Trafikverket förfogar över närmare 4000 järnvägsbroar i olika skick och ålder runt om i landet. Beståndet är i ständigt behov av underhåll och erfordrar kontinuerliga kontroller. Den här rapporten är utformad som en skadeutredning på en enkelspårig järnvägsbro söder om Solvarbo i Säter kommun. Järnvägsbron är i drift och här passerar över 10 000 tåg/år. Allt från snabbtåg till godståg. Bron är av typ balkbro, fritt upplagd över väg. Rapporten är gjord i samråd med företaget Reinertsen Sverige AB. En utredning av bron utfördes 2013 av Reinertsen Sverige AB i vilken beskrivs att ena landfästet kläms mot överbyggnaden till följd av rörelse. De skador som då noterades var att de rörliga lagren var kraftigt snedställda, överbyggnaden var i kontakt med grusskifte samt att en avsevärd uppsprickning av landfäste hade skett. Skadorna bedömdes påverka konstruktionens funktion och ansågs behöva en fortsatt utredning där brons rörelser och skador studeras mera för att kunna ta ställning till framtida åtgärder. Målet med detta arbete är att analysera hur bron har förändrats sedan upprättandet samt att besvara vad som kan ha föranlett förändringarna. Rapporten tas fram som underlag för att kunna ta ställning till framtida åtgärder enligt ovanstående. För att fastställa hur bron rört sig utfördes en inmätning med en totalstation. Därefter upprättades aktualiserade ritningar över bron som sedan jämfördes med befintliga originalritningarna. För att visa vad som kan föranlett förflyttningen gjordes en glidningskontroll med olika laster. Utöver det utfördes en kartläggning av skador på konstruktionen som sedan utvärderades. Jämförelsen visar en kraftig förflyttning av det östra landfästet mot det västra. Rörelsen av landfästet har gjort att de båda frontmurarna lutar i vertikalled.  Glidningskontrollen slår fast att det inte föreligger risk för glidning av enbart jordtryck men att det föreligger risk för glidning vid belastning av tåg samt bromskraft från tåg. På grund av slitage samt bristande underhåll har skador åsamkats på konstruktionen. De synliga skador som återfunnits på bron är sprickor, kalkutfällningar, snedställning av lager samt korrosion av lager och synlig armering. Det som kunde fastställas är hur bron har förflyttat sig i horisontal- och vertikalled och att en orsak till det östra landfästets förflyttning är de horisontella krafter som de passerande tågen för med sig. Genom att undersöka de skador som uppkommit på bron och jämföra dessa med de krav som Trafikverket har på sina broar kunde det fastställas att några av dessa skador beror på bristande underhåll. / The Swedish Transport Administration manage nearly 4,000 railway bridges in different condition and age around the country. These bridges is in constant need of maintenance and requires continuous inspections. This thesis is designed as a damage investigation on a single-track railway bridge south of Solvarbo in Säter municipality. The railway bridge is in operation and serves over 10,000 trains a year, everything from speed trains to freight trains. The bridge is built as a beam bridge, simply supported over a road. The report is made in consultation with the company Reinertsen Sweden AB. An investigation of the bridge was carried out in 2013 by Reinertsen Sweden AB, which describes that the abutments lean onto the superstructure due to motion. The damage noted was that the movable bearings are seriously tilted, the superstructure is in contact with the breast wall and several cracks were found on the abutment. These damages were considered to affect the function of the structure and found needing further investigation to consider possible future actions. The objective of this thesis is to analyze how the bridge has changed since it was built and to find what may be the underlying causes to these changes. The report is aimed to constitute a foundation and a decision basis for further measures. To determine how the bridge has moved a surveying with a total station was performed. Thereafter updated drawings of the bridge were established and later compared with the existing original drawings. To understand why the bridge has moved a sliding control was performed with different loads. In addition an inspection of structural damages was carried out and evaluated. Comparing the drawings showed a significant displacement of the eastern abutment towards the western. The movement of the abutment has made the two bearing walls tilt. The sliding control showed that there is no risk of sliding when only earth pressure is considered, but when loads of the trains are applied there is a risk of sliding. Wear of the bridge has caused several damages in the bridge structure. The visible damages found were cracks, efflorescence, bearing misalignment and corrosion of bearings and visible reinforcement. What could be determined was that the bridge has moved horizontally and vertically and one reason for the movement in the eastern abutment could be the horizontal forces brought by a passing train. By examining the damage caused to the bridge and compare them with the requirements of the Swedish Transport Administration it could be established that some of these damages have raised due to lack of maintenance.

[pt] A avaliação experimental de modelos de plasticidade incremental e a predição da vida à fadiga sobre cargas combinadas requer o uso de máquinas de testes multiaxiais. Neste trabalho é desenvolvida uma máquina tração-torção (MTT) para avaliar modelos de plasticidade incremental. Este sistema eletromecânico utiliza como atuadores principais dois motores de corrente contínua conectados a caixas de redução para gerar os carregamentos de tração axial e/ou torção. O projeto da MTT compreende a análise de sua integridade estrutural, seu dimensionamento, e o cálculo da vida à fadiga de seus principais componentes; o projeto e desenvolvimento de uma célula tração-torção (LTC - load torque cell); o desenvolvimento e implementação das técnicas de controle; e finalmente sua construção e avaliação. Uma técnica de controle PID por modos deslizantes (PID Sliding Mode control) foi especialmente desenvolvida para esta máquina, consistindo em aplicar um sinal de controle descontínuo que força o sistema a deslizar ao longo de uma superfície de convergência. Esta técnica de controle tem a capacidade de controlar continuamente a força axial e/ou o torque aplicado ao corpo de prova de maneira independente, o que permite gerar histórias de cargas não-proporcionais. Os métodos de controle são implementados em uma plataforma computacional em tempo real CompactRio. Deste modo, é possível gerar uma máquina de ensaios de fadiga multiaxial compacta, de fácil manuseio, que não precise de um sistema de controle complexo, e a um baixo custo. A máquina tração-torção foi projetada para atender a uma ampla gama de ensaios de fadiga multiaxial, com uma capacidade de força axial máxima de mais ou menos 200 kN e torque máximo de mais ou menos 1300 N.m. O desempenho da MTT foi avaliado experimentalmente através de ensaios de plasticidade incremental. Para tanto, foram usados corpos de prova de tração-torção para medir seus comportamentos sobre cargas multiaxiais. Ensaios de encruamento não-proporcional, ratcheting (fluência cíclica) multiaxial e ratcheting uniaxial foram realizados em corpos de prova de aço inox 316, aço 1020, alumínio 7075 e alumínio 6063 na MTT, assim como em uma máquina Instron de 100 kN. Um simulador de plasticidade incremental para carregamentos de tração-torção foi desenvolvido, incorporando o modelo de encruamento cinemático não-linear de Jiang-Sehitoglu, e o modelo incremental de encruamento não-proporcional de Tanaka. Os parâmetros do material foram calibrados a partir de ensaios experimentais, permitindo que as simulações fossem capazes de prever o comportamento do material sobre diferentes histórias de carregamento, assim como as taxas de encruamento não-proporcional e de ratcheting. Os experimentos e simulações confirmaram tanto a adequabilidade da MTT desenvolvida, quanto do simulador de plasticidade incremental implementado, baseado nos modelos não-lineares de Jiang-Sehitoglu e Tanaka. / [en] The experimental evaluation of incremental plasticity models and fatigue life prediction under combined loads requires the use of multiaxial testing machines. In this work, an axial-torsion machine (MTT) was developed to evaluate incremental plasticity models. This electromechanical system uses as a main actuators two DC motors connected to gearboxes to generate the axial and/or torsion loads. The design of axial-torsion machine comprises the analysis of its structural integrity, its dimensioning and fatigue life prediction its major components; the design and development of a load torque cell – LTC; the development and implementation of control techniques, and finally, its construction and its performance evaluation. A PID Sliding Model control technique has been specially developed for this machine, which consists in applying a discontinuous control signal that forces the system to slide along a surface convergence. This control technique has the ability to control the axial force and/or torsion applied to specimen test in an independent manner, which allows to generate a non-proportional loading histories. The control methods are implemented on a computing platform in real time CompactRio. Thus, it s possible to developed a compact multiaxial fatigue testing machine, easy to handle, which does not require a complex control system, and at a low cost. The tensiontorsion machine was designed to meet a wide range of multiaxial fatigue tests, with a maximum capacity of axial force of more or less 200 kN and torque of more or less 1300 N.m. The MTT performance was evaluated experimentally by incremental plasticity testing. For this purpose, tensile / torsion specimens were used to measure their behavior under multiaxial loads. Testing of non-proportional hardening, multiaxial ratcheting and uniaxial ratcheting (cyclic creep) were performed on specimens of 316 stainless steel, 1020 steel, 7075 aluminum and 6351T6 aluminum in the MTT, as well as a Instron Machine of more or less 100 kN. A simulator of incremental plasticity to tensile-torsion loads has been developed, incorporating the non-linear kinematic hardening model of Jiang-Sehitoglu, and non-proportional hardening model of Tanaka. The material parameters were calibrated using experimental tests, allowing the simulations to predict the material behavior under different load histories, as well as rates of non-proportional hardening and ratcheting. The experiments and simulations confirmed both the suitability of the developed MTT, as well as the simulator of incremental plasticity implemented, based on non-linear models of Jiang-Sehitoglu and Tanaka.