Substructure and Superstructure: Definition & Differences

Substructure and Superstructure

Substructure and superstructure are two parts of the building structure. Substructure is the part that is underneath the ground while the superstructure is everything above the ground.

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Figure showing Substructure and Superstructure of a General Building.

Substructure Definition

A Substructure is an underlying or supporting structure to superstructure. It is below ground level. Foundation is part of substructure. Substructure is the lower portion of the building which transmits the dead load, live loads and other loads to the underneath sub soil.

So, the substructure is in direct contact with supporting soil. Substructure involves footing and plinth of a building.

Superstructure Definition

A superstructure is the portion of a building which is constructed above the ground level and it serves the purpose of structure’s intended use. It includes columns, beams, slab upwards including all finishes, door and window schedules, flooring, roofing, lintels, and parapets.

In Buildings, the portion of the structure that is above ground level that receives the live load is referred to as Superstructure. The superstructure of a building is the part that is entirely above its foundation or basement. The foundation of the building is part of Substructure.

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On a bridge, the portion of the structure that is the span and directly receives the live load is referred to as the superstructure. In contrast, the abutment, pier and other support structures are called the Sub-structure.

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Substructure and Superstructure of Railway Bridge

The table below summarizes the difference between a superstructure and substructure for better understanding.