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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 Rotation capacity of prestressed concrete members(1992) Eligehausen, Rolf; Li, LongfeiA numerical investigation on the behaviour of plastic hinges in prestressed concrete structures is presented. The object of the study is to determine the rotation capacity of prestressed concrete members which is needed to predict the amount of moment redistribution in hyperstatic prestressed concrete structures. A numerical model has been developed for the analysis of plastic hinges in prestressed concrete structures. It is based on a simply supported beam which simulates the region between two points of zero moment in a continuous beam. A discrete crack model has been applied in the numerical analysis. Realistic constitutive laws of steel, concrete and bond of reinforcing and prestressing steel have been assumed, respectively. The developed model enables an accurate analysis of the load deformation response of a statically determinate prestressed concrete beam with bonded or unbonded tendons under monotonic loading throughout all behaviour states up to failure . The parameters influencing the rotation capacity of prestressed concrete beams were studied by means of the numerical model.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 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 Simulation of cycling bond-slip behavior(1992) Ozbolt, Josko; Eligehausen, RolfIn the present paper results of a numerical analysis for a deformed steel bar embedded in a concrete cylinder and pulled out by monotonic and cyclic loading are shown and discussed. The analysis is performed by the use of axisymmetric finite elements and an improved 3D general microplane model for concrete, instead of the classical interface element approach, a more general approach with spatial discretization modeling the ribs of a deformed steel bar is employed. The pull-out failure mechanism is analyzed. Comparison between numerical results and test results indicate good agreement. The present approach is able to correctly predict the monotonic as well as cyclic behavior including friction and degradation of pull-out resistance due to the previous damage.Item Open Access Nonlinear analysis of strain-softening damage under monotonic and cyclic loading(1992) Bazant, Zdenek P.; Ozbolt, Josko; Eligehausen, RolfThe paper reviews the modeling of damage by the microplane model and presents extensions required for cyclic loading. The general microplane constitutive model is implemented in a three-dimensional finite element code and used in damage and bifurcation analysis of various structures. The results of the analysis are compared with test results and some of the comparisons are shown in the present paper.Item Open Access Size effect in concrete structures(1992) Eligehausen, Rolf; Ozbolt, JoskoThe size effect for notched-tension specimens, three-point bend specimens, pull-out headed anchor specimens and beams loaded in torsion are calculated using a 2D and 3D finite element program. The program is based on the nonlocal microplane model. The calculated failure loads are compared with previously obtained experimental results. Test results and calculated data are compared with the recently proposed size effect law. Results of tests and analysis exhibit significant size effect that should be taken into account in design practice. It is demonstrated that the nonlocal microplane model used in a 2D and 3D finite element code can correctly predict failure loads for similar specimens of different sizes.Item Open Access Influence of crack width on the concrete cone failure load(1992) Ozbolt, Josko; Eligehausen, RolfIn the present paper the influence of the crack width on the concrete cone failure load of headed anchors embedded in concrete is analyzed. The analysis is carried out on a reinforced concrete thick plate specimen using three-dimensional finite elements and the non local microplane model. In order to introduce precracking into the specimen before loading the headed anchor, the specimen is loaded in longitudinal direction by applying tension forces through reinforcement. At different crack levels pull-out of the fastening element is performed. Results of the analysis show that the concrete cone failure load is decreasing with increasing crack width up to ω ~ 0.15 mm to approximately 70 % of the failure load obtained for non-cracked concrete. Further increase of the crack width does not cause further decrease of the failure load. Comparison between numerical and experimental results indicates good agreement.Item Open Access Analysis of headed anchors embedded in concrete using a nonlinear fracture model(1992) Sawade, Gottfried; Eligehausen, RolfThis paper represents an energetical model of the fracture behaviour of concrete where crack opening is considered as time dependent dissipative process. States of mechanical equilibrium can be obtained by simulation of a relaxation process. Applicatlon of this model to calculations of the bearing capacity of anchorages confirms recent approachs based on linear fracture mechanics.Item Open Access Cracking behaviour under non-monotonic loading : literature review(1992) Balász, György L.; Eligehausen, RolfRepeated and long term loads may produce a significant increase of crack widths owing to the increase of concrete deformations resulting in an increase of steel stress in the crack and the increase of slip along the reinforcing bar which causes a decrease of tension stiffening.Crack widths predicted on the basis of short term static tests do not provide a satisfactory guide to crack widths in service. The present study reviews the available data concerning the influence of cyclic and long term loading on the cracking behaviour and discusses the basic influencing parameters together with the proposed methods of predictions. Only a small part of the approaches on carck control are developed to consider the influence of repeated or sustained loads as well. A comprehensive study is required to develop an appropriate prediction based on all significant influences.