No abstract

Safety in the sustainable construction is a game with uncertain reality, with human’s life. Managers in power, involved in the construction project life cycle, create rules for the game and are the main players. The project’s success can be perceived differently by stakeholders. A company’s competitiveness, successful implementation of the projects and effective safety management depends on the strategic allocation of its human resources in order to select a proper project team in alignment with employee capabilities. This requires detailed factors reflecting their role (in line with their interests and attitudes) and knowing which of them has a decisive influence on the successful implementation of the project. The real data describing key factors in this concept can be provided as uncertain conditions. This work presents a novel integrated modified fuzzy group decision-making approach to select and rank the most influential persons ensuring the sustainable prevention of accidents at work in the small and medium-sized construction enterprises. This model includes the Delphi method and fuzzy extensions of Eckenrode’s criteria rating method. The proposed model could be expanded in order to select the most suitable individuals for sustainable management of safety and, moreover, for the effective implementation of safety and health measures.

There has been a tendency to design ever slender building construction using high strength concrete in recent years. Application of HSC is also growing in tunnel construction. One of the most important challenges is to control explosive spalling of concrete and the method recommended by Eurocode 2 (EN 1992-1-2:2008/NA:2010P) is addition of polypropylene fibres to the mix. The purpose of the research described in this paper was to evaluate the changes of mechanical properties of HSC exposed to the effect of high temperature.The tests were carried out on three types of high strength concrete: air-entrained concrete, polypropylene fibre-reinforced concrete and reference concrete having constant water/cement ratio. The properties of hardened concrete including compressive strength, tensile splitting strength, flexural strength and E-modulus were studied. The latter tests were carried out on both on concrete cured at 20 °C and concrete subjected to high-temperature conditions at 300 °C, 450 °C and 600 °C. The results enabled us to evaluate the effect of high-temperature conditions on the properties of high-performance concrete and compare the effectiveness of the two methods designed to improve the high-temperature performance of the concrete: addition of polypropylene fibres and entrainment of air.Keywords: high strength concrete, mechanical properties of HSC, high temperature, effect of high temperature.

The emission of toxic gaseous combustion products from timber constructions influences on the time required for evacuation of people from a building during a fire. In order to prolong the time interval until inflammation of timber constructions, fire retardant solutions are used. It is relevant and very important to determine how the emission of toxic gaseous combustion products from pine timber non-treated and treated with fire retardant solutions used in Lithuania differs during thermal destruction. Measuring carbon monoxide (CO) emissions, the paper focuses on toxicity analysis determined by nonstandard and standard research methods of smouldering and flaming pine timber, both non-treated and treated with fire retardant solutions. The description comprises specimens used in research and their preparation, nonstandard and standard research equipment and methods determining toxicity of smouldering and flaming pine timber, both non-treated and treated with fire retardant solutions. The article presents the analysis of experimental results processed by statistical methods.

The article presents a computer model of the fire extinguishing process using mist nozzles. A previously developed hybrid fire model was used for this purpose. Assumptions and relationships were given to represent a math­ematical model of extinguishing process, which comprises a unique approach to the determination of sprinkling area in an elementary cell of field fire model. A description of simulation tests of the model was given for several different input data, differing by mean diameters of droplets. This enabled a study of their effects on such output parameters as received heat flux, temperature and rate of its growth. For one selected computational cell located on the axis of the nozzle at floor level having the coordinates [10, 10, 1], the obtained results were presented in the form of heat flux and temperature. To simplify the analysis, characteristic parameters of particular curves were listed in the table. Conclusions formulated on the basis of results obtained during tests were specified at the end of work. They confirmed the expected regularity assuming that the extinguishing process was more effective in the case of droplets of a smaller diameter and greater sprinkling intensity. This allows assessing the degree, to which these stream parameters affect the extinguishing effectiveness.