state of bearing at the bolt hole. At elevated temperatures, the finite element analysis produces capacities significantly lower than the analysis at normal temperatures. "

This project involves a failure analysis of the internal structural collapse that occurred in World Trade Center 5 (WTC 5) due to fire exposure alone on September 11, 2001. It is hypothesized that the steel column-tree assembly failed during the heating phase of the fire. The results of this research have serious and far-reaching implications, for this method of construction is utilized in approximately 20,000 existing buildings and continues to be very popular. Catastrophic failure during the heating phase of a fire would endanger the lives of firefighters and building occupants undergoing extended egress times (e.g., high-rise buildings), or relying upon defend-in-place strategies (e.g., hospitals). Computer software was used to reconstruct the fire event and predict the structural performance of the assembly when exposed to the fire. Results from a finite element, thermal-stress model confirms this hypothesis, for it is concluded that the catastrophic, progressive structural collapse occurred approximately 2 hours into the fire exposure.

Neste trabalho avaliou-se o comportamento estrutural do sistema misto madeira-concreto para tabuleiros de pontes, com ênfase na análise dinâmica dos conectores de cisalhamento, para dois tipos de conectores: \"vertical\" e em \"X\". Foram efetuadas duas principais abordagens, numérica e experimental, além de um amplo levantamento teórico sobre o tema com base na literatura disponível. Os ensaios experimentais foram realizados em corpos-de-prova de madeira como também em corpos-de-prova mistos e vigas mistas de madeira-concreto. Todos os corpos-de-prova e vigas foram submetidos a solicitações estáticas e dinâmicas, considerando-se os diversos materiais envolvidos na ligação. A análise numérica dos sistemas mistos foi efetuada com base no método dos elementos finitos, a partir da utilização do software ANSYS. Os resultados experimentais mostraram que ambos os sistemas de conexão perderam efetivamente rigidez para um total de 1 x \'10 POT.6\' ciclos de carga aplicados, sendo a maior parcela desta perda verificada para os ciclos iniciais. Além disso, o sistema de conexão \"vertical\" apresentou maior facilidade de execução quando comparado com o sistema de conexão em \"X\". A partir dos resultados numéricos constatou-se que a perda de rigidez ocorreu devido ao acúmulo do dano localizado nos materiais, nas regiões dos conectores. Os resultados numéricos mostraram uma boa concordância com os resultados experimentais. Para finalizar, foram propostos os valores dos níveis máximos e mínimos de carga cíclica, como também da frequência de excitação a serem utilizados nos ensaios dinâmicos para a verificação da rigidez dos sistemas mistos de conexão. / In this work was evaluated the structural behavior of log-concrete composite deck bridge system, with emphasis in the dynamic analysis of the shear connectors using two types of connectors: \"vertical\" and \"X\". Two main approaches were considered, numeric and experimental, besides a wide theoretical study about the theme with base in the available literature. The experimental studies were accomplished in specimens of wood, wood-concrete specimens and wood-concrete beams. All of the specimens and beams were subjected to static and dynamic loads considering several materials in the composed connection system. The numeric analyze of the composed systems was made with base in the method of the finite elements using the software ANSYS. The experimental results showed that both connection systems reduced stiffness really for 1 x \'10 POT.6\' applied load cycles, and the largest portion of this reduction happens in the initial cycles. Besides, the system of \"vertical\" connection presented larger execution easiness when compared with the system \"X\" connection. The numeric results showed that the reduced stiffness of the connection systems happened due to the accumulation of the located damage of the materials in the areas of the connectors. The numeric and experimental results comparison showed a good agreement. It was proposed values for the maximum and minimum levels of cyclical load, as well as for the frequency to be used in the dynamic tests for the verification of the reduced stiffness of the composite system of connection.

Neste trabalho avaliou-se o comportamento estrutural do sistema misto madeira-concreto para tabuleiros de pontes, com ênfase na análise dinâmica dos conectores de cisalhamento, para dois tipos de conectores: \"vertical\" e em \"X\". Foram efetuadas duas principais abordagens, numérica e experimental, além de um amplo levantamento teórico sobre o tema com base na literatura disponível. Os ensaios experimentais foram realizados em corpos-de-prova de madeira como também em corpos-de-prova mistos e vigas mistas de madeira-concreto. Todos os corpos-de-prova e vigas foram submetidos a solicitações estáticas e dinâmicas, considerando-se os diversos materiais envolvidos na ligação. A análise numérica dos sistemas mistos foi efetuada com base no método dos elementos finitos, a partir da utilização do software ANSYS. Os resultados experimentais mostraram que ambos os sistemas de conexão perderam efetivamente rigidez para um total de 1 x \'10 POT.6\' ciclos de carga aplicados, sendo a maior parcela desta perda verificada para os ciclos iniciais. Além disso, o sistema de conexão \"vertical\" apresentou maior facilidade de execução quando comparado com o sistema de conexão em \"X\". A partir dos resultados numéricos constatou-se que a perda de rigidez ocorreu devido ao acúmulo do dano localizado nos materiais, nas regiões dos conectores. Os resultados numéricos mostraram uma boa concordância com os resultados experimentais. Para finalizar, foram propostos os valores dos níveis máximos e mínimos de carga cíclica, como também da frequência de excitação a serem utilizados nos ensaios dinâmicos para a verificação da rigidez dos sistemas mistos de conexão. / In this work was evaluated the structural behavior of log-concrete composite deck bridge system, with emphasis in the dynamic analysis of the shear connectors using two types of connectors: \"vertical\" and \"X\". Two main approaches were considered, numeric and experimental, besides a wide theoretical study about the theme with base in the available literature. The experimental studies were accomplished in specimens of wood, wood-concrete specimens and wood-concrete beams. All of the specimens and beams were subjected to static and dynamic loads considering several materials in the composed connection system. The numeric analyze of the composed systems was made with base in the method of the finite elements using the software ANSYS. The experimental results showed that both connection systems reduced stiffness really for 1 x \'10 POT.6\' applied load cycles, and the largest portion of this reduction happens in the initial cycles. Besides, the system of \"vertical\" connection presented larger execution easiness when compared with the system \"X\" connection. The numeric results showed that the reduced stiffness of the connection systems happened due to the accumulation of the located damage of the materials in the areas of the connectors. The numeric and experimental results comparison showed a good agreement. It was proposed values for the maximum and minimum levels of cyclical load, as well as for the frequency to be used in the dynamic tests for the verification of the reduced stiffness of the composite system of connection.