In Europe, the prices of natural gas and electricity reached an all-time high during 2022. An approach tomitigate these high prices is to expand the district heating systems in urban areas, this will reduceelectric load as well as to increase the power production in combined heat and power plants. Districtheating has been the dominant heat supply technology in urban areas in Sweden since the 1980s.However, as the number of low energy buildings are increasing, district heating distribution losses mustbe reduced to ensure cost-efficient consumer demand supply. This has led to the idea of the 4th-generation district heating which is characterized by low distribution temperatures.The aim of this study is to simulate low temperature distribution systems in a planned future city districtusing a Python based simulation tool and compare the results with a conventional system. Threedifferent types of low temperature distribution systems are investigated: 1) domestic hot water andspace heating separated, 2) apartment heat exchangers, 3) a cascading low temperature system.Focus is on simulating the distribution losses, distribution temperature and mass flow in the area, butthe scope of the analysis also includes an investigation of the effect of lower return temperatures to thecombine heat and power plant. The result indicate which type of system is most beneficial to implementin this specific area.With regards of distribution losses and temperature drop performs the low temperature distributionsystem with apartment heat exchangers better than the cascading system and the system withdomestic hot water and space heating separated. The mass flow is highly dependent of the temperaturedemand in the heating systems in the buildings and is higher for all low temperature distributionsystems compared to a conventional system.

Over the last few decades, evaluating the performance of existing structures has become increasingly important, particularly as the number of bridges reaching their design life continues to rise. As a result, there is a growing need for effective and accurate procedures to guide the assessment of the current structures' capacity and safety levels to implement appropriate maintenance and rehabilitation strategies. Evaluating a structure's performance involves assessing its ability to carry loads, resist external forces, and maintain its functionality over time. This is a complex process that requires a deep understanding of the structure's behavior, as well as knowledge of the environmental conditions it is subjected to. In recent years, technological advances and an increased understanding of reliability concepts have allowed for the development of more sophisticated tools and methods for structural evaluation. Thus, engineers and researchers can obtain more accurate and reliable data about a structure's performance, which can inform decision-making processes related to maintenance, repair, and replacement. This study aims to present a methodology that guides the assessment of existing structures' performance effectively and accurately. Precisely, the performance is measured in terms of redundancy and robustness. Thus, a comparison of existing reliability- and risk-based indicators is performed through an example application presented in one of the appended papers. The comparison allows an overview of the difference between the available measures and the type of information provided by each one of them. Also, in one of the appended papers a new algorithm for evaluating the failure probability value is proposed. The algorithm is based on metamodel strategies and integrates the advantages of kriging, learning, and copula functions. The proposed algorithm aims to reduce the number of performance function evaluations, so the number of model runs is feasible when using Finite Element Modeling (FEM). By comparing the available redundancy and robustness indicators, it was possible to observe that each measure provides different insights into these two structural properties. Additionally, direct comparison between them is challenging since their units can differ, and the lack of a target or standard values makes their interpretation difficult. Therefore, when using a specific indicator, it is required to specify the definition adopted clearly. Furthermore, the proposed algorithm showed through the validation examples and the case study that it can obtain the failure probability accurately and effectively. Its application resulted in a more economical methodology, in terms of computational cost, compared to other existing reliability methods.

The city of Uppsala is suffering from power shortage, which is creating issues for Region Uppsala, which manages the new city bus depot. Gamla Uppsala Buss (GUB), the operator of the city busses, has bought 12 electrical busses and is planning to increase that number up to 60, which is a political goal. Charging of the electrical busses occurs mostly in the nights, but also during lunch time. In this thesis, scenarios of how different number of buses (12, 36 and 60) relates to the power subscription limit at the depot is studied. The study was made through interviews with industry experts and by creating different scenarios in an Excel-model which was produced in this work. One main conclusion from the interview study was that the regulation control of all the technical components of the system, and foremost the regulation control of the charging of the busses, is a vital component to handle the charging properly. Optimal regulation control requires accurate planning and advanced calculations which relies upon access of data, i.e., charging cycles, battery range and electric energy consumption. The simulations in the Excel-model showed that the bus depot could handle 12 electrical buses with the available power subscription that is today. For 36 or 60 electrical busses additional power had to be added behind-the-meter, which could be obtained with energy storage (batteries), a biogas engine linked to a generator or a combination of those two. The simulations showed that either an energy storage or a biogas engine could compensate for the lack of power, with reasonable proportions. The two technical solutions could also be combined in infinite ways, depending on the goal of Region Uppsala, to fulfill the task. The technical solution that is most feasible for Region Uppsala depends on their priorities. The economics of the solution will of course be a big factor, which has not been included in this work. Another feasible priority could be to choose a technical solution that creates utility for the power system of Uppsala, i.e., mitigating power shortage, with a solution that has a high selfproduction of electric energy and a power consumption profile of the bus depot that is inverted to the rest of the city’s.

Since the 1970's deep mixing columns have been widely used all over the world to improve the performance of soft soil in regard to bearing capacity or deformation behaviour. They are installed by mixing a binding agent, e.g. cement, in situ with the soil. The choice of installation method affects the properties of the column and the surrounding as the soil is disturbed by the installation process. However, the effects of the installation are often neglected during design even though they are plentiful. Besides the lateral displacement that could destabilize neighbouring constructions, the soil in the direct vicinity of the installed column is affected. Laboratory and field tests revealed the formation of three distinct zones outside the nominal diameter of the column which have different strength properties than the initial clay. They are formed due to cylindrical expansion, clay fracturing, and the migration of ions from the binding agent and their strength changes with time due to consolidation, cementation, heating, and thixotropy. Within this thesis, the installation effects that occur in the direct vicinity of the column have been studied in the context of a construction project in Sweden, where deep mixing columns are considered for the reduction of settlements of road and parks areas located on a thick clay layer. Based on analytical calculation methods and field measurements described in the literature, the occurrence and the magnitude of the installation effects have been assessed. The influence of considering these effects was then studied numerically using the finite element program PLAXIS. The simulation included one column within a column group and was performed in 2D assuming axisymmetry. The presence of the neighbouring columns was considered over the boundary conditions. The installation effects in the vicinity of the column comprised three zones which were implemented in the numerical model. For comparison, the simulations were also performed using the "wish-in-place" approach for the column that ignores the occurrence of any installation effects. The stabilized soil is loaded with two layers of new filling material which results in excess pore pressures and settlements that have been studied. The results for the model in which the installation effects were considered could be compared to the results for the model in which the column was wished-in-place. The comparison showed that the consideration of the installation effects leads to a faster consolidation and a significant reduction in settlements. This was observed for different installation patterns, i.e. triangular and square, and varying column spacings of 1.2 and 2.4 m. The positive installation effects were greatest for a smaller spacing and a triangular installation pattern. For a square installation pattern with a spacing of 2.4 m, the consolidation time and the final settlements were both reduced by more than 40%. Even though the assumptions and simplifications require verification, a clear positive influence can be seen for the project in Sweden. If these numerical results are confirmed by field observations, more efficient construction designs could be obtained which ultimately result in reduced costs and carbon dioxide emissions.

Shotcrete is sprayed concrete applied pneumatically under high pressure and was invented in the beginning of the 1900's. This new technique decreased the construction time and since steel fibres were introduced in the shotcrete during the 1970's, shotcrete has been the primary support method for tunnels. Tunnels excavated with the drill and blast method creates a highly irregular rock surface which results in a shotcrete lining with varying thickness. The structural behaviour as well as the loads acting on the shotcrete lining depends on the interaction between the shotcrete, rock and rock bolts. There are several parameters influencing this interaction, e.g. bond strength, the stiffness of the rock and thickness of the shotcrete. All of these parameters are difficult to predict accurately which makes the structural design of the lining to a complex problem. This thesis present the first part of a research project with the long-term goal to improve the understanding of the structural behaviour of the shotcrete lining. To achieve this, numerical modelling have been used to study the build up of stresses and cracking of shotcrete when subjected to restrained loading caused by e.g. temperature differences and drying shrinkage. The response in the lining when subjected to a gravity load from a block has also been studied. The model is capable of describing the non-linear deformation behaviour of both plain and fibre reinforced shotcrete and uses presented in situ variations in thickness to more accurately account for the effects of expected variations in thickness. The thesis discuss and demonstrate the effect of important loads that acts on the shotcrete lining and how the irregular geometry of the rock surface in combination with the varying thickness of the shotcrete affect the development of stresses in the lining. It is also discussed how a full or partial bond failure affect the structural capacity of a shotcrete lining. / Sprutbetong är betong som appliceras pneumatiskt under högt tryckt, en metod utvecklad i början av 1900-talet. Kort därefter gjordes de första försöken att använda sprutbetong som bergförstärkning. Den här nya tekniken minskade produktionstiden och när stålfibrer introduceras under 1970-talet kunde det tunga arbetet med att placera armering minimeras. Sedan dess har sprutbetong blivit den preliminära förstärkningsmetoden, särskilt för tunnlar i hårt berg där tunna lager av sprutbetong ibland kan användas som den enda förstärkningsåtgärden.  Tunnlar byggs normalt genom metoden "borrning-sprängning" vilket leder till att bergytan där sprutbetongen appliceras få r en oregelbunden form. Under sprutning är det svårt att fastställa den exakta tjockleken och sprutbetongen har därmed en oregelbunden tjocklek. Beroende på in situ förhållanden kan oarmerad eller fiberarmerad sprutbetong i kombination med bergbultar användas för att förstärka berget. Det strukturella beteendet och lasterna som påverkar förstärkningen beror på interaktionen mellan sprutbetong, berg och bergbultar. Denna samverkan styrs av flera parametrar som t ex; vidhäftningshållfastheten, bergets styvhet och tjockleken hos sprutbetongen. Dessa parametrar är svåra att förutsäga vilket gör dimensionering av en sprutbetongförstärkningen till ett komplext problem. Den här uppsatsen presenterar den första delen av ett forskningsprojekt med det långsiktiga målet att öka förståelsen för det strukturella beteendet hos en sprutbetongförstärkning. För att uppnå detta har numerisk modellering använts för att studera spänningsuppbyggnaden och uppsprickningen av sprutbetong som utsätts för förhindrade rörelser orsakade av temperaturförändringar eller uttorkningskrympning. Sprutbetongens beteende när den utsätts för en blocklast har också studerats. En numeriskt modell för att analysera spänningarna i sprutbetong som tar hänsyn till tidsberoende materialegenskaper har använts. Modellen kan beskriva det icke-linjära deformationsbeteendet av oarmerad samt fiberarmerad sprutbetong och använder sig av presenterad fältdata för att beskriva de förväntade tjockleksvariationerna. Uppsatsen disskuterar och demonstrerar effekten av viktiga laster som verkar på sprutbetongförstärkningen och hur bergets oregelbundna yta i kombination med sprutbetongens varierande tjocklek påverkar spänningsuppbyggnaden i förstärkningen. Det diskuteras också hur ett fullständigt eller partiellt vidhäftningsbrott på verkar sprutbetongförstärkningens bärförmåga. / <p>QC 20170418</p>

När tillfälliga vägar skall anläggas sker vanligtvis ingen dimensionering i förväg, i de flesta fall dimensioneras och byggs de utifrån erfarenhet. Om en tillfällig väg skall användas som permanent väg efter det att byggnationen är färdigställd, kan det i enstaka fall ske en dimensionering på vägen. Exempel på detta är vid byggnation av vindkraftverk och skogsvägar. Företaget Auctoritas Projektstyrning AB har fått i uppdrag att upphandla samt projektleda nödvändigt fastighetsunderhåll för fastigheten Terränglöparen 9 beläget i Hallonbergen, Sundbybergs kommun. För att genomföra ROT-projektet utreds möjligheten för en tillfällig väg för att underlätta logistiken under produktionstiden. Syftet med arbetet är att utreda tekniska lösningar för uppbyggnad av överbyggnader till en tillfällig väg. Utredningen skulle resultera i ett förslag på lämpliga val med hänsyn tagen till kostnad och regeluppfyllnad. Detta applicerades sedan som en fallstudie med en tillfällig väg till Terränglöparen 9. Författarna har undersökt 10 olika väguppbyggnader med hänsyn till rådande markförhållanden, årsperiod, årsdygnstrafik per körfält samt kostnad. Utöver detta har föreslagen vägsträckning utretts med hänsyn till rådande topografi, fordonens svängradier och bärighetsklass. Detta ledde sedan till ett val av väguppbyggnad samt vägsträckning för en tillfällig väg till Terränglöparen 9. / When temporary roads are being constructed there is normally no design made in advance, in most cases they are built and dimensioned from experience. If a temporary road will be used as a permanent road after the construction is finished, there will occasionally be a complete design of the road. Example of this is when roads are built for wind power stations or forest roads. The company Auctoritas Projektstyrning AB has been assigned to project lead any necessary property maintenance for Terränglöparen 9 situated in Hallonbergen, Sundbybergs county. To go through with the renovations, the company is investigating the possibilities for a temporary road to ease the logistics during the production time. The purpose with this report is to investigate technical solutions for the construction of a temporary road. The investigation should result in a suggestion for appropriate choices with regard to cost and rules. This is later applied like a case study with a temporary road to Terränglöparen 9. The authors have explored ten different road constructions with regards to current land ratio, service years, annual traffic per lane and cost. In addition to this, a proposed road section has been investigated with regards to current topography, turning radius of lorries and load-bearing capacity. This led to a choice of road construction and a road section for a temporary road to Terränglöparen 9.

This thesis treats virtual sensing for fatigue assessment of steel bridges. The purpose is to develop avirtual sensing method to use in the fatigue assessment process. The aim for the virtual sensing method is to only depend on strain measurements located on the bridge structure. The service life of bridges is often limited by fatigue and amending bridge design to improve fatigue resistance was developed in the 1970s. There are several bridges in Sweden, Europe and other countries that have exceeded their theoretical service life with regard to fatigue, and the need to replace them isboth a environmental and economical issue. The bridge over Rautasjokk north of Kiruna, Sweden is a specific example where the theoretical service life is limited by fatigue. Uncertainties in the theoretical fatigue assessment of bridges can be reduced by measuring strains atthe fatigue critical details, and therefore lead to a longer theoretical service life. Monitoring is, however,an expensive method and the procedure of installation and administration requires working time, and monitoring can only provide information at the gauge location. Hence, it is of great interest to optimizethe monitoring system. Virtual sensing is a method that could provide an alternative to conventionalmeasuring techniques. Virtual sensing combine measurement data with information from a model. Virtual sensing for fatigue assessment of the Rautasjokk Bridge was evaluated developing two methods. Both methods uses a finite element model of the bridge combined with strain measurements. The measurements were obtained on February 14 2018 and included a time signal and strain variations at six different locations of the structure. The accuracy of the virtual sensing methods were evaluated by comparing the fatigue damage of virtual sensing with the fatigue damage calculated using measured strains. The fatigue calculations were based on methods presented in the Eurocode EN-1993-1-9. The first method was based on the idea to find a relation between groups of stress ranges for two gauge locations on the bridge. The stress ranges were established by loading influence lines obtained from the finite element model with a fictitious train and the difference between two gauges was stored in a vector, the correlation vector. The correlation vector was applied on the measured stress ranges of the first gauge to estimate the actual stress ranges of the second gauge. No relation between groups of stress ranges for different loading cases was found and the correlation vector method for virtual sensing is not a sufficiently accurate method to apply in the fatigue assessment of the Rautasjokk Bridge. The second method was based on finding a relation between each stress range instead of a group of stress ranges. Influence lines from the finite element model were used to find a relation between each stress range of two gauges. Their relation was stored in a matrix, the correlation matrix. The matrix was applied on the measured stress ranges of the first gauge to estimate the actual stress ranges of the second gauge. The correlation matrix method for virtual sensing estimate the fatigue damage sufficiently accurate at the bridge locations where local stress ranges have the greatest impact on the fatigue damage. Results obtained through virtual sensing only include the same parameters that were used as inputs in the method. A credible virtual sensing method is crucial in order to achieve reliable results. In general, a virtual sensing method requires an extent amount of input data to validate its reliability. Further studies are required to investigate how the uncertainties of the correlation matrix affect the fatigue assessment.

Infrastrukturen i Sverige åldras, uppskattningsvis finns det drygt 2000 broar i landet som är 70 år eller äldre. Det finns flera aspekter att titta på för att utvärdera äldre broars kondition och FE modellering är ett vanligt verktyg som används vid utvärdering. För stålbroar är det ofta utmattning som sätter gränsen för hur länge de kan hållas i drift under säkra förhållanden. Syftet med arbetet var att utvärdera nyttan av FE modeller med olika precision med hänsyn till noggrannheten i deras genererade resultat och kostnad. En stålbro har studerats i detalj, Gamla Lidingöbron och specifikt två punkter på dess bågspann. Ritningar av bron och mätdata från forskningsprojektet \textit{Smart tillståndsbedömning, övervakning och förvaltning av kritiska broar} har legat till grund för arbetet. Mätdata utgjordes av tidshistorier över spänningsvariationer i de två studerade punkterna vid flertalet tågpassager över bron. Punkterna finns på bågspannets sekundära bärverk. Fyra modeller har skapats i BRIGADE/Plus med olika precisionsgrad och spänningshistorier för de studerade punkterna har genererats. Spänningshistorierna har sedan utvärderas med Palmgren-Miners delskadeteori för utmattning. Den förväntade ekonomiska nyttan för varje modell har uppskattats beroende av analyskostnad, sannolikheten för utmattningsbrott samt kostnad för ett eventuellt brott. På grund av brons strukturella verkningssätt blev de förenklade modellernas utmattningsresultat mycket lika resultaten från modellen med hög precisionsgrad. De verkliga axellasterna var mindre än de dimensionerande som användes i modellerna. Detta ledde till att de uppkomna spänningarna i stålet från modellerna blev större än de verkliga, men visade ett liknande beteende. Resultatet blev att modellernas utmattningskapacitet enbart utgjorde ca en femtedel av kapaciteten enligt mätningarna. Resultatet från beräkningen av den förväntade nyttan visade att det inte är ekonomiskt motiverat att använda en modell med hög precision framför en eller flera förenklade modeller. Slutsatsen blev att hög precision i en teoretisk modell inte entydigt är bättre än en förenklad modell. Arbetet har utförts vid institutionen för bro och stålbyggnad på KTH i samarbete med Sweco Civil AB. / The infrastructure in Sweden is aging. More than 2 000 bridges in the country are 70 years or older. When assessing the condition of older bridges, several aspects should be taken into account. FE modeling is one common tool to use in a bridge assessment. Fatigue is generally what limits the service life of steel bridges. The aim of this work was to evaluate the utility of higher precision in FE models, regarding the accuracy of their generated results and costs. One steel bridge has been studied in detail, Old Lidingö Bridge and specifically two points on its arc span. Drawings of the bridge and measurement data from the research project \textit{Smart Condition Assessment, Surveillance and Management of Critical Bridges} has provided the basis of this work. Measurement data has been collected from the two selected points on the bridge with strain gauges, registering the time history of the variations in tension during train passages on the bridge. Four models with different levels of precision have been created in BRIGADE/Plus. These models have generated time histories of the varying tension during  train passages. The time histories have been evaluated with Palmgren-Miner's cumulative damage model for fatigue. The expected economic utility of each set of models has been estimated based on the cost of the analysis, the likelihood failure caused by fatigue and the cost of failure. Because of the structural behavior of the bridge, the results of the simplified models became very similar to the results of the high precision model. The actual axle loads were less than the design loads used in the models. Because of this, the calculated tensions in the models became larger than the actual tensions. This also resulted in the fatigue capacity of the models only being about one fifth of the capacity according to the measurements. The calculation of the expected utility showed that it is not economically justified to use a model with higher precision over models with less precision. High precision in a theoretical model is not unambiguously better than a simplified model. The work has been carried out at the Department of Structural engineering and bridges at KTH in cooperation with Sweco Civil AB.

Abstract When Eurocodes was introduced, there was a requirement where the calculations had to take into consideration whether it's a slab or beam bridge. This means that calculations had to be made with softwares including plate theory. The object of this study is a slab bridge with endshields. The bridge is 66.95 meters long with a 14.38-meter-wide deck made of concrete. The deck is mounted on abutments with bearings and intermediate supports where the columns are fixed to the deck. The purpose of this study is to investigate if bridges defined as plates can be calculated using beam theory, as well as examining different modeling techniques in an attempt to evaluate how this will affect the results. A model using shell elements is established in BRIGADE/Plus and compared to a model in Strip Step 3 made out of beam elements. A base-model is also created in BRIGADE/Plus and is compared to the following modeling changes: Couplings between supports and the plate, “point to surface” or “point to point”. The bridge is modeled without wings to study the impact of the wings. The bridge is modeled without columns to study the impact of the columns. When comparing the values obtained from the two different software’s regarding deadweight, the results were almost identical. This indicates that Strip Step 3 is a suitable tool for verifying models made in BRIGADE/Plus. When studying the results from load-combination 6.10.b (the combination used for dimensioning) small differences can be seen between the softwares. This concludes that it may be reasonable to use Strip Step 3 for this type of bridges. However, there are major differences between the software at the traffic load which should be considered. In order to simplify the modeling process ties between points (nodes) should be used. However, the results obtained over the supports must be ignored due to unrealistic values. When studying the impact of wings/columns it was confirmed that a difference of 10 % appeared. Modeling without wings/columns is not more time efficient either, with that in mind wings and columns should be used when modeling.   Keywords: Plate theory, Beam theory, Strip Step 3, BRIGADE/Plus, FE-modeling / Sammanfattning Vid införandet av Eurokoder ställdes det krav från Trafikverket där beräkningsmodellen var tvungen att ta hänsyn till verkningssättet i sin helhet dvs. om det är en platt- eller balkbro (E. Rosell, Trafikverket, personlig kommunikation, 3 Maj, 2018). Detta innebar att beräkningsmodeller för plattbroar behövdes utföras med program som kan hantera beräkningar enligt platteori. Studieobjektet för detta arbete är en plattbro med ändskärmar. Bron är 66.95 meter lång med en brobaneplatta av betong som har bredden 14.38 meter. Plattan är upplagd på ändstöd med rörliga lager samt mellanstöd där pelare är fast inspända till plattan. Syftet med detta arbete är att undersöka huruvida broar definierade som plattor går att beräkna enligt balkteori, samt att undersöka olika modelleringstekniker i ett försök att utvärdera hur det påverkar resultaten. En modell med skalelement har upprättats i BRIGADE/Plus som jämförs mot en modell i Strip Step 3 utförd av balkelement. En grundmodell skapas även i BRIGADE/Plus som jämförs mot följande modelleringsändringar: Stöd kopplade mellan två punkter jämförs mot koppling mellan pelare och yta i plattan. Bron modelleras utan vingar för att studera vingarnas inverkan. Bron modelleras utan pelare för att studera pelarnas inverkan. Kontrollen av egentyngd visade nästintill identiska resultat vilket tyder på att Strip Step 3 är ett lämpligt verktyg vid verifiering av Brigademodeller. Vid lastkombination 6.10.b (den dimensionerande lastkombinationen för denna bro) uppstår små skillnader. Detta indikerar att det kan vara rimligt att använda sig av Strip Step 3 vid dessa typer av broar. Dock uppstår det stora skillnader mellan programvarorna vid trafiklasten vilket bör beaktas. För att förenkla modelleringen bör kopplingar mellan punkter användas, dock måste resultat som erhålls över stöd bortses från då dessa ger orealistiska resultat. Vid modellering utan pelare/vingar kan det konstateras att värdena skiljer sig ca 10 %. Det är inte heller mycket mer tidseffektivt att ta bort pelare/vingar då dessa går relativt fort att modellera.   Nyckelord: Platteori, Balkteori, Strip Step 3, BRIGADE/Plus, FE-modellering

Around the world bridges are ageing. In Europe approximately two thirds of all railway bridges are over 50 years old. As these structures age, it becomes increasingly important that they are properly maintained. If damage remains undetected this can lead to premature replacement which can have major financial and environmental costs. It is also imperative that bridges are kept safe for the people using them. Thus, it is necessary for damage to be detected as early as possible. This research investigates an unsupervised, model-free damage detection method which could be implemented for continuous structural health monitoring. The method was based on past research by Gonzalez and Karoumi (2015), Neves et al. (2017) and Chalouhi et al. (2017). An artificial neural network (ANN) was trained on accelerations from the healthy structural state. Damage sensitive features were defined as the root mean squared errors between the measured data and the ANN predictions. A baseline healthy state could then be established by presenting the trained ANN with more healthy data. Thereafter, new data could be compared with this reference state. Outliers from the reference data were taken as an indication of damage. Two outlier detection methods were used: Mahalanobis distance and the Kolmogorov-Smirnov test. A model steel bridge with a span of 5 m, width of 1 m and height of approximately 1.7 m was used to study the damage detection method. The use of an experimental model allowed damaged to be freely introduced to the structure. The structure was excited with a 12.7 kg rolling mass at a speed of approximately 2.1 m/s (corresponding to a 20.4 ton axle load moving at 47.8 km/h in full scale). Seven accelerometers were placed on the structure and their locations were determined using an optimal sensor placement algorithm. The objectives of the research were to: identify a number of single damage cases, distinguish between gradual damage cases and identify the location of damage. The proposed method showed promising results and most damage cases were detected by the algorithm. Sensor density and the method of excitation were found to impact the detection of damage. By training the ANN to predict correlations between accelerometers the sensor closest to the damage could be detected, thus successfully localising the damage. Finally, a gradual damage case was investigated. There was a general increase in the damage index for greater damage however, this did not progress smoothly and one case of ‘greater’ damage showed a decrease in the damage index.