The paper presents procedures of the slip calculation in steel and concrete composite structures under quasi-long-term load with flexible stud connectors. To describe the slip relation s = s (P), exponential functions are used as appropriate for using in engineering practice. The former already existing expressions for calculating the slip for short-term loads were generalized. The values of factors for the formula were determined on the basis of the experimental investigation.
Authors:Patricia Duratna, Jan Bujnak, and Abdelhamid Bouchair
Steel-concrete composite trusses as structure systems are not used very often in Europe. One of the reasons may be that the design specifications of composite truss, included in the American standards are not covered in the European standards (Eurocodes). In this study, a finite element model was developed to analyze the behavior of the composite truss. The parametric study, in which the influence of various factors, including the diameter of the shear connectors, the top chord section, the degree of connection, and the material characteristics, on the behavior of the composite truss and the shear connectors was realized. This analyze showed that the shear connection in composite truss reduces its deflection by approximately 50% in comparison to the steel truss. In the study, the significant influence of the top chord section on the shear forces in the shear connectors was observed.
The resistance of steel-concrete composite trusses is significantly influenced by shear connection producing interaction between the steel beam and concrete slab. To create the interaction between these structural parts, it is needed to prevent the relative slip at the steel-concrete interface using the shear connectors. Push-out testing can reflect the more real effect of the longitudinal force and reproduce the distribution of the shear force between the steel section and concrete slab. The finite element analysis is used in the paper to investigate numerically this structural system behavior, exploiting finite element computer procedures.
The design specifications of composite trusses are only partially included in the European standards. However this construction system can be considered as one of the most economical for building and bridge structures. In general, the composite trusses can be used for greater spans up to the 30 m, which allows better use of internal space without restricting columns. They are appropriate also to meet the requirements for building height limitation, the need to run complex electrical, heating, ventilating, and communication systems. To create the interaction between steel and concrete, it is necessary to prevent the relative slip at the steel and concrete interface using the shear connectors. But the local effects of a concentrated longitudinal force and the distribution of the shear force between steel section and concrete slab, as special task, should be appropriately examined. The finite element analyses can be used to investigate numerically this structural system behavior, exploiting several computer procedures. The experimental research has tested these procedures. The outputs of this study are presented in the paper.
Authors:Martin Vavruš, Ján Bujňák, and Peter Koteš
The aim of the paper is to point out the inevitability of the proof-load tests for the real and correct behavior of bridge structures in ultimate limit state and maximum allowable deformations in serviceability limit states. It is needed to point to the most consequences of resistance, reliability, durability and lifetime of the bridge structures. Using the proof-load tests for new bridges is prescribed by the Slovak standard STN 73 6209.
Authors:Peter Michalek, Jakub Kralovanec, and Jan Bujnak
Reactive powder concretes are a set of ultrahigh-strength concrete reinforced with fibers. Their compressive strength is greater than 100 MPa. For assuring connection of steel beams and a concrete slab, steel stud connectors are used. The investigation of that kind of shear connection efficiency, in the case of this higher strength concrete deck using standard push-out test specimens has been executed. The experimental results are presented in the paper.