Structural System

Structural system or structural framing shows how the vertical and lateral loads are being grounded in the building.

Below given are some structural system which are commonly used in the buildings:

• Moment Frame System
• Braced Frame System
• Shear Wall System
• Mixed System

There are some advanced system which are used in highrise structure

• Tubular System
• Outrigger System
• Bundled Tubular System

Moment Frame System

Moment frame system get the stability through the fixed connections between beams and columns.

• Both the frames shown above attain stability using fixed connections, frame 2 is stiffer than frame 1 & has less deflection for same loading.
• Stiffness of the moment frame is proportional to the beam & column capacity.

Braced Frame System

The lateral stability in braced frame is attained diagonal axial member called braces.

• The braces are generally designed to resist the axial forces.
• Stiffness of the braced frame is proportional to length and section size of brace.

Shear wall System

Shear wall system get the lateral stability by wall which have high in-plane stiffness, the stability is attained by push pull mechanism in wall.

• The shear walls need not be concrete only, it can be steel stud shear wall or Timber (CLT) wall.
• Stiffness of a shear wall is proportional to its length and thickness.

Mixed System

Structural system which derives lateral stability from one or more system (moment frame, braced frame or shear walls) are referred as mixed system.

• Stability along shorter direction of building is attained by moment frames & by braced frames along longer direction. (in regard to the sketch above)
• The combination of RC moment frames & shear walls is also quite common for concrete buildings.

Outrigger Structural System

Outrigger are advanced structural system where gravity frames are used for vertical loads and core walls are used to take the lateral loads.

• Outriggers are horizontal members introduced at certain levels of high rise structure to enhance the stability core & push forces into gravity column with larger lever arm.
• Outrigger structural system become much more effective when used with belt walls.