This paper reports and experimental investigation in which the effects of fibre volume fraction and the ratio of unloaded to loaded area on the ultimate bearing capacity of concrete are studied. Two types of loading patterns, namely, concentric and edge loading were adopted. A simple theoretical model is developed and is shown to fit the test observations well.
One of the main agents causing degradation of organic materials exposed outdoors is solar radiation, which gives rise to photo-oxidation reactions. Various aspects of the solar radiation received by surfaces of different orientations on clear days at several latitudes are examined. For small-scale exposure testing an equator-facing surface sloping at 45° to the horizontal is recommended at all latitudes. If exposure testing with vertical panels is required, east or west-facing surfaces are recommended within the tropics, and equator-facing surfaces at higher latitudes.
A model is proposed where the rate at which ground-water is raised by capillarity equals the rate of evaporation. An examination of the constants indicates that the most likely cause of the wet-line rising with time is the leaching of the soluble lime from the mortar with a conseqent increase in its permeability
At flexural cracking, the load capacity of unbonded concrete structures decreases suddenly if the prestressing force is smaller than a certain critical value. Critical prestress values are derived from theoretical considerations for T, I and box sections and experimental verification of the results is given.
An approximate method is presented to study the interacting effect of normal frames on uniform shear walls and the shear lag effect in the normal frames. Based on the axial deformation distribution among columns, a reasonable assumption is further introduced to simplify the method. An example is included to illustrate the application of the proposed method and the accuracy of the simplified method. Based on the simplified method design curves are presented for rapid determination of maximum deflection, wall moment and column axial stress of a uniform structure subjected to point load at top, uniform and triangular load distribution.
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