Structural Forms

• The building fabric as an environmental envelope must be able to safely withstand all the forces to which it will be subjected in its lifetime . 
• There are 3 basic structural forms : 
• skeletal structura ( Framed structure ) 
• Solid structure 
• Surface structure . 

Skeletal structure ( or framed structure ) 

• A skeleton or framework which supports all the loads & resist all the forces acting on a building & transfer them to the soil where the building rests . 
• Examples : North American indian wigwam , reinforced concrete ( R.C. ) & steel frames . 

Solid structure 

• The thick load bearing wall acts as both the enclosing & supporting structure . 
• Examples : Eskimo igloss , reinforced concrete shear wall buildings . 

Surface structure 

• Wall & roof ( load bearing ) both acts as enclosing & supporting structure . 
• two (2) types :

1. Type 1 : Elements are made of thin but solid material which is given the necessary stiffness by being curved or bent . ( e.g. Zulu hut , modern reinforced concrete shell , folded slab structures ) . 
2. Type 2 : Elements consists of a very thin membrane of suitable material suspended or strecthed in tension over supporting members . ( e.g. bedouin ten < millennium Dome . ) 
3. Elements are made of thin but solid material which are given necessary stiffness by being curved or bent . 
4. Elements consists of a very thin membrane of suitable material suspended or stretched in tension over supporting members .