Search

One of the most effective ways to encourage the use of new approaches like BIM consists on applying Project Based Learning (PBL). According to this methodology, teams might gain knowledge and skills by solving a realistic challenge, that is to say, they learn by doing. In this way, team members can experiment and investigate by themselves. BIM contests stands as one of the most encouraging PBL activities. This format has the additional advantage that all teamOne of the most effective ways to encourage the use of new approaches like BIM consists on applying Project Based Learning (PBL). According to this methodology, teams might gain knowledge and skills by solving a realistic challenge, that is to say, they learn by doing. In this way, team members can experiment and investigate by themselves. BIM contests stands as one of the most encouraging PBL activities. This format has the additional advantage that all teams work on the same problem, what eases the comparison of the results. In this sense, the analysis of the proposed Building Execution Plan (BEPs) provides useful insights about the know-how of the different designs. Despite the interest and usefullness of these results, no comparisons of similar BIM work flows have been carried out. To solve this gap, this paper analyzes, for the first time, the BEPs of the BIM projects presented in the different calls of the international contest BIM Valladolid. This analysis provides a useful insight about the most common software in each discipline. The evolution of the software of teams throughout time, as well as the information flows between the modeling and the structural analysis software of the proposals are also presenteds work on the same problem, what eases the comparison of the results. In this sense, the analysis of the proposed Building Execution Plan (BEPs) provides useful insights about the know-how of the different designs. Despite the interest and usefullness of these results, no comparisons of similar BIM work flows have been carried out. To solve this gap, this paper analyzes, for the first time, the BEPs of the BIM projects presented in the different calls of the international contest BIM Valladolid. This analysis provides a useful insight about the most common software in each discipline. The evolution of the software of teams throughout time, as well as the information flows between the modeling and the structural analysis software of the proposals are also presented

Emissions from transportation have a severe impact on the current climate crisis. Therefore, the estimation of these pollutants requires precise measurements that integrate both traffic and vehicle fleet information within a specific country or area. However, the current estimation tools continue using vehicle fleet standards based on recommendations or local studies. A problem for the current estimation models arises due to the difficulty of centralizing the large number of vehicle statistics. This article has taken advantage of the capabilities of both visual programming tools and building information modeling (BIM) to centralize databases from different sources, generating a model that integrates current traffic data and vehicle fleet statistics. The proposed platform estimates emissions and the carbon footprint using TIER 1 emission factors recommended by the European Environmental Agency (EEA). This platform has been successfully applied to a case study to estimate the carbon footprint of the B-20 road in Barcelona, using current vehicle restriction scenarios. This case study presents a maximum difference of -2.72% compared with the estimations made by another similar report. This proposed platform more completely automates the communication among the equations and databases required to estimate traffic road emissions. This work was supported in part by the National Agency for Research and Development (ANID) for the Scholarship Program ``DOCTORADO BECAS CHILE/2019'' Folio under Grant 72200098, in part by the Spanish Ministry of Economy and Competitiveness and the FEDER fund through the projects under Grant BIA2017-86811-C2-1-R (directed by Jose Turmo) and Grant BIA2017-86811-C2-2-R, in part by the Secretaria d' Universitats i Recerca of the Generalitat de Catalunya through Agaur under Grant 2017 SGR 1481, and in part by the Technology Cooperation Project of Shanghai Qizhi Institute under Grant SYXF0120020109.

The Building Information Modeling (BIM) methodology improves architectural and infrastructure projects by digitizing their processes throughout their life cycle stages, such as design, construction, management, monitoring, and operation. In recent years, the automation of these processes has been favored by the use of visual programming (VP) tools that have replaced conventional programming languages for visual schemes. The use of these tools in architectural projects is becoming increasing popular. However, this is not the case in infrastructure projects, for which the use of VP algorithms remains scarce. The aim of this work is to encourage both scholars and engineers to implement VP tools in infrastructure projects. For this purpose, this work reviews, for the first time in the literature, the state-of-the-art and future research trends of VP tools in infrastructure projects. This work was funded by the National Agency for Research and Development (ANID) for the Scholarship Program “DOCTORADO BECAS CHILE/2019”–Folio n°72200098 and by the Spanish Ministry of Economy and Competitiveness and the FEDER fund through the projects BIA2017-86811-C2-1-R directed by José Turmo and BIA2017-86811-C2-2-R. Authors are also indebted to the Secretaria d’ Universitats i Recerca of the Generalitat de Catalunya for the funding provided through Agaur (2017 SGR 1481).

Collecting the information of traffic load, especially heavy trucks, is crucial for bridge statistical analysis, safety evaluation, and maintenance strategies. This paper presents a traffic sensing methodology that combines a deep learning based computer vision technique with the influence line theory. Theoretical background and derivations are introduced from both aspects of structural analysis and computer vision techniques. In addition, to evaluate the effectiveness and accuracy of the proposed traffic sensing method through field tests, a systematic analysis is performed on a continuous box-girder bridge. The obtained results show that the proposed method can automatically identify the vehicle load and speed with promising efficiency and accuracy and most importantly cost-effectiveness. All these features make the proposed methodology a desirable bridge weigh-in-motion system, especially for bridges already equipped with structural health monitoring system.

Infrastructures such as aerial tramways carry unique traffic operations and have specific maintenance requirements that demand constant attention. It is common that old structures lack any type of automatization or monitoring systems, relying only on human judgment. Owners are interested in implementing techniques that assist them in making maintenance decisions, but are reluctant to invest in expensive and complex technology. In this study, researchers discussed with the owners different options and proposed a sustainable and cost-efficient solution to monitor the Sandia Peak Tramway operations with just two strategically located acceleration sensors. To maximize the success options researchers worked with the owners and developed a sensor that satisfied their needs. A Low-cost Efficient Wireless Intelligent Sensor 4—Outdoors (LEWIS 4) was developed, tested and validated during the experiment. Two solar-powered units were installed by the tramway staff and recorded data for three days. When retrieved, researchers analyzed the data recorded and concluded that with only two sensors, the acceleration data collected were sufficient to determine the position and location of the tramway cars. It was also found that the sensor on the tower provides data about the cable–tower interaction and the forces caused by the friction on the system, this being a critical maintenance factor. This work summarizes a methodology for infrastructure owners consisting of guidelines to design a sustainable and affordable monitoring approach that is based on the design, development and installation of low-cost sensors.

This article presents the application of the problem-based learning (PBL) methodology for introducing the civil engineering task of bridge design and construction to high school students wi...

La metodología Building Information Modelling (BIM) está revolucionando la manera en la que se desarrollan los proyectos de ingeniería civil. Una de las muchas ventajas de esta metodología es el desarrollo de modelos 3D, los cuales pueden ser conectados con herramientas de realidad aumentada. Entre las múltiples ventajas de la aplicación de esta tecnología en el campo de la ingeniería civil, resalta la accesibilidad de obtención de un gran nivel de detalle e información de un determinado elemento, facilitando la visualización y comprensión para todos los agentes. Hoy en día, esta tecnología está consolidada en sectores como el turismo o los video juegos, y cada vez está siendo más popular en estudios de arquitectura o inmobiliarias. Sin embargo, la realidad aumentada es una tecnología en desarrollo, y por ahora sus aplicaciones en la ingeniería civil son relativamente escasas. El objetivo del presente artículo es ilustrar el estado actual de la aplicación de BIM y de realidad aumentada en la ingeniería civil. Con tal objetivo, se analizarán los softwares más representativos de realidad aumentada y se analizará su aplicación en un puente elaborado con BIM. Tras este análisis, se obtendrán conclusiones sobre la interoperabilidad entre ambos. Por último, se expondrán las ventajas e inconvenientes encontrados para la aplicación de realidad aumentada en el campo de la ingeniería civil.

Nowadays,low-cost sensors and acquisition devices have been emerging as an obvioussolution to many innovative applications such as Structural Health Monitoring (SHM) systems. In this paper,issues regarding dynamic data acquisition,as well as their respective solutions,are presented. Moreover, a comprehensive description through-out an inexpensive sensor network system using open-source hardware for a real-time acceleration data acquisition has beenpresented. The platform consists of an accelerometer, an Arduino board,and a computeras a data recorder and presenter. Data is recorded through an efficient microcontroller code that can provide a considerable reading frequency (up to 300Hz). Using Python, instant acceleration recording for all the threeaxes has been done. It is shown how the performance of the proposed system is efficientfor the field of SHM systems. 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 directed by José Turmo and BIA2017-86811-C2-2-R, directed by Jose Antonio Lozano-Galant. 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). It is also to be noted that funding for this research has been provided for MR. SEYEDMILAD KOMARIZADEHASL by Agencia Estatal de Investigación del Ministerio de Ciencia Innovación y Universidades grant and the Fondo Social Europeo grant (PRE2018-083238).

The use of Building Information Modelling (BIM) is getting more and more popular since governments worldwide are increasing the demand of this methodology as a requirement in their projects. One of the most encouraging ways to promote the use of this methodology is based on the so-called BIM contests, where practitioners are challenged to build a virtual model of a structure collaboratively. These challenges are usually designed to take the participants out of their comfort zone and to encourage them to experiment in the use of the latest software and collaborative software connections. Unlike other activities encouraging BIM, these contests have the additional advantage of easing the comparison in terms of software, exchange file formats and information flows as all the proposals are framed into a common project with the same working time. Despite the interest of this kind of comparative analyses, no studies of the results of BIM contest proposals can be found in the literature. To fill this gap, this paper analyses the summary reports of the different proposals submitted in three editions (2014, 2015 and 2016) of the BIM Valladolid contest in Spain. The results of this study provide usefull insights into the use of software in a number of disciplines (Architecture, Structural Analysis, Energy Efficiency, Measurements and Budget, Facilities, Planning Execution and Coordination) and the most common file exchange formats. The evolution of teams in software use throughout the different contest editions as well as the information flow among the Architecture and the Structural Analysis disciplines are also analyzed.

Despite its importance in some structures, shear deformation is systematically neglected by most static structural system identification methods. This paper analyzes for the first time in the literature the effect of this deformation in the static inverse analysis of thin web bridges. This study is focused on the observability techniques. The most recent formulation found in the literature is based onthe Euler-Bernoulli beam theory. This formulation is unable to identify correctly the characteristics of a structure (such as flexural stiffness) when shear deformation is not negligible. To solve this problem, the observability method is updated according to Timoshenko's beam theory. This formulation uses an algebraic method which combines a symbolical and a numerical application. Thus, the updated observability formulation is able to obtain not only the flexural stiffness but also the shear one. Besides this, a parametric equation of the estimates is obtained for the first time in the literature. Some examples of growing complexity are used to illustrate the validity of the the proposed formulation formulation.

Traditionally, Spanish schools of civil engineering provide their students a class on “Technical English” in order to develop their language skills. However, this class does not cover all the skills that the student would need in the labor market and mainly focuses in the reading and writing skills, and in a lower degree in the speaking and listening ones. This paper proposes a series of innovative and informal training activities, such as cine-forum on technical civil engineering topics and role playing on real professional situations, that allow Spanish civil engineering students to develop English skills, that can rarely be worked in the classroom (i. e. speaking, negotiating and conversing), which encourage debate, participation, and foster their self-confidence to speak about technical-English topics in public. Although the students’ level of English is much lower than expected, they all agree on the importance of technical English for their future career. The results also show the students’ lack in skills that are difficult to train in regular classes (speaking and talking). Consequently, this situation would require to provide complementary activities like the ones suggested in this project in order to develop these skills and increase the students’ demand for engineering classes taught in English. В последние годы традиционное преподавание с использованием обычной доски дополняется визуальными средствами, такими как слайд-проекторы и видео. Феноменальный рост Интернета привел к появлению новых учебных средств массовой информации, таких как онлайн-курсы общего пользования, которые делают доступными образовательные ресурсы для более широкого и удаленного контингента студентов. Легкий доступ к образованию может повысить мотивацию, что является полезным коммерческим инструментом для университетов. В отличие от других дисциплин, таких как экономика или психология, МООК редко используются для распространения курсов по дисциплинам направления «Строительство». Чтобы восполнить этот пробел и поощрить использование МООК среди строительных университетов, в настоящем документе представлен опыт создания такого курса для многодисциплинарного проектирования мостов, созданных Университетом Кастилии и Ла Манча. Этот курс основан на опыте, полученном на конкурсе по строительству мостов с заданиями для студентов‑магистрантов, организованных Университетом Кастилии и Ла Манча в 2015, 2016 и 2017 годах.

In the field of bridge structural system identification (SSI), Bernoulli beam element models are often used to solve inverse problems. More rarely, Timoshenko beam element models can be calibrated. However, these models account for only the general shear effects, whereas other shear effects, such as shear lag, are not accounted for. However, as wide-flange box girder bridges become prevalent due to design demands, neglecting shear lag may introduce significant errors in predicting the mechanical parameters of the system and, hence, reduce the accuracy. In this paper, for the first time, the shear lag's effect on the vertical deflections is taken into account in an inverse problem. A parametric SSI, the observability method (OM), is updated to address the identification of thin-walled box girder bridges with wide flanges, including the shear lag effects. The structural analytical equations are used to connect the spatial shear effects with the beam-unidimensional-element model to be applied in the inverse analysis, which is referred to as the analytical observability method (AOM-SSI). This updated version of the OM is established and validated to identify the mechanical parameters of a structural test. The identified mechanical parameters show much better agreement with the expected results than those obtained with previous methods. This work was supported by BIA2017-86811-C2-1-R Spanish Ministry of Economy and Competitiveness, Spain. It was also supported by the Innovation Group Project, Natural Science Foundation of Hubei, China (Grant No. 2020CFA047) and the National Natural Science Foundation of China (Grant No.52178104).

[EN] This paper describes a study of the Tempul Aqueduct, one of the first structures designed and built by Eduardo Torroja. At a time when computers did not exist, Torroja's courage and innovation were outstanding. He was in no way constrained by a lack of theoretical knowledge, inadequate materials and the contemporary doubts about cable-stayed structures. In fact, he was able to build one of the world's first prestressed concrete structures, and a precursor to modern cable-stayed and extradosed bridges. This paper briefly reviews the history of the Tempul Aqueduct, gives the results of the analysis of this structure by several Finite Element Models (FEMs), and compares the FEM results to those obtained by Torroja himself. The FEM results confirm the validity of Torroja's conceptual design. The paper also contains a detailed analysis of the influence of the structural system on the behavior of the bridge and the effect of removing the live loads with the aim of providing a better understanding of the context and behavior of the Tempul aqueduct., Funding for this research has been provided to Mr Lozano-Galant by the Spanish Ministry of Economy, Industry and Competitiveness (Research Project BIA2013-47290-R from FEDER funds). The authors are also grateful to Prof. S. Buonopane of Bucknell University and J.L. Temprado, of COMPOSAN, for their assistance and support. The authors also want to thank the CEHOPU-Archivo Torroja, for all the information and support provided.

Structural Health Monitoring (SHM) is essential to assess the accuracy of durability predictions of structures. Using low-cost sensors on structural evaluation has gained significant attention compare to high-cost sensors. Although these may not be as accurate and sensitive as the expensive electronic devices, with efficient code and right use, there is a possibility of getting useful information from them. These sensors can vary based on their functionality and the measurements they provide. For example, one is highly sensitive to the light of its environment while the other kind would give different results in different temperatures. In this paper, three different displacement measuring sensors have been studied. An ultrasonic sensor (HC-SR04) and two different types of laser sensors (VL53L0X and VL53L1X) are investigated in the paper. An Arduino Mega has captured their measured data, and a raspberry pi has made the acquisition. Not only issues regarding coding and placing of these sensors have been presented ultimately, but precise solutions for the aforementioned problems as well as an efficient way of assembling all the sensors are also presented in this paper. The data generated from these electronic devices can be used for Structural Health Monitoring applications. 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 directed by José Turmo and BIA2017-86811-C2-2-R, directed by Jose Antonio Lozano-Galant. 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 1482). It is also to be noted that funding for this research has been provided for MR. SEYEDMILAD KOMARIZADEHASL by Agencia Estatal de Investigación del Ministerio de Ciencia Innovación y Universidades grant and the Fondo Social Europeo grant (PRE2018-083238).

Temperature and humidity measurements provide useful information on multiple areas of civil engineering application such as Structural Health Monitoring (SHM), Structural System Identification (SSI) and structures rehabilitation. Majority of the existing commercial systems are so costly and also these measurement paradigms need many reference spots for a full-scale structure. The aforesaid paradigms are based on collecting data through smart devices, transferring information to each other and in the final stage processing the obtained information collaboratively through cloud computing or the others technologies. Taking into account the above information and obstacles, utilizing the Open Source Platforms (OSP) microcontrollers like Arduino as well as low cost sensors are attracting more and more attention. This paper gives a comprehensive information about the most determinant aspects of the aforementioned kits in terms of their pros and cons, installation procedure, communication protocol, number of the required connections and specific characteristics of the data acquisition system, Las mediciones de temperatura y humedad proporcionan información útil en múltiples áreas de aplicación de la ingeniería civil, como la monitorización de la salud estructural (SHM), la identificación de sistemas estructurales (SSI) y la rehabilitación de estructuras. La mayoría de los sistemas comerciales existentes son muy costosos y además estos paradigmas de medición necesitan muchos puntos de referencia para una estructura a escala real. Dichos paradigmas se basan en la recogida de datos a través de dispositivos inteligentes, la transferencia de información entre ellos y, en la etapa final, el procesamiento de la información obtenida de forma colaborativa a través de la computación en la nube u otras tecnologías. Teniendo en cuenta la información y los obstáculos anteriores, la utilización de microcontroladores de plataformas de código abierto (OSP) como Arduino, así como de sensores de bajo coste, está atrayendo cada vez más atención. Este artículo ofrece una información exhaustiva sobre los aspectos más determinantes de los kits mencionados en términos de sus pros y sus contras, el procedimiento de instalación, el protocolo de comunicación, el número de conexiones necesarias y las características específicas del sistema de adquisición de datos.

In a staggered erected cable-stayed bridge made of concrete, time-dependent phenomena (suchas creep or shrinkage) effects might play an important role in both its geometry and its stress state. In fact, because of these phenomena, stays will indeed lose force and higher bending moments will appear in the structure. To compensate these effects, one or two re-stressing operations are traditionally planned during the life time of long span cable- stayed bridges made of concrete. These re-stressing operations might be technologically challenging and always imply additional costs. To guarantee that allowable stresses and deflections are not exceeded during erection, a number of simulation methods are presented in the literature. Some of these methods, concretely those based on a backward simulation approach, fail addressing the effects of the timedependent phenomena. To simulate these effects, methods based on the forward simulation approach are traditionally followed. Nevertheless, the main trade-off of these algorithms is that their computation is based on complex iterative processes that make simulation more time consuming. Furthermore, these methods are not able to avoid the need of additional re-stressing operations in service to prevent the effects of the timedependent phenomena. To fill all these gaps, a new simulation algorithm, the Forward-Direct Algorithm (FDA), is formally presented in this paper to simulate the construction process of cable-stayed bridges including the time-dependent phenomena effects. This algorithm takes advantage of the unstressed length of the stays concept to carry out a computationally efficient simulation based on an innovative direct simulation approach. The major advantage of this algorithm is the fact that the prestressing operations during construction can be defined to avoid the need of additional re-tensioning operations in service. To illustrate the creep and shrinkage effects, the proposed algorithm is applied to a real cable-stayed bridge. This tool also can be used by the designer or the contractor for construction control of the strand by strand tensioning technique.

This paper presents a finite element model for the analysis of composite beams with partial interaction. In this model, the elements of the composite beams are modeled by six different types of frame elements. Compared with other methods presented in the literature, the main advantages of the proposed method are as follows: (1) intuitiveness, as the different elements of the model present a close and easy to understand relation with the structural behavior of the composite beam; (2) applicability as the method directly provides useful information for the design work; (3) versatility and generalization in dealing with any combination of loading and boundary conditions (Furthermore, the proposed model enables the analysis of statically indeterminate structures, tapered beams as well as structures with non-uniform shear connector distributions.); (4) easy elaboration of models; and (5) possible widespread use of the model, as the proposed method can be implemented in any structural software. To validate the accuracy and the efficiency of the proposed model, a set of FEMs are verified against those results obtained by analytical equations available in the literature for different boundary and loading conditions. Furthermore, a set of parametric studies are performed to investigate the effects of the size of the FEMs along with the influence of the connection stiffness on the behavior of composite beams with different I beams.

Structural collapses have indirectly produced important progress in science. The last lesson learnt from structural collapses reveals the important role of polyrational systems of equations in the Civil Engineering field, as all problems in Physics and Engineering involving scale variables lead to systems of these equations. Since no efficient methods are known to solve this type of equations, a powerful and efficient method to multivariate polyrational equations using observability techniques is presented in this paper. It is pointed out that this method can be applied to solve different Civil Engineering problems. The information obtained by this tool can be used to assist decision making and risk management processes during maintenance and service life. As an example of its use, a structural damage detection problem is solved.

Construction of cable stayed bridges is very challenging. These structures are extremely redundant and the effect of tensioning one cable has the effect of changing the stresses of the already installed cables. In order to achieve a targeted service state at the end of the construction process careful calculations has to be done by the contractor in order to ensure it. However, deviations arise between the modelling of the tensioning process and the actual results obtained on site. In order to adjust the final stresses in the cables, a final restress of the stays is unusually required. This re-stressing operation is usually done for the whole cable, as the strand by strand stressing technique used for the first stressing operations, cannot be used anymore. This last operation is costly, time consuming and has less accuracy, compared with the strand by strand tensioning techniques. The paper will present a method to control the tensioning process on site and to modify it according to the stresses measured in the cables at each stressing stage. In this way, the chances of requiring a restressing operation are diminished.

Traditionally, Spanish schools of civil engineering provide their students a class on “Technical English” in order to develop their language skills. However, this class does not cover all the skills that the student would need in the labor market and mainly focuses in the reading and writing skills, and in a lower degree in the speaking and listening ones. This paper proposes a series of innovative and informal training activities (cine-forum on technical civil engineering topics and role playing on real professional situations) that allow Spanish civil engineering students to develop English skills that can rarely be worked in the classroom (i.e. speaking, negotiating and conversing), encouraging debate, participation, and fostering their self-confidence to speak about technical-English topics in public. Although the students’ level of English is much lower than expected, they all agree on the importance of technical English for their future career. The results also show the students’ lack in skills that are difficult to train in regular classes (speaking and talking). Consequently, this situation would require to provide complementary activities like the ones suggested in this project in order to develop these skills and increase the students’ demand for engineering classes taught in English.

Externally anchored prestressed cables can be employed to enhance the stability of steel truss compression elements significantly. To demonstrate this concept, a system comprising a tubular strut subjected to an external compressive load and a prestressed cable anchored independently of the strut is studied. Energy methods are utilized to define the elastic stability of the perfect and imperfect systems, after which the first yield and rigid–plastic responses are explored. The influence of the key controlling parameters, including the length of the strut, the axial stiffness of the cable and the initial prestressing force, on the elastic stability, the inelastic response and the ultimate strength of the system is demonstrated using analytical and finite element (FE) models. To illustrate the application of the studied structural concept, FE modelling is employed to simulate the structural response of a prestressed hangar roof truss. A nearly two-fold enhancement in the load-carrying capacity of the truss structure is shown to be achieved owing to the addition of the prestressed cable.

The rapid bloom of cable-stayed bridges has been propitiated by the development of erection techniques and improvements of construction materials. Nevertheless, the economic boom of the last decade has deflected attention from economic cost to iconic aesthetical appearance increasing significantly designer’s freedom. This structural freedom has enabled the proliferation of a number of non-symmetric cable-stayed bridges. Despite of the number of built examples, the analysis of non-symmetrical cable-stayed bridges has not received considerable attention from the researchers. In fact, the effects of the main design parameters in the structural behavior of these bridges are not addressed in detail in the literature. To fill this gap, this paper studies the structural response of a number of non-symmetrical cable-stayed bridges. With this aim, a parametric analysis is performed to evaluate the effect of each of the main design parameters (the ratio between the main and the back span length, the pylon, the deck and backstay stiffnesses, the pylon inclination, and the stay configuration) of this kind of bridges. Furthermore, the role of the geometrical nonlinearity and the steel consumption in stays are evaluated.

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Structure and Infrastructure Engineering on 2016, available online at: http://www.tandfonline.com/10.1080/15732479.2015.1101143 This article proposes the application of the observability techniques to deal with damage detection in bridges from their structural response under static loading tests. Unlike previous works based on a symbolic approach to this technique, this article presents its first numerical application. With this aim, a novel algorithm is presented, which reduces the unavoidable numerical errors produced by the lack of precision of computers. To achieve an adequate accuracy in estimations, this numerical algorithm is complemented with another method to define the proper geometry of the corresponding finite element model. The comparison of the observability technique with other existing methods presented in the literature shows that the number of required measurements is significantly lower. Furthermore, contrary to other analysed methods, no information from the undamaged structure is required. The accuracy in estimations provided by the proposed method is very high as the differences with actual values are lower than 1%.

Eduardo Torroja's thin concrete shells stand among the best examples of structural engineering work of the 20th century. At a time when computers did not exist, Torroja's imagination and creativity were not constrained by the limits of the analytical methods available for structural design, and he was able to design and build economically innovative structures of the highest aesthetic quality. One of his major creations was the roof of the Frontón Recoletos, a unique two lobe thin shell that was destroyed during the Spanish Civil War. This paper reviews briefly the history of the Frontón, shows the results of a structural analysis of its roof by several Finite Element (FE) models of different complexity and precision, and compares FE results to those obtained by Torroja. FE results confirm the validity of Torroja's conceptual design, although he seems to have underestimated the internal forces and stresses in the roof. In addition, the paper analyses in detail the influence on the behaviour of the roof from its support conditions and from the stiffening ribs that Torroja designed but that never were built. As a result, the paper enables a better understanding of one of the masterpieces of Structural Art, and of simplified and complex shell analysis models, which is useful for the education of engineers as well as for future designs. © 2010 Elsevier Ltd., Funding for this research has been provided to Mr. Paya-Zaforteza by the Spanish Ministry of Education through its program for postdoctoral stays (Contract No. EX-2008-0669) and to Mr. Lozano-Galant by the Junta de Comunidades de Castilla La Mancha, Spain (Research Project PII2I09-0129-4085). The authors are also grateful to Prof. J. Antuna and J.A. Torroja of the Universidad Politecnica de Madrid, Professors C. Lazar and J.M. Adam of the Universidad Politecnica de Valencia and Professors H. Sundquist and C. Pacoste of the Royal Institute of Technology of Stockholm for their assistance and support. The authors also want to thank the Archivo Torroja and its librarian, Isabel Garcia, for all the information and support provided. Finally, the authors express their gratitude to CEng W. Plunket who carefully reviewed the English of the manuscript and to M.Sc. C. Llopis who lent the authors his original copy of Ref. [23].

Universities rarely have time to develop a major tool for Civil Engineers: their social skills. As a result, recent graduates usually have troubles in presenting their work to different groups of people. During the last years, the internationalisation of Civil Engineering has increased their difficulties as they need to work in a common language that may differ with their first language. In addition, young engineers need to learn how to interact with people from other cultures around the world. These social skills demanded in the current labor market are traditionally learnt by young engineers themselves in a process that might be overwhelming.Being a member of IABSE, and specially participating in their conferences and annual meetings, offers a unique opportunity for young engineers to develop their social skills as they can get in contact and talk in front of a broad spectrum of engineers from both the industry and academia. Furthermore, young engineers can discuss topics and exchange ideas with senior and junior engineers in a friendly atmosphere.

Cable-stayed bridges can be rarely built on a single construction stage and staggered construction is commonly used. The effects of this staggered construction are not only economical as they might also play an important role in the structural behaviour in service. Despite of this importance, these effects are rarely included into the definition of the structural response in service. In order to fill this gap, this paper deals with the effects in service of the staggered erection of steel cable-stayed bridges built on temporary supports. To do so, a criterion based on the minimization of the bending energy in terms of stay forces is applied to several cable-stayed bridges. This study shows the importance of the existence of the pylon-deck connection as well as the number and location of both construction joints and temporary supports during staggered erection, The authors thank the Spanish Ministerio de Economia y Competitividad and the FEDER funds for the funding provided through the research grant BIA2013-47290-R directed by Jose Turmo.

In current practice, the effects of the evolutionary erection of cable-stayed bridge superstructure are rarely included into the simulation of its tensioning process. In fact, stay forces in service are usually defined in early stages of design, when the construction process has not even been conceived in detail yet. In order to fill this gap, the effects of the evolutionary erection of cable-stayed bridge superstructure throughout the tensioning process are studied in this paper. This study is focused on steel cable-stayed bridges erected on temporary supports. For the very first time a new criterion to include the effects of the evolutionary erection of cable-stayed bridges into the definition of the stay forces in the service state is presented., The authors wish to thank the Ministerio de Economia y Competitividad, the Ministerio de Ciencia e Innovacion and the Junta de Comunidades de Castilla-La Mancha (Spain) for the funding provided through the research projects BIA2013-47290-R, BIA2009-13056 and PII2I09-0129-4085 directed by Jose Turmo and founded with FEDER funds.

In order to complete the design of any structure, an adequate simulation of its construction process is required. This simulation tries to guarantee that the structure can be built safely, that is to say that safety thresholds are not exceeded during the construction stages. In the case of cable-stayed bridges, simulation procedures must be prepared to deal with the computational difficulties derived from their statically redundancy. Traditionally, the simulation of the construction process of a cable-stayed bridge is carried out from two alternative simulation approaches: the Backward and the Forward approach. In these two methods structural changes produced during erection are successively added to the preceding (forward simulation) or the following (backward simulation) construction stage. This superposition of stages is the main trade off of these methods because it increases the computation time. Furthermore, these approaches do not enable the direct simulation of intermediate construction stages. To solve these problems the Direct Algorithm (DA) is presented in this work to deal with the simulation of the construction process of cable-stayed bridges built on temporary supports. To speed up the computation, this algorithm takes advantage of the unstressed length of the stays concept. This assumption enables an innovative direct simulation of the construction process that does not require the superposition of stages. The DA is indicated for optimization processes and simulation of changes in the tensioning process of cable-stayed bridges. Furthermore, the DA is so simple that it can be implemented in any computer software.

Cable-stayed bridges are highly statically redundant, light and flexible structures. This complexity highlights the role of the structural system identification (SSI) method in the calibration of the actual properties of the simplified models of these structures. This study proposes the first application of observability techniques to SSI of cable-stayed bridges. This method enables to define which subset of actual structural variables should be measured on site to identify mechanical properties, such as Young s modulus, area and inertia, or stiffnesses (EA and EI) of deck, pylon and stay cables. The effects of the inclination and inertia of the stay cables and the existence of pylon and deck cracking in the observability of different cable-stayed bridges are studied. The results obtained are validated by the models of actual cable-stayed bridges., The authors are indebted to the Secretary of State of the Spanish Ministry of Science and Innovation (Projects TRA2010-17818, BIA2009-10483 and BIA2009-13056) and to the Junta de Comunidades de Castilla-La Mancha (Project PII2I09-0129-4085) for partial support of this work.

This paper proposes a new and innovative algorithm, the Direct Algorithm (DA), which introduces, for the very first time, the unstressed length of the stays concept into the modeling of the construction process of cable-stayed bridges. This assumption enables a fast and direct simulation of construction stages by analyzing independent Finite Element Models when time-dependent phenomena are neglected. The computational speed and the limited computer storing requirements of the DA make it especially indicated for optimization problems. Furthermore, it can be implemented in any structural analysis software. (C) 2013 Elsevier Ltd. All rights reserved., Part of this work was done through a collaborative agreement between University of Castilla-La Mancha (Spain) and Tongji University (China). This included an exchange of faculty and scholars. The financial support from Kwang-Hua Foundation from College of Civil Engineering of Tongji University and from the International Relation Office of University of Castilla-La Mancha is greatly appreciated.

Throughout the tensioning process of cable-stayed bridges changes in geometry, boundary conditions, applied loads as well as material properties may produce unacceptable stresses and/or deflections in the structure. Therefore, an appropriate simulation and structural verification of this process is especially advisable in this kind of structures. Nevertheless, the predicted tensioning process rarely coincides with that measured on site. Usually, deviations between actual and predicted structural behaviour are found in every construction stage. If these deviations are so large that the achievement of the pursued stress state cannot be assured after completion or exceeds safety thresholds, an additional tensioning stage is added. Then, the following calculated tensioning operations are needed. If throughout these stages new differences are measured, new additional tensioning stages would be added. The addition of these additional stages on site is both time- consuming, as the tensioning process must be interrupted, and expensive, as more tensioning operations than the initially calculated ones are required.This paper aims to fill this gap by providing a new method that eases the simulation of deviations in the tensioning strategy on site, the Forward Algorithm. This procedure has been applied to the temporary supports erection method as, despite its importance, no specific investigation of this erection technique has been found in the literature. The Forward Algorithm is especially indicated to control the construction process on site, increasing safety and decreasing construction time.

Traditionally the construction process of cable-stayed bridges is modeled according to the backward approach, as its calculation is much easier using an elastic analysis. In this approach the bridge is disassembled according to the opposite sequence of events which occur during its erection. The main trade off of the backward approach is that time-dependent phenomena, such as creep, shrinkage or cable relaxation, cannot be directly computed as the analysis is performed according to the reversed time direction.In this paper the Forward Algorithm (FA) that is based on the forward approach is formally presented. This procedure has been applied to the temporary supports erection method as no specific investigation of this erection technique has been found by the authors. The FA has the following advantages: (1) Modifications in design and/or tensioning strategy can be easily computed. (2) The effect of time-dependent phenomena can be efficiently included into the calculation of the construction process of the bridge. (3) Differences between the temperatures in the structural elements assumed when doing the structural analysis of the bridge and the real ones when built can be calculated without the need of separate models. (4) The stresses in the mono-strands when the strand by strand prestressing technique is used are obtained directly. (5) Stay and strand elongation, which are very useful to control the prestressing operations, can be also easily computed. All these features make the FA an efficient procedure to control the construction process on site, increasing safety during construction and decreasing construction time. © 2012 Elsevier Ltd., Part of this work was done through a collaborative agreement between University of Castilla-La Mancha (Spain) and Tongji University (China). This included an exchange of faculty and scholars. The finantial support from Kwang-Hua Foundation from College of Civil Engineering of Tongji University and from the International Relation Office of University of Castilla-La Mancha is greatly appreciated.

The temporary supports erection method is a fast and economical way of building cable-stayed bridges. In this method the bridge deck is first erected on a set of temporary and permanent supports and then, the stays are successively placed and tensioned according to a predefined tensioning sequence. A proper definition and analysis of this sequence is very complex as the structure is highly statically indeterminate, exhibits a non linear behavior and has a changing static scheme.Despite its importance, no specific research referring to the modeling of the temporary support erection method has been found as most of the modeling procedures are proposed for the alternative erection technique, the cantilever erection method. The modeling carried out by most of these methods is based on the opposite construction sequence followed on site, this is to say, the structure is disassembled from the desired final stage (. Objective Completion Stage, . OCS).A procedure, the Backward Algorithm (. BA), is formally presented in this paper for calculation of the erection of cable-stayed bridges built on temporary supports. Because of its simplicity the . BA can be reproduced by any structural code that enables the modeling of the prestresses of the stays by means of imposed strains or imposed temperature increments. Another advantage is that no separate models are needed to calculate the evolution of stresses in the strands when the strand by strand tensioning technique is used. Furthermore, the stay elongations when prestressed can be easily obtained when the stays are prestressed in a single operation or strand by strand. This information is important to control the correct and safe prestressing of the stay on site. In addition, it also help the designer to control if the anchor wedge bites the strand in the same position several times during the prestressing process. © 2012 Elsevier Ltd., Part of this work was done through a collaborative agreement between University of Castilla-La Mancha (Spain) and Tongji University (China). This included an exchange of faculty and scholars. The financial support from Kwang-Hua Foundation from College of Civil Engineering of Tongji University and from the International Relation Office of University of Castilla-La Mancha is greatly appreciated.

One of the fastest and more economical ways of erecting cable-stayed bridges consists on building the bridge deck on a set of temporary and permanent supports. Then, the stays are successively placed and tensioned according to a predefined tensioning sequence and the static scheme of the structure is successively changed. Despite this technique has been used for erecting many cable- stayed bridges worldwide, no specific research referring to the modelling of the temporary supports erection method has been found in existing literature. In fact, most of the literature is based on the alternative erection technique, the cantilever erection method, and the temporary supports erection method is usually only described in general terms. This paper aims to fill this gap by providing an algorithm specifically designed to model the construction process of cable-stayed bridges built on temporary supports from a backward approach. This algorithm can be efficiently used to define the initial design of the tensioning sequence and, because of its simplicity; it can be easily implemented in any structural code that enables the modelling of the prestressing of the stays by means of imposed strains or imposed temperature increments.

The condition assessment of pedestrian bridges might be overlooked due to the small scale of these structures. A short list of accidents is provided to justify the necessity of condition assessment on pedestrian bridges. In this paper, the structural system identification by observability method is applied in two traditional arrangements of pedestrian bridges. In the simply supported beam example, the symbolical expressions of the estimation for bending stiffnesses are derived first. The validity of the method is justified by the accurate estimations using error-free measurements. However, as the real-life measurements are inevitably polluted by errors, the effect of measurement errors is thoroughly studied according to measurement errors in a particular measurement, loading cases and errors in all measurements. The simulation errors of the method is also demonstrated by a two-span continuous beam. The results show that the loading case is important regarding the accuracy of the estimations.

Despite of the growing number of built examples, the analysis of non-symmetrical cable-stayed bridges has not received considerable attention from the researchers. In feet, the effects of the main design parameters in the structural behavior of these bridges are not addressed in detail in the literature. To fill this gap, this paper studies the structural response of a number of non-symmetrical cable-stayed bridges. With this aim, a parametric analysis is performed to evaluate the effect of each of the main design parameters (the ratio between the main and the back span length, the pylon, the deck and backstay stiflhesses, the pylon inclination, and the stay configuration) of this kind of bridges. Furthermore, the role of the geometrical nonlinearity and the steel consumption in stays are evaluated.

The structural response of any structure is traditionally predicted by simplistic physics-based models. In these models the mechanical and geometrical properties are assumed as known. Nevertheless, this is not the case in most actual structures where the values of the actual properties (such as axial or flexural stiffness) are unknown due to uncertainties in the materials, in the construction methods or in the stress state. In some cases, a calibration of the computer models is required to improve de accuracy of the predicted structural response. To carry out this task Structural System Identification (SSI) methods can be used. In this paper, a new parametric method for SSI from static excitation response is proposed. This method is based on the observability of the structure, understanding as such the problem of identifying which is the subset of characteristics of the structure, such as Young’s modulus, area, inertia, and/or products of them (axial or flexural stiffnesses) that may be uniquely determined when a subset of deflections and forces at nodes is provided. This method has lead to the development of a powerful mathematical tool to deal efficiently with polynomial systems of equations with a number of applications in many fields of science and engineering. To illustrate the applicability of the proposed method, the analysis of the SSI of two structures of growing complexity is presented.

Most of the methods presented in the literature to define the target service stresses (Objective Service Stage, OSS) of cable-stayed bridges rarely include the time-dependent phenomena effects. Nevertheless, especially in concrete structures, this assumption might be on the unsafe side because time-dependent phenomena usually modify service stresses. To fill this gap, this paper studies the time-dependent phenomena effects into service stresses of concrete cable-stayed bridges. After illustrating the important role of these phenomena in an asymmetrical cable-stayed bridge without backstay, a new method to include their effects into the OSS is presented. An important issue to be considered in this method is the target time in which the OSS is defined to be achieved. The application of this method to two different structures showed the convenience of defining the OSS to be achieved at early times because that way the envelope of service stresses is reduced.

The temporary supports erection method is the most common way of building cable-stayed bridges. In this technique the bridge deck is first built over a set of temporary and permanent supports. Then, during the tensioning process, the stays are successively placed and tensioned by the jacks and the deck is raised from the temporary supports. Several variants of this method are the launching of the bridge and the rotation method. This paper proposes an algorithm to calculate and to control the construction of such bridges when the strand by strand tensioning technique is used. It is based on the unstressed length of the stays concept. The use of such concept enables a fast and direct simulation of construction stages by analysing independent Finite Element Models. As there is no need of superposition of models it is a very convenient way for construction supervision.

Despite its importance in some structures, shear deformation is systematically neglected by most static structural system identification methods. To fill this gap, this paper analyzes, for the first time in the literature, the effect of the shear deformation in the inverse analysis of structures. This study is focused on a parametric structural system identification method: the observability technique. As the majority of the methods, this technique is based on the Euler-Bernoulli beam theory. The method presented in the literature is unable to identify correctly the characteristics of a structure (such as flexural stiffness) when shear deformation is not negligible. In fact, in this method, the effects of shear deformation are close to those produced by measurement errors. To solve this problem, the observability procedure is updated according to the Timoshenko’s beam theory. This formulation uses an algebraic approach combining both a symbolical and a numerical application. Thus, the updated observability formulation is able to obtain not only flexural stiffness but also shear stiffness. Besides this, for the first time in the literature, a parametric equation of the estimates is obtained. Some examples are presented to illustrate the validity of the new formulation.

The time-dependent phenomena effects might play an important role in the structural behavior of a cable-stayed bridge during construction and in service. In fact, because of these effects the target state of stresses (Objective Service Stage, OSS) can only be achieved at a certain target time. In the literature, a number of software have been presented to study creep and shrinkage effects during cantilever erection of cable-stayed bridges. Nevertheless, the effects of these phenomena in the alternative erection technique, the temporary support erection method, have received little attention. Furthermore, none of the presented software are able to: (1) Define a determined OSS for a given time including the time-dependent phenomena effects and the evolutionary erection of the superstructure. (2) Simulate the construction process assuring the achievement of a given OSS without the need of an overall iterative process taking into account time-dependent phenomena. (3) Provide the prestressing sequence in such a way that no additional tensioning operations are required to correct creep and shrinkage effects in service. To fill all these gaps, a new algorithm, the Forward-Direct Algorithm (FDA), is formally presented in this paper to simulate the construction process of cable-stayed bridges built on temporary supports. The main innovation of this algorithm consists of introducing the time-dependent phenomena effects into the unstressed length of the stays concept to calculate the prestressing strains to be introduced during the last re-tensioning operation. The application of the unstressed length concept has major advantages both in the simulation (as the OSS can be achieved without any overall iterative process) and in service (as re-tensioning operations to correct time-dependent phenomena effects can be avoided). To illustrate the creep and shrinkage effects during the construction and in service the FDA is applied to a real cable-stayed bridge. Furthermore, an analysis to define the optimum time to achieve the OSS is presented.