Comparison of Raft and Folded Plate Foundations

摘要

The design of raft depends on several factors like the stiffness of superstructure and foundation, bearing capacity or modulus of subgrade reaction of the soil, column spacing, projection of raft beyond the outer lines of boundary columns and the material strengths used in construction. For a given arrangement of superstructure, soil strength is the most important factor affecting the design and cost of construction of a raft. Folding of a raft or folded plate foundations can be used effectively to reduce the material consumption in a raft construction. A raft folded in straight lines is easy to construct and it increases the stiffness of the foundation, which in turn reduces the total and differential settlements of the structure as a whole. The present study compares the performance of raft and folded plate foundation. The advantages of folding the raft on the structural design of foundation and superstructure are highlighted. The initial designs were prepared using Winkler method and the impact of varying the coefficient of subgrade reaction on the design of raft and folded plate foundations were compared. Then continuum method was used for representing soil and its properties were varied in line with the variation in coefficient of subgrade reaction. The impact of this modeling and variation in soil properties on the foundation and super structure design were also compared. In addition the effect of increase in projections to the raft beyond the outer lines of boundary columns are also presented.