Civil Engineer in South Africa - Volume 23, Issue 5, 1981
Volume 23, Issue 5, 1981
Author A.R. KempSource: Civil Engineer in South Africa 23, pp 175 –181 (1981)More Less
The paper discusses the relevance of ductility on the moment redistribution capacity of reinforced concrete beams. The parameters which reflect the ductility are identified both from a theoretical point of view and in terms of the stipulations in recent codes of practice. The plastic rotation capacities of a wide range of sections and material strengths are evaluated by calculating the moment-curvature relationships over the complete range of non-elastic behaviour. Comparisons are made with the ductility requirements of two codes and the proposals for calculating the ultimate moment capacity and neutral axis depths specified in the new CEB-FIP code. The paper provides a realistic basis for assessing the theoretical moment redistribution capacity of reinforced concrete beams.
Author M.D. WatsonSource: Civil Engineer in South Africa 23, pp 183 –189 (1981)More Less
The sizing of urban flood control ponds is discussed and a simple procedure is presented for preliminary estimates of the storage requirement. The method assumes a constant outflow rate and makes use of an empirical equation for the rainfall intensity-duration-frequency (IDF) relationship. Methods of obtaining the empirical IDF coefficients are presented, as well as regional coefficients which can be used in the absence of local data. The method is easy to use and is presented in the form of graphs.
Source: Civil Engineer in South Africa 23, pp 191 –194 (1981)More Less
Moderne ontwerp van paaie en strate vereis 'n metode waarvolgens verkanting om enige punt op die dwarssnit ontwerp kan word. Bestaande metodes was voldoende vir drie-punt dwarssnitte maar meer ingewikkelde snitte kan nie bevredigend hanteer word nie. Self vir verkanting om die middelpunt van 'n snit, waar die huidige metode wyd aanvaar word, kom daar ongewenste slaptes op die padoppervlak voor. 'n Omvattende metode word aangebied vir die verkanting van 'n willekeurige snit om enige punt wat gebaseer is op die beginsel dat die helling van enige segment in verhouding is met die afstand langs die middellyn.
Modern design of streets and highways requires a design method providing for the development of superelevation around any point on methods are adequate for three-point cross sections but more complicated sections cannot be treated satisfactorily. Undesirable slacks in the pavement occur even when revolving the pavement section about the centre line. The current method is proposed for the development of superelevation about any point of any arbitrary section. It is based on the principle that the slope of any section should be proportional to the distance along the centre line.