Bridges

The paper presents a few examples of designed and constructed bridges which were inspired by quite strange prototypes from nature and even the history or the philosophy. It shows how it is important to establish a good cooperation between the architect and the structure engineer.

This book deals with earthquake-resistant structures, such as, buildings, bridges and liquid storage tanks. It contains twenty chapters covering several interesting research topics written by researchers and experts in the field of earthquake engineering. The book covers seismic-resistance design of masonry and reinforced concrete structures to be constructed as well as safety assessment, strengthening and rehabilitation of existing structures against earthquake loads. It also includes three chapters on electromagnetic sensing techniques for health assessment of structures, post earthquake assessment of steel buildings in fire environment and response of underground pipes to blast loads. The book provides the state-of-the-art on recent progress in earthquake-resistant structures. It should be useful to graduate students, researchers and practicing structural engineers.

Felieton jest jednym z cyklu poświęconego krakowskim mostom. Opisuje historię powstania i modyfikacji Mostu Dębnickiego - ważnego elementu krakowskiej infrastruktury komunikacyjnej na kierunku wschód-zachód. Most ten został pierwotnie zbudowany jako most kolejowy dla dostaw wojskowych, ale potem przebudowano go na most drogowy. Przy tej przebudowie podjęto brzemienną decyzję, o której wzmianka jest w tytule: Zbudowano most nisko nad wodą (w wyniku czego jest zagrożony przy każdej powodzi), żeby zachować widok na Wawel.

A vision-based approach has been employed in Structural Health Monitoring (SHM) of bridge infrastructure. The approach has many advantages: non-contact, non-destructive, longdistance, high precision, immunity from electromagnetic interference, and multiple-target monitoring. This review aims to summarise the vision- and Digital Image Correlation (DIC)-based SHM methods for bridge infrastructure because of their strategic significance and security concerns. Four different bridge types were studied: concrete, suspension, masonry, and steel bridge. DIC applications in SHM have recently garnered attention in aiding to assess the bridges’ structural response mechanisms under loading. Different non-destructive diagnostics methods for SHM in civil infrastructure have been used; however, vision-based techniques like DIC were only developed over the last two decades, intending to facilitate damage detection in bridge systems with prompt and accurate data for efficient and sustainable operation of the bridge structure throughout its service life. Research works reviewed in this article demonstrated the DIC capability to detect damage such as cracks, spalling, and structural parameters such as deformation, strains, vibration, deflection, and rotation. In addition, the reviewed works indicated that the DIC as an efficient and reliable technique could provide sustainable monitoring solutions for different bridge infrastructures.

The purpose of this research is to evaluate and compare the relative merits of the two coating systems for reinforcing bars in concrete. A review is given of the nature and characteristics of both epoxy coated and galvanized steel for use as reinforcement in concrete. Also presented is an overview of the results from recent experimental work on the comparative corrosion behavior of uncoated black steel, epoxy coated steel, and galvanized steel in concrete.

Network arches are tied arch bridges with inclined hangers, which have multiple intersections. In contrast to tied arch bridges with vertical hangers they are mainly subject to axial forces and only little longitudinal bending, leading to possible savings of more than 50% of structural steel. Despite or maybe because of this amazing claim, few network arches have been built. It is the professional experience of the authors that when a network arch is proposed as an alternative to the conventional tied arch bridge with vertical hangers, the responsible persons request an extensive demonstration of its benefits. In this article the authors present a comparative study of conventional tied arch bridges and network arch bridges. Subsequently, the basic structural behavior of a network arch is explained by means of a parametric study of the radial hanger arrangement. This paper concludes that the longitudinal bending moments are about ten times smaller in a network arch than in a tied arch bridge with vertical hangers, leading to important material savings.

Regulations on which designers base their process of designing of any engineer structures should  include and combine mechanics, loads and dimensioning. It is not always the case as far as eurocodes are concerned. Ambiguities appear everywhere, which  sometimes leads to  incorrect understanding of a norm. The authors meticulously analysed  basic mechanical terms. Their digressions began with  the concepts of strain and deformation that have discrepant definitions in sources from other countries. The next part of article discusses the concept of „shear lag”. It is treated as an elementary concept in the eurocodes, although is has not been defined yet. Other sources define it as cooperating width and shear strain in the beam flanges or as stretching. Polish translation mentions the effect of „wide stripes”. The authors focused also on dynamics – especially while discussing first natural frequencies denoted as “n0”. They scrutinised  the norm EN 1991-2 in which dynamic problems of brid...

This paper presents an approach for evaluating residual strength of fire exposed steel bridge girders. The approach involves three stages of analysis that is to be carried out at ambient conditions, during exposure to fire, and after cooling of the fire exposed bridge girder. In the first stage, load carrying capacity of the girder is evaluated at room temperature. In the second stage of analysis, thermal and structural response of the bridge girder is traced under specified fire exposure and loading conditions. In the third stage (after the bridge girder has cooled down), residual capacity of the girder is evaluated by incrementing load on the girder till failure occurs. The proposed approach is applied to carry out a set of numerical studies on a typical steel girder using finite element computer program ANSYS. Results from numerical studies indicate that the maximum fire temperature (and associated temperature in steel) is the most critical factor that influences residual strength of a fire exposed bridge girder. A girder exposed to typical "external" fire conditions, with maximum fire temperatures reaching to 600-700°C, retains about 70 to 80% of its strength on cooling. On the other hand, a steel bridge girder exposed to hydrocarbon fire, with a maximum temperature of about 1100°C, looses most of its strength during heating phase of the fire and experiences failure.

A connected graph X is a block, if and only if for any three vertices u, v and w in X, there exists a path from u to w and the path does not contain v. In present article I present full Matlab codes of the algorithm for finding cut nodes and bridges in the network.

A simply supported bridge is modelled to investigate the effect of a strain rate dependent modulus of elasticity on the dynamic response of the structure to a moving load. The bridge is modelled as a one-dimensional discretized finite element beam and the moving load is represented by a point force. A constant modulus of elasticity is traditionally employed when simulating the dynamic response of structures under moving loads. In this paper, a time-variant modulus is used to calculate strains and displacements and compare them to the traditional approach for different speeds and bridge spans. The time-variant modulus is obtained from the strain rate of the structure which is used in turn to update the strain. The results show significant changes in the modulus and in the resulting load effect as load magnitude and speed increase.

Network arches have inclined hangers that cross each other at least twice. It seems
to happen more often for railway bridges than for road bridges that structural elements above
the bridge deck are acceptable, which justifies investigations of the applicability of network
arches.
The tie can be a longitudinally prestressed concrete slab. This gives less noise, and the
additional self-weight favours the structural behaviour. Alternatives with steel and composite
bridge decks are discussed. For double track railway bridges spanning up to 100 metres the
arches can be rolled H-sections. For larger spans welded box sections are applicable.
For the design of network arches the hanger arrangement is important. Small bending
moments in the arches and small hanger forces are obtained when the upper hanger nodes
are placed equidistantly and all hangers cross the arch with the same angle. The cross
angle’s size depends on several parameters. Hints for a good choice are given. The maximum
hanger forces vary little, thus all hangers have the same cross-section.
To ensure passenger comfort and the stability and continuity of the track, deformations of
railway bridges are constricted. A network arch is a stiff structure with small deflections and
therefore suitable to comply with such demands even for high speed railway traffic.
A network arch railway bridge with a concrete tie usually saves more than half the steel
required for tied arches with vertical hangers and concrete ties.

Deterioration of reinforced concrete and the reliability of deteriorating structures have been, and still are, widely researched fields. A critical aspect of this research effort is the integration of deterioration modelling with reliability assessment. This paper focuses on this issue and illustrates how the integration of these techniques can lead towards more realistic predictions of the time dependent performance of reinforced concrete bridge structures. The introduction of spatial random fields into the proposed approach facilitates the identification of the type and quantity of data required to update models and improve predictions. This is an essential step in the rational prioritisation of maintenance actions for such structures. However, there are still important gaps both in understanding and modelling the deterioration process, as well as in assessing its influence on bridge performance. In this respect, the methodology presented in the paper can be developed further, and...

Στην εργασία αυτή περιγράφεται ένα τμήμα των ορεινών δρόμων και δικτύων επικοινωνίας στην οροσειρά της Ροδόπης, ο δρόμος που  συνέδεε την Ξάνθη με το Πασμακλή (σημερινό Σμόλιαν). Στο κέντρο της ανάλυσης αυτής βρίσκεται η «γέφυρα του παπά», στα Πομακοχώρια της ορεινής Ξάνθης. Η “γέφυρα του παπά”  έχει ιδιαίτερη σημασία επειδή συνδέεται με την ιστορία της οροσειράς της Ροδόπης πριν από τον εξισλαμισμό των Πομάκων.  Η ονομασία της, η ύπαρξη χαραγμένου σταυρού πάνω στο κλειδί του τόξου της, σε συνδυασμό με προφορικές μαρτυρίες και μια πληθώρα ελληνικών τοπωνυμίων της περιοχής, οδηγούν στο συμπέρασμα ότι αποτελεί σημαντικό ορεινό σταυροδρόμι και μάρτυρα του χριστιανικού παρελθόντος της οροσειράς της Ροδόπης.

Kokkas, Nikolaos (2005). The “Priest’s Bridge in the Pomak villages of Xanthi. In G. Mantas & G. Psilopoulos, About stone bridges. Bridge stories. 2nd Scientific Meeting of the Stone Bridges Research Centre.

This paper describes a part of the mountain roads and communication networks in the Rhodope mountain range, the road connecting Xanthi with Pasmakli (present day Smolyan). The “Priest’s Bridge” in the Pomak villages of Xanthi is at the centre of this analysis. The “Priest’s Bridge” is particularly significant because it is associated with the history of the Rhodopes before the islamisation of the Pomaks. Its name, the existence of an engraved cross on the keystone of the arch, in combination with the oral evidence and the great number of Greek place names in the area, lead to the conclusion that the bridge is a significant junction witnessing the Christian past of the Rhodopes.

This paper presents a life cycle cost analysis of carbon fiber reinforced polymer (CFRP) reinforced concrete highway bridges. This study shows that despite the higher initial construction cost of CFRP reinforced bridges, they can be cost effective when compared to traditional steel reinforced bridges. The analysis considers the cost items of initial construction, maintenance, repair, rehabilitation and demolition activities and the associated user costs as determined by traffic volume, speed, operation and crashes. The analysis is performed for a 100-year service life. The cost information has been obtained from the literature, FHWA, and Michigan DOT. The most cost efficient alternative for side-by-side box beam bridges was a medium span CFRP bridge located in a high traffic area. Depending on traffic volume and bridge geometry, a probabilistic analysis revealed that there is greater than a 95% probability that the CFRP reinforced bridge will become the least expensive option between 20 and 40 years of service. The break-even year for the CFRP reinforced bridge is typically at the time of the first major repair activity, a shallow deck overlay, on the steel reinforced bridge.

The concrete road, rail and pedestrian bridges along the Eastern Freeway (originally Doncaster Freeway) in Melbourne Australia, were designed and constructed under the supervision of engineer Bruce Day and the MMBW in the early 1970s. The bridges are a cohesive group reflecting the approach to create an driving experience and urban landscape of high aesthetic value.

Two novel demountable shear connectors for precast steel-concrete composite bridges are presented. The connectors use high-strength steel bolts, which are fastened to the steel beam with the aid of a special locking configuration that prevents slip of bolts within their holes. Moreover, the connectors promote accelerated construction and overcome typical construction tolerances issues of precast structures. Most importantly, the connectors allow bridge disassembly, and therefore, can address different bridge deterioration scenarios with minimum disturbance to traffic flow, i.e. (1) precast deck panels can be rapidly uplifted and replaced; (2) connectors can be rapidly removed and replaced; and (3) steel beams can be replaced, while precast decks and shear connectors can be reused. A series of push-out tests and a beam test were conducted to assess the behavior of the connectors and quantify the effect of important parameters. The experimental results showed that shear resistance and...

The study presents, that the modernization of the Hungarian urban mass transportation happened in three independent fields at the same time between 1867 and 1914. 1. The creation of modern transport infrastructure. The roads and sidewalks were paved with mainly stone, keramit and asphalt. Bridges, over- and underpasses were built. 2. The traffic was regulated, first on local (rule ordinances, city police chief's instructions), later on national level (laws, decrees of the Minister of Interior). Driving on the left side of the road was prescribed by law. The first traffic signs were put onto the streets. 3. At the expense of pedestrian traffic, the rise of vehicle traffic began. Thanks to the advances in technical sciences and technology, the motorization of means of transport has moved forward. As a result, traditional animal drawn vehicles, though slowly, began to be replaced by power-driven vehicles from the 1890s.

The Russo–Polish war, called the November Uprising, begun in Warsaw on the 30th of November 1830; in April of the following year, when the centre of the insurrection was in the straight line east from Warsaw, one of its most important battles took place by the small Muchawka River, separating Iganie village from the Russian garrison in Siedlce (present-day Masovian Voivodeship, Poland). The battle of Iganie is a well-known event in the local historical awareness. In spite of that, in 2014 the local authorities decided to give the permission to dredge the river in the area of the battlefield. It occurred that until recently the site has not been formally registered within the local Heritage Office. Once the archaeologists started the survey, their attention was drawn to the local mill and the adjacent water basin, which has yielded some archaeological evidence connected with the bygone river crossing and early-20th-century hydropower machinery.

The paper presents the new bridge over the river Acheloos in Greece. The position of the bridge poses several construction and design challenges, mostly due to the soil characteristics at the foundation, the increased seismicity of the region and the high flow of the river. The project involves the construction of a small balanced cantilever bridge with three spans of length 47.5m – 80m – 47.5m. The main innovation in the structure is that the deck is supported exclusively on high damping rubber bearings, a technique not commonly encountered in such bridges. The selection of this structural system was a result of the poor geotechnical / foundation conditions, which differed considerably among the piers, as well as their low height. This led to the design of special deck stabilizing systems for the various construction stages. The design included application of the principles of earthquake engineering, an advanced construction schedule and a displacement monitoring procedure. Informa...

Aquest llibre és una petita història de la província de Barcelona vista des del mirador destacat i alterós que donen els ponts, elements arquitectònics i d'enginyeria tradicionals i alhora profundament actuals, els quals formen part del paisatge que veiem cada dia i al mateix temps serveixen com a instruments de comunicació entre les persones i els territoris.

Abstrak Studi ini membahas tentang analisis respon dinamik perilaku gempa pada jembatan rangka pelengkung sebagai akibat dari pengaruh pergerakan tanah dan patahan. Data gempa didapat dari integral waktu gelombang respon percepatan gempa Jiji Taiwan pada tahun 1999 yang kemudian diaplikasikan kepada struktur jembatan rangka pelengkung untuk diteliti perilaku responsnya. Analisis respons dinamik dibuat menggunakan gerakan tanah pada saat gempa pada arah transversal dan longitudinal, bersamaan dengan pergerakan patahan pada arah vertical dan transversal, untuk meneliti perilaku gempa dari model jembatan baja pelengkung yang digunakan. Model analitis dengan sejarah waktu (time history) disimulasikan menggunakan model 3D dengan program ABAQUS. Berdasarkan hasil analisis, perilaku respons dari kedua kasus pada arah transversal dan longitudinal akibat akselerasi menunjukkan bentuk respons yang sedikit berbeda. Selain, itu juga ditemukan bahwa elemen struktur yang mengalami plastis berkumpul pertemuan antara rangka utama jembatan pelengkung dan girder pengakunya.

This paper explores the challenges, opportunities, benefits, and limitations of reliability assessment of major and critical components of infrastructure using structural health monitoring (SHM) data. The focus is on bridges but the discussion is intentionally kept at a general level so that it is applicable to a wide range of infrastructural systems. This paper argues that holistic and strategic approaches are required to pave the way to the realization of the latent befits of SHM and maximising the value of information derived from SHM data. Firstly, it discusses these benefits and situations were implementing SHM can be considered to be potentially most useful. It later discusses two frameworks for seeing the SHM technologies in a broader context of asset management decision making. The first framework is underpinned by prioritisation of structures for monitoring, moves to guidelines for instrumentation and SHM data analysis, and ends with the integration of SHM results into asset management and disaster emergency plans and decisions. The second framework understands SHM as a starting point in a value chain of enabling technologies delivering information to infrastructure stakeholders. A separate section is devoted to deliberations on the emerging and important way of thinking of SHM outputs as ‘big data’ and associated challenges. One of the opportunities brought about by abundant SHM big data is the prospect of creating better ‘digital twins’ – a high fidelity, multi-physics, multi-scale models of structural systems underpinned by and calibrated using SHM data to assess and forecast reliability. Finally, an example of a recently constructed 12-span, 690 m long post-tensioned concrete viaduct equipped with a continuously operating SHM system comprising around 90 channels of strain, temperature, displacement and environmental data, and also subjected to one-off ambient dynamic testing campaigns is presented. The proposed framework for structural reliability assessment of the bridge integrates information on the mechanical properties of construction materials obtained via laboratory and in situ tests, the heterogeneous SHM and dynamic testing data from the full scale structure, and predictions from numerical models of the bridge. Several aspects of this information fusion will be discussed. Dynamic tests and static responses, including time dependent creep and shrinkage behaviour, enable system identification of the structure and creation, via model updating, of numerical (finite element) structural models, or ‘digital twins’, of the physical structure. These models can in turn be used for assessing quantitatively the bridge time dependent condition, health, safety and performance via more realistic numerical reliability evaluations. The collected temperature and strain and displacement data form the basis for generating realistic spatial and temporal load fields for reliability assessment utilizing calibrated numerical models of the structure. The monitoring of responses to traffic loads enables formulation of the dynamic live load demands actually acting on the bridge and response to these.

Najobszerniejszy jak dotąd wybór twórczości eseistycznej Krzysztofa Czyżewskiego umiejscawia Europę Środkową w samym środku najważniejszych dla współczesnego świata pytań i problemów: kryzysu wspólnotowości, pogłębiających się podziałów i coraz ostrzejszych wojen kulturowych.
Dla współtwórcy ośrodka „Pogranicze” Europa Środkowa nie jest tylko geopolityką i nie ma – jak chciał Peter Handke – znaczenia „wyłącznie meteorologicznego”. Jawi się bardziej jako etos i postawa, która wykorzenieniu przeciwstawia przynależność, kompleksowi prowincjonalizmu – siłę prowincji, a ostro zarysowanym granicom – przestrzeń przenikania i współistnienia.
Czyżewski zawzięcie poszukuje żywej i wychylonej ku przyszłości, scalającej narracji, zdolnej stworzyć przeciwwagę narodowych mitów, tak silnie określających naszą rzeczywistość w ostatnich dwóch stuleciach. W leksykonie najważniejszych dla niego pojęć znajdują się zapomniane słowa, takie jak „agora”, „pogranicze”, „obcowanie”, „tkanka łączna” czy magiczny „neimar” – budowniczy mostów.
W swoich eseistycznych peregrynacjach podąża po mapie wyznaczonej przez outsiderów, wygnańców i kontestatorów, wędrownych artystów czy niesfornych intelektualistów, dla których Europa pozostawała i pozostaje ciągle niezrealizowanym w pełni projektem. Często przywołuje Mickiewicza, Vincenza, Rotha, Stempowskiego, Giedroycia, Kołakowskiego, Tischnera, Barańczaka, Venclovę, a nade wszystko Miłosza, którego jest wyjątkowym i wnikliwym czytelnikiem.

The George Washington Bridge spanning the Hudson River between New York and New Jersey is often called the most beautiful bridge in the world. Such a bridge had been envisioned ever since the Brooklyn Bridge was built in the 1890's but the execution of such a large span had to wait for more than a quarter of a century, until 1931. The film tells the story of the building of the bridge, which is also the story of the brilliant engineer, Othmar Amman, who became obsessed with this grandiose plan. For two years he had no income while he worked on its design and solicited politicians for support. New Yorkers were absorbed watching its construction and even participated in its naming through a poll. Appearing in this lively film is Kathleen Hulser of the New-York Historical Society who puts the construction of the bridge into the historical perspective of New York City at the beginning of the 20th century. Archival footage shows a city that is teeming with energy as bridges, tunnels and tall buildings are being built at a rate not seen before in a modern city. It was a great time in the history of engineering when being an engineer was like being a rocket scientist today. Dan Rastorfer, author of 6 Bridges and Christian Meyer, Columbia University School of Engineering, describe the technical challenges of building this magnificent suspension bridge.

Lorsque les techniques de fondations à l’air comprimé se généralisent à la fin du XIXe siècle, leur diffusion témoigne à la fois d’un engouement pour leur efficacité constructive et d’une compréhension plus fine des risques encourus par les ouvriers, attestés par les cas de « maladie des caissons » et de décès. En s’intéressant ici aux accidents du travail et aux dysfonctionnements survenus lors de la réalisation des piles du pont Mirabeau à Paris en 1893, il s’agit de saisir le quotidien concret de ce type de procédés, à la croisée d’une histoire des risques professionnels, d’une histoire de la construction attentive aux métiers et d’une histoire sociale des techniques interrogeant les mondes industriels. En soulignant les liens entre cet environnement de travail contraignant et la condition physique des ouvriers, cet article met en lumière la place qu’occupe encore le facteur humain dans des procédés qui sont généralement considérés comme représentatifs de la mécanisation des chantiers.

in Artefact. Techniques, histoire et sciences humaines, n° 11, 2019, p. 67-108

Synopsis The Howe truss was patented in USA initially in 1840 and again in 1842 and went on to become one of the primary timber truss designs used in North America. The adaptation of the Howe truss in NSW into the two distinct forms known as the " Allan " and " Dare " trusses is well documented, though its usage elsewhere in Australia is largely ignored. This paper will briefly describe the extent of this usage and suggest the manner in which some of the bridge engineering knowledge required for their construction was transmitted.

Network arches are bowstring arch bridges with inclined hangers that cross each other at least twice. The use of many hangers reduces bending in the arch and tie and therefore they can be made very slender. Network arches are likely to remain the world's most slender arch bridges. This publication is about the erection of this very efficient structure. For distances between the arches of less then 18 m the tie should be a concrete slab. The tensile force is taken by longitudinal prestressing cables. The arch is very slender. In many cases the small bending moments and the efficient support against buckling by the hangers favours the use of universal columns or American wide flange beams. In the network arches in Norway the tie was cast on formwork resting on timber piles in the riverbed. The arch and hangers were erected from the concrete lane. The hangers were tightened with great care till the arch carried the tie. A light temporary lower chord is suggested to obtain a steel skeleton with enough strength and stiffness to carry the casting of the permanent concrete tie. During erection the steel skeleton can be moved when lifted at the end of the spans. The temporary lower chord can be reused for many spans or modified for different projects. If the network arch is the main span over a navigable waterway, the steel skeleton can be erected on the approaches and be lifted in place by a pontoon or a crane. If the steel skeleton already has the correct shape, no further adjustment of hanger is necessary. In cold climates the steel skeleton can be erected on ice and lifted onto the abutments. Network arches are very efficient structures. They need less structural steel than other bridges. Efficient methods of erection can make them very economical.

Las crónicas de los viajes reales de Isabel II y Alfonso XII en tren por Extremadura y por Portugal nos han permitido observar la trascendencia de la modernización de los sistemas de transporte en las relaciones económicas, culturales, y políticas entre España y Portugal. En esos años tuvo un gran auge el movimiento iberista. El contenido de los ensayos no era objetivo, y en muchos casos se priorizó la exaltación de la figura del monarca y de los valores patrios. Una de las principales aportaciones ha sido el análisis de la visión de Rada y Delgado de la Exposición de Arte Ornamental Retrospectiva de Lisboa (1882) y en particular de las piezas expuestas: el tesoro de Guarrazar, y el tríptico gótico de la Natividad de Guimarães. Un análisis detenido de las coronas y vestigios de Guarrazar nos ha permitido dar a conocer los primeros planteamientos historiográficos sobre su origen y sus características. Arte e identidad fueron parejos en los escritos de historia del arte. Por último, aunque las crónicas no lo llegasen a analizar hemos comentado las polémicas generadas entre Badajoz y Cáceres por el trazado de la vía internacional a Portugal, las obras de ingeniería, y la composición del tren real.

Isabel II’s and Alfonso XII’s chronicles of the royal travels by train in Extremadura and Portugal are indicative of the key role played by the modernization of transport systems in economic, cultural, and political relations between Spain and Portugal. Royal travels take place in the heyday of Iberianism. Chronicles are not objective, and the exaltation of monarchical and patriotic values is usually prioritized. One of the main contributions of our study lies in the analysis of the views of Rada y Delgado on the Ornamental Retrospective Art Exhibition of Lisbon (1882), especially regarding the treasure of Guarrazar and the Gothic triptych of the Nativity of Guimarães. A careful analysis of the treasure of Guarrazar enables us to provide a first historiographical approach to its origin and characteristics. Art and identity were evenly matched in the writings of Art History. Finally, we discuss a number of aspects not included in the chronicles, such as the controversy between Cáceres and Badajoz on the route of the international train, the engineering works and the composition of the royal train.

Network arches have inclined hangers that cross each other at least twice. It seems to happen more often for railway bridges than for road bridges that structural elements above the bridge deck are acceptable, which justifies investigations of the applicability of network arches. The tie can be a longitudinally prestressed concrete slab. This gives less noise, and the additional self-weight favours the structural behaviour. Alternatives with steel and composite bridge decks are discussed. For double track railway bridges spanning up to 100 metres the arches can be rolled H-sections. For larger spans welded box sections are applicable. For the design of network arches the hanger arrangement is important. Small bending moments in the arches and small hanger forces are obtained when the upper hanger nodes are placed equidistantly and all hangers cross the arch with the same angle. The cross angle's size depends on several parameters. Hints for a good choice are given. The maximum hanger forces vary little, thus all hangers have the same cross-section. To ensure passenger comfort and the stability and continuity of the track, deformations of railway bridges are constricted. A network arch is a stiff structure with small deflections and therefore suitable to comply with such demands even for high speed railway traffic. A network arch railway bridge with a concrete tie usually saves more than half the steel required for tied arches with vertical hangers and concrete ties.

Bridges are magnificent works that symbolize the crossing of obstacles and that have great value to social and economic development, but like any other structure, they deteriorate over time and require periodic inspection and maintenance programs to ensure their functionality. In Brazil, the practice of maintenance on bridges and viaducts is still insufficient, and this can be observed in a large number of bridges with pathological problems, resulting in expensive recovery costs. In this context, the present work sought to inspect and analyze the pathologies of a road bridge in the city of Rio Branco (Acre), to analyze the conservation state of the structure. To achieve this goal, it was carried bibliographic research about pathological manifestations in reinforced concrete bridges and applied a verification checklist based on the Brazilian standard of the bridge inspection, through technical visits and photographic report. The problems found in the structure were investigated and it was analyzed how they contribute to the bridge's conservation state. Finally, it was observed that the structure presents several pathologies that do not affect its structure directly, but if not corrected in the medium term, it can compromise the structure and drastically reducing the service life and durability of the bridge.



As pontes são magníficas obras que simbolizam a transposição de obstáculos e que têm grande valor para o desenvolvimento social e econômico, porém como qualquer outra estrutura, as pontes se deterioram com o tempo e necessitam de programas de inspeção e manutenção periódica para garantir sua funcionabilidade. No Brasil, a prática de manutenção em pontes e viadutos ainda é muito falha e isso pode ser observado no grande número de pontes com problemas patológicos, resultando em onerosos gastos de recuperação. Nesse contexto, o presente trabalho procurou inspecionar e analisar as patologias uma ponte rodoviária na cidade de Rio Branco, Acre, com o objetivo de analisar o estado de conservação da estrutura. Para isso, foi feita pesquisa bibliográfica sobre manifestações patológicas em pontes de concreto armado e aplicada ficha de verificação baseada na norma de inspeção em pontes e viadutos na ponte do estudo de caso, através de visitas ao local e relatório fotográfico. Os problemas encontrados na estrutura foram investigados e analisou-se como eles podem contribuir com o estado de conservação da ponte. Por fim, observou-se que a estrutura apresenta diversas patologias que não comprometem diretamente sua estrutura, mas que se não forem corrigidas a médio prazo podem-se desenvolver, comprometendo a estrutura e reduzindo drasticamente a vida útil e a durabilidade da ponte.

There is quite frequent requirement to provide load-bearing structures in order to safely access components installed at height. This implies, even for the initial and preliminary analysis activities, the construction of scaffolding or the use of special equipment such as lifting platforms. Therefore, considerations regarding technical times and costs to be incurred are objective and necessary. Nowadays, the technological development of the RPAS (Remotely Piloted Aircraft Systems) allows the effective bypass of the above-mentioned difficulties, allowing the carrying out of various checks useful to formulate a possible following campaign of punctual and localized checks. The small size and the sophisticated handling systems gives the possibility of locating with precision in the space at different heights, even in areas characterized by access difficulties. The on-site activities must be conducted by devices and personnel in possession of appropriate authorizations and certifications.
The objective of this article is to propose basic guidelines for carrying out surveys with the support of RPAS. In particular, the technical considerations to be considered for the choice and characteristics of the device and its accessories as well as the necessary actions such as the preparation of the flight plan, risk assessment and communication to the competent groups.

As the transportation infrastructure in the United States is aging and expanding rapidly, demolition and replacement of the existing systems has increasing importance. Highway bridge demolition has become increasingly significant as the bridges reaching their service design life require rehabilitation or replacement. Highway widening to meet capacity increase also involves partial or total removal of highway bridges. This paper presents the fundamentals of highway bridge demolition by explaining the systematic deconstruction, crane usage, and the engineering involved with this process.
Systematic deconstruction is the art and science of preventing unplanned potential energy release during a demolition process. Engineering is needed for the deconstruction process in order to protect the lives of the workers and in order not to damage any other structure in the close proximity of the structure to be demolished. In addition, the expensive machinery used for the deconstruction process needs to be protected. As a result, nearly as much engineering analysis is needed to demolish a structure than to initially build it.
While the stereotypical image of demolition is a wrecking ball or an explosive event, these are not typically used in highway bridge demolition. Explosive demolition is rare, and is used occasionally for very large bridges (as well as other large structures outside of this scope). For a typical highway overpass bridge hydraulic excavators sit on the deck removing concrete with a hydraulic hammer or shear, and then excavators or cranes placed on grade remove the girders.
The bridge structure is analyzed for different excavator positions and different stages of the demolition. The excavator body weight and the hammer tip weights are considered separately for different cases of demolition sequence.
The engineering work required for cranes involves support design for crane bases (tracks or outriggers), pick plan and pick weights (pick sequence, radii, clearances, center of mass, lay-down area), and rigging design (wire rope slings, stability of structure while being picked, local failures of the object being picked or the rigging components).

The bridge over the Beauharnois Canal is the main structure of the Nouvelle Autoroute 30 project, with a total length of 2551 m. It crosses the Beauharnois canal and the St-Laurent Seaway (SLS) with a twin deck, one for each highway direction.

The more than 3,500 citations listed here have been extracted from Volumes 1 and 2 of THE GRAND CANON, a far more expansive, topically arranged worldwide bibliography of the Grand Canyon and lower Colorado River regions of the United States and Mexico. (THE GRAND CANON is a series of publications accessible online at https://ravensperch.org.)  This bibliography focuses on the Hoover Dam, in the Colorado River on the Arizona–Nevada boundary, its power plant, and appurtenant structures. Coverage spans the twentieth century and the twenty-first to date. It includes all issues pertaining to conceptualization, planning, physical construction, and work force management. Also listed are publications concerning Boulder City, Nevada, principally during the period of construction.Appendix 1 is a list of publications about the concrete-arch Mike O’Callaghan–Pat Tillman Memorial Bridge, earlier called the Hoover Dam Bypass, which otherwise is not directly a part of the Hoover Dam infrastructural complex. Minor editing may have been made to some of the original citations taken from THE GRAND CANON, in order to eliminate comments that unnecessarily refer to places other than Hoover Dam.

Nel presente lavoro di tesi, dopo una breve introduzione storica sulla nascita del calcestruzzo armato e sulle sue proprietà, si illustreranno i meccanismi con cui si può produrre il degrado nelle strutture realizzate con questo materiale, analizzando i fattori ambientali e di progetto che maggiormente influiscono sulla funzionalità e la sicurezza di tali opere, trattando poi alcuni metodi di prevenzione del degrado e tecniche di ispezione. Tali argomenti risultano utili per affrontare il caso di studio del viadotto sul Polcevera, detto anche ponte Morandi in riferimento all'ingegnere che l’ha progettato, vittima di un ambiente fortemente aggressivo, posto nelle vicinanze del mare e di un complesso industriale, ma anche di una scarsa attenzione alla manutenzione, fattori che ne hanno determinato il collasso strutturale.