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Design Of Foundation for a Commercial and Residential Building


Pile Foundations. Types ... = SI + SC + SS The allowable bearing capacity and the type of foundations provided later are evaluated based on the settlements limits. – PowerPoint PPT presentation

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Title: Design Of Foundation for a Commercial and Residential Building

Design Of Foundation for a Commercial and
Residential Building
An-Najah National University Engineering
Collage Civil Engineering Department
  • Under the Supervision of
  • Dr. Mohammad Ghazal
  • Prepared by
  • Moayad Qadarah
  • Rajae Omar
  • Luai Abu Sharshuh

Project Description
  • Name Eisheh Taha Oudeh Building.
  • Type commercial and Residential Building.
  • Location Nablus City, Rafedia Main Street,
    opposite to Ben Qutaiba School.
  • Number Of Floors 12 floor, 2 under ground level
    and 10 over.
  • Plane Area 550 m2 for the floor.

  • Evaluation of foundations.
  • Selection of the proper foundations.
  • Design of foundations.

Literature Review
  • Foundations are the part of an engineered system
    to receive transmit loads from superstructure
    to the underlying soil or rock .
  • There are two types of foundations shallow
    deep foundations.
  • Many factors should be taken into consideration
    in choosing foundation types such as soil
    properties , economic factors, engineering
    practice, ....etc


Types of footing
  • Isolated Footing.
  • Combined Footing.
  • Mat or Raft Foundations.
  • Strap or Cantilever Footings.
  • Pile Foundations.

 Isolated Footings
  • Are used to support single columns.
  • This is one of the most economical types of
    footings and is used when columns are spaced at
    relatively long distances.
  • Its function is to spread the column load to the
    soil , so that the stress intensity is reduced .

Combined Foundations
  • Are used in the following cases
  • 1) When there are two columns so close to each
    other in turn the two isolated footing areas
    would overlap.
  • 2) When the combined stresses are more than the
    allowable bearing capacity of the soil.
  • 3) When columns are placed at the property line.


Mat or Raft Foundations
  • Are used to spread the load from a structure
    over a large area, normally the entire are of the
    structure .
  • They often needed on soft or loose soils with low
    bearing capacity as they can spread the loads
    over a larger area.
  • They have the advantage of reducing differential

Strap or Cantilever Footings
  • Cantilever footing construction uses a strap beam
    to connect an eccentrically loaded column
    foundation to the foundation of an interior
    column .
  • Are used when the allowable soil bearing
    capacity is high, and the distances between the
    columns are large .

Pile Foundations
  • They are long slender members that are used
    to carry transfer the load of the structure to
    deeper soil or rocks of high bearing capacity,
    when the upper soil layer are too weak to support
    the loads from the structure.
  • Piles costs more than shallow foundations so
    the geotechnical engineer should know in depth
    the properties conditions of the soil to decide
    whether piles are needed or not.

Bearing Capacity
  • Bearing Capacity is the ability of a soil to
    support the loads applied to the ground .
  • Ultimate bearing capacity is the theoretical
    maximum pressure which can be supported without
  • Allowable bearing capacity is the ultimate
    bearing capacity qu divided by a factor of safety
  • There are three modes of failure that limit
    bearing capacity general shear failure, local
    shear failure, and punching shear failure.

  • When building structures on top of soils, one
    needs to have some knowledge of how settlement
    occurs how fast settlement will occur in a
    given situation.
  • So, There are three types of settlement
  • 1. Initial settlement
  • 2. Primary settlement
  • 3. Secondary settlement

Settlement (Cont.)
  • Total Settlement SI SC SS
  • The allowable bearing capacity and the type of
    foundations provided later are evaluated based on
    the settlements limits. This means that the
    settlement of the proposed foundation would be
    within the acceptable limits if the allowable
    bearing capacity provided is used.

Geotechnical Investigation
  • The studied area is approximately flat with
    slight difference in the three existing
    elevations. The general soil formation within
    Highly fragmented weathered limestone and
    marlstone of soft to medium strength with
    cavities filled with marl soil
  • The geotechnical engineer decided to drill Three
    boreholes trying to cover the whole construction

(No Transcript)
  • The depths of the drilled boreholes were as

Borehole No. Depth (m)
1 16.0
2 10.0
3 10.0
  • laboratory test results
  • ? 20 KN/m³
  • qall. 3.5 kg/cm2

  • Taking the lowest compressive strength value of
    rock core specimens with test results and
    applying the percentage of 5, the strength will
  • b.h1 Qall 5 75 3.75 kg\cm2
  • b.h2 Qall 5 70 3.5 kg\cm2
  • b.h3 Qall 5 78 3.9 kg\cm2
  • But considering the fact that rocks is some
    areas may be encountered in fragmented
    conditions, as well as the presence of there
    fracture rocks and marls, it is recommended to
    consider the bearing capacity value of the rock
    formations countered in the site of not more than
    3.5 kg\cm2 within the described rock layers after
    the removal of all loose fill materials over the

Structural design
Column loads are calculated using (sap
program), the structure subjected to the
following loads 1) Dead Load
(own weight). 2) Super imposed
dead load 350 kg/m2. 3) Live
load 500 kg/m2. Using ACI code, the ultimate
loads are calculated considering load combination
Pu 1.2Dead
1.6Live. Material characteristics used in this
project are fc 240kg/cm2 (B
300) Where
fc is the compressive strength of concrete
fy 4200 kg/cm2
Where fy is the yield strength
of steel
Isolated Footing Design
  • Manual Design steps
  • Area of footing Total service loads on column
    / net soil pressure
  • Determine footing dimensions B H .
  • Assume depth for footing.
  • Check soil pressure.
  • Check wide beam shear Vc gt Vult
  • Check punching shear Vcp gt Pult, punching
  • Determine reinforcement steel in the two
  • Check development length .

Area (m2 ) L(m) B(m) Footing column
2.7 1.8 1.5 F1 c1
2.7 1.8 1.5 F2 c2
2.52 1.8 1.4 F3 c3
2.52 1.7 1.4 F4 c4
2.52 1.7 1.4 F5 c5
2.23 1.65 1.35 F6 c6
20.25 4.5 4.5 F15 C15
14.76 4.1 3.6 F16 c16
18 4.5 4 F19 c19
13.3 3.8 3.5 F20 c20
10 4 2.5 F28 c28
10 4 2.5 F31 c31
10.23 3.3 3.1 F34 c34
10.5 3.5 3 F35 c35
7.02 2.7 2.6 F36 C36
  • Depth of footing will be controlled by wide beam
    shear (one way action) and punching shear (two
    way action).

Wide Beam Shear
Shear cracks are form at distance d from the
face of column, and extend to the compression
zone, the compression zone will be fails due to
combination of compression and shear stress.
Punching Shear
Formation of inclined cracks around the perimeter
of the concentrated load may cause failure of
footing. Max, formation of these cracks occurred
at distance d\2 from each face of he column.
h(m) d(m) Footing column
0.4 0.32 F1 c1
0.4 0.3 F2 c2
0.4 0.32 F3 c3
0.4 0.32 F4 c4
0.4 0.32 F5 c5
0.4 0.32 F6 c6
1 0.9 F15 C15
1 0.9 F16 c16
1 0.9 F19 c19
1 0.9 F20 c20
1 0.9 F28 c28
1 0.9 F31 c31
0.8 0.7 F34 c34
0.8 0.7 F35 c35
0.6 0.5 F36 C36
Steel reinforcement
  • Isolated footing represented as cantilever, so
    the max moment occurs at the face of the column
  • Ultimate moment at the face of the column
  • (Mult) (qultln2)/2
  • Mn Mu\F , where, F0.9
  • Mn Rnbd2
  • ? 1\m(1-( 1-2mRn\ fy ).5)
  • ? Steel ratio
  • m fy\0.85 f'c
  • As ?bd

single footing reinforcement
Reinforcement in long direction/cm Reinforcement in short direction/cm Footing
116/27 114/21 F1
116/28 114/20 F2
116/28 114/20 F3
116/27 114/21 F4
114/27 114/21 F5
116/27 114/21 F6
118/12 118/10 F15
118/12 118/12 F16
118/13 118/13 F19
116/11 116/11 F20
118/10 116/11 F28
118/10 116/11 F31
116/12 114/10 F34
116/12 114/10 F35
114/12 114/12 F36
footing column
Fc1 C7,C8
Fc4 C23,C24
Fc5 C26,C27
Fc6 C29,C30
Fc7 C32,C33
h(m) d(m) L(m) B(m) Footing
.8 .7 6.8 2.5 Fc1
.8 .7 11.5 2.5 Fc2
1.5 1.4 6 4.5 Fc3
1.5 1.4 7 2 Fc4
1.5 1.4 7 2 Fc5
1.5 1.4 9 3 Fc6
1.5 1.4 9 3 Fc7
Steel Reinforcement (Flexural)
By using sap program to get the maximum negative
and positive Moment Mn Mu\F , where, F0.9 Mn
Rnbd2 As ?bd Steel reinforcement for
Fc2 The figure below show bending moment in
x-direction using SAP2000
Mu 93.175ton.m Mn 93.175\.9
103.52ton.m Mn Rnbd2 Rn 21.1kg\cm2 ?
.0054 As 37.8cm2
Use 1 F16\12cm
The figure below show bending moment in
y-direction using SAP2000
Steel reinforcement for Fc2
  • Mu 144.822 ton.m
  • Mn 144.822/ 0.9
  • 160.913ton .m
  • Mn Rnbd2
  • Rn20.1kg\cm2
  • ?.005
  • As 37.5cm2
  • Use 1 F16\12cm

Steel reinforcement for Combined footing
Reinforcement in y direction Reinforcement in x direction Footing
1?16/12cm 1?16/12cm Fc 1
1?18/10cm 1?22/10cm Fc2
1?18/10cm 1?22/10cm Fc 3
1?32/10cm 1?22/10cm Fc 4
1?32/10cm 1?22/10cm Fc 5
Mat foundation Design
  • In this project the mat foundation was designed
    using Sap2000 with the following data ( fc 240
    kg \cm2,
  • fy 4200 kg\cm2 )

Calculating the Thickness for mat
The thickness of mat foundation was calculated
using check for punching in the next calculation
. (the most critical for determining the
thickness for mat in the punching shear ) To
calculate the thickness , it was used the next
equation Pu .751.06(fc).5 bod
Where Pu the load at the column bo
parameter of the bunching area d
thickness of the mat foundation
for mat foundation 1which include (col
21,22,25) Col 21 has the critical load ,Pu
377.29 ton 377.291000 .751.06(240).5(2(d50)
(2(d70))d d 80 cm
Design of mat foundation using sap
2000 Deflection shape When we do the analysis
using sap 2000 it was found that the maximum
settlement was equal to 0.0055 m
reinforcement in x direction we take the maximum
moment at the face of columns and the maximum
between the columns. Then ,the area of
reinforcement will calculate by the Equation As
pbd 1)at the face of column Mu 123 ton
.m p 0.0054 As 0.0054 10080 As 43 cm2 use
10?25 mm/m 2)between the columns Mu 40 ton.m P
0.0016?0.0033 So use pmin 0.003 As26.4 cm2
use 10?18 mm/m
reinforcement in y direction 1)at the face of
column Mu 75 ton.m ? 0.0032 ? 0.0033 use
? min for all the zone. As ? b d 0.0033
100 80 26.4 cm2 Use 10 ? 18 mm /
m secondary reinforcement (Negative moment) the
max. moment equals to 20 ton.m ? 0.0015 ?
0.0033 use ? min for all the zone. As ? b
d 0.0033 100 80 26.4 cm2 Use 10 ?
18 mm / m
Thank you for listening