## Artikeldatenbank

Autor(en) | Titel | Zeitschrift | Ausgabe | Seite | Rubrik |
---|---|---|---|---|---|

Hauf, Gunter; Kuhlmann, Ulrike | Deformation calculation methods for slim floors | Steel Construction | 2/2015 | 96-101 | Articles |

## KurzfassungSlim-floor structures combine the advantages of prefabricated slab elements with steel-frame construction and lead to economic building solutions fulfilling the demands of modern architecture in combination with transparent structural envelopes without intervening columns as well as implicit flexibility for sustainable construction. Over past years, new slim-floor solutions have been developed to broaden the market for composite structures when compared with conventional concrete flat slabs. However, due to the shallow depth of composite slim-floor girders, their structural response, especially their deflection behaviour, differs from normal composite girders. The concrete is already in the cracked condition under service loads in regions of sagging bending moments. The contribution of the concrete chord to the effective moment of inertia Ii,0 of the composite cross-section and the bending moment Mc in the concrete chord are not negligible for the total loadbearing capacity of the composite section. These two effects are not normally considered when calculating the deflections of composite girders based on the effective width given in codes such as EN 1994-1-1 [1]. Therefore, the following paper will show different methods for calculating the deflection of these shallow types of composite girder. x | |||||

Romero, Manuel L.; Cajot, Louis-Guy; Conan, Yves; Braun, Matthias | Fire design methods for slim-floor structures | Steel Construction | 2/2015 | 102-109 | Articles |

## KurzfassungSlim-floor beams are well-known, sustainable and economical solutions for residential, commercial and industrial buildings. However, despite their widespread use, Eurocode 4 contains no specific simplified calculation methods for the fire resistance of integrated and shallow floor beams. There is a clear need for an improved understanding of the performance of structures in fire plus clear and cost-effective design guidance. This paper presents a set of simplified rules for determining thermal fields in the lower flange, web, rebars and slab of slim or integrated floor beams. This calculation methodology is based on existing formulas taken from different parts of Eurocode 4 except for the temperature calculation in the lower flange, which is deduced from a parametrical study using the SAFIR software. x | |||||

New technology paves the way for greener steel | Steel Construction | 2/2015 | 109 | News | |

Hicks, Stephen; Peltonen, Simo | Design of slim-floor construction for human-induced vibrations | Steel Construction | 2/2015 | 110-117 | Articles |

## KurzfassungThis paper presents a simplified design method for evaluating the vibration response of composite floors with slim-floor beams. The methodology is amenable to hand calculations and is appropriate for floors with regularly spaced grids and vibrations that are occasioned by walking activities. From in situ tests that have been undertaken on six floors, it is shown that slim-floor construction can easily satisfy the demanding ISO 10137 response limits for operating theatres and laboratories together with limits recommended by industry for car parks and shopping malls. Comparisons with measurements show that the simplified method presented here provides conservative predictions, and may therefore be used with confidence in design. x | |||||

Leskela, Matti V.; Peltonen, Simo | Effect of unzipping connection behaviour on the composite interaction of shallow floor beams | Steel Construction | 2/2015 | 118-121 | Articles |

## KurzfassungUnzipping connection behaviour is not referred to in EN 1994-1-1 - only ductile and non-ductile shear connections are classified. It might be clear that unzipping connections belong to the non-ductile ones, but not all the non-ductile connections are unzipping ones. Characteristic of unzipping connection behaviour is that, initially, connection stiffness is high and composite action is efficient. However, as the load increases, so the connection loses its shear stiffness very rapidly, and after the onset of plastic behaviour in the beam, the decking no longer contributes to the bending resistance of the initially composite member. This behaviour is most typically seen in shallow floor beams (abbreviated to SF beams) supporting hollow-core decking. This is a companion paper to the one in which the composite action in SF beams with ductile shear connections is discussed. x | |||||

Kuhlmann, Ulrike; Just, Adrian; Leitz, Bernadette; Grabe, JÃ¼rgen; SchallÃ¼ck, Christoph | Simplified criteria and economic design for king piles in combined steel pile walls according to Eurocode 3, part 1-1 | Steel Construction | 2/2015 | 122-132 | Articles |

## KurzfassungThe steady growth in world trade leads to a demand for more port and harbour facilities. One of the most common forms of construction for deep-water harbour quays is the combined steel pile wall. It consists of up to 45 m long H-section king piles plus Z-section intermediate sheet pile infill elements. The intermediate elements and the quay both transfer all forces to the king piles, which as a result are loaded with (bi)axial bending and axial force, so their stability must be checked. Up to now the effect of the soil surrounding the piles was used just in terms of best practice - buckling about the weak axis and lateral torsional buckling were neglected completely. Considering these stability phenomena in design without taking the soil into account would lead to a very conservative approach. As verification of lateral torsional buckling according to EN 1993-1-1 (EC3-1-1) becomes relevant when the embedment is neglected, a more refined analysis has been developed. x | |||||

Eleventh edition of the Edoardo Benvenuto Prize | Steel Construction | 2/2015 | 132 | News | |

Helbig, Thorsten; Kamp, Florian; Oppe, Matthias | An Eye to the Sky - Inclined grid shell dome of 90 m in Astana, Kazakhstan | Steel Construction | 2/2015 | 133-138 | Report |

## KurzfassungA 6500 m² glazed grid shell dome covers the Nazarbayev Centre in Astana, Kazakhstan. Located near the Presidential Palace, this futuristic building, designed by Foster Partners in London, is one of a whole series of prominent architectural buildings in Astana. x | |||||

News: Steel Construction 2/2015 | Steel Construction | 2/2015 | 138 | News | |

## KurzfassungThe DVS EXPO will focus on robotics and virtual welding trainers x | |||||

ECCS News: Steel Construction 2/2015 | Steel Construction | 2/2015 | 139-142 | ECCS News | |

Stadsbrug Nijmegen: a beauty with waves and curves | Steel Construction | 2/2015 | 142-143 | News | |

Schlaich, JÃ¶rg | Hyperbolic structures. Shukhov's Lattice Towers - Forerunners of Modern Lightweight Construction. From Beckh, M. | Steel Construction | 2/2015 | 143-144 | Book review |

Announcement: Steel Construction 2/2015 | Steel Construction | 2/2015 | 144 | Announcement | |

Contents: Structural Concrete 2/2015 | Structural Concrete | 2/2015 | Contents | ||

Andrade, Carmen | Modelling the concrete-real environment interaction to predict service life | Structural Concrete | 2/2015 | 159-160 | Editorial |

Kromoser, Benjamin; Kollegger, Johann | Pneumatic forming of hardened concrete - building shells in the 21st century | Structural Concrete | 2/2015 | 161-171 | Technical Papers |

## KurzfassungDouble-curvature shells, used as supporting structures, are strong and save materials. Major parts of the applied loads can be carried by normal forces. Thus, the stresses are distributed very uniformly and efficiently over the entire cross-section, and long spans can be built with small thicknesses. The state of the art in the construction of shell structures is characterized by a high labour input for formwork and falsework. A new construction method without formwork and falsework has been invented at the Institute for Structural Engineering at Vienna University of Technology. The idea of this new construction method is to build concrete shells with a double curvature originating from an initially plane plate. During the transformation process, the hardened concrete plate is lifted and the elements are bent with the aid of pneumatic formwork until the required curvature is reached. Non-linear finite element calculations, tension tests, bending tests and bonding tests were carried out in order to determine a suitable combination of concrete and reinforcement. The second part of the paper describes a large-scale experiment for the erection of a 17.6 × 10.8 m, 2.9 m high free-form shell. Finally, different applications for the new method are explained. x | |||||

Galmarini, Andreas; Locher, Daniel; Marti, Peter | Predicting the responses of reinforced concrete slab strips subjected to axial tension and transverse load - a competition | Structural Concrete | 2/2015 | 172-183 | Technical Papers |

## KurzfassungSix large-scale tests on reinforced concrete slab strips were carried out at the Swiss Federal Institute of Technology (ETH) in Zurich, Switzerland, in order to investigate the loadbearing behaviour of reinforced concrete slabs subjected to axial tension and transverse load. Four of these tests were used for an international competition to predict the responses of the test specimens. The specimens differed in the axial tension applied and the presence of stirrups. x | |||||

Kassem, Wael | Shear strength of deep beams: a mathematical model and design formula | Structural Concrete | 2/2015 | 184-194 | Technical Papers |

## KurzfassungThis paper presents a proposal for estimating the shear capacity of reinforced concrete deep beams. The proposed model is based on the fixed-angle softened truss model and utilizes a newly proposed formula for the effective transverse compressive stress acting on the beam web. The proposed formula is developed using a stepwise multiple linear regression analysis of the reported shear capacity values of 445 experimental deep beams. The validity of the mathematical model is examined by comparing its response with the experimental results as well as the predictions of other formulas available in the literature, and it results in the one best fitting the measured shear strengths. The mathematical model leads to an explicit single closed-form expression for computing the shear strength of deep beams. The proposed expression is dimensionless and contains four variables that express the horizontal and vertical reinforcement ratios, the concrete strength and the shear span-to-depth ratio. On the basis of the results of this paper, a design formula is proposed with predictions that are more consistent and also more reliable than those of the ACI Code and the Eurocode. x | |||||

Classen, Martin; Herbrand, Martin | Shear behaviour of composite dowels in transversely cracked concrete | Structural Concrete | 2/2015 | 195-206 | Technical Papers |

## KurzfassungIn steel-concrete composite girders, innovative composite dowels can be used to transfer the shear forces between the concrete slab and the steel section. Today, composite dowels are predominately used in engineering structures such as prefabricated composite bridges. However, due to their ease of manufacture, good loadbearing and deformation properties and suitability for slender concrete slabs, these composite dowels are being used more than ever in building construction as well. The present article describes shear tests on puzzle-shaped composite dowels for slender concrete slabs with a depth of only 10 cm. Aside from different reinforcement configurations, the influence of different longitudinal stress states and transverse cracking in the concrete slab have been investigated. In previous studies of the shear force capacity of composite dowels, the influence of transverse cracking has been neglected. However, our own experiments described in this paper show that the shear capacity of composite dowels is significantly affected by concrete cracking. In order to simulate the experiments performed and to analyse the shear behaviour of the composite dowels in cracked and uncracked concrete, a three-dimensional, non-linear finite element model of the shear tests was set up. The results of both the experimental and numerical investigations are summarized in this paper. x | |||||

FernÃ¡ndez-Montes, David; GonzÃ¡lez Valle, Enrique; DÃaz Heredia, Elena | Influence of axial tension on the shear strength of floor joists without transverse reinforcement | Structural Concrete | 2/2015 | 207-220 | Technical Papers |

## KurzfassungThe mechanism governing shear strength in reinforced concrete members without transverse reinforcement subjected to both bending and tensile stress is complex. Further, formulas used to estimate shear failure are inconsistent with each other and do not fit well with experimental findings. This article highlights the differences between the results of experimental tests and the shear strength values estimated with the equations of ACI 318-11, Eurocode 2 (EC2) and modified compression field theory (MCFT). The tests considered are the ones reported in the literature consulted and the tests carried out for this experimental investigation, some with high-performance concrete. The review also puts forward a proposal for improving the method and fitting procedure when estimating the shear failure in a longitudinal reinforced concrete member without transverse reinforcement due to an excessive principal tensile stress in its web. x | |||||

Schlicke, Dirk; Tue, Nguyen Viet | Minimum reinforcement for crack width control in restrained concrete members considering the deformation compatibility | Structural Concrete | 2/2015 | 221-232 | Technical Papers |

## KurzfassungThe current design code EC2 [1] regulates the minimum reinforcement for crack width control in restrained concrete members by taking up the cracking force of the cross section. Although this concept gives straightforward results, its consistent application can lead to high reinforcement amounts with increasing member thickness. The reason is the simplifying assumption of an infinite member length neglecting the deformation compatibility. x | |||||

Costa, Ricardo Joel Teixeira; ProvidÃªncia, Paulo; Dias, Alfredo | Considering the size and strength of beam-column joints in the design of RC frames | Structural Concrete | 2/2015 | 233-248 | Technical Papers |

## KurzfassungSome experimental research studies have reported that longitudinal reinforcement in beams and columns exhibits larger strains inside the joint than at the joint periphery (defined as the intersection of the outer surfaces of beam and column). This may explain why several technical specifications and state-of-the-art programs recommend basing the design of beams and columns on internal force values larger than those at the joint periphery. These results and procedures are questionable and are investigated in this paper. The non-linear finite element analysis presented here for reinforced concrete frames under gravity and quasi-static monotonic lateral loads examines (i) the stress fields in reinforcement inside interior, exterior and roof exterior joints, and (ii) the load-carrying capacity of representative sub-frame models incorporating such joints. The results prove that it is actually safe, with respect to the joint load capacity, to base the design of longitudinal reinforcement in beams and columns on the internal force values at the joint periphery. This result also contributes to the recommendation to use real-size beam-column joint models in the analysis procedure. x | |||||

Xiao, Jianzhuang; Sun, Chang; Jiang, Xinghan | Flexural behaviour of recycled aggregate concrete graded slabs | Structural Concrete | 2/2015 | 249-261 | Technical Papers |

## KurzfassungThis paper proposes a new concept for “recycled aggregate concrete graded slabs”, which can be achieved through graded distribution for the mechanical properties of the recycled aggregate concrete (RAC). In this study, one four-point bending test was used to investigate six RAC graded slabs and three homogeneous slabs with RAC. The major parameters considered were the layers with different recycled coarse aggregates (RCAs) replacement percentages (0, 50 and 100%), the grading pattern (different casting methods) and the reinforcement ratio. It has been concluded that RAC graded slabs have similar flexural behaviour to that of homogeneous slabs with RAC. The reinforcement ratio, the layers with different RCA replacement percentages and the grading pattern can influence the flexural behaviour of RAC graded slabs. Furthermore, the effects of the three factors on both the flexural capacity and the deflection of the RAC graded slabs were studied with finite element method (FEM) simulation using ABAQUS software. Both the experiments and the FEM analysis indicate that the flexural behaviour of RAC slabs can be improved by using this suitable grading method. x | |||||

Colombo, Matteo; Martinelli, Paolo; di Prisco, Marco | A design approach for tunnels exposed to blast and fire | Structural Concrete | 2/2015 | 262-272 | Technical Papers |

## KurzfassungA design procedure based on a simplified FE model for underground tunnels subjected to internal explosion and possibly preceded by fire accidents is proposed in this article. The procedure can provide a valuable tool for designers who have to check the structural safety of a tunnel for the case of an internal blast event. The tunnel geometry considered is the same adopted for the metro line in Brescia, Italy. It has an internal diameter of about 8.15 m, is about 13.7 km long and is located about 23.1 m below the surface. Six segments and a smaller key segment (6+1) make up the tunnel. The ring has an average width of about 1.5 m. The FE model is first tested under static serviceability loads. Dynamic analyses are carried out in order to reproduce the blast scenario. The aim of this work is to generate pressure-impulse (p-i) diagrams for underground tunnels for the case of internal explosion and pre-explosion fire actions. An ultimate limit state criterion based on the eccentric ultimate flexural capacity and capable of including fire-blast interaction is introduced. An innovative layered precast tunnel segment solution made of different fibre-reinforced cementitious composites is compared with a traditional solution with the lining section made of reinforced concrete. The potential applications of this new solution are also discussed in the paper. x | |||||

Van Tittelboom, Kim; Gruyaert, Elke; De Backer, Pieter; Moerman, Wim; De Belie, Nele | Self-repair of thermal cracks in concrete sandwich panels | Structural Concrete | 2/2015 | 273-288 | Technical Papers |

## KurzfassungAlthough the use of insulated concrete sandwich panels results in more energy-efficient buildings, the presence of this insulation layer can induce thermal cracks. As cracks form a preferential path for aggressive agents to enter and degrade the concrete matrix, and as they are not wanted in this application from an aesthetical point of view, they need to be treated. The aim of this study was to seal the cracks in concrete sandwich panels invisibly in an autonomous way. Therefore, the efficiency of various encapsulated healing agents was compared by inducing thermal cracks in concrete sandwich panels, thus causing capsule breakage and the release of the agents into the cracks. It was shown that encapsulation of both polyurethane and a water-repellent agent can result in a reduction in the water uptake by cracks. However, only when a water-repellent agent was released cracks were healed in an almost invisible way. This study has shown that the self-healing approach involving encapsulated polymer-based healing agents can also be applied to concrete sandwich panels, although more research will be needed to meet the specific healing requirements of this application. x |