LOAD-DEFORMATION RELATIONSHIPS FOR SIMPLE STEEL FRAMES WITH UNSTABLE ELEMENTS

Procedures have been developed for investigating the plasticity of steel structures that retain the known, traditional steps of investigation but incorporate, instead of the traditional plastic hinge, the model of interactive hinges or interactive zones. In this way the joint consideration of quite different strength and stability phenomena is possible. With the aid of the load-displacement diagram characteristic of the behaviour of steel structures an answer was sought to the question if the displacement capability of the given structure is sufficient and therefore both the "descending" and the "ascending" sections of the load-deformation diagram have been investigated both theoretically and experimentally

INTERACTION BETWEEN PLATE AND LATERAL-TORSIONAL BUCKLING WITH REGARD TO RESIDUAL STRESSES

The complex of strain hardening of steel, occurring residual stresses, interaction of plate and member buckling significantly affects the stability condition of beam-columns. Theoretical results obtained by the energy method relying on the theory of plastic deformation match test results

THE MODEL OF THE "INTERACTIVE PLASTIC HINGE"

Instead of the plastic hinge the "interactive hinge" and "zone" have been introduced for a mounting base constructed from plates which are of a much higher degree of freedom than the previous ones as they also embrace the effects of strain hardening of the steeel ma- terial, of the residual deformation, as well as of the plate buckling bringing about the "descend- ing" characteristics. The traditional plastic hinge is only suitable to take the rigid and ideally plastic state from among the stability features into account

LOAD TESTS ON THE FOUR-SPAN STRUCTURE OF THE RAILWAY BRIDGE OVER THE TISZA AT CSONGRÁD-SZENTES

New bridges can be opened to traffic only after a subsequent load test. The minimal aim of these checks is to show that the structure fulfils the design requirements given in the corresponding Code and its real behaviour approximates the expected one. However, these pieces of information do not provide an explanation for all the deviations. Therefore, if the objective and financial conditions are given, it is advisable to carry out additional measurements, which can be analyzed later to describe more accurately the behaviour of the structure, which, in turn, widens the possibilities of assuming a more realistic structural model and which provides aid and reference point for design practice in the future

COMPUTER PROGRAM FOR STEEL FRAMES TAKING INITIAL IMPERFECTIONS AND LOCAL BUCKLING INTO CONSIDERATION

Computer technique suits state change analysis of plane steel bar systems. Investigations considered several effects and iufluences such as plastic deformation, geometrical and mechanical imperfections, plate buckling. The analysis relies on modelling the structural member such as to involve several effects and iufluences