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An experimental study carried out to characterize the bond strength of lightweight aggregate concrete (LWAC) to normal density concrete (NDC) and LWAC-to-LWAC interfaces is presented, also including NDC-to-NDC interfaces as reference. A single NDC mixture, with a compressive strength of 50 MPa, and three LWAC mixtures, with density range between 1500 and 1900 kg/m 3 and compressive strength between 45 and 75 MPa, were adopted. Slant shear and splitting tests were conducted to evaluate the interface bond strength, considering different methods to increase the surface roughness of the substrate. Results were analysed and compared with predictions according to Eurocode 2 (EC2) and fib Model Code 2010, and showed significant differences, mainly for rough surfaces. It was found that the role of the binding matrix strength and of the type of aggregate, in the interface strength, is dependent of the roughness of the substrate; the coefficients of cohesion and friction exhibited a good correlation with the roughness parameter “mean peak high”, R pm , being the cohesion also influenced by the matrix strength of the added concrete. It was also concluded that there is no advantage, in terms of shear and tensile strengths of interfaces with LWAC, to increase the surface roughness above a certain limit. [ABSTRACT FROM AUTHOR]

The failure in longitudinally reinforced concrete beams without transverse reinforcement is the most often observed in a support zone due to bending moment and shear force acting simultaneously in a cross section. This kind of failure is called shear failure and in case of slender beams it can lead to dangerous, brittle damage. Therefore the evaluation of reliability of these members is of the paramount importance, all the most because the design procedure given in Eurocode 2 for shear capacity is of an empirical character. In the paper, the reliability analysis of longitudinally reinforced concrete beams designed according to the rules given in Eurocode 2 was performed. Furthermore, the own experimental investigations were presented. The experiments focused on determining shear capacity and observing the failure process in longitudinally reinforced concrete beams without stirrup of a rectangular and a T-shape cross section. The obtained experimental results were used to calculate the difference of safety margins of the designed shear resistance calculated on the basis of the formula from Eurocode 2 according to reinforced concrete beams without transverse reinforcement of different cross sections. [ABSTRACT FROM AUTHOR]

This paper presents the most relevant matters regarding strains of concrete in RC structures subjected to standard load and to high temperature at the same time, with respect to the material model given in Eurocode 1992-1-2 and to literature. Two types of aggregate were considered (siliceous and calcareous) as well as load induced thermal strains phenomenon. [ABSTRACT FROM AUTHOR]

The paper presents comparison of creep measurments in normal concrete and concrete modified with dispersed reinforcement - polypropylene and steel fibres (FRC). The tests were performed for two levels of applied load: 40% and 80% of the destructive load at the load time, respectively, at 1, 4, 7 and 28 days. The resulting creep strain was compared with the calculating method from Eurocode 2, and Pre-norm Fib 2010. Significant differences in the results of the creep calculated based on the Code and measured in the research were noticed. It was also shown that the creep of FRC has different development compared to the normal concrete especially under early-age load. The value of proposed creep factor for young concrete calculated based on study results was few times higher than calculated based on the Code. The creep strain of fibre reinforced concrete loaded at the age of 24 hours was, moreover much higher than of concrete without fibres. The paper illustrated differences in the dynamics and final values of creep deformation of normal concrete and fibre reinforcement concrete. [ABSTRACT FROM AUTHOR]

The Anderberg model introduced in Eurocode 1992-1-2 gives stress-strain relationships of reinforcing bars for high temperature values at multiples of 100 o C. This model was based on tests performed at steady temperature conditions. Therefore, the elongation predicted by this model only accounts for simultaneous action of external load and high temperature. The steel free thermal strain is not included. However, reinforcement of RC elements exposed to fire is subjected to unsteady temperature conditions. This paper presents the Eurocode model in temperature-strain coordinates. The sum of elongations caused by stress and free steel thermal strain is shown against temperature for various stress levels. This model might be useful for estimation of reinforcing bars elongation during advanced analyses of RC structures exposed to fire. [ABSTRACT FROM AUTHOR]

This paper presents an approach to determine the nonlinear bending moment – rotation relations for longitudinal joints of segmental concrete tunnel linings with flat concrete contact areas based on the rules for confined concrete and partially loaded areas according to Eurocode 2. It is demonstrated that the resulting bending moment – rotation relations show better agreement with experimental data than other approaches from the literature. The proposed approach allows to establish the bending moment – rotation relations for both serviceability limit state (SLS) and ultimate limit state (ULS) and thereby a tunnel lining design consistent with Eurocode 2. The practical implications for the design concept of tunnel linings are discussed. [ABSTRACT FROM AUTHOR]

This work was undertaken to compare the use of BS 8110 and Eurocode 2 in the design of structures and focused on outlining the relative gains and/or shortcomings of Eurocode 2 and BS 8110 under certain criteria which are loading, analysis, ease of use and technological advancement. To accomplish this, the analysis and design of the main structural elements in reinforced concrete building was undertaken using the two codes. A modest medium rise building was loaded using the two code and analyzed. Analysis was done using CSI start tedds to obtain the shear force and bending moment envelopes. For the beam, it was found that Eurocode 2 gave higher internal supports moments. For the case of maximum span moments and shear force values, the Euroode 2 values lagged behind. Column load and moments values were generally lower for Euroode 2. In summary, the comparative benefits of using Euroode 2 are that it is logical and organized, less restrictive and more extensive than the BS 8110. The new Eurocodes are claimed to be the most technically advanced code in the world and therefore should be adopted by Nigerian engineers. [ABSTRACT FROM AUTHOR]

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The paper develops a computer strategy for the analysis of cracked reinforced concrete cross sections within the scope of Eurocode 2, using a symbolic algebraic manipulator. The nonlinear constitutive behaviours for either concrete or steel are considered. For concrete, a nonlinear constitutive equation, function of the concrete class, is adopted, as indicated in Eurocode 2 for structural analysis. This equation is more general than the parabola equation used in many models for both ultimate and service design. For the steel, the present model uses a continuous and smooth function that approximates both the elastic and plastic ranges with hardening, instead of the traditional multi-linear forms. The moment-curvature relations are obtained by imposing equilibria for the bending moments and longitudinal forces, assuming that cross sections remain plane after deformation and that there is a perfect adherence between concrete and steel. In addition, closed-form solutions are also proposed and the cross section’s collapse and rotation capacity is determined by the reaching of the ultimate strains for concrete or steel. The paper ends with the presentation of illustrative examples, for rectangular and T- cross sections. [ABSTRACT FROM AUTHOR]

This paper describes the shrinkage of concrete made with recycled aggregates derived from demolition of concrete structures and is based on the 18 500 data matrix generated from 286 studies published in English from 38 countries since 1978. Relative to natural aggregates, the shrinkage of concrete increases at a decreasing rate with coarse recycled concrete aggregate content, giving an average increase of 33% at 100% natural aggregate replacement. This difference between the performance of the two concretes decreases with increasing ambient humidity and concrete strength. Increase in concrete shrinkage with fine and all-in recycled concrete aggregate and other recycled aggregates was found to be too high and variable to make them unsuitable for use in structural concrete. The assessment of the Eurocode 2 (2004), ACI 209·2R (2008) and Bažant-Baweja B3 (2000) models showed that, although the accuracy of the three models is similar, the shrinkage of concrete containing coarse recycled concrete aggregate is generally underestimated. Methods are proposed for determining the shrinkage of concrete made with coarse recycled concrete aggregate together with using Eurocode 2, as well as for minimising its effect on the shrinkage of concrete for a given strength and workability by reducing its cement paste content. [ABSTRACT FROM AUTHOR]

A comprehensive database of recycled aggregate concrete and companion natural aggregate concrete beams’ flexural and shear strength was compiled from 217 experimental results. Strict criteria were applied to determine the failure type. Sub-databases were formed with beams failing in flexure and shear with and without stirrups. On each sub-database the applicability of Eurocode 2 provisions for flexural and shear strength to recycled aggregate concrete beams was tested. The results show that flexural and shear strength of recycled aggregate concrete beams without stirrups is successfully predicted by Eurocode 2. As for beams with stirrups, further research and experimental results are necessary. [ABSTRACT FROM AUTHOR]

In typical precast construction practice of floor slabs using precast concrete hollow core unit (HCU), in-situ concrete is cast on top of the HCU to obtain smooth and even floor finish. The surface of the HCU is seldom given proper treatment prior to casting the concrete topping. The texture and surface moisture condition of the HCU just before receiving concrete topping may affect the overall strength of the slabs when the concrete topping and the HCU act compositely during service. This paper presents the experimental study on shear-flexure capacity of composite slabs using HCU and concrete topping. Full scale three point load test are carried out on 14 composite slab specimens with different surface roughness and surface condition of the HCU before casting the concrete topping. The surface roughness considered is smooth and rough, while the moisture conditions are dry, ponded and optimum wet. The effect of the longitudinal joint between the HCU panels is also considered. The experimental results are also compared with predicted values using the available equation in Eurocode 2 and an equation published by a previous researcher. The results of the experiment show that the HCU surface condition and longitudinal joint affect the stiffness and shear-flexure strength of the slabs. The optimum HCU surface condition which can produce highest stiffness and shear strength is rough and wet conditions, while the longitudinal joint between HCU panels reduces the slab shear strength. The interfacial horizontal shear is not the factor that governs the strength and behaviour of the slabs. The equation available in Eurocode 2 gives non-conservative prediction of the shear strength. In contrary, the equation published by the previous researcher gives conservative prediction of the shear strength. [ABSTRACT FROM AUTHOR]

The objective of the paper is to analyze the efficiency of design methods proposed in different codes according to the load carrying capacity of concrete structures. In particular, three standard recommendations have been considered: the ACI 318 shear design model, the equation by Eurocode 2 and a new design procedure from Model Code 2010. In the paper the flexural concrete members, which are reinforced longitudinally but without transverse reinforcement, are considered. The design values of the load carrying capacity of such members obtained from these three codes were compared with experimental results. An advanced statistical analysis has been applied to predict of dependent variable (load carrying capacity of tested beams) and to perform a comparative analysis. On the basis of the analysis conclusions have been drawn according to the fit between the design methods and the test data. [ABSTRACT FROM AUTHOR]

The analysis of the mechanical behaviour of a reinforced concrete tie subjected to a monotonic loading in the stabilized cracking stage is performed here by way of a theoretical general model that considers the effect of the so-called Goto cracks (secondary cracks). It is shown, in particular, that the average bond stress along the transmission length depends not only on the concrete strength as assumed by the fib Model Code for Concrete Structures 2010, but also on reinforcement ratio and bar diameter. In this regard, tabulated theoretical values of the average bond stress are proposed as a function of the aforementioned parameters. Moreover, the secondary cracks reduce the effect of tension stiffening on the relative mean strain. On the basis of the main results obtained with the general model, some improvements are suggested for the calculation methods proposed by fib Model Code 2010 and Eurocode 2 concerning the average value of the bond stress and taking into account the influence of the secondary cracks on the mean deformation. An improved calculation method is therefore performed. Finally, the theoretical results of crack spacing and crack width obtained with the general and improved methods are compared with experimental data obtained from extensive research on RC ties. [ABSTRACT FROM AUTHOR]

The fib Model Code for Concrete Structures 2010 introduces a new design concept for punching shear based on critical shear crack theory. This paper presents and provides the background to the design provisions for punching shear according to fib Model Code 2010, Eurocode 2 and the corresponding German National Annex to Eurocode 2. The different punching shear design provisions are critically reviewed by means of parameter studies and a comparison of the calculated resistances and test results. The safety levels of the code provisions are verified and the influence of the different punching parameters on the calculated resistances is examined in detail. [ABSTRACT FROM AUTHOR]

The objective of this paper is to review the historical context of design charts for rectangular reinforced concrete columns under biaxial bending, critically assess their evolution in time and provide a new series, compliant to the latest draft of Eurocode 2. The motivation for such a development arises from the different assumptions and recommended values prescribed in the respective National Annexes of individual countries that use the Eurocodes, which essentially yield impossible to design without the aid of specialized, typically commercial, computer codes. Along these lines, a new extensive design chart dataset of unprecedented output quality is made available herein that covers both normal and high-strength concrete as well as different steel grades. The dataset developed is fully validated against conventional procedures while the error induced in design by the use of older design aids is comparatively assessed, clearly highlighting the necessity for a new design charts dataset at least under certain loading and reinforcement configurations. The present charts are expected to provide a valuable tool for the professional community, facilitate the use of Eurocodes and minimize the epistemic uncertainly associated with the use of older or incompatible design charts in the design of reinforced concrete members. [ABSTRACT FROM AUTHOR]

The paper investigates the axial capacity of reinforced columns exposed to fire. The simplified method namely 500 °C isotherm method explained in Eurocode 2 is used to assess the capacity of the column. Finite element software ANSYS is used to perform the thermal analysis. A set of numerical studies were carried out to quantify the effect of various parameters on short columns subjected to fire. The study is performed on columns of different cross-sections to investigate the effect of eight parameters, namely the thermal boundary conditions, grades of concrete, grades of steel, types of aggregate, distribution of reinforcement on column faces, concrete cover, load eccentricity and support conditions. The fire ratings based on various failure criteria are determined, and minimum rating is accepted as design fire rating. A simplified interaction curve to predict the failure of columns under fire subjected to axial load and uniaxial moment for square cross-sections was also developed. [ABSTRACT FROM AUTHOR]

This paper presents experimental, numerical and analytical investigations about the effects of incorporating coarse recycled concrete aggregates (CRCA) on the punching behaviour of reinforced concrete (RC) slabs. For this purpose, four concrete mixes were designed with various substitution ratios of natural coarse aggregates (NCA) by CRCA: 0% (reference mix), 20%, 50% and 100%. Subsequently, eight 1100 × 1100 × 90 mm reinforced concrete slabs (two per concrete type) were cast and subjected to punching tests. The experimental results indicate that the incorporation of CRCA affects the mechanical behaviour of RC slabs according to the following trends: (i) the punching resistance of slabs made of concrete with CRCA (CRCAC) is similar to that of the reference mix; (ii) the stiffness decreases, particularly in the uncracked state; and (iii) the cracking load slightly decreases. The numerical study comprised the development of three-dimensional non-linear finite element models of the slabs. The numerical models were able to trace the experimental responses of the slabs tested, highlighting the influence of the concrete fracture energy on the numerical results. The best predictions of punching strength were obtained when similar fracture energy was adopted for all concrete mixes. Finally, the accuracy of some of the most relevant design codes in predicting the punching strength of CRCAC slabs is assessed. The most accurate estimates were obtained using Model Code 2010 (MC 2010) with levels of approximation II to IV. Eurocode 2, ACI 318 and MC 2010 with level of approximation I provided less accurate and relatively conservative punching strength predictions. [ABSTRACT FROM AUTHOR]

The article provides basic information about the shrinkage of concrete and discusses the major impact on the size and course of the shrinkage. There are the guidelines to estimate the shrinkage strain of concrete bridge structures for the high tensile strength-SCI in accordance with PN-EN 1992-2. The article presents the results of experimental studies which aim was to analyze the course of shrinkage in two types of specimens made of different composition mixes. The studies have also made possible to verify the actual size of the shrinkage strain and designated ones on the basis of the PN-EN 1992-2. [ABSTRACT FROM AUTHOR]

Eurocode 2 consists of four parts that have to be applied in conjunction with the respective National Annexes of the CEN member states. The National Annexes were introduced, in particular, to maintain national safety levels and to account for regional aspects in the different states. The CEN (European Committee for Standardization) will revise and extend all structural Eurocodes by 2018. As part of that process, two main objectives for revising Eurocodes have been formulated: a reduction in the number of Nationally Determined Parameters (NDP) and improving the 'ease of use'. In order to reduce the number of NDP, improve the ease of use and allow for further harmonization without changing the main structure and the design models of Eurocode 2, the National Annexes of EN 1992-1-1 for the different CEN member states have been compared and analysed. Furthermore, the analysis of the National Annexes may help to identify some main aspects for the revision of Eurocode 2. This paper summarizes the analysis of the National annexes of EN 1992-1-1 and makes first proposals for further harmonization. [ABSTRACT FROM AUTHOR]

Prestressed concrete wing-shaped members are frequently used in the construction of long-span roofs in precast concrete buildings. Roofs spanning more than 30 m (100 ft) are built by assembling a number of these thin-walled members. To optimize their design and take advantage of their potential load-carrying capacity, the transfer of large forces from the pretensioned strands to the concrete is critical. Information on the evolution of these forces and of the ensuing deformations is necessary, not only in the long run, but also immediately after concrete casting and during the first few weeks. The Department of Civil and Environmental Engineering of the University of Perugia in Italy and a major prefabrication firm of central Italy have completed an experimental program on pretensioned wing-shaped members to investigate the evolution of prestressing stresses and of camber during the different stages of concrete hardening. The result allowed the careful evaluation of the prestress losses that occur in the first three weeks during concrete placement and curing to emphasize the influence of the temperature history on the development of prestress losses and to calibrate suitable parameters for the prediction of camber growth. Numerical comparisons based on Eurocode 2 are also performed to check the reliability of the numerical procedure adopted by the authors and to ascertain whether using self-consolidating concrete (as in the manufacture of the specimens tested in this project) makes any sizeable difference with respect to the predictions based on Eurocode 2, which refers to ordinary concrete. [ABSTRACT FROM AUTHOR]

In this work, a FORTRAN-based computer program was developed to aid the design of reinforced concrete slabs to Eurocode 2 (EC 2) design requirements at constant reliability levels using First Order Reliability Method (FORM).The design variables for the design of the slab were considered random with safety indices calculated using FORM. It was shown among other findings that the FORM design procedure gave more economical designs considering the area of steel required and final depth of section, than the EC 2 design procedure when a target safety level of 3.0 was considered. Also, example of design using the program was included for various values of target safety indices at constant geometrical, loading and end condition of the slab. The developed program is therefore suitable for application. [ABSTRACT FROM AUTHOR]

An attempt is made to theoretically and experimentally verify the shrinkage curvature models presented in Eurocode 2 and BS 8110. These codes claim that the models originally derived and proven for uncracked sections are suitable, with modification, for predicting the behaviour of cracked sections, although this claim has never been proven experimentally. To achieve verification, an alternative theoretical approach is initially proposed in this paper. In this theoretical model, the effect of shrinkage, creep and the variation in the neutral axis position of the section are taken into account. The stresses developed in the steel and concrete at a cracked section according to this theoretical model are then applied to a finite-element (FE) model representing a portion of the beam from the crack to mid-way between the crack and an adjacent crack. Ultimately, the mean curvature is determined. Experimentally, pairs of beams were cast and subjected to a level of flexural loading to produce a stabilised crack pattern in the constant-moment zone. The behaviour of the beams was monitored for up to 180 days. For any pair of beams, one beam was cast using a high-shrinkage concrete and the other with a low-shrinkage concrete. Each concrete type, however, exhibits similar creep. Therefore, shrinkage curvature can be obtained by subtracting the long-term movements of one beam from the other. These experimentally defined curvatures were compared with the mean curvatures obtained from the FE analysis. The comparison showed reasonable agreement. The curvatures were also compared with uncracked and cracked curvatures predicted by the codes. The curvatures derived in this investigation fell within the boundaries of the uncracked and cracked curvatures predicted by the codes and, for the fully cracked case, the curvatures were closer to the uncracked boundary. [ABSTRACT FROM AUTHOR]

Der Nachweis auf Durchstanzen von Einzelfundamenten ohne Durchstanzbewehrung hat sich nach Eurocode 2 (DIN EN 1992‐1‐1:2011 mit DIN EN 1992‐1‐1/NA:2013) gegenüber der bisherigen Nachweisführung grundlegend geändert. Das betrifft insbesondere den Nachweisschnitt, der im Bereich acrit ≤ 2d ungünstig bestimmt werden muss, und zwar so, dass das Verhältnis von Widerstand zur Einwirkung minimal wird. Im Regelfall erfordert die Auffindung dieses maßgebenden Rundschnitts daher eine Iteration. In diesem Beitrag wird ein einfach handhabbares Hilfsmittel vorgestellt, das die Auffindung des kritischen Nachweisschnitts in Abhängigkeit von der Grundrissgeometrie ermöglicht. Zudem kann mit den dargestellten Bemessungshilfen der Nachweis ausreichender Tragfähigkeit für rechteckige Fundamente ohne Durchstanzbewehrung, die durch mittig angeordnete Stützen mit Rechteck‐ oder Kreisquerschnitt beansprucht sind, in nur wenigen Bemessungsschritten erfolgen. Punching shear design of footings – design aids for isolated footings without shear reinforcement The design for punching shear of isolated footings without shear reinforcement has fundamentally changed in Eurocode 2 (DIN EN 1922‐1‐1:2011 combined with DIN EN 1992‐1‐1/NA:2013) compared to the previous design procedure. This applies in particular to the detection section that must be adversely determined in the region of acrit ≤ 2d in such a manner that the ratio of resistance to the action is minimized. As a rule, therefore, the discovery of this decisive control section requires an iteration. In this paper, an easily manageable tool is presented which allows the discovery of the critical control section depending on the floor plan geometry. In addition, with the illustrated design aids proof of sufficient load capacity for rectangular foundations without shear reinforcement, which are claimed by centrally arranged columns with rectangular or circular cross‐section, could be done in just a few steps. [ABSTRACT FROM AUTHOR]

Seit dem 1.1.2013 gilt in der Schweiz die revidierte Norm SIA 262 Betonbau. In der neuen Fassung wurde unter anderem das Durchstanzmodell gegenüber der Ausgabe von 2003 überarbeitet. Das mechanische Modell mit empirischen Anpassungsfaktoren ist detailliert aufgebaut und unterscheidet sich deutlich vom einfacheren Ansatz im Eurocode 2 (EC2). In der neuen SIA 262 ist der Durchstanzwiderstand auf die mechanische Größe Plattenrotation abgestützt. Im mehr empirisch hergeleiteten Modell des EC2 baut der Widerstand im Wesentlichen auf den geometrischen Bewehrungsgrad auf. Obwohl das Modell der SIA eine mechanische Größe verwendet, sind empirische Ansätze aufgrund zahlreicher Einflussfaktoren beim Durchstanzen unumgänglich. Neben den unterschiedlich definierten Durchstanzwiderständen unterscheiden sich die beiden Normen in der Definition des Abstands zum kritischen Rundschnitt, was eine Vergleichbarkeit erschwert. Dieser Beitrag stellt am Beispiel einer zentrisch belasteten Innenstütze die Unterschiede der Normen in der Nachweisführung dar und analysiert die Ergebnisse bei variierenden Eingangsgrößen. Dabei werden die geometrischen Größen Bewehrungsgrad, Deckenstärke und Stützendurchmesser verändert. Auf die Variation anderer Einflussgrößen, wie die Betonfestigkeit und die Stahlfließgrenze, sowie auf die Betrachtung der Einsturzsicherung wird verzichtet. Hierzu finden sich Untersuchungen und weitere Hintergründe in der Literatur [4] und [5]. Für den Vergleich mit dem EC2 werden die länderspezifischen Regelungen für Deutschland verwendet, da sich der Nationale Anhang für die Schweiz in Bearbeitung befindet. Es wird darauf hingewiesen, dass die für Deutschland festgelegten Parameter in der Regel zu geringeren Durchstanzwiderständen führen als die empfohlenen Werte des EC2. Punching shear resistance of slabs without transverse reinforcement: A comparison of the codes SIA 262:2013 and DIN EN 1992-1-1:2004 + AC:2010 Since 1 January 2013 in Switzerland, the revised code of the 'SIA 262 Betonbau' has been in force. In the revised code the punching model has changed with regard to a few points when compared to the 2003 release. The model is formulated in a very detailed way and differs therefore significantly from the more simple approach of the Eurocode 2 (EC2). In the SIA 262, the punching shear resistance is based on a mechanical quantity, the rotation angle; in the EC2, it is largely based on a geometric quantity, the reinforcement ratio. Although the model of the SIA uses mechanical descriptions, additional empirical adaptions are inevitable because of the numerous factors which influence the punching shear resistance. Besides the different formulations, the distance of the control perimeter differs in both codes, which makes a comparison between them difficult. This contribution outlines an inner column for the comparison of the two codes. Considered are the design procedure and the results for different input parameters. Therefore, the reinforcement ratio, the slab thickness and the column diameter are varied. Not considered are the influence of the concrete strength, the yield limit of the steel and the integrity reinforcement to avoid progressive collapse. Further investigations to these points and additional background can be found in the literature [4] and [5]. For comparison with the EC2, the nationally determined parameters (NDP) for Germany have been used. The NDP for Switzerland are not available because they are currently determined. It should be also mentioned that the NDP for Germany lead to smaller punching shear resistances than the recommended values of the EC2. [ABSTRACT FROM AUTHOR]

Abstract: Results of the latest experiments have revealed that the maximum punching resistance defined from crushing of concrete struts at the perimeter of a column in EC2 is an insufficient criterion for limitation of maximum shear forces at the vicinity of columns. Therefore further limitation has been introduced in STN EN 1992-1-1/NA. The paper will deal with the new requirements concerning of maximum punching shear resistance which is based on the kmax factor and punching shear resistance without shear reinforcement vRd,c. [Copyright &y& Elsevier]

Abstract: The present paper deals with the special situations, when the cover of reinforcement of structural members exceeds 50mm, and it may be appropriate to provide a surface reinforcement. The new Model Code 2010 [1,2] mentions such a reinforcement, but doesn’t specify its type, cover and the area amount. However such a surface reinforcement is able to increase the bending and especially shear resistance of structural members, subjected to bending and shear. In addition to that the surface reinforcement reduces an expansion and width of cracks. According to Eurocode 2 [3], Part 1-1 in Annex J – Detailing rules for particular situations – there are some special cases when such a surface reinforcement should be used. It is necessary to use this reinforcement type when: [•] diameter of designed bars is greater than 32mm, or equivalent diameter of bundled bar exceeds this limit; [•] cover to reinforcement is greater than 70mm (for enhanced durability); [•] crack widths without using surface reinforcement exceed allowed limit; [•] reinforced concrete structure is subject to fire and there is a risk of falling off of a concrete in the later stage of a fire exposure according to Part 1-2 of Eurocode 2 [5,6]. The surface reinforcement should consist of wire mesh or small diameter bars and should be placed outside of links. This paper analyses different values of the surface reinforcement cover and the increase of bending and shear resistance due to surface reinforcement of RC beams. It also includes an explanation of the effect of the surface reinforcement on expansion and width of cracks. [Copyright &y& Elsevier]

Abstract: This article is continuation of earlier work of the author. Apractical method for cross-section strength calculation of flexural reinforced concrete members with rectangular compression zone using curvilinear concrete stress-strain diagrams of Eurocode 2 (EN-2) is presented in this article. The method can be used for strength calculation of members with flanges and reinforcement in compression zone as well. Curvilinear EN-2 stress diagrams are readily superseded by polynomials that can be easily integrated are proposed by the author. It gives opportunity for mathematically accurate, without changing of curvilinear diagram by arbitrary diagrams, determination of value and location for resultant of concrete compression zone stresses and location of neutral axes as well. Calculation is performed for any chosen strain of the layer subjected to the maximum compression. The said strain may be of greater or less value in comparison to that corresponding to the concrete strength. In this way the maximum strength of the member can be estimated when the compression zone strain value varies within chosen interval. The method is suitable in both cases for the members which are commonly (not abundantly) and abundantly reinforced if the neutral axes is located within the cross-section, i. e. within the interval up to the centre of the tensile reinforcement cross-sectional area. Strength of members reinforced with high strength reinforcement which is not sufficiently prestressed or not prestressed at all can be determined by calculation. Formulae can be used for calculation of stress-strain state in persistent situations (not ultimate ones) and for calculation of steel prestress value as well. Rectangular compression zone parameters required for member strength calculation using curvilinear stress diagram are presented in the article. Results obtained by the proposed method are compared with the results obtained using EN-2 formulae. [Copyright &y& Elsevier]

Abstract: This paper describes standard scale fire tests conducted on four precast prestressed hollow core slabs configurations under flexure. The influence of the reinforcement arrangement was investigated using two test parameters: the average axis distance (from 30.1 to 46.7mm), and the type of reinforcement (5mm diameter wires and 9.5mm diameter strands). An ISO 834 standard fire was applied maintaining the load level in a four-point test arrangement constant. The results presented different failure mechanisms, types of cracks, spalling patterns, and fire resistance ratings and it was shown that wires displayed optimal behavior as opposed to strands. A comparison was carried out with the current verification methods provided in Eurocode 2 part 1–2, and showed that verification methods tend to overestimate the calculation of fire resistance when both wire and strands are moved away from the exposed surface. [Copyright &y& Elsevier]

Shrinkage plays an important, sometimes crucial, role in the design of many types of concrete structures as well as in their behaviour after construction. However, the uncontrolled strains are often larger than the expected values. As a matter of fact, there is as yet no perfectly satisfactory physical explanation for shrinkage. In this work, a large database has been set up for shrinkage testing performed by several research centres in Europe. On the basis of the statistical analysis of this database and by observing real structural behaviour, it becomes possible to investigate the current codes of practice regarding the computation of time-dependent shrinkage strains. As comparison with experimental tests has shown that predictions are often inaccurate, a correction factor is proposed in this work to improve the European Code, Eurocode 2, and lead to more satisfactory results. [ABSTRACT FROM AUTHOR]

The results of tests on cracking moment in steel fibre reinforced concrete beams based on waste sand are presented in this paper. The test defined cracking moment was compared with that calculated as proposed by Lok and Xiao, Tan, Paramasivam and Tan and by application of the methods contained in Eurocode 2 as well as in PN-84/B-03264. The best compatibility of the obtained test results with the calculated values was achieved for the Eurocode 2 method. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: The experimental analysis of reduced scale flat slab models under punching, subject to in-plane forces is described and the results are compared with the Eurocode 2 (2004) provisions, the FIP Recommendations for the Design of Post-tensioned Slabs and Foundation Rafts (1998) and ACI 318-08 (2008) , to evaluate their validity. The tests presented here consist of two sets of experimental models: Ramos’s tests Ramos (2003) with six reduced scale flat slab specimens and Regan’s tests Regan (1983) that comprised seven experimental specimens. This work aims to improve the understanding of the behaviour of flat slabs under punching load, in order to properly evaluate the effect of the in-plane forces on the punching resistance. [Copyright &y& Elsevier]

The article discusses a study which investigated the theoretical deflection behaviours of concrete beams reinforced with fibre-reinforced polymer (FRP) bars. The study evaluated the suitability of the present Eurocode 2 Part 1-1 deflection prediction method for FRP reinforced concrete (RC) flexural members and focuses on the appropriateness of using its modified form.

Abstract: In this work a reformulation of the parameters in the nominal curvature method of Eurocode 2  is proposed, with a new definition of the maximum curvature of the column and the deflected shape. A comparison between Eurocode 2  and the proposed formulation is made, considering: variable column heights; concrete classes from the low to high strength concrete; transverse loading; axial loads with different eccentricities; and variable load levels. In general the designs made with the present model give less steel area than in Eurocode 2 and can be used in high strength concrete. [ABSTRACT FROM AUTHOR]

The structural life of a reinforced concrete beam has previously been defined by several stages which include loading of an intact structure to the serviceability stage, corrosion, load reduction before repair procedures, removal of contaminated concrete, patch repair and finally strengthening. Numerical simulations of this service life cycle without strengthening, where time-dependent effects such as creep and shrinkage were included in the constitutive models, were carried out using the phased analysis in the finite-element software Diana. The results of the simulations showed that the failure load is in good agreement with the failure load corresponding to the upper bound of the 95% confidence interval obtained in a previous probabilistic study based on the experimental results. Initial strains owing to shrinkage of the concrete and the repair material were implemented using the Model Code 1990 model (predefined in Diana) and a model for development of free shrinkage strain in beams exposed to one-side drying. This model was developed by Planas and Elices while the material parameters are based on Model Code 1990 or Eurocode 2. Total strains across the cross-section of the beam calculated in the finite-element analyses are compared with data that are available from the experimental study. [ABSTRACT FROM AUTHOR]