EFFECT OF DISTANCE ON THE STRESS DISTRIBUTION IN TWO-DIMENSIONAL PROBLEMS

Abstract

In mass concrete structures of finite dimensions con-taining hollows or cavities of appreciable proportions, the distance of the load from the top of the cavity as well as the distance of the bottom of the cavity from the support (distance factor) and different shapes of cavities (shape factor) influence the distribution of stresses due to a concentrated load, inside the concrete mass in addition to many other factors. This dissertation, is an attempt to find out the influence of these two factors by comparing the nature of the three components of stresses computed at various points on twenty-six numbers of 2D-photoelastic models, the overall dimensions, shape and size of the cavities of which may be commonly met with such structures. The results of the study have been presented in shape of stress concentration factor (S.C.F.) contours drawn on the body of each model for horizontal normal, normal vertical and shear stresses which can be readily used as Monographs to evaluate stresses in structures of similar proportions and identical purposes by multiplying the S.C.F. at a point with the average vertical stress. An objective analysis of the results obtained indicate that the greater the distance of the load from the top of the hole of any shape, the better will be the chance for the intensity of vertical stress to reach the average value and oft the top of the hole a more or less uniform vertical stress is expected if the distance between the top of the hole and load is equal to the width of the hole or more (Diameter in case of circular hole) . It is also revealed that as generally expected, the concentration of the horizontal normal stress above a rectangular cavity is more in comparison to cavities of elliptical or rectangular with semi-circular ends or circular shapes in such structures of comparable dimensions under same load and support conditions. The concentration of normal vertical stress is also more around a rectangular cavity than around the said other shapes which are most common in various water resources civil engineering structures.