Bearing capacity of masonry
Table of contents
Project data
| Titel | Title Untersuchungen zur Reduzierung der Tragfähigkeit von Mauerwerk bei Schwächung des Querschnittes infolge von Aussparungen und Schlitzen | Investigations into reduction of the bearing capacity of masonry in cases of profile weakening due to recesses and slits Auftraggeber | Client Deutsches Institut für Bautechnik (DIBt) Auftragnehmer | Contractor TU Dresden, Fakultät Architektur, Lehrstuhl für Tragwerksplanung Zeitraum | Period 07.2011 – 12.2011 Leiter | Project Manager Prof. Dr.-Ing. Wolfram Jäger Bearbeiter | Contributors Dipl.-Ing. Stephan Reichel |
Report in the yearbook 2011
Tests on slotted masonry
Tests on slotted masonry test specimens
On behalf of the German Institute for Building Technology (DIBt), the Chair of Structural Design headed by Prof. Dr.-Ing. Wolfram Jäger is researching the influence of cross-sectional weakening due to recesses and slots on the load-bearing capacity of masonry.
In order to investigate the effects of horizontal slots near the support on the load-bearing behavior, several tests were carried out on slotted masonry test specimens in the Otto Mohr Laboratory during the course of the project and the results were compared with corresponding reference tests on unslotted test specimens. The behavior of vertically perforated masonry units is of particular importance, since here the outer webs of the masonry units are disproportionately involved in the vertical load transfer. For this reason, vertically perforated bricks were used for the tests.
The slenderness influence was not to be considered in the experiments. Therefore, the tests were initially carried out on small masonry units. Despite the horizontal slot and the associated cross-sectional weakening of 8%, the fracture strength determined experimentally was in some cases quite significantly higher than the previously determined theoretical values.
Since this simple test setup merely reflects a model which, by definition, can only capture the real conditions in a simplified way, two tactile tests were carried out on a section of the wall-slab node in the DB 6000 of the OML to validate the test results. The complex test specimen represented the masonry below and above the ceiling junction as well as a section of the ceiling slab. Of particular interest now were the twisting of the floor slab and the resulting off-center loading of the wall head, as well as the load redistributions in the system. The twisting of the floor slab in the support area resulting from the deflection in the structure was simulated in the test by hydraulically lowering the slab stub. For this purpose, an additional load was applied to the slab stub via a load harness with two presses in order to simulate the force introduced into the node via the slab. Both test specimens were loaded to failure. The loading regime initially provided for a successive increase in the imposed load on the wall and the slab. From a surcharge load of 300 kN, only the load introduced into the test specimen by the compression testing machine was increased. The tests were carried out without any problems. The results are now being incorporated into the evaluation.