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Tensile structures are currently the most advanced lightweight structures. Apart from their very small self-weight, they are also characterized by a double curved form with a negative Gaussian curvature. In addition, this is one of the most recent structural systems to be designed and because of that a lot of research work is still being done on its improvement. This paper will give a brief overview of the development of tensile structures. Their most modern sub-type, membrane structures, was analyzed in more detail. The characteristics of this system, its loading and the structural material it is made of were also studied. Special attention is paid to the form of this structural system. In the end an overview of the most significant objects constructed using the tensile structure system is offered, including the Olympic stadium in Munich as an example of cable net subsystem, and the roof of the central court in Wimbledon and the stadium in Durban as representatives of the membrane subsystem. In addition to the significant advantages of this system, the drawbacks are also highlighted.

For the purpose of determination of technical safety, and additional safety necessitated by public an social reasons, this paper considers methods of relations, probability and combined relation and probability. Also considered are functional failure and collapse failure, as well as the concept of designed service life of the structure. The ultimate safety degree is composed o the part for security regarding the technical and social consequences of collapse. The safety determination method, in technical terms too, strives to avoid the damage which would exceed the bearing capacity of the structure. The relation methods apply the safety degree which was obtained in cases when the similar structures of various dimensions were built, so it is necessary to determine the required dimensions to avoid the structural failure. The Probability method is widely applied using statistical data in the load and strength analysis. The combination of relation and probability methods provides the minimum safety degree as a reliable factor.

Most often, in the case of typefied prefabricated systems, foundations are designed and constructed as prefabricated elements as well. When the structure is exposed to high intensity loading and founded on a weak soil, beam foundations are often used instead of pad foundations. Beam foundations, stiffening girders, as well as beams which support the façade elements or partition walls, are treated as beams on elastic foundations, while joint of these girders to pad foundations or vertical support elements of a precast structure can be treated as semi-rigid. Modeling of systems with semi-rigid joints on elastic foundations, for different levels of rigidity of connections, is illustrated by an example of a frame under static loading. On the basis of the results of the calculation carried out in this paper, it is evident that taking into account the elastic foundations of the member and the corresponding degree of fixation of the member on this foundations significantly affects the magnitude of the forces in the cross-sections of the member, and on the redistribution of influences in the entire structure. Yet, the foundations-and-soil interaction exerted the highest influence on the magnitude of the stress in the foundation structure itself.

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 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.

In respect to the subspace identification method as one of the possible variants of inverse dynamic analyses, behavior of real structural systems with real load and real noise contaminated input/output data was investigated in this work. A useful and non-destructive dynamic parameters evaluation tool - vibration monitoring of the structure - is proposed. The report of original investigation on real models excited by an impulse load in laboratory is also presented. A special contribution is a software program for experiment monitoring and for determination of relevant mechanical characteristics as well as of the location of a possible structural damage.