Concrete beams with spliced reinforcement were subjected to low-amplitude high-cycle sinusoidal loads. Threaded coupler-type splices were utilized with the 16 mm high-yield reinforcing bars. During the tests the maximum stress caused by the sinusoidal load in the bottom reinforcement was kept constant at a value of 242 MPa for all beams. This stress level corresponded to the stress in the bottom reinforcement due to the service load. The minimum stress was varied to obtain various stress ranges. It can be concluded that the threaded couplers In the 16 mm reinforcing bars as used In the reinforced concrete test beams, subjected to a harmonious repetitive loading, have no detrimental effect on the fatigue resistance of the beam.
In order to study the significance of observed inclined cracks and calculated shear concentration in an existing road-over-rall skew bridge deck, a quarter-scale model was tested in the laboratory. This paper concentrates on the experimental study. Flexural strength was obtained despite obtuse corner shear and free-edge inclined cracking.
In 1982 the National Building Research Institute (NBRI) of the CSIR embarked on a project to investigate the provision of appropriate technology engineering services for low-cost housing. Up to then very little research into site criteria for on-site sanitation systems other than septic tank systems had been done anywhere. However; engineers often need such criteria. The specific site criteria proposed In this article should be applied with caution, as they are intended only as an indication of the suitability of the terrain for on-site sanitation systems.
The good performance of the waterbound macadam single-sized coarse aggregate base type in wet regions has revived interest in this once labourintensive method of base construction. Specifications have been improved and guide-lines given for the mechanized construction of waterbound macadam bases. Density standards have been set for typical waterbound macadam bases and the performance of these bases was compared with that of other high quality granular bases. Guide-lines were given for the determination of effective elastic moduli of typical waterbound macadam bases and the mechanistic analysis of such granular base pavements.
A statistical analysis of South African wind speed data Is presented. This Investigation Includes the estimation of annual maximum hourly mean wind speeds and gust speeds and additional Information required for specialized design applications. Alternative procedures for estimating extreme wind speeds are discussed and 50-year design Isopleths for South African hourly mean and gust speeds are given.