Experiment - spolehlivý zdroj informací pro odvození metod návrhu tenkostěnných ocelových nosníků namáhaných na únavu

The limit state of thin-walled steel girders subjected to many times repeated loading is to a great extent affected by the cumulative damage process occuring in the girder webs \"breathing\" under repeated loads.Based on experimental results various approaches to the definition of the fatigue limit state of the above girders are discussed, a number of potential design procedures suggested by other researches validated and set of S-N curves, established so as to serve as a reliable tool for the fatigue analysis of thin-walled girders with \"breathing\" webs presente

Český příspěvek k řešení mezních stavů tenkostěnných konstrukčních systémů

Thin-walled construction as a powerful way to saving steel and the stability limitations involved are discussed. It is shown that this promising trend can be materialised just thanks to the beneficial effect of so-called post-buckled behaviour. As a great part of steel structures are subjected to repeated loading (bridges, crane-supporting girders and the like) it is demonstrated by the results of numerous experiments how the post-buckled reserve of strength is affected by the cumulative damage process generated by the many times repeated character of the loading

The fatigue and serviceability limit states of the webs of steel girders subjected to repeated loading

As a great part of steel structures are subjected to many times repeated loads (bridges, crane-supporting girders and the like), it is demonstrated, by means of the results of numerous experiments carried out by the authors in Prague, how the post-critical reserve of strength, the failure mechanism and the limit states of the webs of steel girders are affected by the cumulative damage process generated by the many times repeated character of loading, and how this phenomenon influences the design of such girders

The "miracle" of post-buckled behaviour in thin-walled steel construction and some limitations to its full exploitation

Thin-walled steel structures, i.e. structural systems made of thin (usually plate) elements, represent a powerful tool for increasing the competitiveness of steel construction. Then, on the other side, it is in the nature of things that the limit state of the systém is in the danger of being substantially reduced by stability phenomena. Fortunately, the situation is remedied by the beneficial effect of post-buckled (post-critical) behaviour, which is in detail described and "mapped" in the contribution. However, attention is also turned to some limitations which in some cases hinder a full exploitation of the phenomenon, one of them, viz. the unavoidable reduction of the post-buckled reserve of strength due to breathing-induced fatigue, being described in detail in the pape

Jednoduchá metoda navrhování stěn ocelových mostních nosníků s nízkými výrobními náklady - jeden z nových výsledků pražského výzkumu dýchání stěn

The main impact of the latest stage of the Prague research on web breathing is the derivation of simple user-friendly formulae such as to make it possible completely to disregard the parasitic effect of the cumulative damage process generated by web breathing. Thereby the way is paved to the application of simple economic-fabrication structural systems in bridge construction, consisting for example of singly-symmetric steel beams made composite with a concrete slab. Such systems substantially reduce the amount of labour needed, and hence the fabrication costs, and that is why they may in numerous cases prove to be advantageous and preferable for small and medium-span bridge structures