Assessment of the use of composite connections with unpropped composite beams

摘要

This paper presents the results from a parametric study carried out to assess under which conditions composite connections can be safely used with unpropped composite beams. A total of 2160 different beam configurations have been considered, utilising different steel grades and loading conditions. The critical factor affecting the required rotation capacity of the connections is found to be the level of dead load stress developed by a beam prior to hardening of the concrete, as this has a big influence on the beam deflections. The influence of several other factors has also been assessed. These include: span to depth ratio, location within the building frame, ratio between the support and span moments, loading type, steel grade and the percentage of the beam strength utilised during design. The connection rotation capacity requirements resulting from this study are compared with the rotation capacity of industry standard composite connection details. The comparison suggests composite connections may only be used with unpropped beams if the construction load stresses in the steel are restricted.