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Structural Concrete

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ISSN (Print) 1464-4177 - ISSN (Online) 1751-7648
Published by John Wiley and Sons

[1587 journals]

Design recommendations for interface shear transfer in MC 2010
- Authors: Norbert Randl
  Pages: n/a - n/a
  Abstract: Interface shear transfer between differently aged concretes is a topic that occurs frequently and in different situations in structural design. In MC2010, the fundamental basics of concrete‐to‐concrete load transfer are given in chapter 6.3 and the according design rules in subchapter 7.3.3.6. The different potential mechanisms contributing to the shear resistance along the interface, i.e. adhesive bond, aggregate interlock, friction and dowel action, are thereby combined and their interrelationship taken into account by interaction factors. This article summarizes the most important results from past and on‐going studies and presents the background to the theory forming the design basis of MC2010, the “Extended Shear Friction Theory”.
  PubDate: 2013-04-16T02:21:35.899423-05:
  DOI: 10.1002/suco.201300003
Bilateral loading experiment and analysis of concrete piers using mortar‐jointed ultra‐high‐strength fiber‐reinforced concrete precast formwork
- Authors: Shinichi Yamanobe; Kimio Saito, Toshimichi Ichinomiya, Yoshihisa Kanamitsu
  Pages: n/a - n/a
  Abstract: The seismic performance of a reinforced concrete pier structure depends greatly on the plastic hinge region at the bottom of the pier. To improve the plastic hinge region of the structure, we propose applying ultra‐highstrength fiber‐reinforced concrete (UFC) formwork to concrete cover at the bottom of the pier. This study describes the structural characteristics of a pier whose bottom was cast by using mortar‐jointed ultra‐high‐strength fiber‐reinforced concrete (UFC) formwork. To investigate the structural characteristics, a bilateral circular cyclic loading experiment and a simulation analysis using a fiber model were conducted. The results showed that the flexural strength remained stable under a large rotation angle; even at the rotation angle of the ultimate state, crushing failure of mortar did not occur and the ultimate state did not result from mortar damage, because the tensile strength of mortarfilled joints is close to zero, and thus excellent flexural crack distribution performance can be achieved.
  PubDate: 2013-04-16T02:21:31.472375-05:
  DOI: 10.1002/suco.201200061
DESIGN FOR SLS ACCORDING TO MC2010
- Authors: György L. Balázs; Philippe Bisch, Adorján Borosnyói, Olivier Burdet, Clare Burns, Alejandro Pérez Caldentey, Francesca Ceroni, Vladimir Cervenka, Mario A. Chiorino, Pier Giorgio Debernardi, Lars Eckfeldt, Mamdouh EL‐Badry, Ekkehard Fehling, Stephen J. Foster, Amin Ghali, Viktor Gribniak, Matteo Guiglia, Gintaris Kaklauskas, Alena Kohoutková, Bob J. Lark, Péter Lenkei, Michel Lorrain, Antonio Marí Bernat, Josko Ozbolt, Marisa Pecce, Maurizio Taliano, Damir Tkalc̆ić, Jean Michel Torrenti, Lluis Torres, Francois Toutlemonde, Tamon Ueda, Jan L. Vítek, Lukás Vráblík
  Pages: n/a - n/a
  Abstract: The present paper provides an overview of serviceability specifications given by the fib Model Code 2010 (MC2010). First the reasons of 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 also provided in order to help application of the design recommendations for crack control (reinforced and prestressed concrete elements) and for deflection control (reinforced and prestressed concrete elements), respectively. 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 limitation of the span to depth ratio. Detailed models are based on physical and mathematical approaches of cracking and deflections. The design crack width is expressed as the multiple of maximum bond transfer length multiplied by the mean strain between cracks. Deflection analysis can be provided by integration of curvatures or using a simplified or a refined method. Vibrations and numerical modelling of cracking are also briefly discussed.
  PubDate: 2013-04-16T02:21:26.512662-05:
  DOI: 10.1002/suco.201200060
Two Layer Concrete Bridge Beams as Composite Elements
- Authors: Iakov Iskhakov; Yuri Ribakov
  Pages: n/a - n/a
  Abstract: Two layer high performance RC beams can be used in the traffic (longitudinal) direction of long‐span bridges. The beam's section consists of two parts. The bottom part is made of normal strength concrete (NSC) and has a “U”‐ type section. The upper one is made of steel fibered high strength concrete (HSC) and has a rectangular section. Using two layer beams is logical, because as the beam span becomes longer and as the service load increases, higher concrete strength is required in the beam's compressed section zone to withstand rather big bending moments. As concrete in the tensile zone of the section contributes little to the beams' bearing capacity, this zone is made of NSC. It is an important economical advantage of two layer beams. Steel fibers are used just in the compressed zone made of HSC. Addition of steel fibers yields higher ductility of the HSC layer, allowing proper design of two layer bridge beams to dynamic loads. For such beams the design parameters include the HSC class, whereas the HSC layer depth is known and equals to the height of the rectangular section part (covering the “U” section). The bottom NSC part (“U” section) of long span beams is usually pre‐stressed. Taking into account this circumstance, the total beam section height should be checked in the service limit state.
  PubDate: 2013-04-16T02:21:21.819907-05:
  DOI: 10.1002/suco.201200055
3D numerical modelling of concrete structural element reinforced with ribbed flat steel rebars
- Authors: Thanh Song Phan; Jean‐Louis Tailhan, Pierre Rossi
  Pages: n/a - n/a
  Abstract: The construction company MATIERE has developed in recent years a new type of reinforcement constituted by ribbed flat steel. The objective of the present work and paper is to obtain information about the bending behaviour of RC structural element reinforced by these ribbed flat steel and also about the cracking process (number of cracks and cracks opening) that they induce, especially in the serviceability limit state. The structural element chosen in the frame of this work is a small beam‐slab (330 x 15 x 80 cm3) subjected to three points central bending. In parallel to this experimental study, a 3D finite element modelling is developed at IFSTTAR to consolidate the experimental results. It appears that the numerical modelling strategy chosen in this work is relevant for analysing both the bending behaviour of a RC structural element and its cracking process.
  PubDate: 2013-04-16T02:21:17.299136-05:
  DOI: 10.1002/suco.201200053
The influence of aggregate fracture on the shear strength of reinforced concrete beams: an experimental and analytical research
- Authors: Juan Sagaseta
  Pages: n/a - n/a
  Abstract: High‐performance concrete such as high‐strength (HSC) or light‐weight aggregate (LWAC) concrete is generally used to reduce member sizes, self‐weight and optimise construction of reinforced concrete structures. The bond between the aggregate particles and the cement paste can be strong enough in HSC and LWAC to cause the aggregate to fracture at cracks, which in turn reduces the shear stress which can be transferred across cracks by means of aggregate interlock. Relatively smooth cracks can also develop in self‐compacting concrete due to low content of coarse aggregate. The contribution of aggregate interlock to shear strength of RC beams is uncertain and depends on parameters such as the amount of shear reinforcement or the contribution of arching action for loads applied close to the support. Existing tests on slender RC beams without shear reinforcement have shown that shear strength is reduced by aggregate fracture. However, there is a lack of similar test data for members with stirrups and for members with varying shear span to effective depth ratio. This paper reviews the findings and contributions in this area from the experimental and analytical research from the author's PhD thesis, which was awarded the fib Achievement Award to Young Engineers in 2011.
  PubDate: 2013-04-16T02:21:10.754484-05:
  DOI: 10.1002/suco.201200015
Performance‐ and Displacement‐Based Seismic Design and Assessment of Concrete Structures in the Model Code 2010
- Authors: Michael N. Fardis
  Pages: n/a - n/a
  Abstract: The scope of fib Model Code 2010 (MC2010) includes full‐fledged performance‐ and displacement‐based seismic design of new structures and assessment of existing ones. This part of MC2010 covers buildings, bridges, or similar concrete structures and aims at well‐defined performance levels under specific seismic hazard levels. Detailing of members for ductility is not based on opaque prescriptions, as in current codes, but on transparent, explicit verification of inelastic deformation demands against capacity limits. The reference analysis method is nonlinear dynamic, but, under certain conditions, inelastic deformation demands may be estimated from linear analysis and the 5%‐damped elastic response spectrum; in that case force demands on force‐controlled, brittle failure modes are estimated from the plastic mechanism through equilibrium. In order to predict with some confidence the seismic deformation demands, the analysis should use realistic values for the member secant stiffness to the yield point. The paper explains the background of the expressions given for this property in MC2010, as well as of those for the deformation limits used in the verifications of seismic deformation demands. The modifications of the MC2010 approach for shear resistance to take into account cyclic loading are also explained and justified.
  PubDate: 2013-03-21T02:30:41.909518-05:
  DOI: 10.1002/suco.201300001
Highlights on the design and construction of 12 Km APM elevated bridge project in Saudi Arabia
- Authors: Essam Ayoub; Charles Malek, Gamal Helmy
  Pages: n/a - n/a
  Abstract: The Automated People Mover (APM) bridge project constructed in Princess Nora University (PNU) in Saudi Arabia and inaugurated in May 2012 is one of the major projects dealing with many challenges in design and construction due to its strict time frame compared to the big scale of the project. Therefore, the design should be accommodated in a way to ensure the ease, the time saving, the lowest cost, the aesthetic and the required high quality of the bridge project elements. For aesthetic reason, a box section type is chosen to form the APM bridge sections for all bridge project parts including straight, bifurcation and curved parts. The present paper highlights on the efficiency of the precast techniques used in the design and the construction of big projects such as the APM bridge project in PNU in Saudi Arabia.
  PubDate: 2013-03-21T02:30:38.831294-05:
  DOI: 10.1002/suco.201200050
Shear Resistance Evaluation of Prestressed Concrete Bridge Beams: fib Model Code Guidelines for Level IV Approximations
- Authors: Beatrice Belletti; Cecilia Damoni, Joop A. den Uijl, Max A.N. Hendriks, Joost C. Walraven
  Pages: n/a - n/a
  Abstract: The design shear resistance of an existing structure can be evaluated through the use of analytical design procedures, and numerical procedures, provided by nonlinear finite element analyses. The new fib Model Code 2010 proposes different calculation methods that fall into four different levels of approximation. With rising level of approximation the complexity and the accuracy of the calculated shear resistance increases. Nonlinear finite element analyses belong to the highest level of approximation but, although they are more and more becoming a usual instrument in the daily design process, building codes do not provide guidance on how to perform these analyses. In this paper nonlinear finite element analyses have been performed on prestressed beams that showed shear failure during experimental loading, in order to assess and criticize the finite element approaches. The aim of this work is to propose guidelines for numerical simulations in order to reduce model and user factors. The results obtained from the nonlinear finite element analyses have been compared with the analytical results using different levels of approximation. The design shear resistance obtained with the highest level of approximation, level IV, that derives from nonlinear finite element analyses resulted to be higher than the design shear resistance obtained with analytical procedures (level I‐II‐III).
  PubDate: 2013-03-21T02:30:33.990788-05:
  DOI: 10.1002/suco.201200046
Finite element study of bond strength between concrete and reinforcement under uneven confinement condition
- Authors: Carlos Zanuy; Manfred Curbach, Alexander Lindorf
  Pages: n/a - n/a
  Abstract: It is well known that many factors affect the bond behaviour between concrete and steel reinforcement. Most of them characterize the confinement degree, which is necessary for an appropriate determination of 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 be hardly 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. In this paper, a 3D finite element approach is presented 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 uniquely described. 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 mode (splitting or pull‐out) obtained in experiments, as well as to provide a rational explanation of the influence of transverse tension.
  PubDate: 2013-03-21T02:30:28.392333-05:
  DOI: 10.1002/suco.201200019
Annual table of contents 2012
- Pages: n/a - n/a
  PubDate: 2013-03-07T06:54:43.291034-05:
  DOI: 10.1002/suco.201390004
Cover Picture: Structural Concrete 1/2013
- Pages: n/a - n/a
  Abstract: The photograph shows a newly completed mall in Chiasso, Switzerland. The shell has the form of an ellipsoid (93 × 52 × 22 m) and its thickness varies between 100 and 120 mm. The shell was built using sprayed concrete and also ordinary concrete in some regions. A number of tailored solutions were also adopted, such as post‐tensioning, addition of fibres and shear studs, to ensure satisfactory performance at both the serviceability and ultimate limit states. More information is provided on pages 43–50 of this issue (Photo: Simone Mengani, Chiasso, Switzerland)
  PubDate: 2013-03-07T06:54:43.291034-05:
  DOI: 10.1002/suco.201390000
Contents: Structural Concrete 1/2013
- Pages: n/a - n/a
  PubDate: 2013-03-07T06:54:43.291034-05:
  DOI: 10.1002/suco.201390003
Structural Concrete 2/2013
- Pages: n/a - n/a
  Abstract: Hugo Corres Peiretti: Conceptual design, the only procedure for achieving sound engineering proposals according to fib Model Code 2010 György L. Balázs et al.: Design for SLS according to fib Model Code 2010 Raphael Breiner, Harald Müller, Isabel Anders (nee Burkart), Michael Vogel: Concrete: treatment of types and properties in fib Model Code 2010 Pierre Rossi, Jean‐Louis Tailhan, Claude Boulay, Fabrice Le Maou, Eric Martin: Compressive, tensile and flexural basic creep behaviours of a same concrete Jung‐Chul Kim, Taeseok Seo: Behaviour of concrete in a stress continuity region after cracking under restrained drying shrinkage Robert Lark, Ben Isaacs, Tony Jefferson, Robert Davies, Simon Dunn: Crack healing of cementitious materal using shrinkable polymer tendons Tian Sing Ng, Stephen J. Foster: Development of a mix design methodology for high performance geopolymer mortars Miguel Fernández Ruiz, Thibault Clément, António Pinho Ramos, Aurelio Muttoni: Design for punching of prestressed concrete slabs
  PubDate: 2013-03-07T06:54:43.291034-05:
  DOI: 10.1002/suco.201390002
Crack healing of cementitious materials using shrinkable polymer tendons
- Authors: Ben Isaacs; Robert Lark, Tony Jefferson, Robert Davies, Simon Dunn
  Pages: n/a - n/a
  Abstract: This paper presents an experimental study on autogenous healing in a recently developed shrinkable polymer cementitious material system. Small scale hollow prismatic mortar beams with un‐bonded shrinkable polymer tendons were loaded until a crack of predefined width had formed. The specimens were then subjected to a range of combined heating/curing regimes to activate the shrinkable polymer and to promote autogenous healing of the cementitious material prior to reloading to failure. Upon reloading, specimens loaded with the shrinkable polymer tendons remaining after heating and curing achieved between 120 % and 195 % of their initial peak loads whilst specimens tested with the shrinkable polymer tendons removed after the heating and curing stages, recovered on average 80 % of their initial peak loads. The overall conclusion was that, provided a supply of water is present and sufficient heat is applied for polymer activation, the material system is effective at not only closing cracks and applying a prestress but also at enhancing the self‐healing of cracks in cementitious materials.
  PubDate: 2013-02-18T03:36:28.695404-05:
  DOI: 10.1002/suco.201200013
Residual compressive and flexural strength of a recycled aggregate concrete after elevated temperatures
- Authors: Jianzhuang Xiao; Yuhui Fan, M.M. Tawana
  Pages: n/a - n/a
  Abstract: A recycled aggregate concrete (RAC) with different replacement percentages of recycled coarse aggregates (RCAs) (i.e., 0, 30%, 50%, 70%, 100%) was experimentally investigated at elevated temperatures. The residual compressive strength as well as the residual flexural strength of the RAC after elevated temperatures was studied and evaluated. The relationship between the residual compressive strength and the residual flexural strength of the RAC with the elevated temperature was proposed. Furthermore, the relationship between the residual flexural strength and compressive strength of the RAC was compared and analyzed. It is found that both the residual compressive strength and the residual flexural strength of the RAC decrease with an elevation in temperature, and the effect of the replacement percentage of the RCAs on the residual flexural strength and the residual compressive strength of RAC was found to be obvious.
  PubDate: 2013-02-18T03:36:27.532429-05:
  DOI: 10.1002/suco.201200037
Investigation of normal impact process of hemispherical‐nosed projectiles into concrete structures
- Authors: Najmeh Khazraiyan; Gholam Hossein Liaghat, Hossein Khodarahmi
  Pages: n/a - n/a
  Abstract: This research study involves obtaining an analytical model for perforation of a hemispherical hard projectile into the unreinforced concrete targets. Dynamic cavity expansion theory and the reflection of compressive waves from the end of the concrete targets are used for development of the analytical model. The effect of friction coefficient is also investigated in the analysis. Numerical modeling of the problem has been performed in LS‐DYNA code for validation of analytical results. Johnson‐Holmquist‐concrete and rigid material models have been employed for the concrete and the projectile respectively. The impact velocity range, considered in this work, is between 250 to 850 m/s. No projectile erosion is considered in this velocity range. The analytical results have been compared with numerical results and have shown good agreement with numerical simulations.
  PubDate: 2013-02-18T03:36:26.240222-05:
  DOI: 10.1002/suco.201200047
Concrete: treatment of types and properties in MC 2010
- Authors: Harald S. Müller; Isabel Anders, Raphael Breiner, Michael Vogel
  Pages: n/a - n/a
  Abstract: The fib Model Code 2010 presents within chapter 5.1 “Concrete” besides basic definitions and well established constitutive relations on structural concrete various new approaches and updated models compared to the former CEB‐FIP Model Code 1990. This holds in particular true for strength, stress and strain characteristics of structural concrete, for creep and shrinkage as well as for sophisticated durability related processes. The validity of the models has been extended to several types of concrete such as high strength concrete, self‐compacting concrete and lightweight aggregate concrete. The durability related models are suited either to facilitate a full probabilistic service life design or to apply simpler code‐type approaches. This contribution gives a concise and selective overview on some of the models. Background information is summarized and the improvements of the updated models are focused on. In addition some simple design aids are given to allow e.g. for a pre‐design, but also for the case of a full probabilistic service life design for durability.
  PubDate: 2013-02-18T03:36:22.891635-05:
  DOI: 10.1002/suco.201200048
Model Code 2010: mastering challenges and encountering new ones
- Authors: Joost Walraven
  Pages: n/a - n/a
  Abstract: The Model Code for Concrete Structures 2010 is a recommendation for the design of structural concrete, written with the intention of giving guidance for future codes. As such, the results of the newest research and development work are used to generate recommendations for structural concrete at the level of the latest state of the art. While carrying out this exercise, areas are inevitably found where information is insufficient, thus inviting further study. This paper begins with a brief introduction to the new expertise and ideas implemented in MC 2010, followed by a treatment of areas where knowledge appeared to be insufficient or even lacking and where further research might be useful.
  PubDate: 2013-01-17T07:20:23.648854-05:
  DOI: 10.1002/suco.201200062
Development of a mix design methodology for high performance geopolymer mortars
- Authors: Tian Sing Ng; Stephen J. Foster
  Pages: n/a - n/a
  Abstract: This paper presents the development of a mix design method for geopolymer mortar mixes with a principal focus on compressive strength. It is based on the hypothesis that the overall strength of geopolymer mortar is dependent on the strength of the geopolymer binder materials, the packing density of the aggregates in the mortar and the amount of geopolymer binder. First, the strength of the binder was experimentally evaluated. Fly ashes obtained from two different sources and ground granulated blast furnace slag were used as the main ingredients to produce the geopolymer binder. Correlation between packing density of the aggregates in mortar and their influence on the demand of binder and compressive strength were investigated. Finally, a conceptual framework for geopolymer mortar mix design approach is proposed. In addition to describing the mortar mix design methodology in a rational way, it is hypothesised that the approach can also be extended for the development of geopolymer concrete mix.
  PubDate: 2013-01-07T10:21:12.050005-05:
  DOI: 10.1002/suco.201200018
Concrete shells – Towards efficient structures: Construction of an ellipsoidal concrete shell in Switzerland
- Authors: Aurelio Muttoni; Franco Lurati, Miguel Fernández Ruiz
  Pages: n/a - n/a
  Abstract: Concrete shells have been widely used in the past as economical and suitable solutions for a number of structures such as roofs, silos, cooling towers or offshore platforms. Taking advantage of their single or double curvature, bending moments and shear forces are limited and the structure develops mostly membrane (in‐plane) forces, allowing to span large distances with limited thicknesses (typically of only some centimetres). In the last decades, the advances on numerical modelling, formwork erection and concrete technology open a new set of possibilities for use of concrete shells. In this paper, the design and construction of a shell with the form of an ellipsoid (93×52×22 m) and with variable thickness between 100 and 120 millimetres is described. The shell was built using sprayed concrete and also ordinary concrete in some regions. A number of tailored solutions were also adopted such as post‐tensioning, addition of fibres and shear studs to ensure satisfactory performance both at serviceability and ultimate limit states.
  PubDate: 2013-01-07T10:21:10.524516-05:
  DOI: 10.1002/suco.201200058
Cracking of RC members revisited. Influence of cover, ϕ/ρs,ef and stirrup spacing. An Experimental and Theoretical Study.
- Authors: Alejandro Pérez Caldentey; Hugo Corres Peiretti, Alejandro Giraldo Soto, Joan Peset Iribarren
  Pages: n/a - n/a
  Abstract: An experimental program aimed at studying the effect of cover, ratio between diameter and effective reinforcement ratio (ϕ/ρs,ef), and the influence of stirrup spacing in the cracking behavior of reinforced concrete elements is presented. The experimental program 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 Model Code under way when the tests were carried out (and today 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.
  PubDate: 2013-01-07T09:31:28.004809-05:
  DOI: 10.1002/suco.201200016
Behaviour of concrete in a stress continuity region after cracking under restrained drying shrinkage
- Authors: Tae‐Seok Seo; Jung‐Chul Kim
  Pages: n/a - n/a
  Abstract: Some studies have investigated the time‐dependent characteristic of concrete for predicting stress under restrained shrinkage. However, these studies investigated the shrinkage behaviour of concrete in restrained conditions before cracking, and no study has investigated the behaviour of concrete due to restrained shrinkage in the stress continuity region after cracking. Therefore, in this study, the shrinkage behaviour of concrete in the stress continuity region after cracking was investigated in uniaxial restrained specimens, and the restrained tensile stress of concrete in this region was analysed by a bond analysis. The results showed that the effective tensile Young's modulus considering tensile creep was approximately 22∼26 % of the static modulus of elasticity. Moreover, the analytical results of the restrained tensile stress of concrete considering the effective tensile Young's modulus were in accordance with the experimental results.
  PubDate: 2013-01-07T09:31:24.375297-05:
  DOI: 10.1002/suco.201200034
Experimental evaluation of large circular RC columns under pure compression
- Authors: Tai‐Kuang Lee; Cheng‐Cheng Chen, Austin D.E. Pan, Kai‐Yuan Hsiue, Wei‐Ming Tsai, Ken Hwa
  Pages: n/a - n/a
  Abstract: Eight sets of large‐scale circular short reinforced concrete columns were tested under monotonically axial compression. The primary variables are the transverse reinforcement class (spiral vs. circular tie), splice type, end hook length, and staggered length of adjacent circular ties. The tests confirmed the acceptable performance of the newly proposed circular tie in ACI 318M‐11. In addition, the circular tie scheme that the ends terminate with hooks that engage a longitudinal steel bar and bend into concrete core respectively, is acceptable for performance and ease of construction. The effectiveness of its end hook length and staggered length of adjacent circular ties is also investigated.
  PubDate: 2013-01-07T09:24:08.181038-05:
  DOI: 10.1002/suco.201200012
fib Model Code for Concrete Structures 2010: a landmark in an ongoing development
- Authors: Joost Walraven; György L. Balázs
  Pages: 1 - 2
  PubDate: 2013-03-07T06:54:43.291034-05:
  DOI: 10.1002/suco.201390005
fib‐news: Structural Concrete 1/2013
- Pages: 79 - 85
  Abstract: fib‐days in Chennai, India fibUK Technical Meeting in recognition of Andrew Beeby Design of Concrete Bridges: fib short course in Ankara, Turkey New fib officers Gordon Clark visits Japan Short notes Congresses and symposia fib membership benefits Acknowledgement
  PubDate: 2013-03-07T06:54:43.291034-05:
  DOI: 10.1002/suco.201390001
Global safety format for non‐linear analysis of reinforced concrete structures
- Authors: Diego Lorenzo Allaix; Vincenzo Ilario Carbone, Giuseppe Mancini
  Pages: n/a - n/a
  Abstract: Semi‐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.
  PubDate: 2012-12-06T06:11:08.940813-05:
  DOI: 10.1002/suco.201200017
Conceptual design, the only procedure for achieving sound engineering proposals according to fib Model Code 2010
- Authors: Hugo Corres Peiretti
  Pages: n/a - n/a
  Abstract: Conceptual design is the approach to create an idea finding a solution towards a new proposal for a structure or to solve a detail in a specific structure. It is a personal approach which one learns over time and with experience. It is, normally, not dealt with at university. It is greatly important to produce sound structures. The fib Model Code 2010 introduced this concept, in the first clause of chapter 7, Design. The content in this clause explains the general approach of how to develop conceptual design. This paper will show different examples of conceptual design following the general guidelines stated in Model Code.
  PubDate: 2012-12-06T06:11:07.597652-05:
  DOI: 10.1002/suco.201200042
Reliability‐based Nonlinear Analysis According To MC 2010
- Authors: Vladimir Cervenka
  Pages: n/a - n/a
  Abstract: Fib Model Code 2010 introduces the numerical simulation as a new tool for design of reinforced concrete structures. The model of resistance based on non‐linear analysis requires adequate model validation and a global safety format for design verification. The numerical simulations combined with random sampling offer an advanced safety assessment. Approximate methods of global safety assessment are discussed and compared in a case study. Example of a bridge design supported by non‐linear analysis is shown.
  PubDate: 2012-12-06T06:11:06.16845-05:0
  DOI: 10.1002/suco.201200022
Design for punching of prestressed concrete slabs
- Authors: Thibault Clément; António Pinho Ramos, Miguel Fernández Ruiz, Aurelio Muttoni
  Pages: n/a - n/a
  Abstract: Prestressing in flat slabs helps in controlling deformations and cracking under service loads and allows reducing the required slab thickness, leading thus to more slender structures and being therefore an economic solution for long spans. However, as a consequence of the limited thickness of these members, punching is typically governing at ultimate limit state. Investigations on the topic of punching shear strength have shown that the presence of prestress 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. The approach provided by codes of practice for punching design in presence of prestressing may however differ significantly. Some neglect the influence of the introduced bending moments due to prestressing and the sections at which deviation forces of the tendons are considered may be located at different distances from the edge of the supported region. In this paper, the influence of prestressing on the punching shear strength of members without shear reinforcement is investigated by using the fundamentals of the Critical Shear Crack Theory. On that basis, and accounting also for 65 tests available in the scientific literature, the suitability and accuracy of a number of design codes, such as Model Code 2010, Eurocode 2 and ACI 318‐11, is investigated and compared.
  PubDate: 2012-11-26T14:10:21.689194-05:
  DOI: 10.1002/suco.201200028
Compressive, tensile and bending basic creep behaviours of a same concrete
- Authors: Jean‐Louis Tailhan; Claude Boulay, Pierre Rossi, Fabrice Le Maou, Eric Martin
  Pages: n/a - n/a
  Abstract: The present paper concerns the relation between compressive, tensile and flexural creep behaviours related to a same concrete. In this frame, experimental tests and a numerical simulation are performed. The mean conclusion of this study is that, due to the strong scale effect related to the tensile and bending creep behaviours of a “standard” concrete mix design, it is not possible to simulate, numerically (with classical Kelvin‐Voigt chains), the bending creep behaviour of that type of concrete knowing the compressive and tensile ones obtained on specimens geometries usually used in laboratories.
  PubDate: 2012-11-26T14:10:20.345551-05:
  DOI: 10.1002/suco.201200025
Three dimensional FE analysis reinforced concrete structures using lattice equivalent continuum method
- Authors: Syed Ishtiaq Ahmad; Tada‐aki Tanabe
  Pages: n/a - n/a
  Abstract: Lattice equivalent continuum model (LECM) has proven to be very effective in analyzing reinforced concrete structures in two dimensional cases. That model is extended for three‐dimension and is fitted for finite element formulation to analyze three dimensional reinforced concrete structures. In any of the three principal directions, stress strain behavior of concrete will be affected by stress state at other two directions. Consequently, stress strain curves of concrete will shift from uniaxial pattern. This phenomenon is considered in this work by selecting peak stresses of concrete in three alternative approaches. Effectiveness of those approaches is also evaluated. Calculation results show good reproduction of the test data, which indicates the validity of this proposed 3D modeling of reinforced concrete.
  PubDate: 2012-11-26T14:10:19.566016-05:
  DOI: 10.1002/suco.201100009
Design for service life: implementation of Model Code 2010 rules in the operational code ISO 16204
- Authors: Steinar Helland
  Pages: n/a - n/a
  Abstract: CEB/FIP Model Code 1990 (MC‐1990) did represent the technology and focus some 20 years ago. It soon became evident that the document had some important lacunas. In 1995 the General Assemblies in the two organisations 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. In 2006, fib approved bulletin no 34 Model Code for Service Life Design (MC SLD). All these 3 extensions have since matured and are today incorporated in the new fib Model Code 2010 (MC‐2010). The main purpose for a fib Model Code is to act as a model for operational standards. The obvious counterpart for a body like fib operating world‐wide is ISO. The initiative taken by MC SLD has therefore further matured in ISO TC‐71/SC‐3/WG‐4 and was during summer 2012 accepted as ISO 16204 “Durability – Service Life Design of Concrete Structures”. According to the obligations given in 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.
  PubDate: 2012-08-28T11:20:21.19859-05:0
  DOI: 10.1002/suco.201200021