Revitalization of buildings and structures using single-layer mesh metal domes and the peculiarity of their work
Abstract
During the revitalization, a set of works is carried out, providing for the preservation of the architectural appearance of buildings with the creation of internal filling and interiors and engineering and technological equipment in accordance with modern standards and requirements. In world practice, there are many unique examples that clearly demonstrate the specifics of these works with the use of metal domes. The effectiveness of dome coverings is known, but there are still unresolved issues that are partially considered in this work.
Examples of revitalization of buildings and structures using metal domes of coatings include: - a glass cone over a shot tower in Melbourne; - a glass dome with a mirrored cone and ramps in the revived Reichstag in Berlin; - glass domes over the gas meters in Vienna; - The glass dome of the Takamatsu Marugamecho shopping area in Japan; - the dome over the bullring in Khetiv.
Most often, shallow metal mesh domes are used in construction practice. Such structures make it possible to form a smaller building volume, but their work becomes much more complicated under the action of a load. And to date, the problems of calculating the stability of such domes have not been sufficiently resolved. The main reason is the discrepancy between the experimental data and the performed calculations. The actual shape and position of the mesh dome nodes, as well as its real stress-strain state during operation differs from the state developed by the project. The accumulated deviations of the dome geometry during its installation, manufacturing defects and damage received during operation significantly change the ideal design scheme used in the calculations and increase the probability of buckling.
The impossibility of erecting such structures with ideal geometric parameters due to errors arising from objective reasons is noted. These errors lead to the complication of the connection of the mounting structural elements of the domes in the nodes.
It is shown how large the differences in assessing the safety of a structure can arise if the standard deviation of a random variable responsible for the imperfection of the arrangement of nodes is incorrectly estimated.
Reliable unloading analysis is vital to ensure that the large span structure is reliably loaded into its design position. Potential failure caused by manufacturing defects and local effects such as defective welding and bolting can be detected and prevented in advance.
Research on the progressive destruction of spatial structures is not enough. The main reason for this: it is intuitively believed that spatial structures have a large number of duplicate elements and the ability to redistribute efforts. However, it has been demonstrated that failure of some critical elements can lead to progressive destruction of spatial structures.
To obtain the relationship between the critical load of buckling and the amplitude of the initial imperfections, the known results of experimental studies were used, where the accuracy was high in measuring imperfections and in carrying out loading of spherical shells. The obtained dependence allows introducing corrections for the value of the critical load of buckling of mesh domes, where the following is used as the initial data: - reduced dome thickness; - the largest amplitude of the measured initial imperfections of the shape after the erection of the structure at the construction site.
