02 Fakultät Bau- und Umweltingenieurwissenschaften
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/3
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Item Open Access Befestigungen mit Verbundankern. [Teil 1](1984) Eligehausen, Rolf; Mallée, Rainer; Rehm, GallusSeit 1975 wurden Verbundankersysteme verschiedener Firmen bauaufsichtlich zugelassen, wobei die Systeme hinsichtlich der Zusammensetzung des Mörtels praktisch identisch sind. Diese Zulassungsbescheide regelten die Verwendung von Einzelankern sowie Ankerpaaren mit Ankern in der aus Lastspannungen erzeugten Druckzone von Beton- und Stahlbetonbauteilen. Die Anwendungsbedingungen wurden u. a. aus den beschriebenen Versuchen abgeleitet und sind ausführlich erläutert. Weitere wichtige Informationen über das Tragverhalten von Verbundankern mit großen Rand- und Achsabständen unter Kurzzeit-, Dauer- und Ermüdungsbelastung sowie bei unterschiedlichen klimatischen Bedingungen (Trocken- oder Naßlagerung) und bei erhöhten Temperaturen sind zu entnehmen. Zwischenzeitlich wurden wesentliche neue Erkenntnisse über das Tragverhalten von Verbundankern bei engen Rand- und Achsabständen sowie von Verankerungen in Rissen gewonnen, die bei der Neufassung der Zulassung berücksichtigt wurden. Diese Neufassung enthält auch wesentliche Vereinfachungen für die Bemessung von Befestigungen mit Verbundankern. In diesem Beitrag wird das Tragverhalten von Verbundankern unter Kurzzeitbelastung beschrieben und es wird auf Langzeiteinflüsse eingegangen. Weiterhin werden die in den Neuzulassungen festgelegten Anwendungsbedingungen erläutert.Item Open Access Computer simulation of anchoring technique in reinforced concrete beams(1990) Cervenka, Vladimir; Pukl, Radomir; Eligehausen, RolfThe load transfer in reinforced concrete structures by means of anchoring elements is very common in modern concrete technology. Anchoring elements are often inserted in the bottom surface of a structure and the load is transfered by tensile action of the concrete. In case of shear failure, the anchores are located in the most exposed tensile zone of beams. The shear failure can be thus influenced by anchoring elements. This effect was analysed by means of the finite element program SBETA, which is based on the nonlinear-elastic constitutive model. The comparison with experiments for several loading configurations was made. In the second part a computer simulation of similar experiments was conducted.Item Open Access Computer simulation: splitting tests of concrete thick-walled rings(1992) Pukl, Radomir; Schlottke, Bernd; Ozbolt, Josko; Eligehausen, RolfTwo non-linear program systems are used for a computer simulation of splitting failure of thick-walled concrete rings under internal radial pressure. Results of the numerical analyses for plane stress models, axisymmetrical model and 3D model are compared with available experimental data and empirical formulas. It is shown, that the behavior observed in experiments can be simulated, using advanced material models, namely the non local microplane model and SBETA material model based on the crack hand theory. With increasing outer radius of the ring, a size effect can be observed.Item Open Access Quantitative evaluation of clogging phenomena in river beds(1982) Geldner, Peter; Kobus, HelmutClogging phenomena in rivers are of extremely complex nature, and a development of a clogging layer depends on a large variety of influences. In this paper a quantitative approach for the evaluation of a defined hydrodynamic clogging parameter is presented. This approach is based on the inverse use of type curves representing characteristics of the interaction between surface water bodies and the aquifer. The method is applied to field data of discharge measured in seepage ditches at levee protected sites. Since conventional approaches are limited to the assumption of quasi-steady-state flow, a stochastic method for the evaluation of time-variable hydrographs is also outlined.Item Open Access Bewehrungsrichtlinien und bauliche Durchbildung (EC 2, Abschnitt 5)(1992) Eligehausen, Rolf; Litzner, Hans UlrichDie Bewehrungsrichtlinien für Betonstahl (EC 2, Abschnitt 5.2) entsprechen zum großen Teil den Regelungen von DIN 1045. Auch die Form der zu führenden Nachweise unterscheidet sich nicht. Ein wesentlicher Unterschied besteht jedoch darin, daß im Gegensatz zum deutschen Regelwerk in EC 2 alle Nachweise im Grenzzustand der Tragfähigkeit zu führen sind. Daher können infolge des abweichenden Sicherheitskonzepts trotz gleicher physikalischer Grundlagen Unterschiede in den Bemessungsergebnissen auftreten.Item Open Access Fracture size effect: review of evidence for concrete structures(1994) Bazant, Zdenek P.; Ozbolt, Josko; Eligehausen, RolfThe paper reviews experimental evidence on the size effect caused by energy release due to fracture growth during brittle failures of concrete structures. The experimental evidence has by now become quite extensive. The size effect is verified for diagonal shear failure and torsional failure of longitudinally reinforced beams without stirrups, punching shear failure of slabs, pull-out failures of deformed bars and of headed anchors, failure of short and slender tied columns, double-punch compression failure and for part of the range also the splitting failure of concrete cylinders in the Brazilian test. Although much of this experimental evidence has been obtained with smaller laboratory specimens and concrete of reduced aggregate size, some significant evidence now also exists for normal-size structures made with normal-size aggregate. There is also extensive and multifaceted theoretical support. A nonlocal finite element code based on the microplane model is shown to be capable of correctly simulating the existing experimental data on the size effect. More experimental data for large structures with normal-size aggregate are needed to strengthen the existing verification and improve the calibration of the theory.Item Open Access Post-processing tools for nonlinear fe analysis of concrete structures(1990) Cervenka, Vladimir; Pukl, Radomir; Eligehausen, RolfFinite clement analysis of the cracking process in concrete structures brings new requirements for the post-processing environment. Crack direction and location are important for identification of the failure mode. The problem have been solved in the finite element program SBETA which was developed by the authors for simulation of the failure processes in reinforced concrete structures. The post-processing system creates the graphical images of crack patterns. Graphical sequences for simulation can be generated.Item Open Access Relating hydraulics and ecological processes(1991) Hjorth, Peder; Kobus, Helmut; Nachtnebel, Hans Peter; Nottage, Albert; Robarts, RichardAny major modification of the hydraulic system results with some retardation in a response of the ecosystem trying to adapt to the new conditions. It is difficult to imagine situations where hydraulics and ecosystems are not related. Thus, harmonizing hydraulics with ecology means to identify alternative hydraulic measures which yield simultaneously economic benefits and improvement, preservation or at least a best fit of the environmental situation. Often, these objectives are subjected to an inherent conflict and therefore harmonizing is dependent on the preference structure of the modern society, which is inclined to sustainable development. The objective of this chapter is to develop a framework (methodology) which might assist in relating hydraulics and ecology with respect to specific goals under site and problem dependent constraints.Item Open Access Behavior of deformed bars anchored at interior joints under seismic excitations(1983) Eligehausen, Rolf; Popov, Egor P.; Bertero, Vitelmo V.A mathematical model of a deformed bar anchored at interior joints of ductile moment resisting reinforced concrete frames subjected to severe earthquakes is presented. It includes the formulation of an accurate model for the local bond stress-slip relationship, use of a simple model for the stress-strain relationship of the reinforcing steel and the numerical solution of the differential equation of bond. The analytically predicted response of anchored beam bars compares well with tbe results of a series of tests for monotonic and cyclic loading. The influence of major parameters of the behavior of anchored bars is shown by an extensive numerical study. The results of this investigation are used to offer practical recommendations for the anchorage of beam bars at interior joints.Item Open Access The sub-systems. 4 : Groundwater(1991) Herrmann, Reimer; Hubert, P.; Kobus, HelmutGroundwater constitutes the most important freshwater resource of the earth, it is two orders of magnitude larger than the total water volumes of rivers and lakes. It is a renewable resource, characterized by stability of its chemical composition and stability of temperature. Percolation of water through the subsurface has a good purification effect due to the combined action of filtration, sorption, chemical reactions and microbiological processes. Groundwater is utmost important as drinking water resource, since it is less prone to pollution than surface waters due to the protection effects of the covering layers. However, industrial and agricultural activities have led to groundwater pollution problems which are sometimes irreversible and in any case very difficult and expensive to recover. This endangers the long-term use for drinking water supply, and any efforts for sustainable development have to consider the vulnerability of groundwater resources to pollution, which shows great regional diversity, by suitable groundwater protection efforts.