Modification of the effective area method on two-way loaded shallow foundations

Özet

In rectangular/square based and two-way loaded (two-way eccentric) shallow foundations, four zones in which the resultant load might act are defined in the effective area method. Three out of the four zones that are employed in the determination of the effective areas overlap around kern. Only one zone that has a triangular-shaped effective area (called as case 1 in the literature) out of the four zones has no overlap with the others. The resultant load will always be out of the kern for case 1, and also it might be out of the kern for the remaining three cases. Design of foundations is not acceptable in general if the resultant load acts out of the kern. In the present study, the four cases are reconsidered. The zones on which the resultant load can be acting for the four cases are modified because these zones are overlapped partly. The modification has been made to have clear borders between the zones. On top of that, zone 4 is divided into two. A new zone corresponding to the area of kern is defined as zone 5. The design will be accepted if the resultant load acts within zone 5 (the kern). Also, the graphs in use to determine the dimensions of the effective areas are eliminated since it is not precise. Formulas are derived to determine the dimensions of the effective areas instead of using the graphs. Two new criteria are discovered and proposed to check whether the resultant load acts outside, inside or on the borderline of zone 5 (the kern).