Numerische Untersuchungen von Kernaussteifungen zur Validierung physikalischer Modellversuche

Abstract

The shear centre of an cross-section is an essential value for the right calculation of a beam. Such a beam is used for modelling for stiening high-rise buildings with the theoretical background from Beck and Schafer [7]. The beam has many openings and it is impossible to say precisely where the shear centre is. Two theses have been produced at the Institute of Building Construction and Technology on this subject, dierentiated only by the settings of the bearing support. Mr. DI. Zierhofer's [28] thesis studied the classical high-rise core, a cantilever beam, while Mr. Purhringer's [17] looked at a straddle-mounted single-span beam. In both cases, test specimens were prepared from hard PVC and physical tests were performed. The investigations were to be con rmed by a follow-up calculation using the RFEM FEA program. However, in neither case did this lead to the desired result and it was concluded that further analysis with other programs was necessary. To this end, both theses were calculated with the SCIA Engineering and So stik programs and the results were compared. The curve for the shear centre is quantitatively similar in numerical as well as analytical (following Becker [3]) tests. In the case of test specimens with closed cross sections near to bearing, there is an increase in eccentricity with length of beam. For test specimens with open cross sections at the support, the picture is dierent. In test results as well as numerical calculations, the eccentricity diminishes with increasing depth and shows good correspondence at points. The amount of eccentricity is highly correlated with the stiness of the slat. The higher the aperture ratio HOpening / HSlat , the lower the stiness and the further the drill resting place moves towards the theoretical maximum position of the open cross section. With a closed cross section at the xing point, there is generally lower eccentricity as with an open one. Further studies on the straddle-mounted beam from the thesis [28] yielded the following picture: the graphs of the FE analyses and tests are qualitatively similar. In general, the eccentricity under the FE analyses is greater than for the tests and invariably approaches the theoretical value for the open cross section. In numerical results, large aperture ratios lead to decreases in eccentricity in the middle third of the beam.