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Bedair, Osama  An analytical expression to determine "realistic" shear buckling stress in coldformed lipped channels  Steel Construction  1/2015  5358  Articles 
KurzfassungCurrent North American and European design provisions ignore the rotational restraint when evaluating local web shear buckling stresses in coldformed steel channels. This paper offers a new analytical expression for computing local buckling shear stresses in coldformed channel members taking into account the rotational restraints imposed by the flanges and the lips. The expression derived is suitable for hand calculations and can replace current code expressions in order to achieve economical steel designs. Comparisons with existing design formulas currently used in practice for the limiting conditions show a difference within 5 %. x


PhÃ¤nomenta Science Center in LÃ¼denscheid, Germany  Steel Construction  1/2015  58  News  
NÃ¼tzel, Oswald; Saul, Reiner  Longterm corrosion protection for bridge cables with butyl rubber tapes using the ATIS CableskinÂ® system  Steel Construction  1/2015  5964  Reports 
KurzfassungATIS Cableskin® is a corrosion protection system for bridge cables which uses proven materials to strike out in a new direction. These innovative ideas mean that, for the first time, corrosion protection work on scaffolds and in enclosures will be a thing of the past, and the costs and traffic restrictions are massively reduced. It is worth highlighting the extremely long lifetime of this corrosion protection. x


Winterstetter, Thomas; Alkan, Mustafa; Berger, Radu; Watanabe, Maiko; Toth, Agatha; Sobek, Werner  Engineering complex geometries  the Heydar Aliyev Centre in Baku  Steel Construction  1/2015  6571  Reports 
KurzfassungThe present paper describes the engineering design by Werner Sobek for the new Heydar Aliyev Centre in Baku, a masterpiece of 3D freeform architecture by Zaa Hadid. x


EUROFER: Chinese steel imports confuse buyers in Europe as Chinese steel producers exploit the export tax regime  Steel Construction  1/2015  71  News  
ECCS News: Steel Construction 1/2015  Steel Construction  1/2015  7274  ECCS News  
Call for entries: European Steel Design Awards 2015  Steel Construction  1/2015  7476  News  
Announcement: Steel Construction 1/2015  Steel Construction  1/2015  76  Announcement  
ECCS individual membership  Steel Construction  1/2015  76  News  
Contents: Structural Concrete 1/2015  Structural Concrete  1/2015  Contents  
Annual table of contents 2014  Structural Concrete  1/2015  Annual table of contents  
MÃ¼ller, Harald S.  From accomplishments to challenges  Structural Concrete  1/2015  1  Message from the fib President 
Ignatiadis, Anett; Fingerloos, Frank; Hegger, Josef; Teworte, Frederik  Eurocode 2  analysis of National Annexes  Structural Concrete  1/2015  316  Technical Papers 
KurzfassungEurocode 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. x


Wang, Lijie; Caspeele, Robby; Van Coile, Ruben; Taerwe, Luc  Extension of tabulated design parameters for rectangular columns exposed to fire taking into account secondorder effects and various fire models  Structural Concrete  1/2015  1735  Technical Papers 
KurzfassungFire, as one of the most severe load conditions, has an important impact on concrete structures. Not only does a fire affect the material strength, it affects structural stiffness and stability as well. A concrete column, compared with other structural members, in most cases has to cope with both vertical forces and bending moments transferred by slabs and beams. Consequently, it is essential to find a reliable and practical way of establishing interaction curves for the overall structural behaviour of concrete columns subjected to fire. In this paper, a crosssectional calculation method based on the material models of Eurocode 2 is explained and adopted in order to calculate interaction curves for a typical rectangular column exposed to the ISO 834 standard fire. Subsequently, an iterative approach is introduced to develop interaction curves taking into account secondorder effects in the case of all the four faces of a column exposed to fire. The maximum permissible slenderness ratios for columns in different fire durations are obtained and compared with Eurocode 2 provisions. Finally, this method is used to calculate the maximum permissible slenderness ratios for columns exposed to hydrocarbon and natural fires. x


Duplan, FranÃ§ois; AbouChakra, Ariane; Turatsinze, Anaclet; Escadeillas, Gilles; BrÃ»lÃ©, StÃ©phane; Javelaud, Emmanuel; MassÃ©, FrÃ©dÃ©ric  On the use of European and American building codes with lowstrength mortars  Structural Concrete  1/2015  3644  Technical Papers 
KurzfassungThe standard European building specifications, grouped in a ninevolume Eurocode, describe different approaches for determining the properties of commonly used building materials such as steel, aluminium, concrete, etc. x


Cairns, John  Bond and anchorage of embedded steel reinforcement in fib Model Code 2010  Structural Concrete  1/2015  4555  Technical Papers 
KurzfassungThis paper describes the changes to design provisions for embedded steel reinforcement in the fib Model Code for Concrete Structures 2010. The changes introduce new coefficients for steel grade and clear spacing between bars, and extend the range of concrete strengths covered. The way in which the contribution of hooks or anchorages is calculated has been revised and the contribution of end bearing to laps and anchorages of compression bars is recognized. The revised rules represent a move away from a distinction between laps and anchorages per se towards a distinction based on the presence or absence of transverse pressure perpendicular to the bar axis within the bond length. The benefits of staggering laps with only a proportion of bars lapped at a section are also reviewed. Finally, the potential impact of lap and anchorage performance on structural robustness is discussed, and it is concluded that this can only be achieved if bar yield precedes splitting mode bond failures. x


Prince, M. John Robert; Singh, Bhupinder  Bond behaviour of normal and highstrength recycled aggregate concrete  Structural Concrete  1/2015  5670  Technical Papers 
KurzfassungThe effect of concrete grade on the bond between 12 mm diameter deformed steel bars and recycled aggregate concrete (RAC) has been investigated with the help of 45 pullout tests with concentric rebar placement for coarse recycled concrete aggregate (RCA) replacement levels of 25, 50, 75 and 100%. For all the three concrete grades, the measured bondslip relationships indicate similar mechanisms of bond resistance in the RAC and the natural aggregate (NA) concrete. The most accurate and least conservative predictions of the measured bond strengths were obtained from the local bondslip model in the fib Model Code for Concrete Structures 2010. Bond strength normalized to fc(3/4) resulted in an improved match with test data and increased with an increase in the RCA replacement levels and decreased with an increase in compressive strength. An attempt to explain this behaviour has been sought in terms of brittleness index, an analogous parameter from rock mechanics. An empirical bond stress versus slip relationship has been proposed for the 12 mm diameter bar and it is conservatively suggested that similar anchorage lengths for this bar in all three concrete grades can be adopted for the RAC and the NA concretes. x


Mihaylov, Boyan  Fivespring model for complete shear behaviour of deep beams  Structural Concrete  1/2015  7183  Technical Papers 
KurzfassungThis paper presents a fivespring model capable of predicting the complete pre and postpeak shear behaviour of deep beams. The model stems from a twoparameter kinematic theory (2PKT) for the shear strength and displacement capacity of deep beams under single curvature. Four of the springs of the model represent the shear resistance mechanisms of the beam, while the fifth spring models the flexural behaviour. The model predicts not only the loaddisplacement response, but also the deformation patterns of the beam and how these patterns change with increasing load. Validation studies are performed by using 28 tests from the literature, showing excellent results. The model is used to interpret the tests and to draw conclusions about the behaviour of deep beams. It is shown that shear strength variations of up to 60 % between nominally identical specimens can be caused by variations in the path of the critical shear cracks. It is also demonstrated that loss of bond of large reinforcing bars increases the shear capacity of deep beams. Finally, the fivespring model is shown to predict the postpeak shear behaviour effectively, which is important for the analysis of structures under extreme loading. x


Zhou, LinYun; Liu, Zhao; He, ZhiQi  Further investigation of transverse stresses and bursting forces in posttensioned anchorage zones  Structural Concrete  1/2015  8492  Technical Papers 
KurzfassungIn the posttensioned anchorage zone, the load transfer path of an anchor force can be visualized by an infinite number of isostatic lines of compression (ILCs). The method was initially proposed by Guyon and recently attracted significant interest from a number of researchers. Based on the work of these predecessors, an updated mathematical model has been proposed in order to analyse the bursting forces and the distribution of transverse stresses in the anchorage zone. Compared with the results of a finite element analysis, the updated equations are more accurate than the previous ones. Based on the observation that the sixthorder polynomial expression is better than the fourthorder one, as far as the solution of bursting stresses is concerned, it can be reasonably postulated that a de facto function of the ILCs must exist. Additionally, it is equally interesting that the bursting forces derived with the updated analytical model are the same as those obtained with the formula in the current AASHTOLRFD Bridge Design Specifications based on numerical stress analyses. x


Amin, Ali; Foster, Stephen J.; Muttoni, Aurelio  Derivation of the &sgr;w relationship for SFRC from prism bending tests  Structural Concrete  1/2015  93105  Technical Papers 
KurzfassungThe material characterization of steel fibrereinforced concrete (SFRC), which is required for its implementation in design codes, should be based on nominal properties that describe its postcracking strength in tension. In the case of brittle and quasibrittle materials, such as concrete, the tensile parameters are often derived indirectly. However, for materials with more ductility, such as SFRC, there is conjecture as to whether or not an indirect measure may be used to establish the stress versus crack opening displacement relationship, such as the use of a three or fourpoint prism test combined with an inverse analysis. In this paper a simple and efficient inverse analysis technique is developed and shown to compare well with data obtained from direct tension tests. Furthermore, the methodology proposed by the fib Model Code for Concrete Structures 2010 has been investigated and recommendations made to improve its accuracy. x


Scholzen, Alexander; Chudoba, Rostislav; Hegger, Josef  Thinwalled shell structures made of textilereinforced concrete  Part I: Structural design and construction  Structural Concrete  1/2015  106114  Technical Papers 
KurzfassungAt RWTH Aachen University recently, a pavilion was constructed with a roof shell made of textilereinforced concrete (TRC), a composite material consisting of a finegrained concrete and highstrength, noncorroding textile reinforcement in the form of carbon fibres. The thinwalled TRC shell structure demonstrates impressively the loadbearing capacity of this innovative composite material. The present paper discusses the practical issues concerning the construction, such as the fabrication of the TRC shells using shotcrete, the concepts developed for the arrangement of the textile reinforcement and the erection of the shells on top of the precast concrete columns. The issues concerning the design, assessment and numerical simulation of the loadbearing behaviour of TRC shells are presented in the companion paper (Part II). x


Scholzen, Alexander; Chudoba, Rostislav; Hegger, Josef  Thinwalled shell structures made of textilereinforced concrete  Part II: Experimental characterization, ultimate limit state assessment and numerical simulation  Structural Concrete  1/2015  115124  Technical Papers 
KurzfassungThe present paper describes a design approach for textilereinforced concrete (TRC) shells which reflects the interaction between normal forces and bending moments based on the crosssectional strength characteristics of the material determined experimentally. The influence of oblique loading on the composite strength of TRC elements with flexible reinforcement is included in a normalized interaction diagram for combined loading. As an example, the design approach is applied to the ultimate limit state assessment of a TRC shell in double curvature. Furthermore, the general applicability of the design approach is discussed in the light of the nonlinear loadbearing behaviour of TRC. Due to its strainhardening tensile response, stress redistributions within the shell result in loadbearing reserves. Details of the structural design and production solutions developed and applied during the realization of the TRC shell structure are described in the companion paper (Part I). x


Jung, Bastian; Morgenthal, Guido; Xu, Dong; SchrÃ¶ter, Hendrik  Quality assessment of material models for reinforced concrete flexural members  Structural Concrete  1/2015  125136  Technical Papers 
KurzfassungNonlinear constitutive models for concrete in compression are frequently defined in design codes. The engineer generally uses either the linear (in SLS) or nonlinear (in ULS) compression model. However, a large variety of different approaches exists for describing the behaviour of the cracked concrete tension zone, and the selection of a corresponding model is usually based on qualitative engineering judgement. The aim of this paper is to assess the prediction quality of several concrete material models in order to provide a quantitative model selection. Therefore, uncertainty analysis is applied in order to investigate the model and parameter uncertainty in the bending stiffness prognosis for flexural members. The total uncertainty is converted into a prognosis model quality that allows a quantitative comparison between the material models considered. The consideration of the reinforced concrete in tension is based on the characterization of the tension stiffening effect, which describes the cracking in an average sense. In the interest of the practical applicability of the models considered, even for large structures, no discrete crack simulations based on fracture mechanics are considered. Finally, the assessment identifies that the prediction quality depends on the loading level and, furthermore, the quality across the models can be quantitatively similar as well as diverse. x


Holomek, Josef; Bajer, Miroslav; Barnat, Jan; Schmid, Pavel  Design of composite slabs with prepressed embossments using smallscale tests  Structural Concrete  1/2015  137148  Technical Papers 
KurzfassungThe loadbearing capacity of steelconcrete composite slabs using thinwalled steel sheeting with prepressed embossments is in most cases determined by their resistance in longitudinal shear. The design of composite slabs still requires fullscale laboratory bending tests to be performed. Smallscale shear tests cannot include all of the influences affecting the bent slab. However, by using an appropriate procedure, the shear characteristics obtained from such tests can be used to determine the bending capacity of the slab. Two such procedures are compared in this paper. x


fibnews: Structural Concrete 1/2015  Structural Concrete  1/2015  149157  fibnews  
KurzfassungThe fib in Russia: new standards; Worldwide representation at ACF 2014; DISC2014: the past and the future; Old for new: Penang Bridge; A venerable institute turns 80; JPEE2014 in Lisbon; fib MC2010 course in Brazil; Short notes; Nigel Priestley † 19432014; Congresses and symposia; Acknowledgement x
