bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a new bridge construction method using suspension structures
Authors: Kasuga Akio 
Published: October 2013

AbstractA 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.
Green concrete structures
Authors: Glavind Mette 
Published: October 2013

AbstractThere 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.
Anchorage failure and shear design of hollow‐core slabs
Authors: Araujo Carlos Antonio Menegazzo , Loriggio Daniel Domingues , Da Camara José Manuel Matos Noronha 
Published: October 2013

AbstractA 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.
Life cycle assessments of concrete structures – a step towards environmental savings
Authors: Hájek Petr , Fiala Ctislav , Kynčlová Magdaléna 
Published: October 2013

AbstractConsidering 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.
Footbridge across the River Svratka in Brno, Czech Republic
Authors: Stráský Jiří , Štefan Petr , Nečas Radim 
Published: October 2013

AbstractThis 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.
Design and optimization of fabric‐formed beams and trusses: evolutionary algorithms and form‐finding
Authors: Veenendaal Diederik , Coenders Jeroen , Vambersky Jan , West Mark 
Published: October 2013

AbstractFabric 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.
The 2010 fib Model Code for Structural Concrete: a new approach to structural engineering
Authors: Walraven Joost C. , Bigaj‐van Vliet Agnieszka 
Published: October 2013

AbstractThe fib Model Code is a recommendation for the design of reinforced and prestressed concrete which is intended to be a guiding document for future codes. Model Codes have been published before, in 1978 and 1990. The draft for fib Model Code 2010 was published in May 2010. The most important new element in this Model Code is “Time” in the sense of service life. Additionally, the Model Code contains an extended state‐of‐theart chapter on the structural materials concrete and steel but regards non‐metallic reinforcement and fibres as reinforcement as well. Many loading conditions are considered, ranging from static loading to non‐static loading, considering earthquake, fatigue and impact/explosion. Five methods are offered to verify structural safety. Attention is given to verification of limit states associated with durability, robustness and sustainability. Finally, verification assisted by numerical methods and by testing is considered. Other elements that are links in the chain of life cycle design are construction and conservation. In the part on conservation the conservation strategy is treated in combination with conservation management, condition survey and assessment, and evaluation and decision‐making.
Determining the in situ concrete strength of existing structures for assessing their structural safety
Authors: Steenbergen R.D.J.M. , Vervuurt A.H.J.M. 
Published: October 2013

AbstractEN 13791 applies when assessing the in situ compressive strength of structures and precast concrete components. According to the code itself, it may be adopted when doubt arises about the compressive strength of a concrete. For assessing the structural safety of existing structures, however, the method given in EN 13791 does not seem to be applicable and may lead to an unsafe approach for determining the characteristic concrete strength. This paper presents an alternative method for determining the characteristic concrete strength from cylinders obtained in situ. The method proposed is based on EN 1990 (Eurocode basis of design) and the corresponding Annex D. The method according to EN 13791 is outlined in this article. Moreover, the practical implementation of the method in accordance with clause 5.2 of EN 1990 is explained and an example is given. Finally, both methods are compared with each other. It is demonstrated that EN 13791 does not apply to safety assessments of existing concrete structures and the use of this code may lead to unsafe situations.
Design according to MC2010 of a fibre‐reinforced concrete tunnel in Monte Lirio, Panama
Authors: Caratelli Angelo , Meda Alberto , Rinaldi Zila 
Published: October 2013

AbstractThis paper discusses the possibility of using precast tunnel segments in fibre‐reinforced concrete without traditional reinforcement. The case study of a hydraulic tunnel in Monte Lirio, Panama, excavated with a tunnel boring machine (TBM) by SELI S.p.A., has been analysed.The segments were designed according to the draft of Model Code 2010. In order to achieve the required performance and to optimize the structural behaviour, three different types of steel fibre were considered in the research.The design was backed up by full‐scale tests on precast segments. In particular, 18 full‐scale tests were performed, including point load tests simulating the thrust of the TBM and bending tests. The results show the good behaviour of the elements and indicate the fibre‐reinforced concrete suitable for the precast elements.
DEM simulation of concrete fracture and crack evolution
Authors: Beckmann Birgit , Schicktanz Kai , Reischl Dirk , Curbach Manfred 
Published: October 2013

AbstractA two‐dimensional simulation of concrete behaviour using the discrete element method (DEM) is presented in this work. The main aim of this paper is the modelling of the failure process and crack initiation. The failure process of a concrete prism during a compression test is simulated. A substructure representing the concrete components – aggregate and cement matrix – is introduced. It is shown that convex and concave concrete specimens can be treated, whereas the particle geometry always remains convex. The crack patterns of the concrete specimens resulting from the simulation are shown and compared with laboratory experiments. It is shown that the calculated peak load does not depend on the particle number used in the simulation. The ratio of lateral strain to longitudinal strain of the concrete specimen during load application is simulated and compared with experimental results.
Seismic performance of concrete bridges during Canterbury earthquakes
Authors: Palermo Alessandro , Wotherspoon Liam , Hogan Lucas , Le Heux Mitchel , Camnasio Elena 
Published: October 2013

AbstractIn less than six months, the city of Christchurch, New Zealand, experienced two major earthquakes: on 4 September 2010 and 22 February 2011. The former was generated by the rupture of the previously unknown Greendale fault, releasing a magnitude Mw 7.1 earthquake 30–40 km away from the Central Business District (CBD); the latter event, of magnitude Mw 6.2, was less than 10 km from the CBD on an unknown buried fault at the edge of the city. There was widespread damage to the lifelines covering not only Christchurch City but also the closest districts of Selwyn and Waimakariri. The different nature of the fault ruptures and locations of the two events resulted in a variation in damage levels between the earthquakes throughout the region.Teams from various organizations performed inspections on over 800 bridges throughout the affected Canterbury region. No major collapses were registered among concrete bridges and only 20 bridges required closure due to damage caused by the two earthquakes. Owing to the nature of the Canterbury soils, extensive liquefaction and lateral spreading occurred throughout the region. It was this lateral spreading that caused most of the traffic disruption and closure of bridges, due to damage to the abutments and approaches, foundation settlement and rotation.The authors aim to give a detailed overview of the damage assessment and seismic performance of the Canterbury bridges during these two earthquakes, emphasizing unexpected issues that are still not properly detailed in New Zealand and overseas standards.
Analysis of the subgrade stiffness effect on the behaviour of ground‐supported concrete slabs
Authors: Alani Amir M. , Aboutalebi Morteza 
Published: October 2013

AbstractThis paper confirms that the structural behaviour of ground‐supported slabs is a non‐linear function of the structural properties of slabs as well as the supporting soil. The findings reported emphasize that the suggested equations used in design codes pay insufficient attention to the effect of the supporting ground stiffness within the context of the mechanical behaviour of slabs as far as ductility is concerned. The results presented demonstrate that ground stiffness has a significant effect on the ductility of ground‐supported slabs. It also pays particular attention to the possibility of determining the ductility limit of slabs.
Design model for the fatigue behaviour of normal‐strength, high‐strength and ultra‐high‐strength concrete
Authors: Lohaus Ludger , Oneschkow Nadja , Wefer Maik 
Published: October 2013

AbstractFatigue 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.
Performance of olive waste ash concrete exposed to alkali‐silica reaction
Authors: Al‐Akhras Nabil M. 
Published: October 2013

AbstractThis work investigates the effect of olive waste ash (OWA) on the durability of concrete exposed to alkali‐silica reaction (ASR). Three OWA contents were considered in the work: 7, 15 and 22 %, with crushed Pyrex glass used as reactive fine aggregate. The other experimental parameters investigated in the study were: w/c ratio (0.4 and 0.5) and air content (non‐air‐entrained and air‐entrained). The OWA concrete specimens were submerged in 1‐N NaOH solution at 40 °C to accelerate the ASR. The ASR damage was monitored by measuring the expansion of concrete prisms and the decrease in compressive strength.The study demonstrates that OWA concrete is more resistant to ASR deterioration than plain concrete. The durability of OWA concrete with respect to ASR damage improved with the increase in OWA content. The OWA concrete with a w/c ratio of 0.4 exhibited a better performance with respect to ASR deterioration than the OWA concrete with a w/c ratio of 0.5. The air‐entrained OWA concrete exhibited better durability with respect to ASR damage than the non‐air‐entrained OWA concrete.
Dynamic response of concrete footbridges
Authors: Stráský Jiří , Nečas Radim , Koláček Jan 
Published: October 2013

AbstractExperience with the analysis and performance of 15 lightweight concrete footbridges is presented from the point of view of their dynamic response caused by moving people. The footbridges are formed either by a stress ribbon or by a slender deck supported by arches or suspended from pylons. The dynamic response was determined according to a procedure given in a 1998 draft of Eurocode 2: Design of Concrete Structures – Part 2: Concrete Bridges. Thirteen footbridges have been built and so far no complaints about their dynamic behaviour have been recorded.
Transverse thermal stresses in concrete box cross‐sections due to climatic exposure
Authors: Larsson Oskar , Thelandersson Sven 
Published: October 2013

AbstractSpatial and temporal temperature variations in a concrete structure due to variations in the surrounding climate will produce movements which, if restrained, may induce stresses in the structure. To get a better understanding of transverse thermal stresses due to climatic effects in concrete box cross‐sections, the FE simulations in this study have been performed using extensive climatic input data directly or by using simplified methods to simulate the temperature and resulting stress fields in a section of the hollow concrete arch of the New Svinesund Bridge. Studies of other cross‐sections with varying depth, width and wall thicknesses have also been performed to investigate the geometrical influence. The results reveal an overestimation of the maximum thermal tensile stress when using a linear temperature differential approach compared with the direct use of climate data that includes the non‐linear part of the temperature distribution. The effect of depth, width and orientation is negligible compared with variations in thickness between slabs and walls. For box sections with slabs/walls having different thicknesses, the transverse thermal stresses will be significantly larger in the thinner members, irrespective of the actual orientation and position of the member.
Cracking of RC members revisited: influence of cover, ϕ/ρs, ef and stirrup spacing – an experimental and theoretical study
Authors: Pérez Caldentey Alejandro , Corres Peiretti Hugo , Peset Iribarren Joan , Giraldo Soto Alejandro 
Published: October 2013

AbstractThis article describes an experimental programme aimed at studying the effect of cover, ratio between diameter and effective reinforcement ratio (ϕ/ρs, ef) and the influence of stirrup spacing on the cracking behaviour of reinforced concrete elements. The experimental programme was conceived in order to contribute to the debate – fuelled by the publication in recent years of Eurocode 2 EN1992‐1‐1 and the revision of the Model Code under way when the tests were carried out (and now published as a finalized document) – regarding the influence of these parameters on cracking. Important theoretical aspects are discussed, including where the crack width is estimated by current code formulations and what relevance this may have on the correlation between crack opening and durability of RC structures, especially with regard to structures with large covers. The effect of stirrup spacing, a variable absent from current codes, is also discussed.
Global safety format for non‐linear analysis of reinforced concrete structures
Authors: Allaix Diego Lorenzo , Carbone Vincenzo Ilario , Mancini Giuseppe 
Published: October 2013

AbstractSemi‐probabilistic safety formats for the non‐linear analysis of reinforced concrete structures are of practical interest for structural designers. The safety format proposed in EN 1992‐2 enables a safety assessment through a non‐linear structural analysis and the application of a global safety factor, which is defined as the ratio between the representative and design values of the material resistances. A more realistic estimate of the global safety factor can be obtained from the distribution of the structural response. This paper proposes a safety format based on the mean values of the material resistances and a global resistance factor. Its practical application in the structural design of concrete beams and columns is also presented.
Finite element study of bond strength between concrete and reinforcement under uneven confinement condition
Authors: Zanuy Carlos , Curbach Manfred , Lindorf Alexander 
Published: October 2013

AbstractIt is well known that many factors affect the bond behaviour between concrete and steel reinforcement. Most of them characterize the degree of confinement, which is necessary for an appropriate determination of the bond strength and bond‐slip relationship according to most extended models. Nevertheless, there are situations where the confinement is not known in advance or it can hardly be defined. That is, for example, the case of reinforced concrete under transverse pressure or tension. Under such conditions the confinement varies both longitudinally and circumferentially. This paper presents a 3D finite element approach to study the bond capacity of cases where the bond strength of the specimen is the result of the different contribution provided along the steel‐concrete interface and cannot be described uniquely. A surface‐to‐surface contact model with frictional behaviour and debonding is used to study the influence of the local stress state at the interface. The model is able to reproduce the different failure modes (splitting or pull‐out) obtained in experiments and provide a rational explanation of the influence of transverse tension.
Resistance of reinforced concrete members with hollow circular cross‐sections under combined bending and shear – Part I: experimental investigation
Authors: Völgyi István , Windisch Andor , Farkas György 
Published: October 2013

AbstractPart I of this paper introduces an experimental programme carried out on RC members with thick‐walled hollow circular cross‐sections to study their behaviour under combined bending and shear. The study looked at ultimate resistance and propagation of characteristic crack pattern as well as the shape and behaviour of the failure sections as a function of wall thickness, amount of longitudinal and transverse reinforcement, shear span and axial force. Test results were used to verify a newly developed calculation model describing the behaviour of the members investigated at failure under combined bending and shear. This model will be presented in Part II.
Sound engineering through conceptual design according to the fib Model Code 2010
Authors: Corres‐Peiretti Hugo 
Published: October 2013

AbstractConceptual design is the approach that creates an idea in order to find a solution to a new proposal for a structure or solve a detail in a specific structure. It is a personal approach that is learned over time and with experience. It is not normally dealt with at university, but is vitally important for producing sound structures.The fib Model Code for Concrete Structures 2010 introduced this concept in the first section of chapter 7 “Design”. The content of that section explains the general approach to developing conceptual design.This paper will show different examples of conceptual design following the general guidelines stated in the Model Code.