Short span bridges are commonly used throughout the United States to span small waterways and highway overpasses. New technologies in the civil engineering industry have aided in the creation of many unique designs of these short span highway bridges in efforts to decrease construction cost, decrease maintenance costs, increase efficiency, increase constructability, and increase safety. Three innovative systems, the Integral Abutment Bridge, “Bridge-in-a-Backpack”, and the Folded Plate Girder bridge will be analyzed to study how the bridges behave under various types of loading. Detailed finite element models were created for integral abutment bridges of varying geometry. These models are used to study how the live load distribution transversely across the bridge is effected by varying geometric properties and varying modeling techniques. These models will also be used to determine live load distribution factors for the integral abutment bridges and compare them to current American Association of State Highway and Transportation Officials specifications. The “Bridge-in-a-Backpack” and the Folded Plate Girder bridges were each constructed with a variety of instruments to measure the bridge movements. Readings from these instruments are used to determine the bridge response under various loading conditions. Bridges were analyzed during their construction process, during static live load testing, and during long term seasonal changes. The results from these studies will aid in the refinement of these innovative designs.

Bridges without expansion joints are called "integral bridges." Eliminating joints from bridges crates concerns for the piles and the abutments of integral bridges because the abutments and the piles are subjected to temperature-induced cyclic lateral loads. As temperatures change daily and seasonally, the lengths of integral bridges increase and decrease, pushing the abutment against the approach fill and pulling it away. As a result the bridge superstructure, the abutment, the approach fill, the foundation piles and the foundation soil are all subjected to cyclic loading, and understanding their interactions is important for effective design and satisfactory performance of integral bridges. The ability of piles to accommodate lateral displacements is a significant factor in determining the maximum possible length of integral bridges. In order to build longer integral bridges, pile stresses should be kept low. This research project investigated the complex interactions that take place between the structural components of the integral bridge and the soil through experimental and analytical studies. A literature review was conducted to gain insight into the integral bridge/soil interactions, and to synthesize the information available about the cyclic loading damage to piles of integral bridges. The ability of the piles and the abutments to withstand cyclic loads was investigated by conducting large-scale cyclic load tests. Three pile types and three semi-integral abutments were tested in the laboratory. Experiments simulated 75 years of bridge life for each specimen by applying over 27,000 displacement cycles. Numerical analyses were conducted to investigate the interactions among the abutment, the approach fill, the foundation soil, and the piles. The original VDOT semi-integral abutment hinge experienced shear key failure as observed in two large-scale laboratory tests. The revised hinge detail did not exhibit any sign of damage. Both abutments tolerated 75-year worth of displacement cycles without any appreciable change in their behavior. Semi-integral abutments are recommended for longer integral bridges because they can reduce pile stresses. As the need to build longer integral bridges grows, the role of the semi-integral abutments is expected to become more important. The data from the experimental program indicates that steel H-piles are the best pile type for support of integral abutment bridges. Concrete piles are not recommended because under repeated lateral loads, tension cracks progressively worsen and significantly reduce vertical load carrying capacity of these piles. Pipe piles have high flexural stiffness, which results in an undesired condition for the shear stresses in the abutment. For this reason, stiff pipe piles are not recommended for support of integral bridges. Numerical analyses indicate that the interactions between the approach fill and the foundation soils create favorable conditions for stresses in piles supporting integral bridges. Because of these interactions, the foundation soil acts as if it were softer, resulting in reduction in pile stresses compared to a single pile in the same soil without the approach fill above it. / Ph. D.

The advantages of Integral Abutment Bridges (IABs) include reduced maintenance costs and increased useful life spans. However, comprehensive and practical analysis tools for design of IABs have not been developed to account for the impacts of thermal displacements on abutment and foundation components, including the components of mechanically stabilized earth (MSE) walls that are often used around the abutment piling. During this research, over 65 three-dimensional numerical analyses were performed to investigate and quantify how different structural and geotechnical bridge components behave during thermal expansion and contraction of the bridge deck. In addition, separate three-dimensional numerical models were developed to evaluate the usefulness of corrugated steel pipes around the abutment piles. The results of this research quantify the influence of design parameter variations on the effects of thermal displacement on system components, and thus provide guidelines for IAB design, where none had existed before. One of the findings is that corrugated steel pipes around abutment piles are not necessary. One of the most important products of this research is an easy-to-use Excel spreadsheet, named IAB v2, that not only quantifies the impact of thermal displacement in the longitudinal direction, but also in the transverse direction when the abutment wall is at a skew angle to the bridge alignment. The spreadsheet accommodates seven different pile sizes, which can be oriented in weak or strong directions, with variable offset of the abutment from the MSE wall and for variable skew angles. The spreadsheet calculates the increment of displacements, forces, moments, and pressures on systems components due to thermal displacement of IABs. / Ph. D.

The term ???Integral Abutment Bridges??? is used broadly all over the world these days. While the expansion joints used in bridges were once a scientifically proved cure to the problem of natural expansion and contraction, there are the excessive maintenance costs being accumulated annually due to the deterioration of essential functions from deicing chemicals and debris. This drawback triggered the advent of Integral Abutment Bridges. The performance of Integral Abutment Bridges at almost no extra costs in seasonal and daily cyclic contraction and expansion can be assessed as a monumental landmark of civil engineering technologies with respect to the massive budget reductions. However, since Integral Abutment Bridges are destined to expand or contract under the laws of nature, the bridge design became more complicated and sophisticated in order to complement the removal of expansion joints. That is why numerous researchers are attracted to Integral Abutment Bridges with deep interests. Accordingly, in designing the piled abutments of Integral bridges, it is essential to precisely predict the bridge???s behavior in advance. Researchers have been broadly carried out during the last several decades on the behavior of piled bridge abutments. However, most of the studies have been analyzed with focus on structural elements or soils, respectively for the static and dynamic loads such as thermal variations and earthquake loads. This presented research developed 3D numerical models with 3 m, 4 m, 5 m, 6 m, 7 m, and 8 m-tall abutments in the bridge using the finite element analysis software MIDAS CIVIL that simulate the behaviors of Integral Abutment Bridges to study the soil-structure interaction mechanism. In addition, this work evaluated and validated the suitability to the limit of the abutment height in Ontario???s recommendations for Integral Abutment Bridges by a parametric study under the combined static loading conditions. In order to be a balanced research in terms of a multidisciplinary study, this research analyzed key facts and issues related to soil-structure interaction mechanisms with both structural and geotechnical concerns. Moreover, the study established an explanatory diagram on soil-structure interaction mechanisms by cyclic thermal movements in Integral Abutment Bridges.

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