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Item type:Publication, Access status: with files , Numerical analysis of shear crack propagation in a concrete beam without transverse reinforcementCrack formation and growth in reinforced concrete members is, in many cases, the cause for the collapse of buildings. Such serious failures impair the structural behavior and can also damage property and persons. An intensive investigation of the crack propagation is indispensable. Numerical methods are being developed to analyze crack growth in a concrete member and to detect fracture failure at an early stage. For reinforced concrete components, however, further research and action is required in the analysis of shear cracks. This paper presents numerical simulations and continuum mechanical modeling of bending shear crack propagation in a concrete beam without transverse reinforcement. As numerical method to map discrete cracks the extended finite element method (XFEM) is applied. The crack propagation is compared with the smeared crack approach using concrete damage plasticity material model. For validation, the crack patterns of a real beam tests are compared with the results of the different finite element models. The numerical analysis will provide further understanding of crack growth and redistribution of inner forces in concrete members. The XFEM makes it possible to predict the fracture behavior of concrete members.Publicationtype: Journal ArticleScopus© Citations 11 258 316 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Shear design of concrete bridge decks without shear reinforcement(2019-08-22); ; Many older concrete bridge decks in Europe, mostly built without transverse reinforcement, show a significant lack of shear capacity due to increasing traffic loads and changes in design. Strengthening the slabs for shear is difficult and very expensive. Thus, more reliable design methods are urgently needed to overcome the calculated safety deficit and in order to avoid unnecessary retrofitting. In this paper a new design method will be presented which gives at least 40 % higher shear capacities than current design rules (EN 1992-1-1:2004; Eurocode 2 Part 1 (2004), in the following EC2-1). This approach is based on the examination of full-scale tests of cantilever slabs and statistical evaluation of a database with test results of reinforced concrete slabs under concentrated loads. Next, this paper shows the advantages and limitations of probabilistic analysis.Publicationtype: Conference Paper232 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , An efficient Latin hypercube sampling for probabilistic nonlinear finite element analysis of reinforced concrete structuresProbabilistic analysis of concrete members is mainly needed for safety evaluations of existing structures. The well-known Monte Carlo simulation is very time-demanding and is therefore not suitable for use in practice, especially for nonlinear finite element analysis of concrete structures. This paper presents a new optimal Latin hypercube sampling method for design of a computer experiment taking into account the sensitivity factors regarding the behaviour of the considered system. The method avoids extensive numerical calculations. The basic idea of this sampling strategy is to use a weighting factor for each dimension of the probability space in order to consider the different influences of the random variables in the optimisation process of Latin hypercube samples. The method is evaluated using examples of reinforced concrete structures, including an example regarding the spatial variability of concrete properties. The results show that with only 10 simulations the statistical values of the load-bearing capacities of concrete structures can be determined with high accuracy, if the new weighted Latin hypercube sampling is used.Publicationtype: Conference Paper276 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Investigation of the soil structure interaction of integral bridges(2019-08-22); ; The assumption for the subgrade reaction modulus of bridge abutment has an influence on the design of integral bridges. The modulus is mainly influenced by the type of filling material, the filling and compaction process, partly or unsaturated soil conditions and by the cyclic stress-strain path. The soil reactions are further dependent on the deflections and stiffness of the bridge structure. The uncertainty of most of the parameters has led to huge differences between upper and lower limits of earth pressures which have to be applied in the design of integral bridges. The aims of the investigation, are to get an improved understanding of the underlying non linear mechanical relations and to develop recommendations for design of integral bridges. The soil-structure interaction is investigated with model tests under 1g conditions. Complex finite element simulations using Abaqus software show the cyclic behavior under partly saturated conditions. The results of the physical and numerical models are compared and discussed. It is shown, that the subgrade reaction modulus is not a constant value and therefore a more sophisticated rheological non-linear spring embedment function is needed.Publicationtype: Conference Paper208 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Increasing the design shear strength of concrete bridge decks by tests and statistical analysis of a shear database(2019-06); ; Publicationtype: Conference Paper168 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 376 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Querkrafttragfähigkeit von Stahlbetonplatten ohne Querkraftbewehrung unter konzentrierten Einzellasten: Teil 2: Vorschlag für ein neues Bemessungskonzept(2019-04); ; Shear capacity of reinforced concrete slabs without transverse reinforcement under concentrated loads. Part 2: Proposal for a new design model. Despite intense national and international research activities, the shear capacity of reinforced concrete slabs without shear reinforcement has not yet been satisfactorily clarified. Numerous older deck slabs of concrete bridges show a lack of shear resistance in the transverse direction. Retrofitting is hardly possible. In this paper, a design model is presented on the basis of tests and statistical investigations, which results in approx. 50 % greater shear capacities than according to current regulations.Publicationtype: Journal Article254 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Ermüdungsfestigkeit zyklisch beanspruchter Stahlbetonbalken ohne Querkraftbewehrung(2018-05); Fatigue strength of RC beams without transverse reinforcement under cyclic loads. The shear design of RC members without transverse reinforcement (e.g. slabs, bridge decks, footings of wind energy plants) for fatigue loads is based on empirical approaches, which had been rarely validated by experiments. This paper presents theoretical, experimental and numerical studies, which aim to give a better understanding of the load transfer in RC members without web reinforcement under static as well as cyclic loads. Furthermore, the approach of Eurocode 2 will be examined.Publicationtype: Journal Article170 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Shear Capacity of Concrete Slabs Without Shear Reinforcement Under Concentrated Loads Close to SupportA large number of existing concrete bridge decks in Europe show a deficit of shear capacity according to current design rules. Retrofitting can hardly be done and is very expensive. Thus, new and more reliable design methods are urgently needed. This report describes 8 full-scale tests on cantilever concrete slabs (3.25 × 4.5 m, thickness 0.25 m) without shear reinforcement under concentrated loads. The experimental studies presented in this paper were conducted to get a better understanding of the load bearing behavior of cantilever slabs and to quantify the influence of the direct load transfer of concentrated loads close to line supports.Publicationtype: Conference Paper61 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Versuche zur Querkrafttragfähigkeit von Stahlbetonplatten unter auflagernahen Einzellasten : Versuchsbericht(2017-11-06); Test report on a series of tests on the shear capacity and load transfer of reinforced concrete slabs without shear reinforcement under concentrated block loads.Publicationtype: Technical Report662 503