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Structural Span Reference

Economical span ranges by structure type

Beam & Slab Spans

Structure Type	Description	Economical Span	Max Span	Typical Depth
RC Flat Slab	Flat slab	6~9 m	12 m	L/30~L/35
RC Beam + Slab	Beam + slab	6~12 m	15 m	L/12~L/15
PT Slab	Post-tensioned slab	8~13 m	18 m	L/40~L/45
Steel Beam	Steel beam	6~15 m	20 m	L/15~L/20
Steel Truss	Steel truss	12~30 m	60 m	L/10~L/15
Glulam Beam	Glulam beam	6~15 m	25 m	L/12~L/17
Wood Joist	Wood joist	3~5 m	6 m	L/15~L/20
Precast Hollow Core	Hollow core slab	6~12 m	16 m	200~400mm

Long Span Structures

Structure Type	Description	Typical Span	Max Span
Space Frame	Space frame	20~60 m	100+ m
Cable Structure	Cable structure	30~100 m	200+ m
Shell Structure	Shell structure	20~60 m	100+ m
Arch	Arch	15~50 m	100+ m
Membrane/Tent	Membrane/tent	10~50 m	100+ m

Depth rule of thumb (Depth rule of thumb):
RC Beam: span ÷ 12~15 | Steel Beam: span ÷ 15~20 | Timber: span ÷ 12~17 | Truss: span ÷ 10~15
Example: 10m RC beam → depth ≈ 667~833mm → 700mm standard