Steel-concrete composite continuous decks are widely used in viaducts and bridges with medium span length (40-100 m). Such decks are usually composed of two steel beams or a single box girder, even in the case of wide concrete slabs (>20 m), that can be sustained by cantilevered cross-beams or be transversally prestressed. In this kind of structure the usual assumption of bending theory, according to which the plane cross-sections remain plane after loading, is not realistic because the slab undergoes a significant warping which is responsible of a non-uniform stress distribution on the slab cross section (shear-lag effect). In the design of such decks, the main codes of practice (e.g. Eurocode 4) suggest to take into account the shear lag effect by reducing the slab width (effective width method) according to simple formulas, depending on the bridge geometry, obtained and validated for external static actions. However, their use for other kinds of actions, such as geometrical actions (support settlements), concrete shrinkage and thermal actions, is not supported either by numerical analyses nor by experimental tests. The paper presents new formulations for evaluating the slab effective widths of steel concrete composite bridge decks depending on the kind of loading. Such formulations have been validated by means of a wide parametrical analysis performed thanks to a numerical procedure proposed by the authors. The method proposed can catch the effects of a single load layout, as well as the maximum effects obtained by considering the envelopes of bending moments as usual in bridge design.
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|Titolo:||Load-consistent effective widths for composite steel-concrete decks|
|Data di pubblicazione:||2007|
|Appare nelle tipologie:||Contributo in atto di convegno su volume|