Behaviour of pinned steel column baseplates

Baseplates assumed to offer so called pinned restraint only, are a common design feature for steel structures. Yet their actual behaviour has hardly been explored and rational rules for their design are not in evidence. While present design practice is undoubtedly adequate, it is nevertheless of interest to explore its limitations and its conservatism. In particular the moment capacity of nominally pinned baseplates is of interest, as this may add to structural capacity both in service and during construction. The deformation behaviour is also of interest, as is the response of the soil under the footing. The present paper gives a progress report on an investigation to obtain behaviour characteristics of two bolt, nominally pinned baseplates, founded on reinforced concrete footings and having an intermediate grout layer. The connection is subject to applied moment and axial force (a).