Stress tests on slabs made of steel and stone

Hoyerswerda, a multi-storey building dating from 1910 is currently being refurbished. Due to the existing large span width of the steel block ceilings and the problems regarding the mathematical verification of such ceilings with spans larger than 2 m as well as the intended live load, the structural safety and serviceability of selected ceiling areas were to be verified by experimental loading and the possibility of transferring these results to untested ceiling areas of the same type was to be investigated. The slabs are a type of Kleines slab with perforated bricks and flat iron in the joints. The slabs rest on masonry walls or the bottom flanges of steel I-beams. Due to the existing slab support widths of up to 3 m, it had to be expected that the desired load safety would not be achieved as a result of the load tests.

The area load of up to 7.50 kN/m² (dead load plus live load) to be verified was realized by equivalent loads by distributing the load over a total of 24 load application points (approx. 30 cm × 60 cm). In each case, four individual loads were combined via a beam system and the force was controlled by a hydraulic cylinder coupled to an electrical load cell. The load-induced deflections were measured using inductive displacement transducers (IWA).

The results of the tests showed that, at the time of testing, there was sufficient load safety and serviceability with regard to the intended use for the loaded ceiling areas spanning up to 3 m, and in some places even further load increases would have been possible. The deflections determined in the test were in some cases significantly below the expected values, which means that there is also sufficient load-bearing safety and serviceability for the adjacent, less wide-span ceiling sections. Thus, the results can be transferred to similar slab areas that were not tested.