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With the increase in terrorist attacks in recent years, the effects of explosions on building become highly topical. In this regard, the paper deals with the analysis of blast loaded steel structures. When a blast loaded structure is analysed, as known, two major design issues and scientific challenges have to be approached and solved. The first issue derives from the analysis and description of the input dynamic load (time-pressure wave), being dependent on the type of explosion and explosive, while the second issue is related to the analysis of the actual dynamic response of the structure under impact. As such, real field blast tests using the so called ANFO explosives are first presented. The examined constructional system consists of steel rolled beams with two different type of cross sections (HEB100 and IPE120). The actual experimental observations are then assessed and compared with both SDOF and FE models carried out in ABAQUS. In doing so, the actual shape (i.e. decaying path for the pressure load) of the experimental blast wave is used, together with two further approximations for its description. The comparative calculations are then proposed for selected control points, in terms of mechanical and kinematic quantities (i.e. displacements, accelerations and strains). A critical discussion of the so collected comparative results is hence proposed

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Blast events and scenarios, as known, represent extreme phenomena that may result in catastrophic consequences, both for humans and structures. Accordingly, for engineering applications, the reliable description of expected blast waves is a crucial step of the overall design process. Compared to ideal theoretical formulations, however, real explosive events can be strongly sensitive to a multitude of parameters and first of all to the basic features (size, type, shape, etc.) of the charge. In this regard, several advanced computer codes can be used in support of design and research developments. Besides, the input parameters and solving assumptions of refined numerical methods are often available and calibrated in the literature for specific configurations only. In this paper, with the support of the ANSYS Autodyn program, special care is dedicated to the numerical analysis of the blast wave propagation in the air due to several charges. Five different explosives are taken into account in this study, including RDX, DAP-2, DAP-E, Polonit-V, and homemade ANFO. The effects of different mixtures are thus emphasized in terms of the predicted blast wave, as a function of a given control point, direction, explosive mass, and composition. As shown, relatively scattered peak pressure estimates are collected for a given explosive. Comparative results are hence proposed towards selected experimental data of the literature, as well as based on simple analytical predictions. The collected overpressure peak values are thus discussed for the selected explosive charges.

Abstract. Problems of fatigue life prediction of materials and structures are discussed in the paper. Service loading is assumed as a continuous loading process with possible discontinuous events, which are caused by various operating conditions. The damage in a material is due to a cumulative degradation process. The damaging process is then represented either by rain-flow matrices or by a fatigue damage function which is derived using some hypothesis of a fatigue failure criterion. Presented theoretical procedure enables a very effective estimation of a service life and/or reliable evaluation of residual life of any structures under various types of loading and environmental conditions. This approach creates a good basis for powerful expert systems in structural and mechanical engineering. The aim of the paper is to present briefly some results of analysis of load-bearing steel structure loads of special railway crane PKP 25/20i which was utilized in some specific ad relatively hard operating conditions. Virtual models of the structure were being used in an analysis of acting working dynamics loads influence to be able to forecast fatigue life of load-bearing of the crane jib.