Styčníky ocelových konstrukcí - doporučení pro numerické modelování a stanovení únosnosti vybraných typů styčníků

Abstract

Ph.D. thesis deals with design and assessment of steel truss structure joints. The current design procedures, given in ČSN EN 1993-1-8, are complicated and have only a limited scope of use. In practice, however, joints that do not fall under the conditions specified by Eurocode and therefore cannot be clearly assessed on the basis of the standardized formulas for calculation load bearing capacity of joints often occur. That is why need arises to verify the behavior of such joints, which results in the constant development not only in the field of designing of steel structures. Two main problems in design of steel truss structure joints were solved in this thesis. Typical types of joints, namely welded hollow section joints and the end plate bolt connections, were selected. In each part of the thesis current analytical methods which can be used for design of selected joints were summarized. The main task of the work was numerical modeling of joints under consideration, focusing on possibilities of using numerical models for the advanced assessment of these joints. Besides, the new design procedures for welded joints were verified in the thesis. These procedures, which are recommended in the foreign publication, are not implemented in the codes and also are not widespread into practice. The possibility of using MPC algorithm in the numerical modeling for connecting various types of finite elements and for boundary conditions input was verified. The use of deformation limits for evaluation of numerical models results was checked. Some experiments of selected types of end plate bolted joints have been performed (CHS joints, or L profiles joints respectively). These tests were primarily carried out to verify numerical models and also available analytical methods (for CHS joints). The direct numerical model outputs were modified. This modification was made with respect to real laboratory conditions taking into account the effect of the trial press machine slip stiffness and the initial slip. The main aim of the Ph.D. thesis is summarization of current analytical methods and other design possibilities of the steel truss structure joints, verification of little known design methods, proposal of possible modifications of current formulas for determination of joints load bearing capacity and recommendations for creation and evaluation of numerical models of steel joints. A primary (concrete) founding is summarized at the end of each section. Final (overall) proposals and recommendations are presented in the conclusions of the thesis.