IN Composite Steel and Concrete Bridge Trusses

The article analyzes the distribution of longitudinal shear forces for the design of composite steel and concrete bridge trusses. Numerical analyses are based on elastic-plastic 3D GMNA (ANSYS software) verified by previous experimental research and 2D LA (Scia Engineer software). The primary interest is devoted to the elastic distribution of the longitudinal shear required in bridge design even in ultimate limit states. The investigation of the peaks of longitudinal shear above truss nodes in the elastic domain and the influence of both the shear connection and the upper steel truss chord rigidities is presented. Simultaneously, the design approach according to the bridge Eurocode is shown plus the subsequent plastic redistribution of longitudinal shear, including its distribution within the bridge collapse. A further investigation concerns the signification of the concentration of shear connectors within the peaks of longitudinal shear above steel truss nodes. Finally, some practical recommendations resulting from the studies are suggested.

Shear Connector Advanced Model

The perforated shear connector, which is successfully being used for shear connection of a steel beam and a concrete slab in steel and concrete composite beams, was in detail tested at the Czech Technical University in Prague (CTU) in two standardized types. Based on the test results formulae for the static shear strength of this connector were derived. Only three tests with repeated loading of one connector type, when material fatigue occurs, were carried out.

Composite Steel and Concrete Trusses

The paper deals with distribution of shear flow and forces in shear connectors of composite trusses. Within elastic behaviour the distribution is highly non-linear and determines design of shear connection, in bridges, class 3 and 4 sections, when loaded by fatigue or the shear connectors are non-ductile. Within plastic behaviour the plastic redistribution takes place depending on the rigidity and strength of the shear connection.

Numerical Model of Modified Perforated Shear Connectors

The behaviour of perforated shear connectors for composite steel and concrete structures is investigated. The main focus is on the experimental and numerical analysis of the perforated shear connector under static loading. The experimental part was based on push-out tests with a slightly modified basic connector. The numerical model of the above mentioned connector in FEM software ATENA was investigated because of verification experimental results.

Resistance of Small Diameter Stud Shear Connectors

The investigation on enlargement of current restricted use of welded studs as shear connectors in accordance
with Eurocode CSN EN 1994-1-1 (2006) which, however, limits the diameter of the studs to 16-25 mm is described. In the first part of the article a survey of new technologies and new devices for welding of small diameter studs are presented. Secondly, the experimental investigation is commented with results of push-out tests having studs with 10 and 13 mm diameter and various quality of the concrete part.