A new swing bridge for an electrified double-track railway has been proposed in Malaysia to replace an existing 40-year-old single-track swing bridge. The proposed swing bridge has two equal cantilevers each 45 m long and features a steel ”sail” on both sides as the main longitudinal structural element. The 9.1 m wide bridge deck is a composite design  -  steel structure with concrete slab. The swing span will be powered by means of an electrohydraulic drive situated in the centre pier and slews over the centre bearing located below the centre pivot shaft.

Flat lintels are an often used and effective method of bridging over wall openings. They consist of a composite system of tension chord and the overlying masonry, which is only considered in regulations in this combined construction. The special features of the construction and design are explained in the present article through the example of aerated concrete flat lintels, with the verification of loadbearing capacity being described and explained based on the latest regulations in technical approvals taking into account the relevant European structural design codes and their national annexes.

The construction of underground structures in metro rail projects is always challenging as the project works normally affect a large number of adjacent surface structures with stringent settlement criteria and protection requirements. Project implementation becomes even more complex when the overburden is shallow and the area of the cross-section is comparatively large. In the case of design and build metro rail projects, the Client provides a tender stage design to the Contractor's designer; this initial design is often based on limited data and does not consider the construction phase in detail. This is a significant challenge for the Contractor's designer as the new design has to consider all relevant parties and boundary conditions with respect to the compatibility of other parts of the project. This paper describes such a challenge at Mumbai metro line 3, where a crossover structure had to be implemented during the detailed design as a change of scope. The initially proposed crossover cavern was re-arranged during the detailed design. The main emphasis of this paper is to explain the revised crossover arrangement, for optimized construction feasibility, construction staging and geotechnical stability of the excavation. After the options presented by the Contractor's designer met the original objectives, the detailed design of the primary support and modified construction sequence was carried out in accordance with the principles of NATM design.

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Fatigue design according to CEB-FIP Model Code 90 is limited to concrete grades up to C80. In addition, the design rules include a strength-dependent reduction in the fatigue reference strength, which leads to uneconomical design of high-strength concrete. Considering comprehensive knowledge now available concerning the fatigue behaviour of normal-strength and high-strength concretes, the amount of this reduction can no longer be justified. A new design model for compressive fatigue loading and its derivation is presented in this article. A comparison between the new design model and the current standard ones reveals that the new design model ensures safe and economical design of normal-strength, high-strength and ultra-high-strength concrete. This new design model is included in the new fib Model Code 2010.

The performance-based durability design of reinforced concrete structures for corrosion of reinforcement is currently limited to the initiation period. That includes modelling the transport processes of chlorides and carbon dioxide into the concrete structure. Up to now, the subsequent time period after depassivation of the reinforcement, in which corrosion propagates, could not be modelled in a comparable manner. The task of the research project presented here, which was part of German Research Unit 537, was to develop a design model that enables a reinforced concrete structure to be designed against reinforcement corrosion for its entire service life. Therefore, a physically well-defined damage model for corrosion propagation was chosen as a basis. All system parameters in the damage model were investigated on the basis of numerical and laboratory studies carried out in the subprojects of the research unit. Statistical analysis allowed the simplification of the complex damage model into a user-friendly design model. This paper presents the working steps, the basic results of the analysis and the user-friendly full-probabilistic design model for reinforcement corrosion.

A design model for composite beam-to-reinforced concrete wall joints is presented and discussed in this paper. The model proposed is the component method extended to this type of joint. The characterization of the active components is therefore performed in terms of force-deformation curves. In this type of joint, special attention is paid to the steel-concrete connection where “new” components, not covered in EN 1993-1-8, are activated. The application of the model allows the designer to obtain the joint properties in terms of the moment-rotation curve. The accuracy of the proposed model is verified by comparing it with available experimental and numerical results. The latter were developed in the FE program ABAQUS and previously validated by experimental results.

The following article deals with the design of the inner lining of the Gotthard Base Tunnel and the determination of the design loads. The determination of the loads is based on the geological conditions encountered and takes into account the installed support measures and the deformation, occurring. The observational method also makes a considerable contribution. Together with the criteria stated above, it proved possible to find a definition of the hazard scenarios and the resulting rock pressure in order to optimise the design of the inner lining.

Der folgende Beitrag behandelt die Dimensionierung der Innenschale des Gotthard Basistunnels und die Ermittlung der hierfür anzusetzenden Lasten. Die Lastenermittlung basiert auf der angetroffenen Geologie unter Berücksichtigung der eingebauten Sicherungsmittel und der eingetretenen Deformationen. Einen nicht unwesentlichen Beitrag dazu leistete die Beobachtungsmethode. Zusammen mit den vorgenannten Kriterien gelang es, eine Definition der Gefährdungsbilder und den damit gegebenen Gebirgsdrücken zu finden, um schließlich die Dimensionierung der Innenschale zu optimieren.

This paper provides an overview of serviceability specifications given by the fib Model Code for Concrete Structures 2010 (fib MC2010 [1]). First, the reasons behind crack control and deflection control are discussed, then specific design rules are provided. Simple rules as well as detailed models are also presented. Numerical examples are provided in order to assist in the application of the design recommendations for crack control and deflection control (reinforced and prestressed concrete elements).
Simple rules mean indirect control of cracking or deflections without calculations. Indirect crack control may include limitation of stresses and selection of maximum bar diameter or maximum bar spacing. Indirect deflection control normally means limiting the span-to-depth ratio.
Detailed models are based on physical and mathematical approaches to cracking and deflections. The design crack width is expressed as the maximum bond transfer length multiplied by the mean strain between cracks. Deflection analysis can be provided by integrating curvatures or by using a simplified or refined method. Vibrations and numerical modelling of cracking are also briefly discussed.

CEB/FIP Model Code 1990 (MC-1990) did represent the technology and focus some 20 years ago. However, it soon became evident that the document had some notable lacunas. In 1995 the general assemblies of the two organizations endorsed CEB/FIP bulletin No. 228, extensions to MC 1990 for high-strength concrete, and in 2000 a similar extension to MC 1990 for lightweight aggregate concrete as bulletin No. 4.
The fib approved bulletin No. 34 Model Code for Service Life Design (MC SLD) in 2006. All these three additions have since matured and are now incorporated in the new fib Model Code for Concrete Structures 2010 (MC-2010).
The main purpose of an fib Model Code is to act as a model for operational standards. The obvious counterpart for a body such as fib operating worldwide is ISO. The initiative taken by MC SLD has therefore further matured in ISO TC-71/SC-3/WG-4 and it was accepted as ISO 16204 “Durability - Service Life Design of Concrete Structures” during the summer of 2012.
According to the obligations given in the WTO Agreement on Technical Barriers to Trade, it is hoped that these principles will be further implemented in national and regional standards.
This article describes the need for a transparent methodology when dealing with service life design, and the process - originating from a group of enthusiasts one decade ago - through fib and finally reaching international consensus in ISO.

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Prestressing in flat slabs helps to control deformations and cracking under service loads and allows the required slab thickness to be reduced, thus leading to more slender structures and an economic solution for long spans. However, as a consequence of the limited thickness of these members, punching typically governs at the ultimate limit state. Studies of the punching shear strength have shown that the presence of prestressing in flat slabs has a number of potential beneficial effects, namely the vertical component (force) carried by inclined tendons, the in-plane compression stresses and the bending moments developed near the supported region. However, the approach provided by codes of practice for punching design in the presence of prestressing may differ significantly. Some codes neglect the influence of the bending moments introduced as a result of prestressing and the sections at which the deviation forces of the tendons are considered may be located at different distances from the edge of the supported region. The influence of prestressing on the punching shear strength of members without shear reinforcement is investigated in this paper by using the fundamentals of the critical shear crack theory. Using that as a basis, and also taking into account 65 tests available in the scientific literature, the suitability and accuracy of a number of design codes, e.g. Model Code 2010, Eurocode 2 and ACI 318-11, are investigated and compared.

Nach einer Betrachtung des Marktanteils von Verbundbrücken in Frankreich im Vergleich zu anderen Lösungen wird die Kosteneffizienz der Verbundbrückenbauweise gegenüber Spannbetonbrücken im kurzen und mittleren Spannweitenbereich erläutert. Dieser Beitrag stellt neue technische Entwicklungen des Entwurfs und der Bemessung von Verbundbrücken vor, durch die die Wettbewerbsfähigkeit dieser Bauweise in Frankreich zurückgewonnen wurde und wodurch Verbundbrücken von den Betreibern gegenüber anderen Lösungen favorisiert werden. Der Beitrag geht auch auf neueste Entwicklungen und Innovationen im Bereich des Verbundbrückenbaus ein. Besonderes Augenmerk wird dabei auf die Montage gerichtet. Weiterhin werden die Bemessungsregeln zur Rißbreitenbeschränkung des jungen Betons der Fahrbahnplatte erläutert.

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Pillar systems in mines are statically indeterminate systems. The paper presents the results of numerical investigations to evaluate the effects of panel dimensions on pillar loads. It is shown that pillar load in deep mines is strongly influenced by the lateral and vertical extent of extraction panels. The commonly applied tributary area concept does not account for these effects and is an oversimplification that has to be applied with caution. The effects of local pillar failures on stability of pillar workings are examined using simple models. It is shown that limiting panel dimensions by substantial barrier pillars can reduce the danger of regional pillar collapses and enhance overall mine stability.

This paper presents the design considerations for typical photovoltaic panel arrays having aluminium members. Section and member design checks are performed according to Eurocode 9 on the basis of the wind, snow and seismic loads of Eurocodes 1 and 8. Improvements to the design are then sought, starting by reducing the distance between the vertical posts and then by changing the thickness of specific sections. Following that, the effects of member imperfections and connection flexibility are studied using a reduced flexural rigidity and different rotational stiffness values respectively. The degree of dynamic coupling when the array is placed on the top floor of an existing building as well as the influence of founding the vertical posts on compliant ground are also evaluated.

Steel design codes continue to be expanded to permit the use of more advanced methods of non-linear analysis. Designers looking to employ such methods need to validate their analysis software and, just as importantly, verify their ability to utilize it properly. The literature contains many benchmark problems and results to help achieve this, but nearly all are limited to two-dimensional behaviour. This paper is intended to contribute a new set of benchmark problems in order to help satisfy the need for a database of examples in which accurate modelling of three-dimensional or spatial behaviour is essential.

The mining complex Chuquicamata, of the National Copper Corporation of Chile (CODELCO), is located in the Atacama Desert, 1, 650 km north of Santiago, and 2, 870 m above sea level. Since the large copper ore reserve that lies below the “Chuquicamata” open pit (Fig. 1) will no longer be economically feasible to mine from the end of this decade, the mine is currently developing the required infrastructure to switch the operation to an underground mine type, where the block caving method with macro-blocks will be used to mine out copper ore. The future mine will count with four production levels, corresponding to one of the largest underground mining operations in the world, with a production rate of about 140, 000 t/d. This article presents design aspects of the permanent underground infra-structure works, which encompass several deep and steep tunnels and vertical shafts for the future mine access and operation.
Der Bergbaukomplex Chuquicamata der National Copper Corporation of Chile (CODELCO) liegt in der Atacama-Wüste, 1.650 km nördlich von Santiago und 2.870 m über dem Meeresspiegel (Bild 1). Ab Ende dieses Jahrzehnts wird der Abbau der Lagerstätte im Tagebau nicht mehr wirtschaftlich sein. Daher werden derzeit die notwendigen Infrastrukturanlagen errichtet, um den Betrieb auf Untertagebau umzustellen, wobei das Kupferz im Blockbruchbau mit Makro-Blöcken abgebaut werden soll.? Das Bergwerk wird künftig über vier Produktionsebenen verfügen und mit einer Produktion von etwa 140.000 t/d zu einem der größten Bergwerken der Welt zählen. Dieser Beitrag stellt einige Planungsgesichtspunkte für die dauerhafte unterirdische Infrastruktur vor, die mehrere tiefliegende und steile Tunnel und Vertikalschächte für die Erschließung der Lagerstätte und den Betrieb des Bergwerks umfasst.

The new Central Subway extension through downtown San Francisco consists of three underground stations and 2.7 km TBMdriven twin tunnel. This paper provides a description of the preliminary analyses and design of the ground support and final lining for the Union SquareMarket Street Station (UMS) along Stockton Street. This station will serve the Union Square Shopping District and connect to the BART Powell Street Station. Due to shortage of space above ground and to minimize surface disruption, the UMS station design requires a complex hybrid method consisting of a 20 m deep braced cut-and-cover box with a mined enlargement bulb below it with a height of 9.3 m and a width of 17.8 m.
The majority of the UMS station will be excavated in saturated alluvial deposits. Undifferentiated old bay deposits will be encountered in the invert, underlain by dense marine sands. The groundwater varies from 5 to 10 m below ground level, so uplift of the combined bulb/box structure has to be taken into account.
The Finite Element (FE) analysis of the UMS station cavern reflects the separate construction phases of the station platform box and the bulb to account for soil-structure interaction and load-sharing effects. FE analyses are used to estimate support requirements including ground improvement and to predict surface settlements.

Die Erweiterung der Central Subway durch die Innenstadt von San Francisco beinhaltet drei Stationsbauwerke und 2,7 km maschinell vorgetriebene Doppelröhrentunnel. In diesem Artikel erfolgt eine Beschreibung der Voruntersuchungen und Vorbemessung der Stützmaßnahmen sowie der Innenschale der Union SquareMarket Street Station (UMS) im Verlauf der Stockton Street. Diese Station soll dem Union Square Shopping Distrikt dienen und zur BART Powell Street Station verbinden.
Aufgrund der beengten Platzverhältnisse und zur Minimierung der Beeinträchtigung der Oberfläche ist ein “hybrides” Konzept der UMS-Station erforderlich. Dieses besteht aus einer 20 m tiefen ausgesteiften Baugrube (Box) und einer darunterliegenden bergmännisch hergestellten Kaverne (Bulb) mit 9,3 m Höhe und 17,8 m Breite.
Der Großteil der UMS-Station befindet sich in gesättigten alluvialen Ablagerungen. Undifferenziert werden alte Bucht-Ablagerungen und dichte marine Sande in der Sohle vorgefunden. Der Grundwasserspiegel variiert in einer Teufe zwischen 5 bis 10 m unter der Oberfläche, aus diesem Grund ist der Auftrieb des kombinierten Bauwerks bestehend aus Bulb und Box zu berücksichtigen.
In Finite Element (FE) Berechnungen der UMS-Station werden die einzelnen Bauphasen des Stationsbauwerks, sowohl von Box als auch Bulb, modelliert, um die Wechselwirkungen von Baugrund-Bauwerk und die jeweiligen Lastumlagerungen zu berücksichtigen. Mittels FE-Berechnungen werden schließlich die notwendigen Stützmaßnahmen - diese beinhalten auch Bodenverbesserungsmaßnahmen - und die Oberflächensetzungen festgelegt.

Nowadays, it is more and more often necessary to design two-dimensional reinforced concrete elements to satisfy both architectural demands and to comply with traffic safety requirements in the design of road and railway infrastructures. In fact, the demand for non-regular structural geometry is increasing in both cases.
As a consequence, the use of finite element analyses to model structures and calculate internal actions is constantly growing because closed-form solutions are generally unavailable for irregular shapes. Therefore, the problem of reinforcement design needs our attention because steel bars, in general, should be placed in non-orthogonal directions and can vary over the structure.
Consequently, there are two different kinds of design problem: choice of reinforcement direction and evaluation of the reinforcement ratio between the chosen directions, with the aim of minimizing the total amount.
Such problems can be easily overcome by generalizing a mechanical model consolidated in the literature for orthogonal reinforcement for skew directions. The model is set up according to the ultimate plastic behaviour of the elements. An optimization technique based on genetic algorithms is then applied to the new model to reduce the amount of reinforcement.
This paper describes both the ultimate resisting mechanism with generic reinforcement directions and the way genetic algorithms are employed to optimize the amount of reinforcement.

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Fabric formwork entails the use of fabrics as the main contact material for a concrete mould. The fabric is either hung or prestressed in a supporting falsework frame. Beams or trusses cast in fabric formwork are inherently non-prismatic and have been shown to offer potential for structurally efficient shapes. The casting of beams or trusses in fabric formwork is a highly non-linear problem due to the interaction of the fluid concrete with the woven, prestressed fabric material. Numerical models need to be developed for the engineering of these elements. To this end, it is demonstrated that it is feasible to integrate manufacturing constraints in an automatic optimization process. This is achieved by creating an automated computational framework that includes fabric form-finding and finite element analysis, which operate within an optimization process that uses principles from biological evolution. The results show structurally efficient and manufacturable beams and demonstrate potential for optimization in general that explicitly includes fabrication considerations.

Currently, long-term monitoring systems are mandatory for major civil engineering structures such as bridges, tunnels and dams. Generally, they monitor a set of physical, chemical and mechanical parameters in critical sections of the structure by incorporating appropriate sensors. The set of data collected demonstrates great potential in the prevention of damage and contributes to more efficient maintenance of the structures monitored. This work presents the long-term monitoring system installed on the new Lezíria Bridge over the River Tagus in Portugal. The system was developed to control some aspects of the construction process and to survey the service life of the structure. A set of structural, durability and environmental parameters defining the bridge condition are remotely assessed in real-time via a fibreoptic network. Aspects such as architecture, installation and functionality of the monitoring system are discussed and the innovative aspects of the implementation are highlighted. In this context, the main goal of this work is to present the long-term monitoring system of Lezíria Bridge, sharing the experiences, the solutions and the procedures adopted, given their potential usefulness in the implementation of similar projects.

The new metro line in Thessaloniki includes, besides the excavation of two twin tunnels, the construction of 13 stations with central platform in settlement-reducing top-to-down construction method. Due to restrictions in available space, it was necessary to dispense with the construction of an inner shell. Further constraints were the soft and highly inhomogeneous soil, the large excavation depths in groundwater, and the earthquake-resistant design of the structures. The special foundation works executed for permanent uplift safety as well for the soil strengthening in front of the excavation walls are described for representative stations.
Die neue U-Bahn in Thessaloniki umfasst, neben dem Schildvortrieb zweier Röhren, die Errichtung von 13 Bahnhöfen mit zentralem Bahnsteig in verformungsarmer Deckelbauweise. Wegen der engen Platzverhältnisse musste dabei auf eine Innenschale verzichtet werden. Weitere erschwerende Randbedingungen sind der weiche, stark inhomogene Untergrund, die große Aushubtiefe im Grundwasser und die erdbebengerechte Auslegung der Tragkonstruktion. Für typische Bahnhöfe werden die Spezialtiefbaumaßnahmen zur dauerhaften Auftriebssicherung sowie zur Verstärkung des Fußwiderlagers der tiefen Baugruben vorgestellt.