Answer to Question #294845 in Civil and Environmental Engineering for Sam

Question

Given a rectangular column of dimension 650X450 mm is required to support axial dead load is 815 kN, axial live load is 680 kN, dead load moment is110 kN.m and live load moment is135 kN.m acting on the major axis. All loads in service condition. Concrete compressive strength is 27.6 MPa, steel yield strength is 410. Assume longitudinal reinforcement bar diameter 25mm and ties diameter is 12mm

By using ACI interaction diagram design the required longitudinal reinforcement

Design the required ties and sketch the column section with all necessary details

Answer 1

Isolated footing is the single or individual footing which transfers load to the underground soil. It is provided when a single column is to be provided. A foundation is the part of the substructure which makes a direct contact or rested inside the ground. A footing is a unit of the foundation that could be deep or shallow.

Isolated footing is generally provided for shallow depths. Shallow foundations have their depths less than the widths. Isolated footing is used for isolated column. Footing is provided, either as simple footing, sloped footing or stepped footing.

In simple isolated footing, base of uniform depth is provided. In sloped footing, base of uniformly sloping downward pattern is provided. In stepped footing, base is constructed in steps to distribute the load uniformly to the foundation soil.

Simple isolated footing is simple to construct, which reduces the time for construction and it distributes the load in a uniform manner.

Sloped footing is more economical than the simple isolated footing, because the amount of concrete is reduced towards the edges. It requires more supervision during the construction and thus consumes more time in construction. As the effective trapezoidal load pattern is formed due to the load on the footing, the sloped footing is suitable for such cases. A slope of 45° is provided in sloped footing.

In the stepped footing, cross section is overlapped with each other. Load coming from column on the footing is distributed in steps.