Integral bridges (IBs) are defined as a class of rigid frame bridges with a single row of piles at the abutments cast monolithically with the superstructure. In the last decade, IBs have become very popular in North America and Europe as they provide many economical and functional advantages. However, standard design methods for IBs have not been established yet. Therefore, most bridge engineers depend on the knowledge acquired from performance of previously constructed IBs and the design codes developed for conventional jointed bridges to design these types of bridges. This include the live load distribution factors used to account for the effect of truck loads on bridge components in the design as well as issues related to the seismic design of such bridges. Accordingly in this study issues related to live load effects as well as seismic effects on IB components are addressed in two separate parts. In the first part of this study, live load distribution formulae for IB components are developed and verified. For this purpose, numerous there dimensional and corresponding two dimensional finite element models (FEMs) of IBs are built and analyzed under live load. The results from the analyses of two and three dimensional FEMs are then used to calculate the live load distribution factors (LLDFs) for the components of IBs (girders, abutments and piles) as a function of some substructure, superstructure and soil properties. Then, live load distribution formulae for the determination of LLDFs are developed to estimate to the live load moments and shears in the girders, abutments and piles of IBs. It is observed that the developed formulae yield a reasonably good estimate of live load effects in IB girders, abutments and piles. In the second part of this study, seismic performance of IBs in comparison to that of conventional bridges is studied. In addition, the effect of several structural and geotechnical parameters on the performance of IBs is assessed. For this purpose, three existing IBs and conventional bridges with similar properties are considered. FEMs of these IBs are built to perform nonlinear time history analyses of these bridges. The analyses results revealed that IBs have a better overall seismic performance compared to that of conventional bridges. Moreover, IBs with thick, stub abutments supported by steel H piles oriented to bend about their strong axis driven in loose to medium dense sand are observed to have better seismic performance. The level of backfill compaction is found to have no influence on the seismic performance of IBs.

In this thesis, the influence of soil-structure interaction (SSI) of end-frame bridges for high-speed railways was studied. Impedance functions, representing the SSI, was calculated and analyzed. The impedance functions were applied to end-frame bridge models which were analyzed for use in HSR. A new high-speed railway link is currently being planned in Sweden by the Swedish Transport Administration (Trafikverket). \textit{Ostl\"{a}nken} is planned to run between the cities of Stockholm and Link\"{o}ping with a maximum speed limit of 320km/h. As high-speed traffic induces high dynamic impact on bridges, dynamic analysis to ensure safety and passenger comfort is needed according to Eurocode. Thus, there is a demand of dynamically safe bridges that are also cost-effective. One cost-effective bridge is the soil integrated end-frame bridge, however, there are no design advice in Eurocode today on how to take SSI into consideration. The aim of the thesis has therefore been to investigate if the influence of SSI on end-frame bridges for HSR. This thesis was executed using the frequency domain approach to solve dynamic problems in finite element software. Furthermore, impedance functions have been obtained representing the SSI. Impedance functions take dynamic stiffness and dynamic damping into consideration where the damping consists of two parts: material damping and radiation damping due to energy dissipation in the form of elastic waves. To limit the model size, an absorbing region (AR) was used to mitigate waves originating from the source. The accuracy of impedance functions is dependent on several parameters and demands a great computational capacity to reach, mostly governed by the radiation condition. A parameter study of impedance functions was conducted, including parameters such as geometry, modulus of soil and detail levels. The impedance functions were then attached to bridge models on which trains modelled as moving point loads were applied. Envelopes of the acceleration and displacements have been presented and analyzed. Shear strain checks were made in order to verify the assumption of linear-elastic material behavior of the embankment. By using SSI in form of impedance functions attached to bridge models, numerical results show a great reduction of vibrations in models. The study suggests that a large end-frame, either long or high or both, may reduce acceleration as well as displacements. A stiffer embankment material may further reduce vibrations. Shear strain checks confirm that the assumption of linear-elastic soil behavior was true. / I det här exjobbet har påverkan av jord-struktur interaktion (soil-structure interaction - SSI) av ändskärmsbroar för höghastighetsbana blivit studerat. Impedansfunktioner som representerar SSI har beräknats och analyserats. Impdansfunktionerna har sedan applicerats på bromodeller och analyserats för höghastighetstrafik. Sveriges första höghastighetsbana håller just nu på att planeras av Trafikverket. Ostlänken kommer att bli den första delen och är planerad att gå från Stockholm till Linköping med en högsta hastighet av 320 km/h. Då höghastighetstrafik introducerar stor dynamisk på verkan på broar behövs dynamisk analys genomföras enligt Eurocode för att kunna säkerställa broarnas säkerhet och komfortkrav. Därför finns idag ett behov av dynamiskt säkra broar som också är kostnadseffektiva. En typ av kostnadseffektiv bro är den med jord integrerade ändskärmsbron. I dagens Eurocode finns dock inga konstruktionsråd vad gäller jord-struktur interaktion av ändskärmarna. Målet med detta examensarbete har därför varit att undersöka påverkan av SSI och besluta huruvida användandet av ändskärmsbron på höghastighetsbanor är legitimerat, eller om den ska undvikas. Det här examensarbetet har utgått från att lösa dynamiska problem i frekvensdomänen med hjälp av FEM. Impedansfunktioner som representerar jord-struktur interaktionen har tagits fram. Impedansfunktioner tar dels hänsyn till dynamisk styvhet och dels dynamisk dämpning. Den dynamiska dämpningen består av två delar; den första är materialdämpning och den andra är vågdämpning där energi dissiperar i vågform. För att begränsa FE modellens storlek har en absorbing region tillämpats för att absorbera vågorna vid randen. Impedansfunktionernas konvergens beror på flertalet parametrar och kräver en hög datakapacitet för att fås, mestadels beroende av radiatorvillkoret. En parameterstudie utfördes för att kunna analysera sensitiviteten hos impedansfunktionerna. Vidare applicerades dessa impedansfunktioner på skal- och balk-bromodeller på vilka HSLM laster påfördes. Skjuvtöjningskontroller gjordes för att verifiera att antagandet om linjärelastiskt materialbeteende var korrekt. Genom att ta hänsyn till SSI i form av impedansfunktioner tyder numeriska resultat på att vibrationer kan reduceras i hög grad. Envelopper visar att en stor ändskärm, antingen lång, hög eller bådadera, kan reducera accelerationer liksom förskjutningar. En styvare bank kan ytterligare reducera vibrationer.