Artikeldatenbank
Autor(en)  Titel  Zeitschrift  Ausgabe  Seite  Rubrik 

Nüsse, Gregor  Developing a high quality sandwichpanel envelopesystem for office and multistorey buildings (P 977)  Steel Construction  4/2016  372  News 
Announcements: Steel Construction 4/2016  Steel Construction  4/2016  372  Announcements  
Contents: Structural Concrete 4/2016  Structural Concrete  4/2016  Contents  
Doniak, Íria LíLcia Oliva  Local and global integration for a sustainable future  Structural Concrete  4/2016  520521  Editorials 
von GreveDierfeld, Stefanie; Gehlen, Christoph  Performancebased durability design, carbonation part 2  Classification of concrete  Structural Concrete  4/2016  523532  Technical Papers 
KurzfassungAt present, prescriptive regulations with regard to concrete cover and composition are applied to provide sufficient durability of reinforced concrete members under exposure conditions with different degrees of severity. In view of current knowledge on deterioration mechanisms and their modelling, it is planned to change from these deemedtosatisfy specifications to a performancebased design approach in future standards. In such specifications, concrete durability design is based on the statistically characterized performance of concrete, determined in standardized tests with respect to defined classes of concretes with similar performance. x


Andrade, Carmen; Cesetti, Alessandro; Mancini, Giuseppe; Tondolo, Francesco  Estimating corrosion attack in reinforced concrete by means of crack opening  Structural Concrete  4/2016  533540  Technical Papers 
KurzfassungThe corrosion of reinforcement in concrete is the most common degradation phenomenon of reinforced concrete structures. Reinforced concrete elements subjected to corrosion generally crack due to the expansive nature of oxides. One very important task is estimating the corrosion level using a nondestructive method in order to establish both the actual safety of the structure and a priority intervention plan. x


Hussein, Luaay; Amleh, Lamya  Analytical modelling of bond stress at steelconcrete interface due to corrosion  Structural Concrete  4/2016  541552  Technical Papers 
KurzfassungAn analytical model is proposed for bond stresses at the corroded steelconcrete interface in reinforced concrete. The concrete around the corroded bar is modelled as a thickwalled cylinder  consisting of an inner cylinder of an anisotropic material and an outer cylinder made of an isotropic material  subjected to internal pressure exerted by the growth of corrosion products on the concrete wall at the interface. A frictional model is used to combine the action of confining pressure due to radial pressure produced by principal bar ribs and the pressure resulting from expansion of corrosion products. The analysis results using the proposed model show good agreement with the experimental results of several researchers. x


Zych, Mariusz  Modification of the simplified method of crack control included in EN 19923  Structural Concrete  4/2016  553563  Technical Papers 
KurzfassungThe methods of crack control for liquidretaining RC tank walls are analysed taking into account external load (EN 199211) and imposed strain occurring at the construction stage (EN 19923), i.e. during the concretehardening period. The convergence ranges of the simplified method of crack control included in EN 19923 and the detailed calculation methods included in EN 199211 and EN 19923 are defined. Apart from the compatibility areas, overestimation of the acceptable reinforcing bar diameter &phgr;s*, illustrated in Fig. 7.103N in EN 19923, was proved. Coefficients k&phgr;1 and k&phgr;2 are defined, which enable the calculation of the acceptable reinforcing bar diameter &phgr;s* in order to obtain the values complying with the direct calculations. For practical purposes, graphs have been plotted to facilitate the definition of coefficients k&phgr;1 and k&phgr;2 without performing direct calculations. On the basis of the analyses performed and the relations proposed, it can be concluded that there is a possibility or a necessity to increase or decrease the acceptable reinforcing bar diameter &phgr;s* depending on the concrete mechanical properties and geometrical properties of an RC tank wall. x


Tian, He; Zhang, Y. X.; Yang, Chunhui; Ding, Yining  Recent advances in experimental studies of the mechanical behaviour of natural fibrereinforced cementitious composites  Structural Concrete  4/2016  564575  Technical Papers 
KurzfassungThis paper presents a review of recent research and development work involving natural fibrereinforced concrete (NFRC). The recent developments in NFRC reinforced with different types of natural fibre, such as sisal fibre, bagasse fibre, coir fibre, banana fibre, eucalyptus fibre, flax fibre, jute fibre and pinus radiate fibre, are covered. Natural fibres and their modification methods are introduced first and the development history of natural fibrereinforced concrete and the relevant research into the mechanical behaviour of NFRC in both the short and longterm are reviewed. The applications of NFRC are also summarized. x


irgulis, Giedrius; vec, Old ich; Geiker, Mette Rica; Cwirzen, Andrzej; Kanstad, Terje  Variation in fibre volume and orientation in walls: experimental and numerical investigations  Structural Concrete  4/2016  576587  Technical Papers 
KurzfassungPrevious research with fibrereinforced slab elements has shown that the surface roughness of formwork and the presence of rebars affect fibre orientation and fibre volume distribution. This paper discusses the orientation and volume distribution of steel fibres in wall elements cast from a single point. Aparticular focus of the work was the effect of formwork tie ba rs on fibre orientation and distribution. Numerical simulations and Xray computed tomography were appliedto quantify the fibre orientation and distribution, and the mechanical performance was determined using threepoint bending tests on sawn beams. The Thorenfeldt model (applied in the Norwegian proposal for the new fibrereinforced concrete guideline) was used to estimate the residual flexural tensile strength based on fibre orientation and distribution. x


di Prisco, Marco; Martinelli, Paolo; Parmentier, Benoit  On the reliability of the design approach for FRC structures according to fib Model Code 2010: the case of elevated slabs  Structural Concrete  4/2016  588602  Technical Papers 
KurzfassungThis paper focuses on the reliability of the design approach proposed in the fib Model Code for Concrete Structures 2010 for estimating the ultimate capacity of fibrereinforced concrete (FRC) elevated slabs on the basis of different tests for material characterization. The fracture properties of the material are determined through threepoint bending tests on notched beams and through double edge wedge splitting (DEWS) tests carried out on cylinders cored in the fullsize test structure. As a case study, an FRC elevated flat slab 0.2 m thick is considered which consists of nine bays (panels) measuring 6 × 6 m (overall size 18.3 × 18.3 m) and is supported by 16 circular concrete columns. The ultimate bearing capacity of the slab determined experimentally is compared with the design value predicted by means of a procedure based on limit analysis following fib Model Code 2010. The results show that the method proposed in fib Model Code 2010 using the characteristic values and the classification is reliable. Even if the tests are affected by a significant standard deviation and the two experimental campaigns with threepoint bending tests give a significant difference between class “5c” and class “3e”, the structural test results in a loadbearing capacity that is always larger than the predicted one, which considers a safety coefficient for the material &ggr;F = 1.5. x


Simões, João T.; Bujnak, Jan; Ruiz, Miguel Fernández; Muttoni, Aurelio  Punching shear tests on compact footings with uniform soil pressure  Structural Concrete  4/2016  603617  Technical Papers 
KurzfassungPunching shear is usually the governing failure criterion when selecting the depth of reinforced concrete footings. Despite the fact that large experimental programmes aimed at the punching strength of slender flat slabs have been performed in the past, only a few experimental campaigns on fullscale compact reinforced concrete footings can be found in the literature. This paper presents the results of an experimental programme including eight reinforced concrete footings with a nominal thickness of 550 mm. These experiments investigated the influence of column size, member slenderness and the presence of compression and shear reinforcement. The tests were performed using an innovative test setup to ensure a uniform soil pressure. The experimental results show that slenderness influences the punching shear strength as well as the effectiveness of the shear reinforcement. The experiments also show that an important interaction occurs between bending and shear for high levels of shear force near the column (the typical case of compact footings or members with large amounts of shear reinforcement). Different continuous measurements recorded during the experimental tests allow a complete description of the kinematics and strains at failure. On that basis, experimental evidence is obtained showing that crushing of the concrete struts near the column is the phenomenon that triggers the punching failure of compact footings. x


Mobin, Jalal Salehi; Kazemi, Mohammad Taghi; Attari, Nader K.A.  Cyclic behaviour of interior reinforced concrete beamcolumn connection with selfconsolidating concrete  Structural Concrete  4/2016  618629  Technical Papers 
KurzfassungA significant amount of research on selfconsolidating concrete (SCC) technology has been devoted to evaluating the suitability of the material for its use in structural applications. However, more research is required to confirm the adequacy of SCC structural members for resisting gravity and seismic loads. This study focuses on the experimental investigation of the seismic performance of interior reinforced concrete beamcolumn connections with SCC. Four beamcolumn connection specimens, three with SCC and one with normally vibrated concrete (NC), were designed for this experimental study. Factors such as concrete type (SCC or NC) and axial load ratio (0, 7.5 and 15 % of column section capacity) were assumed to be the variables in designing the specimens. Beamcolumn connections made with NC and SCC were studied and compared under reversed cyclic loading. The performance of SCC specimens is comparable with NC specimens in terms of strength, displacement and ductility, but SCC specimens show lower energy dissipation capacity. x


von der Haar, Christoph; Marx, Steffen  Development of stiffness and ultrasonic pulse velocity of fatigue loaded concrete  Structural Concrete  4/2016  630636  Technical Papers 
KurzfassungDamage processes in fatigue loaded concrete structures depend on the number and amplitude of the load cycles applied. Damage evolution is linked to a reduction in concrete stiffness, and it is thought that this reduction causes stress redistributions at component level which have a favourable impact on the service life of a structure. Until now, the stiffness reduction and stress redistribution have never been successfully measured in laboratory tests or in situ. It is only known that the real service life is longer than the calculated one and that indicators of stiffness reduction, such as component deflection, increase with the number of load cycles applied. x


Hümme, Julian; von der Haar, Christoph; Lohaus, Ludger; Marx, Steffen  Fatigue behaviour of a normalstrength concrete  number of cycles to failure and strain development  Structural Concrete  4/2016  637645  Technical Papers 
KurzfassungThe fatigue behaviour of concrete is gaining new relevance against the backdrop of continuous developments in concrete construction. Modern types of concrete are achieving ever higher strengths; hence, concrete structures are becoming increasingly attractive for new fields of application such as onshore and offshore wind turbines. The fatigue of concrete has a special relevance for these cyclically loaded structures and knowledge of the number of cycles to failure is no longer sufficient for their design. There are further questions concerning strain and stiffness development and the combination of fatigue loading and maritime environmental conditions which have been investigated with new testing methods at Leibniz Universität Hannover within the scope of the “ProBeton” research project. The first results of this project, which is supported by the Federal Ministry for Economic Affairs and Energy, are presented here. x


Classen, Martin; Herbrand, Martin; Kueres, Dominik; Hegger, Josef  Derivation of design rules for innovative shear connectors in steelconcrete composites through the systematic use of nonlinear finite element analysis (FEA)  Structural Concrete  4/2016  646655  Technical Papers 
KurzfassungToday, the development of innovative shear connectors for steelconcrete composites is accompanied by a large number of experimental investigations, which are obligatory when proposing suitable design formula and carving out their limitations of use. Using the example of the socalled pin connector, the present paper illustrates to what extent validated finite element models of novel shear connectors can be used to replace expensive and timeconsuming shear tests and how these finite element models can support the deduction of design concepts. The pin connector considered was developed for connecting steel sections to very slender highstrength concrete slabs in which conventional shear connectors such as headed studs cannot be used due to the limited embedment depth. In order to clarify the shear behaviour and loadcarrying mechanisms of these novel connectors, nonlinear finite element models were set up using the commercial FE software Abaqus. Subsequently, the FE models were used to perform systematic parametric studies. This paper describes the numerical results and also explains the stepwise development of an entire engineering model for determining the longitudinal shear capacity of smallscale pin connectors, including all the necessary limitations of use. The proposed modelling strategy and the methodology for the deduction of design rules can be transferred and assigned to other types of shear connectors. x


LópezLópez, Andrés; Tomás, Antonio; SánchezOlivares, Gregorio  Behaviour of reinforced concrete rectangular sections based on tests complying with seismic construction requirements  Structural Concrete  4/2016  656667  Technical Papers 
KurzfassungThe prediction of the seismic behaviour of reinforced concrete elements using numerical models has become a field of growing interest in recent years due to the importance of the effects induced by seismic loads applied to reinforced concrete structures. The simulation of the hysteretic behaviour of the plastic hinges generated in the structure when the seismic load acts requires the use of models that are able to describe the sectional behaviour of structural members. Thus, the main objective of the present paper is the adjustment of several empirical expressions that reduce the computational time needed to simulate the yield and ultimate behaviour of a given reinforced concrete rectangular section under either monotonic or cyclic loading. The expressions are calibrated with a selection of tests, taken from a published database of more than 1000 tests, according to the criterion that the selected specimens comply with the seismic construction requirements of the main international building codes (EC2, EC8 and ACI318). Owing to their robustness and the acceptable computation time for lowdimensional problems, genetic algorithms are used for this calibration. The equations proposed can be employed by structural engineers for the design and analysis of actual structural elements used in ordinary reinforced concrete buildings located in seismic areas, and provide more accurate results than other expressions. x


Ma, ChauKhun; Awang, Abdullah Zawawi; Omar, Wahid; Liang, Maybelle; Jaw, SiowWei; Azimi, Mohammadamin  Flexural capacity enhancement of rectangular highstrength concrete columns confined with posttensioned steel straps: experimental investigation and analytical modelling  Structural Concrete  4/2016  668676  Technical Papers 
KurzfassungThe loadcarrying capacity and deformability of concrete columns can be substantially enhanced by confining with posttensioned steel straps. As interest in highstrength concrete (HSC) grows among structural engineers and researchers due to its superior performance, this confining technique is being extended to HSC columns with the hope that it can eliminate the undesired properties of HSC, especially its brittleness. However, experimental studies involving confined HSC columns subjected to eccentric loads are comparatively limited. It can be seen from past research that most studies of external confinement were conducted on smallscale normalstrength concrete (NSC) cylinders subjected to concentric loads. Since most columns are subjected to eccentric loads in reality, the scarcity of test data has prevented the potential of this confining technique from being fully exploited. In this paper, this confining technique is called the steelstrapping tensioning technique (SSTT) for brevity. Nine HSC columns were tested under eccentric loads. The specimens were grouped into three groups with each group having an unconfined HSC column as a control specimen, a twolayer SSTTconfined HSC column and a fourlayer confined HSC column. The experimental results show that the flexural capacities of HSC columns can be enhanced with SSTT. The deformability of confined HSC columns is significantly improved with such confinement. x


Gupta, Pramod K.; Khaudhair, Ziyad A.; Ahuja, Ashok K.  A new method for proportioning recycled concrete  Structural Concrete  4/2016  677687  Technical Papers 
KurzfassungA new modified mix proportioning method for producing normalstrength concrete using recycled concrete aggregate, called the equivalent coarse aggregate mass (ECAM) method, is proposed in this paper. The basic concepts of the proposed method with calculations for mix design are presented by designing 14 mixes and testing 99 concrete samples (57 cubes and 42 cylinders). Experimental work was carried out in two phases. In the first phase, an experimental programme was conducted to verify the proposed mix design method by studying a single parameter  uniaxial compressive strength. Five different mixes with initial 0, 25, 50, 75 and 100 % replacement by mass were designed, cast and tested in this phase. It was concluded from the first phase that the proposed method can be adopted for designing the recycled concrete up to a nominal replacement ratio of 50 %. Accordingly, the second phase of experimental study was carried out to design three different grades of concrete strength using the proposed method to investigate the mechanical properties of the recycled concrete. Seven different mechanical properties  compressive strength, splitting tensile strength, modulus of elasticity, Schmidt hammer test, ultrasonic pulse velocity test, fresh density and hardened density  were investigated and are presented and discussed here. x


fibnews: Structural Concrete 4/2016  Structural Concrete  4/2016  688695  fibnews  
Kurzfassung11th fib PhD International Symposium in Tokyo x


Inhalt: UnternehmerBrief Bauwirtschaft 4/2016  UnternehmerBrief Bauwirtschaft  4/2016  Inhalt  
Gesamtausgabe UBB 4/2016  UnternehmerBrief Bauwirtschaft  4/2016  124  Gesamtausgabe  
Schalk, Günther  Von neuen Schlössern und Haushaltslöchern...  UnternehmerBrief Bauwirtschaft  4/2016  1  Editorials 
Kurz informiert: UnternehmerBrief Bauwirtschaft 4/2016  UnternehmerBrief Bauwirtschaft  4/2016  2  Kurz informiert  
KurzfassungBVMB: “Bürokratieabbau darf kein Lippenbekenntnis bleiben!” x


Siegel, Caroline; Traut, Johannes  Mindestlohn bei Subunternehmern: Haftungsrisiko!  UnternehmerBrief Bauwirtschaft  4/2016  38  Berichte 
KurzfassungBaufirmen stehen vielfach unter Druck. Nicht nur hinsichtlich der Herstellung der Bauleistungen, die sie täglich erbringen, nimmt die Zahl der Vorschriften immer mehr zu. Auch haben Bauunternehmen beispielsweise Regelungen aus dem Arbeitsrecht zu beachten. Von hoher Praxisbedeutung sind hier insbesondere die Vorschriften zu Mindestarbeitsbedingungen und zum Mindestlohn am Bau. Werden Mindestarbeitsbedingungen des Baugewerbes  ob im eigenen Betrieb oder durch Subunternehmer  nicht eingehalten, bestehen massive Haftungs und Bußgeldrisiken. Der UBB stellt in diesem Beitrag die Anforderungen im Überblick dar und gibt Tipps zur Risikobegrenzung. x
