Matakuliah
Tahun
Versi
: S2094 / Rekayasa Pondasi
: 2005
: 1.1
Pertemuan 07
Daya Dukung Pondasi Dangkal
Shallow Foundations
• Shallow Foundations versus Deep
Foundations
Shallow Foundations
• Usually the more economical option
• As a general rule, consider deep
foundations only when shallow
foundations do not give satisfactory
design
• Types of Shallow foundations
• Spread footings (square, circular,
rectangular)
• Combined Footings
• Continuous Footings
• Mat or Raft Foundations
Combined/Strap Footing
Construction Methods
• Excavation; Backhoe followed by
handwork
o Neat footing-no formwork used
o Formed footing
Mat (or Raft) Foundation
Computation of Bearing
Pressure
Bearing Pressure
– Gross Bearing Pressure (q)
– Net Bearing Pressure(q´)
Bearing Capacity
– Ultimate Bearing Capacity (qult)
– Allowable Bearing Capacity (qa)
Computation of Bearing
Pressure
Column Load (Ex 5.1)
q
Wall Load (Ex 5.2)
P Wf
A
 uD
P Wf
b u
q b
D
B
Net Bearing Pressure
Net Bearing Pressure (q´)
q  q   zo
Floating Foundation
– When q´ = 0
– Example: Student Center Building at MIT
Estimated without floatation settlement = 1.0ft
and settlement with partial floatation was 2-3
inches
Eccentric Loads or Moments
Eccentric Loads or Moments
Eccentric Loads or Moments
qmin
 P Wf

e
 
 uD 1  6 
B
 A

qmax
 P Wf

e
 
 u D 1  6 
B
 A

Two-way Eccentric Loads or
Moments
Eccentric Loads or Moments
 P Wf

eB
eL 
q  
 u D 1  6  6 
B
L
 A

For contact pressure to remain (+) ve
everywhere,
6eB 6eL

 1.0
B
L