Steel frame wind bracing systems are usually made of hot rolled profiles connected to frame elements directly or through a gusset plate. The behaviour of angle bracing members is generally complex since controlled by tension or compression, bending and torsion. The common practice is to transform the problem of complex behaviour into the buckling strength of a truss member. This paper deals with an analytical formulation of the force-deformation characteristic of a single angle brace subjected to compression. A strut model takes into consideration the effect of brace end connections and softening effect of its force-deformation characteristic. Two different boundary conditions, typical for engineering practice, are dealt with. Experimental program of testing the behaviour of angle brace in portal sub-frame specimens is described. Results of experimental investigations are presented. They are used for the validation of developed model. Conclusions are formulated with reference to the application of validated brace model in the analysis of braced steel frameworks.
Four and a half years of African Swine Fever (ASF) in population of free-ranging wild boars and domestic pigs revealed a number of novel insights into the disease epidemiology. Until November 20th, 2018, in total 3048 cases in wild boars and 213 outbreaks in domestic pigs have been confirmed. In spite of low contagiosity as well as low rate of ASF spread in wild boars the disease has an enormous socio-economical impact on the production of pigs in Poland. One of the most important aspects which directly influences the dynamics of ASF spread is the unpredictable hu- man activity. Another important factor responsible for continuous ASF spread is fast recovery of wild boar population in spite of efforts taken by hunters. Assuming our scientific opinion ASF seems to be present in wildlife for the incoming few or several years. Therefore, extraordinary measures should be prepared and undertaken to limit the risk of the occurrence of future out- breaks in domestic pigs. One of the most crucial issues is implementation of strict biosecurity measures in all domestic pigs holdings.