Spread Footing Design

The foundation is that part of the structure, which is usually placed below the ground surface and transmits the load to the underlying soil. If satisfactory soil directly underlies the structure, it is merely necessary to spread the load, by footings or other means, in order to reduce the bearing pressure and therefore prevent excessive settlement or rotation. The program computes the soil bearing pressures induced by a square or rectangular spread concrete footing subject to vertical load and biaxial moment, and analyzes the stability of the structure. In addition, it performs the concrete design based on the Ultimate Strength Design Method of the ACI 318. Load combinations per the ASCE 7. The footing is assumed to be perfectly rigid with constant thickness, and rotates about its mass center to maintain the equilibrium of forces. A remarkable feature of the program is its ability to determine the soil pressures under the footing with any service load combination, including uplift loading. The pressures may also be calculated when only a part of the footing is in contact with soil. This is especially useful when a footing with small vertical load and big moments is designed, such as a footing at the corner of a building under lateral loads.
		Input Data The required input data includes the footing and column dimensions, the materials' properties, the allowable soil bearing pressure, and the acting service and factored loads. In addition, the program accepts a number of load cases, such as dead, live, snow, wind and seismic.
		Example Consider a 12' x 8' x 16" spread footing with a soil cover of 1ft. subjected to the following loads: P=100 k, Mx=50 k-ft, Mz=60 k-ft, Pu=140 k, Mux=100 k-ft, Muz=100 k-ft. The gross allowable soil pressure is 3.0 ksf. Find out the adequacy of the footing dimensions and design the steel reinforcement. The 16" x 16" column is eccentric 6" in both directions.

Output The program checks the footing stability for the service combined loads and performs the concrete design, which includes the one-way shear, punching shear and bending for the factored combined loads. In each case the controlling load combination is identified and reported. A detailed step-by-step report is available to the touch of a tab, which is updated with every new change. In addition, ASDIP Foundation uses a pre-formated colorful text-with-values output for easier identification of the problem areas. ASDIP Foundation generates a graphical view of the designed footing and the resulting pressures and forces, as shown. The program also generates the moment and the shear plan views for the controlling combination, as well as a view of the construction section and elevation with the reinforcement information.