Search

The paper deals with a brief presentation of a part of the performed experimental tests of the prefabricated reinforced concrete structural system 'AMONT' for construction of various types of modern industrial halls. The test results are analyzed for two industrial halls both constructed according to this structural system but in the different phases of construction, tested in the full scale by application of AMBIENT vibration method. From the obtained Fourier spectra for measured ambient vibrations in two orthogonal direction for the structure without walls and the other with façade and filling walls, a significant discrepancy in their natural frequencies has been observed, and some conclusions about the influence of panel walls on dynamic characteristic the frame structure have been drawn out. The paper used some data of the research after the earthquake in Montenegro which took place on 15th of April 1979.

The mass content of aggregate (ma) and of cement (mc) of concrete comprise coefficient calculated as ma/mc. Some methods used for designing of concrete mixtures take into consideration this coefficient. In this paper, concrete mixtures were prepared so that mass of cement, water cement factor and granulometric composition have been varied. Values of the coefficient ma/mc in experimental research ranged between 7,20 in concrete mixtures mixed with 250 kg of cement to 3,60 in concrete mixtures mixed with 500 kg per 1m3. From the aspect of compressive strength of concrete, it has been established that optimum values of the coefficient ma/mc depend on the granulometric composition and water cement factor. At higher water cement factors, larger values of ma/mc coefficient are required to achieve the maximum strength under the given conditions.

The paper points out to the differences of the First order theory and Second order theory and of the significance in practical calculations. The paper presents theoretical foundations and expressions of calculations of impacts on the stability of structure, that is, review of the Second order theory in a bridge with members semi-rigid connections in joints. In the real structures in general and the especially in the prefabricated structures the connection of members in the nodes can be partially rigid which can be very significant for the changes in tension and deformation. If the influence of the normal forces is significant and the structure is slender then it is necessary to carry out a calculation according to the Second order theory because the balance between internal and external forces really established on the deformed configuration and displacements in strict formation are also unreal. The importance and significance of the calculations and distribution of impact according to the Second order theory were presented in numerical examples as well as the calculation of critical load as well as the buckling length of members with semi-rigid connections in joint.

The paper presents the conceptual design of the footbridge made of laminated wood. The supporting system of the main bearing elements is made of the laminated wood in the system of arch with three joints and the bridge deck is made of the composite timber concrete structure system. The load patterns for which the dimensions of the supporting bridge structures were adopted (verified according to Eurocode) are presented.