Strength tests performed on three sizes of precast concrete portal culverts from two different manufacturers indicate that the SABS 0100 code requirements for shear strength for pinned support portal culverts are conservative. Some of the pinned support culverts exhibited adequate shear strength to meet the design requirements. Shear failures, however, were brittle and the results indicate that changes In detailing may be required.
During the construction of a section of National Route N13 (Johannesburg Southern Bypass) two large cuttings ware excavated. The first, in andesite lava, was adjacent to a Rand Water Board pipeline and the second, In quartzites, adjoined private dwellings. The cuttings were restrained with stressed anchors and unstressed dowels and the exposed faces were protected by concrete panels. The geotechnical design of the lateral support In the andesite was problematic, owing to the unpredictable variations In rock weathering. By contrast, the quartzite cutting was uniformly weathered, with consistent patterns of jointing, and design problems were concerned mainly with the overlying transported soil.
The development of finite element techniques for inelastic stability analysis of frame structures was addressed. This included the formulation of beamframe elements with a layered representation of the cross-section, the use of elastic-plastic constitutive models and the incorporation of a simplified updated lagrangian large deformation algorithm. Extensive numerical experimentation was reported, from which guidelines for efficient modelling were derived. Satisfactory comparisons between analyses in the paper and previously published solutions were achieved.