Universität Stuttgart
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Item Open Access Rationale of detailing provisions in MC 78 and identification of missing items(1986) Eligehausen, RolfThe quality of a structure depends significantly on the quality of the detailing of the reinforcement. If failures occur, they are often caused by poor detailing, but rarely by incorrect structural analysis. Therefore the MC 78 pays close attention to this subject. The corresponding provisions are given in Section 17 and 18 of the Model Code.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 The rotation capacity of plastic hinges in reinforced concrete beams and slabs(1986) Eligehausen, Rolf; Langer, PeterA mathematical model for calculating the rotation capacity of plastic hinges in reinforced concrete beams and slabs is presented. The model is based on the integration of the section curvature along the beam, taking into account the contribution of concrete between cracks (tension stiffening) and the shifting of the tensile force by shear cracks. The material behavior of reinforcing bars, concrete and bond is described as realistically as possible. The analytically predicted rotation capacities of about 70 beams compare favourably with the experimental results. The parameter studies demonstrate that the plastic rotation capacity of hinges given by the CEB-FIP Model Code is unconservative for cold worked deformed reinforcing bars with a low ratio tensile strength to yield stress and a low value of the uniform elongation.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 Studies to minimize the effects of bond slippage in exterior joints of R/C ductile moment resisting frames(1984) Eligehausen, Rolf; Russ, A.A mathematical model of a deformed bar anchored in a concrete block described in Ref. 1 has been extended to cover also hooked bars. The analytically predicted response of straight and hooked bars anchored at exterior joints compares well with available experimental results. An extensive numerical investigation has been carried out to show the influence of significant parameters on the anchored bar behavior. The results of this investigation are used to offer practical recommendations for the anchorage of bars at exterior joints.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 Rotation capacity of plastic hinges and allowable degree of moment redistribution(1987) Eligehausen, Rolf; Langer, PeterAccording to experimental and analytical studies, the shape of the stress-strain curve in the inelastic range has a significant influence on the rotation capacity of plastic hinges. The ductility of modern cold-worked reinforcing steel may be rather small, resulting in low values for the plastic rotation capacity. Therefore it is proposed to classify reinforcing steel in two groups: Type 1: Steel with high ductility Type 2: Steel with reduced ductility In the region of splices by overlapping, mechanical devices or welding, the average steel strains are rather small (often below the yield strain). Therefore it is proposed that splicing of the reinforcement by any type of splice is not allowed in the region where the formation of plastic hinges is anticipated in the analysis. Because of its importance for the plastic rotation capacity and the possible degree of moment redistribution, it must be possible to distinguish the type of steel (type 1 or type 2) clearly and easily on site, e.g. by different rib patterns.Item Open Access The rotation capacity of plastic hinges in reinforced concrete beams and slabs(1987) Eligehausen, Rolf; Langer, PeterA mathematical model for calculating the rotation capacity of plastic hinges in reinforced concrete beams and slabs is presented. The model is based on the integration of the section curvature along the beam, taking into account the contribution of concrete between cracks (tension stiffening) and the shifting of the tensile force by shear cracks. The material behavior of reinforcing bars, concrete and bond is described as realistically as possible. The analytically predicted rotation capacities of about 70 beams compare favourably with the experimental results. The parameter studies demonstrate that the plastic rotation capacity of hinges given by the CEB-FIP Model Code is unconservative for cold worked yield stress and a low value of the uniform elongation.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.Item Open Access Behaviour of metallic anchors under generalized excitations(1989) Eligehausen, Rolf; Vintzéleou, ElizabethIn this paper are briefly presented the results of an experimental program which was carried out with the aim to investigate the behaviour of several types of metallic anchors (undercut, expansion and chemical anchors) under both monotonic and cyclic shear actions. Several parameters were investigated within the program, namely: the presence of cracks crossing the anchor, the distance of the anchor from the free edges of the concrete section, the presence of transverse reinforcement, the loading history, etc. The influence of these parameters on the mechanical characteristics of anchors is illustrated in this paper, while empirical formulae for the calculation of the maximum shear force vhich may be transferred by metallic anchors are given.