Kombinovaný spoj vysokých tenkostěnných ocelových vaznic

Abstract

Thin-walled cold-rolled cross-sections are increasingly used in construction, especially in the roofing of large-span halls used today, for example, for the creation of large logistics centers, civic amenities and other types of buildings and technological structures. Their use has advantages especially in saving materials, in reducing construction costs, and easier handling of individual structural elements due to lower weight. One of the few disadvantages of these elements may be the complicated design and assessment methodology. Certain disadvantages also include, due to the subtlety of thin-walled structures, their lower robustness, and thus lower resistance of structures to non-standard methods of stress and other emergency situations. In the currently recommended design procedures (Eurocode 3), the design procedures are not sufficiently affected, especially in the place of installation and joints of thin-walled structures. The load-bearing capacity of a structure made of thin-walled elements depends to a large extent on the load-bearing capacity of details at the place of mounting on the supporting structure and at the points of interconnection of individual thin-walled elements. Therefore, in the case of thin-walled structures, it is necessary to use additional structural elements, such as local reinforcement, stabilizing elements, supports and other structural measures, such as doubling the profiles or grading the material thickness of different parts of the structural elements. It is especially important to ensure that the designed joints do not introduce local instability into the structure and are sufficiently rigid and load-bearing. The presented dissertation is focused on the behavior of high thin-walled purlins (300 and 350 mm) at the point of connection to the supporting structure and the evaluation of whether the existing standard approach can be used to design this type of detail. The detail of the connection was examined in variants with and without a reinforcing clip. The details of the placement of thin-walled purlins were first investigated experimentally. The aim of the experiments was to determine the behavior and bearing capacity of the detail of the connection of roof purlins to the supporting structure. Another goal was to determine the effect of the additional reinforcement clip on the overall load-bearing capacity of the connection. For this reason, the individual load assemblies were tested both with and without a reinforced clip. As part of the experiments, material tests of the sheets of the tested purlins were also performed. The obtained laboratory results were compared with the outputs of numerical simulations of the performed experiments. All created models were performed as complex spatial models and included geometric, structural, and material nonlinearities. Non-linear contacts were set at the points of contact of the individual parts of the model, considering the friction between the surfaces. As the effort was made to create the most concise model of the tested assembly, it was necessary to create models of joints that will capture as much as possible the actual behavior of the joints in the structure. The obtained knowledge was also compared with the analytical procedure according to the standard. Then conclusions were drawn on the applicability of existing standard approaches for the studied purlin joints and the possibilities of numerical modeling as a complement to the experimental approach.