The Analysis of Bearing Capacity of Axially Compressed Cold Formed Steel Members

This paper presents a calculation method for axially compressed cold formed stainless, high strength and carbon steel profiles. Results of different authors in this field published in international journals depict current trends in this field. Paper also presents author’s numerical and experimental analysis of cold-formed centrally compressed elements. Numerical analysis was carried out by finite element method and program for the nonlinear static and dynamic structural analysis - PAK. The results obtained by experimental and numerical methods included boundary conditions, maximum force, buckling curve etc. Small difference observed in the values obtained by these different methods. Results werw compared to values predicted by international designing code in order to analyze if they are too conservative for cold formed steel sections

Problematika projektovanja međuspratnih ploča sa aspekta nosivosti, sigurnosti i energetske efikasnosti

This article provides information about the possibilities of design and construction floor slabs concerning three very important aspects: the capacity, safety and energy efficiency.Nowadays, in the Republic of Serbia exclusively solid concrete slabs are designed and built,which are at least 20cm thick.The justification for this solution is to obtain, in its plane, a rigid plate-diaphragm that is able to endure seismic forces on the walls, proportionally to the stiffness of those walls.At the same time this solution has many disadvantages and it is a great load that limits the length of the span. That heavy load is directly proportional to the size of the seismic forces. The20 cm thick, solid concrete slab has a large heat capacity, and specific heat c (J / kgK), which are not energy efficient,as the warm air is accumulated, conductedtowards to the walls and also retained near the ceiling, while people are near the floor.There are other solutions of design and construction floor slabs that meet demands far more than a solid concrete slab.These are the reinforced concrete site-cast waffle slab.These slabs are extremely stiff and stable, optionally in both directions and can have a reduced mass up to 50% compared with solid concrete slabs.The authors will introduce one waffle-slab solution of reinforced concrete slabs, which satisfies, in addition to above mentioned, even the energy efficiency demand. It is a solution by Stirofert-technology built with structural expanded polystyrene as a stay-in-place formwork during the phase of concrete pouring and construction. This same stay-in-place formwork is a powerful insulation on ceiling with a preventing effect against heat-accumulation and heat losses towards the walls; same time equalizing the temperature of air near the floor and ceiling.Zbornik radova Građevinskog fakultet

Obnovljivi izvori građevinskih materijala za novo vreme građenja objekata visoke energetske efikasnosti

This article provides information about the possibilities and technologies [2] available for the building industry in the Republic of Serbia, and concerns the trends - which expansion is expected in Europe and worldwide - the of use of renewable sources of building materials. Exploitation of sand and gravel from rivers and dry mines in many EU countries is prohibited. Excavation of clay from clay deposits and blasting the rock mass are considered as a violation of the natural environment and resulting with scars on our planet Earth.Renewable sources of construction materials are considered materials which each year can be renewed and which are the most common by-product of agricultural production.Materials obtained by recycling existing materials already used in construction, as well as by-products of industrial production are also considered sustainable materials.Renewable materials are supporting the new, worldwide trend in building industry, called "Green Building" with the aim of reducing harmful CO2 emissions.This paper will discuss renewable materials obtained as a by-product of agricultural production such as grain straw (wheat, barley, rye and oats), cane and hemp shiv obtained by mechanical breakingof hemp stems.These materials are cheap because they are by-products and they are energy efficient, which is particularly important nowadays.The construction of buildings with the above mentioned materials should be well planned to ensure the durability, fire resistance and particularly the pleasant and comfortable stay for the people.The walls made of this material must be solved, and ensured to avoid occurrence of rodents and other pests that may be carriers of dangerous and contagious diseases.Zbornik radova Građevinskog fakultet

Testing of pH-value of sugar solutions from sugar factories

It is known that sugar solutions can induce chemical attack on exposed concrete and cement mortars, but there is neither regulation nor standard for corrosion testing of cement stone due to the exposure of sugar solutions or recommendations for concrete mix design which will be subjected to this type of corrosion. There are even different opinions whether it is a low, medium or strong chemical aggressive type of attack on the concrete. When concrete is exposed to chemical attack, one of the most important parameter is the acidity of the environment, expressed in pH values. The authors of this paper gave results in studying various pH values of solution of sugar, molasses, and combinations thereof. The effects of concentration of sugar in the solution at the pH and their changes over time were also presented. The conclusions provide an explanation for consequences on concrete subjected to sugar solution, which occur primarily in sugar factories but also in other food processing industrial units