Data has been collected from several European ready-mixed concrete plants in order to analyse some data-based statistical aspects of the concrete family concept. Concrete strength records of concrete families were obtained from seven different concrete plants. This data is used to investigate the presence of autocorrelation in the transposed data of concrete family strength records. Further, strength records from two Belgian concrete plants are investigated in more detail and used to investigate how the concrete family concept, the applied transformation method and the family composition guidelines influence the general quality of accepted batches.

It is proposed to build concrete bridges with tendons fully encapsulated in plastic ducts and without the use of reinforcing steel. In this case the durability of the proposed bridge depends only on the durability of the concrete because corrosion is no longer a determining factor regarding the lifetime of the structure. The requirements of the serviceability and ultimate limit states are fulfilled by providing post-tensioned tendons with strands fully encapsulated in plastic ducts and watertight anchorages. Since the proposed bridge does not contain any steel, which would be endangered by material-related corrosion, there is no need for insulation to the deck. Consequently, there is also no need for pavement and edge beams. This concept of building bridges represents a breakthrough with regard to sustainability and durability of concrete bridges and is applicable to small and mediumsized bridges. The method has already been implemented for the design of the Egg-Graben Bridge in the Großarl valley in the province of Salzburg, Austria. Prior to the actual construction of the bridge, large-scale tests were performed to obtain practical values for the serviceability, ductility and loadbearing capacity of this structural system.

The concept of casting concrete in fabrics, fabric formwork technology, has resurfaced at various times and in different forms throughout the past century. The following paper traces developments that have used fabrics for concrete formwork, including different types of flexible formwork, controlled permeability formwork and pneumatic formwork. This paper presents a comprehensive historical overview of fabric formwork, listing key innovators, technological developments and their advantages, and offering examples of structures built with these methods. The information gathered is used to present a taxonomy of these related formwork technologies as well as a formal definition of the term “fabric formwork” that encompasses them. The paper is intended to introduce readers to these technologies and offer readers already familiar with these methods additional historical background.

The purpose of this paper is to improve the performance of a twodimensional finite element approach, called the Rotating Compression Field Model (RCFM). The RCFM capability for reproducing the non-linear behaviour of reinforced concrete (RC) beams, tested in shear with monotonic load increase, has been tested and amended. Concrete is treated as a quasi-orthotropic material with smeared cracks and smeared reinforcement. A modified version of the Sargin relationship for concrete in compression is adopted, introducing a new model for the softening branch of the stress-strain compression curve in the RCFM to take into account compression softening and the effect of confinement due to inplane reinforcement. In addition, this paper considers out-ofplane confinement effects using the model suggested by Eurocode 2.
A key issue in the RCFM approach consists of relating the decay of effective concrete strength to the deviation angle between the inclination of the compression stress field at first cracking and its inclination at the load level considered. The validity of this relation has been extended from the original 15° up to more than 30°.
A new stress-strain curve is implemented in the code to model the tensile behaviour of concrete without reinforcement (tension softening) in addition to the tension stiffening effect already present for concrete with reinforcement. This model leads to a successful comparison with experimental results on RC beams for a significant range of design parameters and mechanical material properties.

A deformation criterion is proposed for the fatigue failure of concrete in tension. According to the criterion, a fatigue failure is imminent when the total deformation approaches the deformation at maximum stress in a corresponding static test. This criterion was originally proposed for bond slip by Balázs in 1991. It is tested on two series of new and old concrete cylinders loaded in cyclic tension. How the criterion may be used to predict the number of load cycles to failure for existing structures under cyclic tensile loading is also shown.

Strengthening reinforced concrete (RC) beams in shear using carbon fibre-reinforced polymer (CFRP) has been found to enhance, significantly, the shear capacity of existing RC beams. In previous studies the use of steel plates bonded externally to the RC beams was found to improve the shear performance of these beams. Most of the previous work was conducted on RC beams having rectangular sections. The main objective of this paper is to gain a better understanding and enhance the experimental database of shear behaviour of RC T-beams strengthened with externally bonded reinforcement (EBR) systems. The present study encompasses some of the important parameters such as direction of EBR fibre alignment and the strengthening materials made of carbon-fibre sheets, steel plates or steel bars for shear strengthening. The contribution of EBR to the shear capacity of the T-beams was computed using three design codes and compared with the experimental output. A series of RC T-beams was tested experimentally with the CFRP and steel strips carefully aligned and spaced. A reference T-beam and a rectangular beam were tested as well to explore the effect of the internal shear reinforcement and the existence of the flange on the shear capacity of the beam.

A unique suspension method developed over a period of more than 10 years produces a rational structure in the form of a single-span composite truss bridge. For this structure, the steel truss and concrete deck are constructed on the spanning cables. During construction the horizontal forces of these cables are anchored into the ground, but after completion of the bridge the forces are transferred to concrete upper and lower chords as prestressing forces. A single-span composite truss bridge of this type can be constructed without temporary supports or falsework. Using this method to bridge a deep valley produces benefits in terms of both construction costs and sustainability. A single-span bridge requires less excavation than other bridge types, and utilizing a composite truss with this construction method can minimize the environmental impact of the construction.

This bridge, which won a fib Award for Outstanding Concrete Structures in 2010, connects a newly developed area (Spielberk Office Centre) with an old city district. It is situated in the vicinity of a new international hotel and a prestige business area. Close to the bridge there is an old multi-span arch bridge with piers in the river. It was evident that any new bridge should also make use of an arch structure, but with a bold span not needing piers in the riverbed, see Fig. 1. Due to poor geotechnical conditions, a traditional arch structure with a large horizontal force to be resisted was considered too expensive. Therefore, a self-anchored stress ribbon and arch structure was chosen. The smooth curves so characteristic of stress ribbon structures allowed a “soft” connection of the bridge deck at both banks.

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 Island Tower Sky Club is a super high-rise RC apartment block constructed in Fukuoka City, Japan, which makes inventive use of the most advanced building technologies. The building is 145 m tall with 42 storeys. It is composed of three similar, slender towers with three-fold rotational symmetry. The towers are connected at three different levels by aerial gardens and contain various vibration control devices to assure a high level of safety. The aerial gardens are connected to the towers by vibration control dampers to reduce the overturning effects of the towers caused by seasonal winds and large earthquakes. An elaborate control system can reduce the storey acceleration response by 30 %. At the upper two storeys of each tower, super-plastic zincaluminium alloy dampers are also used. To reduce the storey acceleration response, the base of the building is isolated using a hybrid system of bearing supports and dampers. The validity of the control system implemented is confirmed by human power vibration tests conducted at the aerial gardens.

A number of studies in recent years have attempted to understand and calculate the shear strength of hollow-core slabs, but no consensus has been reached on this issue. The current design methods for hollow-core shear resistance are derived from experimental results and elastic theories that are not usually directly related to the behaviour at the ultimate limit state. Moreover, some manuals on this subject do not discuss anchorage failures, which although not common in this type of slab, may influence the shear strength. This paper considers the anchorage failure of strands using the concepts of Eurocode 2 and presents an analytical methodology for shear design based on the modified compression field theory (MCFT). Furthermore, the safety concepts of Eurocode 2 are properly presented and evaluated using the experimental data available in the literature. The proposed methodology is proved to be accurate and is simple enough for use in design. Comparisons with CSA A23.3 and Eurocode 2 are also shown.

The possible deleterious effects of coiling and long-term storage of coiled wires on the stress relaxation behaviour of prestressing steel wires has been checked by means of experimental work and a simple analytical model. The results show that if the requirements of standards are fulfilled (minimum coiling diameters), these effects can be neglected. However, some other factors, such as previous residual stresses, long-term storage or storage at high temperatures, can trigger or emphasize this damage to the material. In the authors' opinion, checking the final curvature of the wires after uncoiling prior to prestressing, as required in some standards, is to be recommended.

In 2008, ACI 318 initiated a six-year task of reorganizing the format of the ACI Building Code for Concrete Structures. This is the first major reorganization of the code in nearly 40 years. The reorganization effort moves the code from a behaviour-based to a member-based design approach. This article presents the philosophy of the code development, efforts leading up to the reorganization and an outline of the 2014 code format.

Typical for extreme events is their multidisciplinary nature, and, consequently, solutions for protection against extreme events should mirror their inherent characteristics. This article discusses different types of hazards and extreme events in order to illustrate the complexity and scale of the problem. Concepts for judging hazards and associated risks are dealt with. Some features of the traditional risk concept are discussed, followed by a proposal for an extended risk concept, to be applied when dealing with extreme hazards. The emphasis will be on aspects that are typical of “low-probability/high-consequence risks”, particularly industrial risks. The potential role of structural (concrete) protective systems for mitigating the consequences of industrial accidents is emphasized. Throughout this article, the role of structural designers and their possible contribution to the debate on adequate protection against extreme events is addressed.

Considering the volume of concrete produced and the number of concrete structures built, the problem of the associated environmental impact forms a significant part of the entire global problem of sustainable development. Utilization of environmentally optimized concrete structures thus creates a potential for increasing the quality of construction and consequently a reduction of the environmental impact. A life cycle assessment (LCA) is a complex, multi-parametric assessment of the environmental impact of the structure over its whole life cycle. It covers, in one assessment process, all the essential environmental issues, including CO2 emissions, energy consumption, water consumption, waste generation, etc. In the case of concrete, selected criteria should support the design and construction of high-quality and at the same time environmentally friendly concrete structures. The principal problem is to collect relevant environmental input data for specific concrete types plus transport and production processes which can be used in the LCA procedure.

There are numerous ways of improving concrete structure's environmental performance. An overview of these are presented and exemplified in the present article. They include choice of raw materials, mix design of the concrete, production processes, construction processes, design and use during service life and the end-of-life demolition-crushingreuse. Thus the whole life cycle is considered. This will be the key content of the future fib 3.8 guidelines on green concrete structures which will also include some background information and specific benchmark data.

The environmental impact and the effect of its reduction must be assessed quantitatively if we are to show clearly the effect of lowering the environmental impact of concrete and concrete structures. One of the quantitative evaluation methods is to regard and verify the environmental impact of concrete and concrete structures as an environmental performance in accordance with the performance-based design method. This article briefly describes the performance-based environmental design method prepared by fib Commission 3 TG3.6 and shows an example of the application of the design method applied to a concrete structure.

The sheer amount of concrete in use and in stock compared with other building materials throws up environmental issues such as the huge amount of CO2 emitted when cement and concrete are produced and transported and the enormous amount of waste generated when concrete is disposed of. In addition, we are beginning to deplete aggregate resources at a fast rate. Concrete has conventionally been regarded as being difficult to recycle. The construction industry has addressed these problems and carried out research and development regarding the recycling of concrete since the 1970s. Recycling technology has been shifting from simple crushing into scrubbing with some preparations to produce high-quality recycled aggregate for structural concrete, and recycling of concrete in a completely closed loop has now become technically feasible. This paper reviews the development history of recycling technologies in Japan from the viewpoint of the properties of recycled aggregate and recycled aggregate concrete as well as the environmental impact such as CO2 emissions and waste generation in recycling. The paper also presents the outline of completely recyclable concrete, with which closed-loop circulation of component materials is realized.

Many national codes in Asia are heavily influenced by those from either Europe or the USA. The climatic, technological and economic conditions together with the material properties in Asia are, however, quite different from those in Europe and the USA, and even different among Asian countries. Thus, many Asian countries need their own national codes with suitable concepts and technologies. At the same time, many construction projects in Asia are carried out in multi-national environments in which various national codes are applied, meaning that international code harmonization is necessary. In order to work for the global issue, such as the construction of a sustainable world, Asia, as the largest economic zone in the 21st century, should take on a leading role. For this purpose, international code harmonization with the new direction of life cycle management (LCM) would provide an efficient way.
The International Committee on Concrete Model Code for Asia (ICCMC) was established in 1994 as the first international body in Asia. The ICCMC issued the Asian Concrete Model Code (ACMC) in 2001, the first international structural code in Asia. The ACMC is an umbrella code with a performance-based concept and a multi-level document structure, which makes it suitable for the considerable diversity in Asia. It is also the first international code covering maintenance and repair, which makes the ACMC ready to adopt the LCM concept. The ACMC has been a model for various national codes. The main features of the ACMC, i.e. the performance-based concept, durability design concept, seismic design concept and the inclusion of maintenance/repair, are shared with JSCE Standard Specifications in Japan. The ICCMC has been working together with ISO/TC71 towards international code harmonization.

This article explains a method for determining how semi-continuous joints influence the deflection, natural frequency and bending moment distribution of single-span beams with constant inertia under uniformly distributed load. The method is adequate for simple hand calculations, allowing the structural engineer to assess potential savings already in the pre-design phase. Further, the economical potential of semi-continuous joints according to EN 1993-1-8 [1] is demonstrated by an application example.

Structural glass corresponds to an innovative material with extraordinary aesthetical and architectonic potential that has undergone significant technological advances in recent years, yielding it stronger and safer. For this reason, the use of structural glass has increased considerably in the last decade and is now an unavoidable presence in most of recent reference buildings.
The structural capacity of glass elements is brought in from reinforcing techniques of different types. One of the possibilities corresponds to pre stressed cables reinforcement. This technique is very effective in terms of resistance and deformability and corresponds to a light reinforcing element rendering the so called spider web effect. In the framework of the research project “S-Glass: Structural performance and design rules of glass beams externally reinforced” [1] study the behavior of laminated glass beams reinforced by too twin external steel rods.
The work presented in the current paper is within the framework of S-Glass project aiming at characterizing the behavior of reinforced laminated glass beams in the non-crack regimen. For this purpose experimental and numerical analysis were prepared. The numerical model was used for a cable layout optimization analysis. Furthermore an analytical solution is put forward, which tackles the beam-cable load transfer indetermination. Final conclusions are established on the bases of a comparison established between experimental, numerical and analytical results.

This paper reports on recent developments in high-strength and stainless steel tubular members and connections. It includes carbon steel tubes with a yield stress up to 1350 MPa and stainless steel tubes. The paper describes high-strength tubes in terms of residual stresses, material properties at elevated temperatures, member behaviour, welded connections under static loading, fatigue strength of welded connections, fabricated sections utilizing high-strength steel tubes and stainless steel tubular members and connections.

The current version of the Eurocode for the design of joints does not include any brace load capacity reduction for welded hollow section joints with tensile chord preloading as opposed to those without. However, the more recent 2nd edition of the CIDECT design guides or the ISO standard for welded hollow section joints includes a strength reduction due to tensile chord stresses. This paper presents the results of experimental and numerical investigations into how tensile chord stresses influence the capacity of circular hollow section X-joints. The conclusion of this study is a new chord load function proposal for circular hollow section joints subjected to tensile chord stresses.

Steel tubes may be loaded by concentrated lateral loads such as support or impact loads. Impact loading, for example, is an important load case for buried pipelines that are struck during excavation activities, or large-diameter tubes during transportation (handling accidents). This paper presents an analytical model based on shell theory to determine the elastic-plastic load deformation behaviour. Test results are given as well as the results of finite element calculations. The finite element results and the model equations are in good agreement with the experimental results and illustrate the tube denting response.

Hybrid girders represent an economical alternative to homogeneous girders because they achieve greater flexural capacity with less material. One of the potential applications of hybrid steel plate girders is their use in bridges. One potential method of construction for these bridges is the push launch method in which patch loading may affect the design. The aim of this paper is to present the advanced conclusions of research work dealing with these two fields simultaneously: hybrid steel plate girders subjected to the particular case of patch loading. It is shown that, contrary to the EN 1993-1-5 formulation, the influence of the fyf /fyw ratio (namely, the hybrid grade) is negligible for both unstiffened and longitudinally stiffened girders according to the EN 1993-1-5 assumptions. Suggestions for considering these findings in design codes are provided at the end of the paper.