Foundation Design Software: Spread, Combined, and Strap Footings

A strap footing is one that usually supports two columns, and therefore is a special type of combined footing. If a property line exists at or near the edge of an exterior column, an isolated footing would be placed eccentrically under this column and it would tend to tilt. Overturning of the exterior footing is prevented by connecting it with the adjacent interior footing by a strap beam. 

The use of a strap footing may be justifiable under conditions where the distance between columns is large and a large excavation area must be avoided. It is common practice that the bottom surfaces of the exterior footing, the strap beam, and the interior footing be at the same elevation, but the thickness of each element may be different, depending on the strength requirements.

This foundation design software computes the soil bearing pressures induced by a strap footing under the action of vertical loads and bending moments, per the latest ACI design criteria. It designs the reinforcing steel for the interior and exterior footings, and checks the one-way and two-way shear stresses. In addition, the program generates the shear force and bending moment diagrams in order to design the reinforcement for the strap beam. The concrete footings design is based on the Ultimate Strength Design Method of the ACI 318. Load combinations per the ASCE 7. Both columns may be eccentric in the longitudinal direction.

Input

The input options are conveniently organized in tabbed pages. The required input data includes the footings, strap and columns dimensions, the material 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, to be combined internally. Alternatively, you can model a set of pre-combined loads.

Output

This module checks the overall footing stability under the service combined loads and performs the concrete design of the two footings and the strap beam, which includes the one-way shear, punching shear and bending moments under the factored combined loads. In each case the controlling load combination is identified and reported.

For a quick overview of the design results click the “At a Glance” tab. A more detailed step-by-step calculations are available at the “Detailed” 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. Use the Print Preview command to see a preview of the pre-formatted report on-screen, which includes the color graphics generated by the software.

ASDIP FOUNDATION generates a graphical view of the footing design and the resulting pressures and forces. The program also generates the moment and the shear diagrams for the controlling load combination for granular checking, as well as a view of the construction section and elevation with the reinforcement information.

A combined footing is one that usually supports two columns. If a property line exists at or near the edge of an exterior column, an isolated footing would be placed eccentrically under this column and it would tend to tilt. Overturning of the exterior footing is prevented by supporting the two columns on a common footing.

The use of a combined footing may be justifiable under conditions where the distance between columns is short and the stability of an exterior isolated footing would be compromised. It is common practice to size the combined footing so that the resulting soil bearing pressure is uniform. To accomplish this, the footing shape is sometimes trapezoidal or rectangular, depending on the loads. A combined footing is usually analyzed as a beam in the longitudinal direction and as a footing in the transverse direction.

This foundation design software computes the soil bearing pressures induced by a cantilever footing under the action of vertical loads and bending moments, per the latest ACI design criteria. It designs the reinforcing steel, and checks the one-way and two-way shear stresses. In addition, the program generates the shear force and bending moment diagrams in order to design the reinforcement in the longitudinal direction. The concrete footings design is based on the Ultimate Strength Design Method of the ACI 318. Load combinations per the ASCE 7.

Input

The input options are conveniently designed in tabbed pages. The required input data includes the footing and columns dimensions, the material 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, to be combined internally. Alternatively, you can input a set of pre-combined loads.

Output

This software checks the footing stability in overturning, sliding and uplift under the service combined loads, and performs the concrete footings design, which includes the one-way shear, punching shear and bending under the factored combined loads. In each case the controlling load combination is identified and reported.

For a quick overview of the design results click the “At a Glance” tab. A more detailed step-by-step calculations are available at the “Detailed” tab, which is updated with every new change. In addition, This foundation design software uses a pre-formated colorful text-with-values output for easier identification of the problem areas. Use the Print Preview command to see a preview of the pre-formatted report on-screen, which includes the color graphics generated by the software.

ASDIP Foundation generates a graphical view of the footing design and the resulting pressures and forces, as shown. The program also generates the moment and the shear diagrams for the controlling combination, as well as a view of the construction section and elevation with the reinforcement information.