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The traffic scenarios that may cause extreme load effects are of great importance to the safety assessment of bridge structures. The traditional simulation method of traffic flow cannot depict the distribution pattern of vehicles on the bridge deck when the maximum effect is induced. In this paper, a probabilistic Gaussian mixture model (GMM) for heavy vehicle scenarios on the bridge deck under free-flow condition is proposed for long-span bridges based on collected Weigh in Motion (WIM) data. The scenarios of extreme response under free-flow occur more frequently than congestion scenarios and are of similar value and relevance in the daily management and safety assessment of long-span bridges. A non-stationary Poisson process is utilized to simulate the uneven occurrence of heavy vehicles in different lanes, and it is assumed that they are located within the artificially defined cells on the bridge deck. Then, Nataf transformation is employed to consider the correlation of gross vehicle weights (GVWs) within close range in the same lane. The numerical study is carried out on a long-span cable-stayed bridge to investigate the effects of correlation in GVWs and stationarity of vehicle distribution location on the structural responses. The load responses calculated by the proposed model and Monte Carlo method for different effects are compared with the values derived from code model. The results show that with the increase of the correlation level of the neighboring GVWs, the simulated responses are more prone to get extreme values, which means an increasing probability of the most unfavorable spatial distribution of on-bridge vehicles. The same results are also found under the non-stationary simulation state for vehicle location. The non-stationary Poisson process provides an efficient, highly feasible method, which is also in the safe side, for simulating the vehicle spatial distribution for specific effects., The support from the National Natural Science Foundation of China (Grant number 51878495), the Academician Project Foundation of CCCC (Grant numbers: YSZX-01-2020-01-B), the National Key R&D Program of China (Grant number 2018YFB1600100) and the Shanghai Sailing Program (Grant number: 21YF1449300) is gratefully acknowledged. The opinions and conclusions presented in this article are those of the authors and do not necessarily reflect the views of the sponsoring organizations., Peer Reviewed, Postprint (author's final draft)

With the rapid development of society and the economy, significant infrastructure, such as roads, buildings, high-speed railways, and bridges, have been built all over the world. However, the increase in operating time and environmental loads have destabilized the structures, resulting in slow structural damage. Such damage, if not detected in time, can threaten normal structural operations, or even cause significant hazards. Therefore, the operational safety of urban infrastructures, as an important practical issue, has attracted increasing attention from multi-disciplinary fields, such as public security, earth obser- vation, civil engineering, and so on., Postprint (published version)

We are now entering the third decade of the 21st Century, and, especially in recent years, the achievements made by researchers and professionals have been exceptional, leading to major advancements in the fast-growing field of the Built Environment.Frontiers has organised a series of Research Topics to highlight the latest advancements in research across the field of Built Environment with articles from the members of our accomplished Editorial Boards. This editorial initiative in question, led by Dr. Zhen Chen, Specialty Chief Editor of Frontiers Construction Management is focused on new insights, novel developments, current challenges, latest discoveries, recent advances, and future perspectives in the field of Built Environment.The Research Topic solicits brief, forward-looking articles from the Editorial Board Members that describe the state of the art, outlining recent developments and major accomplishments that have been achieved and that need to occur to move the field forward. Authors are encouraged to identify the greatest challenges in the sub-disciplines, and how to address those challenges.The goal of this special edition Research Topic is to shed light on the progress made in the past decade in the Built Environment field, and on its future challenges to provide a thorough overview of the field. This article collection will inspire, inform, and provide direction and guidance to researchers and practitioners in the field.We welcome original research, reviews, perspective, outstanding achievements in the Built Environment field and thought-provoking opinion pieces to this Research Topic., Topic editors: Zhen Chen — University of Strathclyde, United Kingdom Akira Matsumoto — Nihon University, Japan Joan Ramon Casas — Universitat Politecnica de Catalunya, Spain Vagelis Plevris — Qatar University, Qatar George Tsiatas — National Technical University of Athens, Greece Hongling Guo — Tsinghua University, China Yongkui Li — Tongji University, China Sakdirat Kaewunruen — University of Birmingham, United Kingdom, Postprint (published version)

The present research aims to assess the reliability of Ultrasonic Tomography (UT) of void detection in post-tensioning ducts due to inappropriate execution of grouting. The methodology is based on the construction of the Probability of Detection (PoD) curves for this specific non-destructive technique, by relating the probability of success to identify a specified ungrouted region. The PoD curves are built on data collected during a testing campaign in the laboratory, under fully known grouting conditions. Six walls containing prestressing strands and bars in metallic and plastic ducts with simulated voids of different sizes were designed and executed. Both water-filled (infiltration) and empty voids (ungrouted region) were simulated. The classical frequentist and Bayesian approaches are used to derive the PoD curves. Since the available experimental data are limited, the Bayesian approach provides more reliable data and is, thus, proposed as the best alternative. It is finally concluded that the minimum size of the voids in metallic ducts that UT can detect with 95% confidence and 90% probability, is around 30 cm and this value will be used in future inspection campaigns in posttensioned bridges., Peer Reviewed, Postprint (published version)

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Structure and Infrastructure Engineering on 2024, available online at: http://www.tandfonline.com/10.1080/15732479.2024.2350035., Keyed dry joints are commonly utilised in segmental bridges for shear stress transmission. The aim of this study is to explore the shear behaviour and capacity of large shear key dry joints. The considered parameters included key base height, key number and concrete strength. The key base heights were found to have a significant impact on the failure mode and shear carrying capacity. When the key base height is increased by 100%, the shear carrying capacity of the joint is increased by 156%. Digital image correlation (DIC) and distributed fibre optic sensing (DFOS) technologies revealed the characteristics of load transfer in the large shear key, validated the principle of inclined strut column and observed the changing angle of inclined column with the increase in shear key size. Moreover, due to the shear transfer at the large key teeth, there is a trend of separation in the lower contact surfaces of the joint. Based on these findings, an improved calculation method for the shear strength of large key dry joints was established. The calculation results show more accurate predictions for large key dry joints than available calculation methods developed for smaller keyed dry joints., Peer Reviewed, Postprint (author's final draft)

La carretera C-31 presenta un traçat sinuós amb nombroses corbes tancades i de baixa visibilitat. Per augmentar la seguretat del tram es planteja la modificació del traçat suprimint diverses d'aquestes corbes, per això cal la construcció d'un viaducte com a traçat alternatiu., La carretera C-31 presenta un trazado sinuoso con numerosas curvas cerradas y de baja visibilidad. Para aumentar la seguridad del tramo se plantea la modificación del trazado suprimiendo varias de estas curvas, para ello se requiere la construcción de un viaducto como trazado alternativo., The C-31 road has a route with numerous closed and low-speed curves and visibility. To increase the safety of the course, the modification of the route is proposed eliminating several of these curves, this requires the construction of a viaduct as an alternative route.

The project case of Qiwu Bridge using link slab action between simply supported composite spans is introduced. The 60¿m-span girder of Qiwu Bridge is the longest and heaviest among the composite girders erected by bridge-erecting machine in China. Qiwu Bridge consists of a series of 3 simply supported spans built with composite girders and connected at the pier supports by a link slab. This solution has both advantages of (1) smooth driving condition and enhancement of durability by removing expansion joints and (2) clear structural behavior as simply supported spans. A finite element model was established to simulate and predict the mechanical response of this semi-continuous solution. Numerical results showed that the removal of the shear connection around the link slab decreased the stress level but also caused a stress mutation. Qiwu Bridge was also monitored by vibrating wire strain gages to follow its actual structural response. From preliminary monitoring data and numerical results, it can be concluded that the proposed construction method and the static scheme is safe for the 60-span composite girder with a large safety margin. Further experimental results will be obtained during the service stage of the bridge to validate the in-service performance of the proposed steel-concrete composite bridge with link slab., The first author acknowledges the support provided by the China Scholarship Council (No. 202106260050). The third author acknowledges the support provided by the Spanish Ministry of Science and Innovation through the research project PID2021-126405OB-C31 and AGAUR for support to consolidated research groups., Peer Reviewed, Postprint (author's final draft)

One of the main challenges for bridge damage identification using monitoring data is to acquire sensitive damage features but insensitive to operational and environmental effects as well as noise. Specifically, the temperature as part of environmental variability can mask structural damages in bridges. Principal Component Analysis (PCA) has been applied here as a well-known and robust technique for removing environmental variability and obtain damage-sensitive indices. As a first aim, PCA is used considering only ambient vibrations and the natural frequencies are considered as damage indicators. As a second objective, PCA in conjunction with Hilbert Huang Transform (HHT) and Variational Mode Decomposition (VMD) are applied to eliminate the environmental influence in transient vibrations due to traffic. The combined methodology is applied to the case of a numerical benchmark by using the Instantaneous Phase Difference (IPD) as novel vibration damage feature in the case of non-stationary vibrations. The results show that the proposed strategy to use the non-stationary vibration due to traffic instead of ambient vibration seems a promising tool for damage identification and, therefore, its capabilities in real bridge applications are worth exploring further when experimental data from real bridges will become available., The authors thank Prof. Eleni Chatzi, ETH Zurich, for giving us the data as well as documentation from the numerical bridge utilized in the case study. To the Dirección de Investigación de la Universidad Peruana de Ciencias Aplicadas for the support provided for the realization of this research work through the UPC-EXPOST-2023-1 incentive., Peer Reviewed, Postprint (author's final draft)

The need for measurable data from physical assets to actively feed a living Digital Twin (DT) is paramount. The requirements and needs that the gathered data should fulfill in order to be practically implemented in the stream data pipeline are heterogeneous, some of them general and other case-specific. This article summarizes a set of identified challenges and requirements for a seamless infusion of well-established Structural Health Monitoring (SHM) systems within DT platforms, without the objective of solve all of them. This identification is performed based on a review of traditional SHM systems with a vast array of information sources as well as on the review of techniques for the systematic digitalization of existing assets. On the other hand, ten real demo cases belonging to Ashvin, an H2020 Research and Innovation project, are providing real world testing beds for an active development of SHM infused in DT systems. Multiple information sources are studied in those sites, which also enriches with more realism, the identification of requirements and challenges presented herein. These assets provide a perspective to researchers about practical implications of these needs., All authors acknowledge the funding of ASHVIN, “Assistants for Healthy, Safe, and Productive Virtual Construction Design, Operation & Maintenance using a Digital Twin” an H2020 project under agreement 958161., Peer Reviewed, Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura, Postprint (published version)

Tesi amb menció de Doctorat Internacional, Tesi en modalitat de cotutela: Universitat Politècnica de Catalunya i Tongji University, (English) During the lifetime of long-span bridges, the traffic conditions are affected by the surroundings and will typically vary and also unpredictably change. In this thesis, a prior site-specific traffic load spatial distribution model and its updated posterior version considering actual traffic conditions via Bayesian inference were proposed. This thesis mainly contains three aspects of research. Firstly, a probabilistic Gaussian mixture model for heavy vehicle scenarios on the bridge deck under free-flow condition is proposed for long-span bridges based on collected WIM data. A non-stationary Poisson process is utilized to simulate the uneven occurrence of heavy vehicles in different lanes, and it is assumed that they are located within the artificially defined cells on the bridge deck. Then, Nataf transformation is employed to consider the correlation of gross vehicle weights (GVWs) within close range in the same lane. The Monte Carlo method is employed with the proposed probabilistic model for modeling complex spatial distributions of heavy vehicles. Secondly, due to the fact that the traffic conditions are affected by the surroundings and will typically vary and also unpredictably change during the lifetime of long-span bridges, the prior site-specific traffic load spatial distribution model and its updated posterior version considering actual traffic conditions via Bayesian inference are proposed. A Bayesian inference approach is developed for the updating of spatial load distribution in the extremes LE scenarios utilizing the particle filter (PF). The updated load profile and corresponding load intensity for different traffic states proposed in this thesis, can be the basis to define accurate traffic load models for long-span bridges. Finally, the application of the proposed methodology to a real bridge is presented. The effects of correlation in GVWs and stationarity of vehicle distribution location on the structural responses are investigated and discu, (Català) Al llarg de la vida útil de ponts de gran llum, les condicions del trànsit es veuen afectades per l'entorn viari i poden variar de manera important. A la tesi es proposen tant un model "a prioni" de la distribució espacial de tràfic específic per a un pont com la seva versió "a posteriori" mitjançant inferència Bayesiana. Es contemplen 3 aspectes de recerca. En primer lloc es construeix un model probabilístic de la situació dels vehicles pesants al tauler en condicions de trànsit fluid rnediant dades WIM. Per simular la no homogeneïtat de la distribució dels vehicles pesats en diferents carrils s'utilitza un procés de Poisson no estacionari i s'assumeix que es troben situats dins unes cèl·lules prèviament definides. A continuacio, s'utilitza la transformacio de Nataf per tenir en ouenta la correlacio entre pesos de les vehiculos proximos situats en el mateix carril. La simulació de Monte Carlo juntament amb el model probabilístic proposat són la base per modelitzar la distribució espacial de vehicles pesants al pont. En segon lloc, atès que les condicions de trànsit al pont varien amb el temps, les distribucions espacials prèviament obtingudes s'actualitzen mitjançant inferència Bayesiana per tenir en compte les condicions actuals de trànsit. Per això s'utilitza el mètode de filtre de partícules (PF). Gràcies a això, les distribucions de càrrega i la seva intensitat obtinguts per a diferents situacions de trànsit que es proposen a la tesi, poden ser la base per definir models de càrrega de trànsit més precisos en els ponts de gran llum. Finalment, s'aplica la metodologia proposada a un pont real. S'estudien els efectes de la correlació de pesos entre vehicles pesants i l'estacionarietat de la distribució dels vehicles en la resposta del mateix. Els valors obtinguts amb el mètode proposat i simulació de Monte Carlo per a diversos efectes es comparen amb les obtinguts amb les normatives presents. Els resultats mostren que amb l'increment de la correlació, la, (Español) A lo largo de la vida útil de puentes die gran luz, las condiciones del tráfico se ven afectadas por el entorno viario y pueden variar de manera importante. En la tesis se proponen tanto un modelo "a priori" de la distribución espacial de trafico específico para un puente como su versión "a posteriori" mediante inferencia Bayesiana. Se contemplan 3 aspectos de investigación. En primer lugar, se construye un modelo probabilístico de la situación de los vehículos pesados en el tablero en condiciones de tráfico fluido mediante datos WIM. Para simular la no homogeneidad de la distribución de los vehículos pesados en diferentes carriles se utiliza un proceso de Poisson no estacionario y se asume que se encuentran situados dentro de unas células previamente definidas. A continuación, se utiliza la transformación de Nataf para tener en cuenta la correlación entre pesos de los vehículos próximos situados en el mismo carril. La simulación de Monte Carlo junto con el modelo probabilístico propuesto son la base para modelizar la distribución espacial de vehículos pesados en el puente. En segundo lugar, dado que las condiciones de tráfico en el puente varían con el tiempo, las distribuciones espaciales previamente obtenidas se actualizan mediante inferencia Bayesiana para tener en cuenta las condiciones actuales de tráfico. Para ello se utiliza el método de filtro de partículas (PF). Gracias a ello, las distribuciones de carga y su intensidad obtenidos para distintas situaciones de tráfico que se proponen en la tesis, pueden ser la base para definir modelos de carga de trafico más precisos en los puentes de gran luz. Finalmente, se aplica la metodología propuesta a un puente real. Se estudian los efectos de la correlación de pesos entre vehículos pesados y la estacionalidad de la distribución de los vehículos en la respuesta del mismo. Los valores obtenidos con el método propuesto y simulación de Monte Carlo para varios efectos se comparan con las obtenidos con las no, Postprint (published version)

Este Anteproyecto tiene por objeto definir una solución para la ejecución de una nueva pasarela peatonal de conexión entre el nuevo barrio de La Catalana y el barrio de Sant Joan Baptista de Sant Adrià de Besós. Uno de los objetivos principales es estableces un recorrido cívico y directo entre la futura zona residencial y la zona de equipamientos docentes actuales en el barrio de Sant Joan Baptista. La propuesta debe convertir el camino escolar en un recorrido amable y cómodo, al mismo tiempo que genere un espacio público de calidad. Es por ello que se plantean diversas soluciones alternativas de pasarelas teniendo en cuenta el valor estético, que se integren en el entorno y que sean lo mas económicas posibles. Se realiza un estudio de alternativas con seis propuestas diferentes justificando la solución adoptada.

A hybrid girder bridge adopts a steel segment at the mid-span of the main span of a continuous concrete girder bridge. The critical point of the hybrid solution is the transition zone, connecting the steel and concrete segments of the beam. Although many girder tests revealing the structural behavior of hybrid girders have been conducted by previous studies, few specimens took the full section of a steel–concrete joint due to the large size of prototype hybrid bridges. In this study, a static load test on a composite segment to bridge the joint between the concrete and steel parts of a hybrid bridge with full section was conducted. A finite element model replicating the tested specimen results was established through Abaqus, while parametric studies were also conducted. The test and numerical results revealed that the concrete filling in the composite solution prevented the steel flange from extensive buckling, which significantly improved the load-carrying capacity of the steel–concrete joint. Meanwhile, strengthening the interaction between the steel and concrete helps to prevent the interlayer slip and simultaneously contributes to a higher flexural stiffness. These results are an important basis for establishing a rational design scheme for the steel–concrete joint of hybrid girder bridges., This research was funded by Spanish Ministry of Science and Innovation (grant number PID2021-126405OB-C31), Shanghai Science and Technology Commission (grant number 20XD1432400) and Guangdong Yejian Construction Drawing Review Center Co., Ltd. (grant number GDYJ-RD-17)., Peer Reviewed, Postprint (published version)

Alkali-activated concrete mixed with waste dredged sand (DS) is a new type of green concrete. In addition to reducing resource consumption and CO2 emissions, this approach is also cost-effective. Therefore, the ongoing research on its application in real industrial production is of great importance. This study examined the impact of the steam curing system on the mechanical properties and microstructure of alkali-activated dredged-sand concrete (AADSC). Different alkali equivalents and DS contents were used to produce AADSCs, and such AADSCs were cured using different steam curing schemes. The results show that steam curing significantly improves the early strength and 28-day strength under low alkali equivalent. The curing promotes the 1-day strength at 3% alkali equivalent from 2.1 MPa to 27 MPa after steam curing, and the 28-day strength increase was 7.8%. It is also found that the rise in compressive strength does not have a direct correlation with the energy consumption of steam curing. Even though the energy consumed by steam curing at 40 °C was 67% more than that at 60 °C, the 1 d strength under 40 °C steam curing was 7.5% lower. However, low-temperature steam curing retains more room for concrete strength increase. These results indicate the importance of a reasonable steam curing regime for the strength of AADSC., Acknowledged financial supports include the National Key R&D Program of China (Grant No. 2021YFB2600200), the Fundamental Research Funds for the Central Universities (Grant No. B230205017), State Key Laboratory of High-Performance Civil Engineering Materials (Grant NO. 2019CEM002), and National Natural Science Foundation of China (Grant No. 51979090)., Peer Reviewed, Postprint (author's final draft)

Bridges are vital components of transport infrastructures, and therefore, it is of utmost importance that they operate safely and reliably. This paper proposes and tests a methodology for detecting and localizing damage in bridges under both traffic and environmental variability considering non-stationary vehicle-bridge interaction. In detail, the current study presents an approach to temperature removal in the case of forced vibrations in the bridge using principal component analysis, with detection and localization of damage using an unsupervised machine learning algorithm. Due to the difficulty in obtaining real data on undamaged and later damaged bridges that are simultaneously influenced by traffic and temperature changes, the proposed method is validated using a numerical bridge benchmark. The vertical acceleration response is derived from a time-history analysis with a moving load under different ambient temperatures. The results show how machine learning algorithms applied to bridge damage detection appear to be a promising technique to efficiently solve the problem’s complexity when both operational and environmental variability are included in the recorded data. However, the example application still shows some limitations, such as the use of a numerical bridge and not a real bridge due to the lack of vibration data under health and damage conditions, and with varying temperatures; the simple modeling of the vehicle as a moving load; and the crossing of only one vehicle present in the bridge. This will be considered in future studies., Peer Reviewed, Postprint (published version)

A part of the retaining earth wall of the main line of the Catalonian railways (FGC), close to the station of Terrassa collapsed abruptly and without any previous warning. The collapse of this part of the wall provoked the disruption of the operation of trains for three days due to the difficulties in the debris removal. The re-construction of the wall lasted several months. After investigation, it became evident that the failure was due to the pit corrosion of the main reinforcement due to the leakage of a pipeline containing water with chlorides (drinking water network). From the results of the investigation, the main parameters related to the durability of the concrete in the wall were deduced. Once the failed section of the wall was refurbished, it was possible the inspection of the condition state of the reinforce-ment mainly in the rest of the wall (around 100 meters), removing extrados land. The assessment of the actual state and remaining service life of the rest of the retaining earth wall was carried out based on the different behaviour of each part, due to the different leakage in relation to the failed section. Based on this evidence, the residual service life of the rest of the wall was estimated as adequate during the remaining years of railway operation, The second author acknowledges the financial support provided by the Spanish Ministry of Science and Innovation through the research project PID2021-126405OB-C31 and AGAUR (Government of Catalonia) for the support to consolidated research groups., Postprint (published version)

Dry joints with keys are often used in precast concrete segmental bridges (PCSBs) to transfer shear stresses. Large dry joints with keys can often provide greater shear bearing capacity, which can meet the needs of rapid construction and simple assembly. This study focuses on the shear response of super-sized dry joints with keys under direct shear. Various monitoring methods, including digital image correlation (DIC) and distributed optical fiber sensing (DFOS), were used to systematically study the stress process of large concrete keys. The results show that as the size of the key teeth increases, the shear bearing capacity and ultimate vertical displacement of the specimens also increase. DIC and DFOS techniques provide detailed information on key tooth failure, which is beneficial for subsequent stress analysis of shear keys., The authors acknowledge the support provided by the Spanish Ministry of Science and Innovation through the research project PID2021-126405OB-C31 and AGAUR (Government of Catalonia) for support to consolidated re-search groups, and CSC scholarship of China (202206710009)., Peer Reviewed, Postprint (published version)

Tesi en modalitat de cotutela: Universitat Politècnica de Catalunya i Tongji University, Tesi en modalitat de compendi de publicacions, (English) The steel-concrete composite structural solution has been widely applied in the execution of simply supported bridges since the merits of concrete compressive strength and steel tensile strength can be efficiently utilized. However, there is an inverse stress situation in the hogging moment region of a continuous composite girder, where the concrete tensile cracks and steel buckling are both likely to happen. Normal composite bridges adopt Full Shear Connection (FSC) due to convenient construction and clear mechanical properties. However, large tensile stress in concrete is generated in hogging moment regions in continuous girders. In response to this issue, Partial Shear Connection (PSC) achieved by reducing shear connection efficiency in hogging moment region of continuous composite bridge can help to decrease the interaction extent between concrete slab and steel girder, thus reducing the concrete cracking and simultaneously maintaining the ultimate bearing capacity and overall stiffness of the structure. Meanwhile, casting an extra concrete bottom layer to a steel-concrete composite box girder (double composite action) in a hogging moment region can also prevent steel buckling and improve the mechanical performance of the continuous composite bridge. In order to study the structural performance of composite girder with PSC and double composite action, this thesis presents an in-depth study through the combination of experimental, numerical and analytical studies as follows: (1) To study the mechanical properties of the rubber sleeved stud connector, five groups of 15 push-out specimens were fabricated and tested. Numerical models were established. The results of the test and numerical analysis show that the rubber sleeved stud (RSS) connector effectively reduces the shear stiffness of the push-out specimen without changing the load carrying capacity. (2) To study the structural performance of composite girders with partial shear connection, four simply, (Español) La solución mixta acero-hormigón se ha utilizado ampliamente en la construcción de puentes simplemente apoyados, ya que en esta configuración longitudinal es como mejor se aprovecha la alta resistencia a compresión del hormigón junto con la alta resistencia a tracción del acero. Sin embargo, la solución se vuelve contraproducente en la zona de flexión negativa de puentes continuos, donde la fisuración a tracción del hormigón y la abolladura del acero son fenómenos probables. Los puentes mixtos adoptan ua solución de conexión completa (CC) debido a la facilidad constructiva y respuesta estructural. Para reducir las tensiones de tracción en la zona de flexión negativa, una solución alternativa es la conexión parcial (CP), que ayuda a reducir la interacción entre la losa de hormigón y la viga de acero, reduciendo la fisuración en el hormigón aunque manteniendo la resistencia y la rigidez global de la estructura. Por otro lado, colocar un recrecido de hormigón en la zona inferior de la zona de apoyos (doble acción mixta) puede prevenir la abolladura de las chapas metálicas y mejorar la respuesta de los puentes mixtos continuos. Con el objetivo de estudiar el comportamiento estructural de puentes mixtos continuos con conexión parcial y doble acción mixta, en esta tesis se desarrolla un estudio completo combinando experimentación con soluciones numérica y analíticas con el siguiente contenido: (1) Estudiar las propiedades mecánicas del conector enfundado en neopreno (CEN), mediante el ensayo push-out en laboratorio de 5 grupos de 15 muestras y establecer modelos numéricos de su comportamiento estructural. Los resultados experimentales y estudios numéricos han puesto de manifiesto que este tipo de conector reduce de manera efectiva la rigidez transversal sin variar la capacidad de carga. (2) Estudiar el desempeño de vigas mixtas con conexión parcial, mediante el ensayo en laboratorio de 4 vigas simplemente apoyadas y dos vigas continuas mixtas, cargadas estáticam, Postprint (published version)

The environmental and operational influence is still a challenging problem owing because they mask structural damage in civil structures such as bridges. However, advances in signal processing and new artificial intelligence and machine learning tools make it possible to derive more robust and accurate methodologies for damage detection and location. This study proposes a novel bridge damage feature by combining the advantages of variational mode decomposition (VMD), Hilbert Transform (HT) and principal component analysis (PCA) algorithm in the presence of environmental variability and using the non-stationary traffic induced vibration. The proposed methodology considers three steps to analyze the dynamic response. The first step is to pre-process the vibration data (accelerations) using VMD, so the raw data is decomposed into a number of intrinsic mode functions (IMF). The second step is to apply the HT to the decomposed IMFs. Finally, Instantaneous Phase Difference (IPD) is obtained and used as damage indicator. PCA is applied to the IPD in order to eliminate the environmental influence and define appropriate criteria for damage detection avoiding false alarms. This methodology is applied to the case of a numerical model of a continuous bridge, showing promising results for damage detection and location under varying environmental and operational conditions., Postprint (published version)

In the H2020 European project ASHVIN “Assistants for Healthy, Safe, and Productive Virtual Construction Design, Operation & Maintenance using a Digital Twin”, a set of Key Performance Indicators (KPIs) and Performance Indicators (PIs) to plan and control productive, resource efficient, and safe maintenance are being developed for transport infrastructure. This paper is presenting PIs and KPIs for the assessment and monitoring of the following aspects: Productivity, Resource Efficiency, Cost, Health & Safety during the operational life cycle stage, which is mainly focusing on the inspection and maintenance planning. Quantifiable and measurable PIs and KPIs are proposed and applied on two demonstration projects, highway bridge in Spain and airport runway in Croatia, as part of transportation infrastructure. Proposed PIs and KPIs are integrated into digital twins of the analyzed assets and into decision making tools for risk based maintenance planning. This paper presents the overview of the proposed digital PIs and KPIs applied on two demonstration projects and the integration into decision support tools for efficient and sustainable maintenance planning., Postprint (published version)

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works., A long-distance displacement and continuous sensor based on distributed optical fiber sensing (DOFS) with the ability to measure the horizontal displacement of deep excavation was investigated herein. The feasibility and the accuracy were verified based on different numerical algorithms derived and finite element analysis (FEA). The evaluation of robustness under ambient noise and operational errors was conducted. The laboratory tests and on-site monitoring works were carried out. The experimental results confirm that the new optical frequency-domain reflection (OFDR)-based sensor can accurately measure the horizontal displacement field of the deep pit on the basis of 1-cm spatial resolution within 30-m soil depth. This allows to achieve real time and automated monitoring of the deep excavation, providing advanced safety monitoring of the excavation works., Peer Reviewed, Postprint (author's final draft)

Pre-stressed concrete with post-tensioned (PT) cables historically represented an attractive alternative to ordinary reinforced concrete (RC). A wide portion of the world-wide existing concrete bridges was PT. As the nominal service life of those structures expires, several collapses occurred, highlighting the problem of the inspection. The main issue is that PT cables may be affected by relevant corrosion phenomena related to the presence of air or water inside the duets: such 'hidden' defects need to be determined through reliable testing methodologies. This paper presents the in-progress research aiming to quantify the influence of the damage of the single cable on the entire structure. The case study is an ltalian viaduct composed of simply supported beams connected by an upper slab. An extensive investigation campaign was carried out to locate and quantify the damage. Starting from the data collected on-site a series of damage conditions of cables can be simulated., Peer Reviewed, Postprint (published version)

The ultra-fine dredged sand (DS) from the lower reaches of the Yangtze River is a large amount of solid waste with the potential to be recycled and applied as a replacement for fine aggregate. This article discussed the utilization of dredged sand by producing alkali activated materials (AAMs). The chemical and physical characteristics of the DS were analyzed. The effect of the DS on durability and mechanical characteristics of the alkali activated slag/fly materials were studied with different precursor systems. From the results, it was found that the addition of DS improved the 28 d strength and even 56 d strength. The 25% DS content increased the compressive strength of both slag rich and fly ash (FA) rich AAMs by about 5%, and the microstructure showed a denser matrix at this content. However, excessive DS can cause a decrease in flowability, early compressive strength and a decline in the compactness of the matrix. Adding an appropriate amount of DS can control the drying shrinkage. The 25% DS content has an inhibitory effect on the shrinkage development of slag rich mortar, while the similar effect on FA rich mortar appears at a content of over 50%. The adoption of DS addition to produce AAMs improves the ecological benefits of concrete engineering projects on the Yangtze River coast., Acknowledged financial supports include the National Key R&D Program of China (Grant No. 2021YFB2600200), the Fundamental Research Funds for the Central Universities (Grant No. B230205017), State Key Laboratory of High-Performance Civil Engineering Materials (Grant NO. 2019CEM002), and National Natural Science Foundation of China (Grant No. 51979090)., Peer Reviewed, Postprint (published version)

Distributed fiber optic sensors (DFOS) can detect structural cracks and structural deformation with high accuracy and wide measurement range. This study monitors the segmental prestressed bent cap, assembled with a large key dry joint, based on optical fiber technology, and it allows the comparison of its damaging process with that of a monolithic cast in place counterpart. The obtained results, comprising cross-section strain distributions, longitudinal strain profiles, neutral axis location, crack pattern, and the damage process, show that the DFOS technology can be successfully used to analyze the complex working stress state of the segmental beam with shear key joints, both in the elastic range and at the ultimate load, and to successfully identify the changing characteristics of the stress state of the segmental capping beam model when elastic beam theory no longer applies. The DFOS data confirm that the shear key joint, as the weak point of the segmental cap beam, results in the high stress concentration area, and the damage rate is higher than that of the cast-in-place beam. The accurate monitoring by the DFOS allows for the realization that the damage occurs at the premature formation of a concentrated compression zone on the upper part of the shear key., This research was funded by the National Natural Science Foundation of China (Grant 51979090). Qinghai Provincial Key R&D and Transformation Plan (Grant No. 2019SF127) and CSC scholarship of China (202206710009)., Peer Reviewed, Postprint (published version)

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Structural Engineering International on 2023, available online at: http://www.tandfonline.com/10.1080/10168664.2022.2154731., Infrastructure systems, such as bridges, are a driver for the economic growth and sustainable development of countries. Similarly, the development of operation and maintenance strategies for infrastructure systems may aim at optimal management using Key Performance Indicators (KPIs) such as reliability, redundancy, availability, safety, economy, environmental performance and resilience. Recent research and development projects, such as COST TU1406, highlight that infrastructure managers make decisions based on a mix of qualitative and quantitative data from various sources paired with models of various levels of complexity as well as expert judgement. Similarly, recent state-of-the-art academia reports on a variety of different decision-making models applicable to the optimal management of infrastructure systems may be used. Within IABSE Commission 5 on Existing Structures, Task Group 5.4 has performed a survey on implemented decision-making models among 23 infrastructure managers from 20 countries. It highlights some similarities in relation to KPIs, condition rating and limit state checks. This has stimulated the standardisation of decision making. The application of risk-based methods, performance prediction and intervention modelling are somewhat more scattered and may call for further research and development as well as training. The need to bridge the gap between implemented decision-making models and research is of paramount importance., Peer Reviewed, Alfred Strauss , Prof., University of Natural Resources and Life Sciences, Vienna, Austria; André Orcesi , Dr, Cerema, Research team ENDSUM, DTecITM/DTOA/GITEX, Champs-sur-Marne, France; Department MAST-EMGCU, Université Gustave Eiffel, IFSTTAR, Marne-la-Vallée, France; Andreas Lampropoulos, Prof., University of Brighton, Brighton, UK; Bruno Briseghella, Prof., Fuzhou University, Fujian, People’s Republic of China; Dan M. Frangopol, Prof., Lehigh University, Bethlehem, USA; Hélder S. Sousa, Dr, University of Minho, Minho, Portugal; Joan Casas , Prof., Universitat Politécnica de Catalunya, Barcelona, Spain, Postprint (author's final draft)

This material may be downloaded for personal use only. Any other use requires prior permission of the American Society of Civil Engineers. This material may be found at https://ascelibrary.org/doi/abs/10.1061/JBENF2.BEENG-5955., A partial connection–prestressing (PCP) method is proposed in this paper to decrease the prestress that was transferred to steel girders in the negative moment region of steel–concrete composite bridges. The partial connection is achieved by the application of rubber-sleeved studs (RSS) in the prestressed concrete slab in the negative moment region. Since there is no experimental research on the PCP method in continuous composite girders, to the best of the authors’ knowledge, two continuous composite girders were tested under a four-point static load to evaluate their mechanical performance. The test results showed that without decreasing the ultimate strength and overall stiffness of the steel–concrete composite girders, the PCP method enhanced the cracking load (Pcr) 3.1 times. In addition, 12.5% of the prestressing force was transferred into the steel girder at the internal support section with the PCP method, and the girder without the PCP reached 25.9%. Then, to elucidate the partial interaction effect and prestressing effect on continuous girders’ mechanical behavior, numerical models were developed and calibrated with the test results. From the numerical analysis, compared with normal composite girders, the application of RSS or prestressing could improve Pcr by 11.8% and 157.0%, respectively, and the value increases to 234.3% when RSS and prestressing are applied at the same time. The results indicate that the application of RSS in the negative moment region could effectively increase the prestressing efficiency in the concrete slab and enhance the bridge's durability., This research is sponsored by the National Natural Science Foun-dation of China (No. 51978501) and the Major Research and De-velopment Project of Jiangxi Province (No. 20165ABC2800)., Peer Reviewed, Postprint (author's final draft)

Seismic risk is a challenging problem in tall buildings due to the possibility of loss of human life and economic caused by seismic events. Peru is located at the interaction of the South American plate and the Nazca plate, which is why various seismic events of moderate to large magnitude occur. Today there are many ways to solve these problems and it is a very challenging case to reinforce tall buildings. In addition, technological advances in software facilitate and help through programmed models in tall buildings that analyze their structure characteristics such as drift, shear and others. This article proposes a comparative analysis of three types of dissipators: viscous fluid, friction, and metal creep through a Time-History analysis in a 15-story high-rise building located in Peru. The proposed methodology considers three stages: (i) definition of the characteristics and properties of the structure in accordance with Peruvian Standard E.030, in addition three accelerograms are used for the dynamic time-history analysis and maximum displacements and drifts are determined by ETABS software. (ii) calculate the design drift of the tall building and the properties of the viscous fluid, friction, and creep dissipator. In addition, calculations are made for the design parameters of each dissipator, and it is modeled as required for the case study. (iii) the new drifts and the damping values that the building presents for each dissipator are analyzed. According to the results obtained, the dissipator with the best results is of the flow type, since it has better performance in drifts and manages to produce an average damping of 96.87% for tall buildings. While the viscous dissipators obtain a 57.85% damping and the friction ones are estimated at 81.57%., Postprint (published version)

Es proposa un canvi de solució en la metodologia constructiva i en la solució del viaducte sobre el riu Cardener al PK 47+571 de la C-55. El viaducte original es va constituir amb una solució executada tram a tram per mitjà de bigues prefabricades més una capa de compressió que actua de capa de rodadura pels vehicles. Dit això, en el present projecte es planteja la possibilitat d'executar aquest viaducte pel mètode constructiu d'empenta per llinda i, en comptes de bigues, es proposa executar una secció calaix, la qual té molta més inèrcia i és més eficaç., Se propone un cambio de solución en la metodología constructiva y en la solución del viaducto sobre el río Cardener en el PK 47+571 de la C-55. El viaducto original está constituido por una solución ejecutada tramo a tramo por medio de vigas prefabricadas más una capa de compresión que actúa de capa de rodadura para los vehículos. Dicho esto, en el presente proyecto se plantea la posibilidad de ejecutar este viaducto por el método constructivo de empuje por dintel y, en lugar de vigas, se propone ejecutar una sección cajón, la cual dispone de mucha más inercia y es más eficaz., A change of solution is proposed in the construction methodology and in the solution of the viaduct over the Cardener river at PK 47+571 of the C-55. The original viaduct is constituted by a solution executed section by section, by means of prefabricated beams plus a compression layer that acts as a rolling layer for vehicles. With that said, in the present project, it is proposed the possibility of executing this viaduct by the methodology of incremental launching and, instead o beams, a box cross-section is proposed; which is a section with much more inertia and more efficient.

One of the objectives of structural health monitoring (SHM) is to maximize the information while keeping the number of sensors, and consequently the cost of the sensor system, to a minimum. Besides, the sensor configurations must be robust in the sense that the feasibility of small errors inherent to the process must not lead to large variations in the final results. This paper presents novelties regarding the robustness evaluation to model and measurement errors of four of the most influential optimal sensor placement (OSP) methods: the modal kinetic energy (MKE) method; the effective independence (EFI) method; the information entropy index (IEI) method; and the MinMAC method. The four OSP methods were implemented on the Streicker Bridge, a footbridge located on the Princeton University Campus, to identify five mode shapes of the bridge. The mode shapes, obtained in a FE model’s modal analysis, were used as input data for the OSP analyses. The study indicates that the MKE method seems to be the most suitable method to estimate the optimal sensor positions: it provides a relatively large amount of information with the lowest computational time, and it outperforms the other three methods in terms of robustness in the usual range of number of sensors., Peer Reviewed, Postprint (published version)

This is the peer reviewed version of the following article: Delgadillo, RM, Casas, JR. Bridge damage detection via improved completed ensemble empirical mode decomposition with adaptive noise and machine learning algorithms. Struct Control Health Monit. 2022; 29( 8):e2966. doi:10.1002/stc.2966 , which has been published in final form at https://doi.org/10.1002/stc.2966. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving., Structural health monitoring field is growing in the use of more modern techniques and tools in order to identify damages in civil structures. The improvements in signal processing techniques and data mining have, recently, been employed due to their powerful computational ability to detect damage in bridges. Despite the majority of researchers have been studying laboratory-scale implementations and theoretical developments, the limited data to identify structural faults in real bridges are still a problem. The current study presents a novel approach for damage identification by using two improved methods such as decomposition techniques and machine learning algorithms. Since the data obtained from the traffic vibration in real bridges are non-linear and time varying, the Hilbert–Huang transform is used to process the vibration data. Additionally, a phenomenon of mode mixing is presented in the current decomposition methods, such as empirical mode decomposition (EMD). Therefore, a novel improved completed ensemble EMD with adaptive noise (ICEEMDAN) was adopted. After the signal decomposition and identification of the damage parameter, a symbolic data analysis and clustering-based approach were developed. Additionally, an unsupervised machine learning algorithm was used to group substructures with similar behavior and then detect damages. This learning method was used for automatically classifying the damages using a moving windows process sequentially applied to the structural response of the bridge. The validity of the approach is demonstrated using real data collected from a truss bridge. The results show that the proposed mixed method was effective and can endow better results in bridge health monitoring., The first author would like to thank Ministry of Education of Peru with the Educational Credit Program PRONABEC – Bicentennial Generation Scholarship for the great support as part of the work on his PhD diploma thesis. The authors also wish to thank the Prof Chul-Woo Kim, Department of Civil and Earth Resources Engineering, Kyoto University, Kyoto, Japan for giving us the data as well as documentation from the steel truss bridge utilized in this research work., Peer Reviewed, Postprint (author's final draft)

In this paper, the project case of Qiwu bridge in Jiangxi Province using link slab action between simply sup-ported spans is introduced. The structural system of Qiwu Bridge consists of a series of 3 simply supported steel-concrete composite spans connected at the pier supports by a link slab, so at this point only continuity through the concrete slab is achieved (semi-continuous bridge). This solution has both advantages of smooth driving condition of continuous bridge and enhancement of durability by removing expansion joints and clear structural behavior as simply supported spans. A non-linear finite element model of Qiwu Bridge was estab-lished through ABAQUS to simulate and predict the mechanical response and structural performance of this semi-continuous solution. Numerical results showed that the removal of the shear connection between steel beams and concrete slab close to the supports magnificently increased the stress level in the shear stiffness mutation region and made it easier to crack. A monitoring plan is also introduced to follow the actual structural response of Qiwu bridge during construction and along the service life to check the long-term performance of the proposed solution. The monitoring system is also described in the paper and the preliminary results during the early construction stages are also presented., Postprint (published version)

This deliverable presents a report of the needs for structural control on buildings (initial imperfections, deflections at service, stability, rheology) and on bridges (vibrations, modal shapes, deflections, stresses) based on state-of-the-art image-based and sensor-based techniques. To this end, the deliverable identifies and describes strategies that encompass state-of-the-art instrumentation and control for infrastructures (SHM technologies)., Objectius de Desenvolupament Sostenible::8 - Treball Decent i Creixement Econòmic, Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura, Preprint

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Structural Engineering International on 2022, available online at: http://www.tandfonline.com/10.1080/10168664.2022.2048436, In the hogging moment regions of steel–concrete composite continuous girder bridges, a detrimental condition appears such that concrete slab bears tensile stress and the steel girder bears compressive stress. Decreasing the shear connection in the hogging moment regions helps to improve the mechanical performance for steel–concrete continuous composite girder bridges. In this paper, analytical models for the calculation of composite girders considering partial shear connection (PSC) action are discussed. A project case of Qiwu Bridge in Jiangxi Province using partial shear connection action is introduced. A nonlinear finite element model of Qiwu Bridge is established through ABAQUS® to simulate and predict the mechanical properties and structural performance. Based on the finite element method results, the influence of PSC on various parameters is analysed by performing a parametric analysis. Numerical results show that arranging a partial shear connection region can effectively reduce the crack region and disperse areas having high stress concentration, but shear stiffness mutation can significantly increase the stress level at the edge of the partial shear connection region., This work was supported by the China Scholarship Council [Grant number: 202106260050] and the Zhejiang Provincial Program of Traffic Engineering Construction [Grant number: 2020031]., Peer Reviewed, Postprint (author's final draft)

Casting an extra concrete bottom layer to a steel-concrete composite box girder in a hogging moment region can increase sectional stiffness and prevent steel buckling. However, a lower sectional neutral axis may not be favorable to concrete slab cracking and steel flange stress control. To this end, a double composite girder segment was proposed and investigated. Particularly, a static loading test on a large-scaled two-span continuous girder specimen with the double composite action in hogging moment region was conducted for mechanical investigation. Meanwhile, parametric analysis was carried out as well for a rational design scheme of the double composite section. The test results revealed that the load-carrying capacity of double composite section could be increased due to the contribution of extra bottom concrete layer. The transverse deformation of steel parts was favorably constraint. The parametric analysis results indicated that slab thickness that was 15% of steel girder height could provide most obvious contributions to the improvements of both sectional load-carrying capacity and cracking moment. Due to the additional reinforcement, the steel web thickness of double composite girder can be saved 16.7% and the steel bottom flange thickness only needs to meet the constructing requirement compared with common composite girder. Besides, the analysis also showed replacing the tub section with steel box section in the hogging moment region can reduce the stress on top flange by 24.4%. These results are an important basis for establishing a rational design scheme for the novel double composite section., This research is sponsored by the National Natural Science Founda-tion of China (No. 51978501) and the China Scholarship Council (No. 202106260050). The supports are gratefully appreciated., Peer Reviewed, Postprint (author's final draft)

Tesi en modalitat de compendi de publicacions, In recent years the scientific community has been developing new techniques in structural health monitoring (SHM) to identify the damages in civil structures specially in bridges. The bridge health monitoring (BHM) systems serve to reduce overall life-cycle maintenance costs for bridges, as their main objective is to prevent catastrophic failures and damages. In the BHM using dynamic data, there are several problems related to the post-processing of the vibration signals such as: (i) when the modal-based dynamic features like natural frequencies, modes shape and damping are used, they present a limitation in relation to damage location, since they are based on a global response of the structure; (ii) presence of noise in the measurement of vibration responses; (iii) inadequate use of existing algorithms for damage feature extraction because of neglecting the non-linearity and non-stationarity of the recorded signals; (iv) environmental and operational conditions can also generate false damage detections in bridges; (v) the drawbacks of traditional algorithms for processing large amounts of data obtained from the BHM. This thesis proposes new vibration-based parameters and methods with focus on damage detection, localization and quantification, considering a mixed robust methodology that includes signal processing and machine learning methods to solve the identified problems. The increasing volume of bridge monitoring data makes it interesting to study the ability of advanced tools and systems to extract useful information from dynamic and static variables. In the field of Machine Learning (ML) and Artificial Intelligence (AI), powerful algorithms have been developed to face problems where the amount of data is much larger (big data). The possibilities of ML techniques (unsupervised algorithms) were analyzed here in bridges taking into account both operational and environmental conditions. A critical literature review was performed and a deep study of the accuracy an, En los últimos años la comunidad científica ha desarrollado nuevas técnicas en monitoreo de salud estructural (SHM) para identificar los daños en estructuras civiles especialmente en puentes. Los sistemas de monitoreo de puentes (BHM) sirven para reducir los costos generales de mantenimiento del ciclo de vida, ya que su principal objetivo es prevenir daños y fallas catastróficas. En el BHM que utiliza datos dinámicos, existen varios problemas relacionados con el procesamiento posterior de las señales de vibración, tales como: (i) cuando se utilizan características dinámicas modales como frecuencias naturales, formas de modos y amortiguamiento, presentan una limitación en relación con la localización del daño, ya que se basan en una respuesta global de la estructura; (ii) presencia de ruido en la medición de las respuestas de vibración; (iii) uso inadecuado de los algoritmos existentes para la extracción de características de daño debido a la no linealidad y la no estacionariedad de las señales registradas; (iv) las condiciones ambientales y operativas también pueden generar falsas detecciones de daños en los puentes; (v) los inconvenientes de los algoritmos tradicionales para procesar grandes cantidades de datos obtenidos del BHM. Esta tesis propone nuevos parámetros y métodos basados en vibraciones con enfoque en la detección, localización y cuantificación de daños, considerando una metodología robusta que incluye métodos de procesamiento de señales y aprendizaje automático. El creciente volumen de datos de monitoreo de puentes hace que sea interesante estudiar la capacidad de herramientas y sistemas avanzados para extraer información útil de variables dinámicas y estáticas. En el campo del Machine Learning (ML) y la Inteligencia Artificial (IA) se han desarrollado potentes algoritmos para afrontar problemas donde la cantidad de datos es mucho mayor (big data). Aquí se analizaron las posibilidades de las técnicas ML (algoritmos no supervisados) teniendo en cuenta t, Postprint (published version)

This thesis develops a new structural strengthening technique: converting existing reinforced concrete structures to composite sections by inserting connectors after controlled demolition with high-pressure water. The key point of the research, of a technological nature, is the technique of hydro demolition, which is very unusual in strengthening projects. This technique, applied to existing structures (reinforced or prestressed concrete) makes new reinforcement techniques possible, thanks to the opening of voids and the non-affectation of the existing reinforcement. At present, this technique is mostly used for complex demolition or repair work but not for strengthening. It is in these demolished areas where it is easy to re-reinforce with new rebars, or to insert connectors (to convert to composite section), prior to injection with fluid repair mortars. The increasing robotisation of the hydro demolition terminals already allows an autonomous and programmed advancement of various demolition parameters, even underwater. The resulting interfaces are very solid and crack-free and have good production rates. This ensures a high connection strength, as there are no loose bores and the connectors can be inserted in reinforced areas. This results in very strong reinforcements, as high gradients are transmitted. This results in very strong reinforcements, as high shear forces could be transmitted. To take advantage of the rapid progress of hydro demolition, the use of traditional concretes is discarded and the adaptation and use of high performance mortars (hardening in a few hours) is investigated. To improve post-breaking behaviour, locally in the bolt head area, and to reduce cracking, structural polymeric fibres are incorporated into the interface mortar. This work explores a new structural reinforcement technique, and the development is limited to beam-type elements, although the concept is generically extensible to other structural typologies (walls, D-regions, etc., Esta tesis desarrolla una nueva técnica de refuerzo estructural: convirtiendo estructuras existentes de hormigón armado o pretensado a secciones mixtas, mediante la inserción de conectadores previa demolición controlada con agua a alta presión. El punto clave de la investigación, de carácter tecnológico, es la técnica de hidrodemolición, muy poco habitual en realizaciones de refuerzo. Esta técnica posibilita nuevas técnicas de refuerzo, gracias a la apertura de huecos y la no afectación del armado existente. Es en estas zonas demolidas dónde resulta simple el rearmado con nueva armadura, o la inserción de conectores (para convertir a sección mixta), previo a la inyección con morteros de reparación fluidos. La creciente robotización de los terminales de hidrodemolición ya permiten un avance autónomo y programado de varios parámetros de la demolición, incluso en estruturas sumergidas. Las interfases resultantes son muy sólidas, libres de fisuración y con rendimentos de avance elevados. Gracias a ello se garantiza una gran solidez de la conexión, al no existir taladros con holguras y al poder insertar los conectores en zonas armadas. De esta forma se consiguen refuerzos de gran potencia, al trasmitirse rasantes elevados. Para aprovechar el rápido avance de la hidrodemolición, se descarta el uso de hormigones tradicionales y se investiga la adaptación y empleo de morteros de altas prestaciones (endurecimiento en pocas horas). Para mejorar el comportamiento en post-rotura, a nivel local en la zona de la cabeza del perno, y para reducir la fisuración, se incorporan fibras poliméricas estructurales al mortero de interfase. Este trabajo explora una nueva técnica de refuerzo estructural, y para su desarrollo se limita a elementos tipo viga, aunque el concepto de forma genérica es extensible a otras tipologías estructurales (muros, regiones D, etc.). El trabajo da continuidad a investigaciones y realizaciones previas realizadas en USA y Suecia, dónde se ¿post-conectan¿ puente, Postprint (published version)

We live in an environment of ever-growing demand for transport networks, which also have ageing infrastructure. However, it is not feasible to replace all the infrastructural assets that have surpassed their service lives. The commonly established alternative is increasing their durability by means of Structural Health Monitoring (SHM)-based maintenance and serviceability. Amongst the multitude of approaches to SHM, the Digital Twin model is gaining increasing attention. This model is a digital reconstruction (the Digital Twin) of a real-life asset (the Physical Twin) that, in contrast to other digital models, is frequently and automatically updated using data sampled by a sensor network deployed on the latter. This tool can provide infrastructure managers with functionalities to monitor and optimize their asset stock and to make informed and data-based decisions, in the context of day-to-day operative conditions and after extreme events. These data not only include sensor data, but also include regularly revalidated structural reliability indices formulated on the grounds of the frequently updated Digital Twin model. The technology can be even pushed as far as performing structural behavioral predictions and automatically compensating for them. The present exploratory review covers the key Digital Twin aspects—its usefulness, modus operandi, application, etc.—and proves the suitability of Distributed Sensing as its network sensor component., This research was funded by Fondazione CARITRO Cassa di Risparmio di Trento e Rovereto, grant number 2021.0224., Peer Reviewed, Postprint (published version)

Nowadays, the seismic study of corroded reinforced concrete elements is a matter of increasing concern, in particular as regards links such as bridges in infrastructural networks. As the first step in an ongoing research, a prestressed concrete bridge overpass (continuous two spans with one central pier between the bents) was selected to perform response spectrum seismic analyses considering corrosion degradation. This was based on the development of a finite element model of the structure and allowed the assessment of the degrading seismic capacity of the reinforced concrete bridge pier at different periods caused by general and pitting corrosion. For this purpose, corrosion models from existing literature were used. An unchecked factor of this first research step is that corrosion can also affect bonding between the longitudinal reinforcing bars and concrete, thus increasingly reducing ductility and safety performance. Moreover, in a corroded structure bond strength and confinement capacity can also decrease due to the transverse reinforcement area loss, and concrete cover cracking and spalling. The new step developed in this work focuses on the bonding failure effects due to corrosion processes and how this affects the seismic performance of the deteriorated pier. The analysis is based on the introduction and validation of an empirical model for the assessment of the remaining bonding in corroded concrete elements with respect to experimental results., Postprint (published version)

A reduction in composite action using a partial shear connection (PSC) in the hogging moment region of a steel–concrete bridge can mitigate the concrete tensile cracking risk while maintaining the structural ultimate bearing capacity. To date, specific mechanical effects, important for the establishment of evaluation theory, have not been studied. To this end, four girders and six push-out specimens were tested for the effect investigation. Numerical analysis with material damage plasticity models and an analytical study were conducted for parametric and mechanistic investigations. The push-out test results showed that a wrapping rubber sleeve reduced the shear stiffness of the stud by 91.9%, whereas its strength varied slightly. The girder test results showed that arranging rubber sleeved stud (RSS) connectors in the composite girders reduced the girder load-carrying capacity and bending stiffness by 17% and 12%, respectively. Moreover, the concrete tensile cracking performance was improved. The analysis results showed that, for reducing the concrete tensile stress, the RSS connector in the girder had a more favourable effect on prestress distribution than increasing the ordinary stud spacing. In addition, an evident stress concentration appeared when the stud distance was increased. According to the analytical analysis of the girder under negative bending, the concrete tensile stress is exponentially related to the interlayer stud stiffness, and the exponential is expected to be 5/3. The research revealed the detailed mechanical behaviour of the girder with a PSC and simultaneously compared the effects of the two PSC methods. This research will help establish design and evaluation methods for PSC action., This research was sponsored by the National Natural Science Foundation of China (No. 51978501), Fundamental Research Funds for the Central Universities (No. 22120210437), and China Scholarship Council (No. 202106260050). This support is greatly appreciated., Peer Reviewed, Postprint (author's final draft)

The effects of corrosion focusing on the consequences of bond strength deterioration for a reinforced concrete bridge pier in a seismic affected area are examined in this research. A bond degradation model based on the local bond stress-slip model presented in FIB Model Code 2010 is chosen. A motorway overpass object of a previous study, which considered the rebars cross-section reduction effect only, has been selected to assess the seismic capacity of the corroded pier in the time domain when bond degradation due to corrosion is also taken into account. The modification of strength capacity and ductility of the structural element is analyzed and the effect of corrosion during the whole service life of the structure is obtained. It is concluded that the effect of bond degradation is more critical for the safety of the pier than the effect of rebars cross-section loss., Peer Reviewed, Postprint (published version)

Structural health monitoring (SHM) is being widely used for the safety assessment and management of existing bridges and structures. One of the objectives related to SHM is to maximize the information gained from the structural testing, while keeping the number of sensors and consequently the cost of the sensor system to a minimum. The current work investigates four of the most influential optimal sensor placement (OSP) methods: the modal kinetic energy (MKE) method, the effective independence (EFI) method, the information entropy index (IEI) method and the MinMAC method. The methods were developed in MATLAB and used as input data the modal analysis results of a finite element model built in ANSYS of the Streicker Bridge, a pedestrian bridge located on the Princeton University Campus. The resulting sensor positions were estimated for a configuration with 14 sensors, and the four OSP methods were evaluated for different numbers of target sensors in terms of different OSP criteria: the determinant (DET) of the Fisher information matrix, the information entropy index (IEI) and the root mean square (RMS) of the off-diagonal entries of the MAC matrix. The study indicates that the EFI method should be chosen to estimate the optimal sensor positions as it provides the largest amount of information with a relatively low computation time., The authors are indebted to the Spanish Ministry of Economy and Competitiveness for the funding provided through the research project BIA2017-86811-C2-1-R. All these projects are funded with FEDER funds. Authors are also indebted to the Secretaria d’ Universitats i Recerca de la Generalitat de Catalunya for the funding provided through Agaur (2017 SGR 1481)., Postprint (author's final draft)