On Problems of Mechanical Properties of Structural Steel in Load-Carrying Structure of Historical Building Construction

摘要

The paper is focused on the problems of the mechanical properties of steel used for load-carrying structures of civil engineering constructions, especially from the viewpoint of properties of old steels used in historical constructions in comparison with current steels. Chemical composition and physical-mechanical properties of historical steels can be important, for example, in the case of reconstructions, when for the static assessment and evaluation of existing constructions subjected to new (higher) loading actions, material properties of load-carrying structure must be known. In the case of constructions aged about 100 years, usually no project documentation and no information about used material and its properties exist. Then, the properties must be determined using material tests carried-out on the test specimens taken from the real existing structure. But here the sampling of test specimens is limited by the possibilities of existing structural system and by the dimension of particular members from which the specimens are taken, so that the test specimen dimensions and number are limited. Thus, the evaluation of material properties for obtaining representative design values can be more difficult and less reliable than in the case of the large test number. But the main problem is to determine the usable design values of material properties (design yield and ultimate strength) to utilize them for the reliable static re-design of existing structure under actual loading actions. Some problems indicated above have been shown on the example of the material analysis of steel load-carrying structure of slaughterhouse aged more than 100 years. This analysis has been performed recently within the framework of the construction exploration in connection with the intended revitalization of historical "industrial zone" in the city of Brno, Czech Republic.