Analysis of the causes of defects due to quality roofing membranes mechanical anchoring
Anchoring of the layers of flat warm roofs using anchoring elements is nowadays one of the most used technology. This is a frequent technology to repair damaged roofs (total reconstruction, increasing the load on the wind loads, partial repairs etc.). In the European building market there are several suppliers of the enchoring equipment who declare their product’s properties in the european technical approvements (ETA). The goal of the article is to demonstrate results of the carried out measurements and their possible impact into practical application of the mechanically anchored systems. This allows reduce the amount of defects to improving flexible watertight membranes. The topic can be considered actual and due to the large number of defects precisely for these types of roofs.
Eurocode 3: Design of steel structures
Structural engineers should be encouraged that at least in steel, design conforming to Eurocode 3 (BS EN 1993-1-1) is not signifi cantly different to BS 5950. In fact, if the changes in presentation are stripped away, in most areas design is almost identical to both standards. This is of course to be expected, as the steel itself knows no difference, and the UK has enjoyed the benefi ts of mature design standards for decades – it would be very surprising if there were dramatic changes from previous UK practice. There are wellknown changes:
1 – Material properties
The most important criteria in selecting a material are related to the function of the part qualities such as strength, density, stiffness and corrosion resistance. For sheet material, the ability to be shaped in a given process, often called its formability, should also be considered. To assess formability, one must be able to describe the behavior of the sheet in a precise way and express properties in a mathematical form; one also needs to know the properties that can be derived from mechanical tests. As far as possible, each property should be expressed in a fundamental form that is independent of the test that is used to measure it. The information can then be used in a more general way in the models of various metal-forming processes. It is seen that the properties that affect material performance are not limited to those that can be measured in the tensile test or characterized by a single value. Measurement of homogeneity and defects may require information on population, orientation, and spatial distribution. Many industrial forming operations run very close to a critical limit so that small changes in material behavior give large changes in failure rates. When one sample of material will run in a press and another will not, it is frequently observed that the materials cannot be distinguished in terms of tensile test properties. This may mean that one or two tensile tests are insufficient to characterize the sheet, or that the properties governing the performance are only indicated by some other test.