The ultimate strength of 24 specially manufactured precast reinforced concrete portal culverts were experimentally determined. Twelve culverts were tested with roller supports and twelve with pinned supports. All the failures occured in the shear span, as defined in the British Code BS 8110; Part I, of the culverts, with the ultimate strength of the roller support culverts less than that of the pinned support culverts. The results are compared with those predicted by three different codes. The British Code mentioned above gives the best prediction for the ultimate strength and the prediction can be improved with a change in the definition for the shear span.
A simplified procedure was descriptionbed for modelling the effects of material non-linearity in elastic-plastic-stability problems in framed structures. An equivalent bilinear moment curvature relationship was assessed by subdividing the cross-section into the minimum number of rectangular elements or concentrated areas required to reflect the dimensions of the section and different materials. These representative relationships were determined before commencing the structural-analysis and enabled a typical member in a frame to be represented by one three-noded element. The method was illustrated by examples of a reinforced concrete frame and continuous composite beams in which the different materials were represented by realistic stress strain curves with strain-weakening or strain-hardening properties.