A Structural System related to Structural engineering refers to a load resisting system of a structure. These structural systems consist of different members which are inter-connected to form a structural system and transfer load to the base.
Structural System can also be called as a method of assembling and constructing structural elements of a building so that they support and transmit applied loads safely to the ground without exceeding the allowable stresses in members.
What is Substructure
The part of the structural system which is below the ground level is called substructure. It mainly consists of foundations for the building and column,walls below ground level. Nowdays multistory structures has basement parking and these basements are also included in substructure. So basically the structural system which is beneath the ground is called substructure.
The main function of the substructure is to support and anchor the superstructure safely into the Earth. Its function shows that it is the critical link in the distribution of building loads and as it is below the ground it is hidden form the view. It must be designed to accommodate both the form and layout of the superstructure. So though substructure is hidden beneath the ground it needs special attention in designing.
The main member which comprises the substructure is foundation. There are different types of foundation used for transfer of loads.
Foundations are basically of two types:
- Shallow Foundation
- Deep Foundation
01. Shallow Foundation:
When depth of foundation for a structural system is normally less than or equal to 3m it is called as Shallow Foundation and the name itself suggest that it is a foundation having lesser depth for foundation. Some of the shallow foundations are Isolated Footing, Combined Footing, Eccentric Footing, Trench Footing, Raft or Matt Footing etc.
02. Deep Foundation:
When depth of foundation for a structural system exceeds the above criteria for depth of shallow foundation it is called as Deep Foundation as its name suggest. Some of the deep foundations are Pile foundation, Pile and Raft footings, Caissons etc.