Abstract
The composite behaviour of fixings acting in shear between gypsum board and thin steel sections depends on the effective properties of the board material in compression at the base of the fixing and the contribution of the head of the fixing as it rotates. An elastic method is presented to determine the stiffness of the fixings, which uses the effective elastic modulus of the gypsum board determined from a ‘dowel’ test in bearing based on the BS EN 383:2007 test. The deformation of the board in front of the fixing was determined by finite-element (FE) modelling as acting over a constant strain zone of approximately 1·5 times the fixing diameter. A plastic method is also presented to determine the shear resistance of fixings into gypsum board based on the compression resistance obtained from a dowel test on the BS EN 383:2007 test. The theory is compared with the results of FE models using Abaqus for 3·5 mm dia. fixings into 12·5 mm thick gypsum board and with tests on fixings in shear and dowel tests; the correlation is shown to be good. A small-scale push test is proposed to determine fixing properties in shear.