Universität Stuttgart
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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 Size effect of the concrete cone failure load of anchor bolts(1992) Eligehausen, Rolf; Bouska, Petr; Cervenka, Vladimir; Pukl, RadomirThe concrete cone capacity of headed anchor bolts subjected to axial tension load was experimentally investigated using 35 concrete specimens of three different sizes. The dimensions of the test specimens were varied in proportion to the embedment depth h (h = 50, 150 and 450 mm). Material properties were measured on accompanying specimens. The measured failure loads are compared with other experimental and numerical investigations. According to the present results the failure loads increase in proportion to h 16, that means close to the prediction by linear fracture mechanics.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 Analytical model for deformed bar bond under generalized excitations(1981) Ciampi, Vincenzo; Eligehausen, Rolf; Bertero, Vitelmo V.; Popov, Egor P.Ein mathematisches Modell zur Berechnung des Verhaltens eines Rippenstabes, verankert in eng verbügeltem Beton und beansprucht durch beliebige zyklische Belastungen hoher Intensität wird erläutert. Es umfasst die Formulierung eines vereinfachten Modells für die Beziehung zwischen örtlicher Verbundspannung und örtlichem Schlupf, das aus umfangreichen, in Berkeley durchgeführten Versuchen abgeleitet wurde; die Benutzung eines einfachen, jedoch ausreichend genauen Modells für das Spannungs-Dehnungs Gesetz des Bewehrungsstahles und die numerische Lösung der Differentialgleichung des Verbundes. Ein Beispiel ist dargestellt und erläutert.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 Creep and fatigue analysis of reinforced concrete structures(1992) Eligehausen, Rolf; Kazic, Mihajlo; Sippel, Thomas M.A computional procedure for the creep and fatigue analysis of reinforced concrete structures exposed to flexure is presented. The fatigue loading effects are modified into an equivalent creep analysis. The analysis is based on the finite element method employing beam elements. The material behavior of steel, concrete and bond between reinforcement and concrete are described as realisticly as possible. For the reinforcing steel the stress-strain behavior as measured in tests or given in codes is assumed. For the stress-strain behavior of concrete in compression under static loading, the proposal by Park/Pauley is taken. The influence of sustained or fatigue loading is taken into account by using the isochrone σ-ε-relationship valid for t > t o or N > 1 respectively; whereby the creep coefficients for both type of loadings are taken from MC90. For sustained and fatigue loading the isochrone bond stressslip relationship is used. The creep coefficients are taken from MC90. The accuracy of the proposed model is checked by comparing the behavior of some test beams under sustained and fatigue loading with the predictions.Item Open Access Computer models of concrete structures(1991) Cervenka, Vladimir; Eligehausen, Rolf; Pukl, RadomirThe application of the nonlinear finite element analysis of concrete structures as a design tool is discussed. A computer program for structures in plane stress state is described and examples of its application in the research of fastening technique and in engineering practice are shown.Item Open Access Hysteretic behavior of reinforcing deformed hooked bars in R/C joints(1982) Eligehausen, Rolf; Bertero, Vitelmo V.; Popov, Egor P.The force-slip relationships of deformed hooked bars embedded in well confined concrete and subjected to monotonic and cyclic loadings were experimentally studied. The results were used to deduce an analytical model for the hook behavior under generalized excitations. The model is similar to the one for the local bond stress-slip relationship of deformed bars, but with some modifications to account for the different behavior of hooks. The main results of this study are reported.Item Open Access Local bond stress-slip relationships of deformed bars under generalized excitations(1982) Eligehausen, Rolf; Popov, Egor P.; Bertero, Vitelmo V.The local bond stress-slip relationships of deformed bars embedded in confined concrete under monotonic and cyclic loading for various bond conditions were investigated in an extensive experimental study. The results were used to deduce an analytical model of the bond behavior under random excitations. By evaluating experimental results of long anchorages, the model was extended to cover the bond conditions found in joints of R/C frames under severe seismic excitations. The model was successfully used to predict the behavior of deformed bars anchored at interior joints and subjected to various loading histories.