An-Najah National University
Engineering Collage
Civil Engineering Department
May 2012
Under the Supervision of:
Dr. Isam Jardaneh
Prepared by:
Ahmad Zaid
Sameer Mara’abi
Ahmad Mansour
Type: Residential Building.
Location: Nablus City, Bayt Wazan, behind Al-Najah
National University (New Campus).
Name: Al-Thuraya Residential Building.
Number Of Floors: 7 floor, 2 under ground level and 5
over.
Plane Area: 850 m2 for the floor.
Nablus City
Project Location
SCOPE OF PROJECT
 Select the most appropriate types of foundations for the
project.
 Design the selected footings.
 Estimate costs of the foundations designed.
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
Mat
or Raft Foundations.
Strap
Pile
Footing.
or Cantilever Footings.
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
settlements.
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 failure;
 Allowable bearing capacity is the ultimate bearing capacity qu
divided by a factor of safety (F.S).
Settlement
 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:
Settlement
1. Initial settlement
2. Primary settlement
3. Secondary settlement
End of Primary Consolidation
Cα
Logarithm of Time
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 area which we studied not in the same elevations. The general
soil formation is Gray to white, weathered, high limestone formation
covered by brown silty clay, boulders and vegetation. Occasional
pockets filled with soil are expected within the rock formation.
laboratory test results:
Unit weight of the soil = 18 KN/m3
Cohesion (C) = 30
Angle of Internal Friction (φ) = 15
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 =250 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:
f’c =300kg/cm2 (B 300)
Where:
f’c is the compressive strength of concrete
fy = 4200 kg/cm2
Where:
fy is the yield strength of steel
Isolated and Combined Footing Design
 Manual Design steps:
1) Area of footing = Total service loads on column / net soil pressure
2) Determine footing dimensions B & H .
3) Assume depth for footing.
4) Check soil pressure.
5) Check wide beam shear : Vc > Vult
6) Check punching shear
: Vcp > Pult, punching
7) Determine reinforcement steel in the two directions.
8) Check development length .
THICKNESSES OF FOOTINGS
Depth of footing will be controlled by wide beam shear and punching
shear.
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.
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) =(qult*ln2)/2
Mn =Mu\Φ , where, Φ=0.9
ρ =0.85 f˜c / fy (1 – 1 – (2.61* 106 * Mu / b d2 f˜c ) )
WHERE
ρ: Steel ratio
As = ρbd
Example for Single Footing
Footing 1: "C14“
Slab area = 17.22 m2
Beams area = 11.7 m2
Columns section area = 0.25 m2
Slab weight= Area * DL =87.82 KN
Beams weight = Area * Thickness * Density =87.75 KN
Column weight = Area * Height * Density= 18.75 KN
 For One Store :
Service dead Load = ∑ Load = 194.32 KN
Service Live Load = Tarea * 2.5 = 72.3 KN
 For seven Stores
PD= 194.32 * 7 = 1360.24 KN
PL = 72.3 * 7 = 506.1 KN
f˜c = 30 Mpa
fy = 420 Mpa
qall = 200 KN/ m2
Solution Steps
1) Determine the dimensions:
Af = Pa/ qall = 9.33 m2
A= B * L 
L = 3.5 m , B = 2.8 m

New Area = 9.8m2
2) Calculate d from wide beam shear:
Vu = qu (L – d)
qall = Pu / Af = 249.2 KN/m2
Vu = 249.2 (1.15 – d)
øVc= (0.75) (1/6) ( 30 ) (1000) (d) = 684.65 d
But;
øVc = Vu
684.65 d = 286.6 – 249.2 d
 d = 0.30 m
3) Check Punching Shear:
Ao = b1 * b2
b1 = c1 + 2(d/2) = 0.8m
 Ao = (0.8*0.8) = 0.64 m2
 Vup = Pu - quAo = 2441 KN
 øVup = 1301.4 KN
So;
 Vup > øVcp
…….. This is Not Ok
 Try d = 0.40 m
Then;
Ao = 0.81 m2
Bo = 3.6 m
 Vup = 2398.6 KN
 øVcp = 1952.1 KN
……. Not Ok
 d = 0.50 m
Vup = 2351.3 KN
Vcp = 2711.23 KN
L = 3.5m
d= 0.5m
B = 2.8m
h = 0.55m
4) Design for Flexure:
Mu = qul2 / 2 = 164.8 KN.m
ρ = 0.00177
As= ρ b d = 885mm2
Asmin = 0.0018 b = 990 mm2
As < Asmin
 Use Asmin = 990 mm2 = 5 ø 16/m
…….. Not Ok
In each direction
5) Check Development Length:
L – cover = 1.15 – 0.08 = 1.07
Ldt = 0.48 (420) * 16 / (30)
= 0.59
L- cover = 1.07 > L dt = 0.59
 It is Ok no need for Hook.
Figure in the next slide illustrate the details of the footing
reinforcements of F14
Example for combined Footing
 Weights on A2 :
Slab weight = 11.3 KN
Beam's weight = 20.97 KN
Column weight = 15.75 KN
∑Dead Load = 48.02 KN
Live Load = 12.52 KN
 Total load:
PD = 336.14 KN
PL = 87.64 KN
 Loads on column B1 :
Slab Area = 9.66 m2
Beam Area = 6.961 m2
Column section area = 0.24m2
 Weights on B1 :
Slab weight = 49.3 KN
Beam weight = 52.21 KN
Column weight = 18 KN
∑ Load = 119.51 KN
Live Load = 41.55 KN
 Total loads :
PD = 836.57 KN
PL = 290.85 KN
Solution Steps
1) Determine the dimensions:
Af = ∑ Q / qall = 7.76m2
L = 4.2 m
B = 1.9m
2) Calculate d from wide beam shear:
Pu1 = 543.6 KN
Pu2 = 1469.24 KN
Avg. Load factor = ∑Pu / ∑Pa = 1.3
 Pu1 Modified = 1.3 (Q1) = 551KN
 Pu2 Modified = 1.3 (Q2) = 1465.65 KN
qu = ( Pu1 (mod) + Pu2 (mod) ) / L = 480.15 KN/m
 Vu = 552.3 – 480.15 d
………………………………(a)
ØVc = 1300.8 d
….…………………………..(b)

d = 0.31 m,
Use (d = 0.35 m)
3) Check Punching Shear :
 For Left Column :
Ao = 0.6825m2
bo = 3.4 m
 For Right Column :
Ao = 0.7475 m2
bo = 3.6 m
 Check for Left Column:
Vup = Pu – quAo = 223.3 KN
øVcp = 1613.2 KN
 øVcp > Vup ……………… Ok
 Check For Right Column :
Vup = 1106.74 KN
øVcp = 1708.1 KN
 øVcp > Vup …………………..Ok
4) Design For Flexure :
Because of all negative moments we will use Asmin for all Footings;
Asmin = 0.0033 (1900) (400 )
= 2508 mm2
Use 4ø 16 /m
 For Left Column :
Mu = qul2 / 2
qu = Pu1 / ( B * b1) = 446.2 KN/m
Mu = 55.8 KN.m/m
ρ = 0.00122 < 0.0018
Take;
Asmin = 0.0018 ( 650 ) ( 400)
= 468 mm2
…. Use 4 ø 16 /m
 For Right Column :
qu = Pu2 / ( B * b3 ) = 671 KN/m
Mu = 188.7 KN.m
ρ = 0.00422
As = ρ b d = 1698.55 mm2
….. Use 4 ø 16 /m
S =( 1000 ) / [(0.0018)(1000)(400)/201]= 279 mm
….. take S = 250 mm
Figure below illustrate the details of the footing reinforcements of
combined footing
Table Below Shows the Details & The Reinforcements of
the Single & Combined Footings
Type of
Footing
Columns
representing
Dimensions
Reinforcement Reinforcement
in Long
in Short
Direction
Direction
F1
C16, C14, E16,
E14, G16, G14,
J16, J14 .
3.5*2.8*0.55
5∅16/m
5∅16/m
F2
A13, A15, A16,
M13, M15, M16 .
2.0*2.0*0.35
5∅16/m
5∅16/m
F3
B5, B7, D1, D5,
D7, H3, H6, L6 .
4.0*3.6*0.65
5∅16/m
5∅16/m
F4
(A2+B1) ,
(L3+M4) .
4.2*1.9*0.40
5∅16/m
5∅16/m
This slides presents the quantities and cost estimations
of all geotechnical elements that are used in this project.
The activities studied at this project include the
following: site investigation, excavation, planning, soil
improvements, frame work, concrete and reinforcement.
Primavera software is used to schedule the above
activities.
In addition to that the cost estimates for each activity is
done and also presented.
Table below shows the geotechnical activities that are incorporated in
this project. The table shows the activity identification (activity ID),
activity name, and activity original duration in days.
Activity ID
Activity Name
Original Duration in days
1
Site preparation and investigation
2.00d
2
excavation of agricultural soil
3.00d
3
2.00d
4
soil improvement
site planning and setting wood
borders
5
excavation for footings
14.00d
6
blinding
formwork and reinforce and
concrete for foundation
2.00d
Water proofing for footings
formwork and reinforce and
concrete for columns neck
Water proofing and backfilling for
footings
formwork and reinforce and
concrete for ground beams
2.00d
Water proofing for ground beams
formwork and reinforce and
concrete for ground floor
2.00d
Total
74.00d
7
8
9
10
11
12
13
2.00d
20.00d
5.00d
4.00d
15.00d
2.00d
Scheduling the Geotechnical Activities
Primavera software is used to scheduling the geotechnical activities and the
dependency between various activities. These activities and their scheduling are
illustrated in the next Figure.
Cost Estimates
The materials and the activities costs of this project are calculated in
Dollars .
The table below shows each item and it’s cost .
Activity Name
Excavation
Back filling
Compaction and insulation
Concrete
Steel
Total cost
Cost in dollars
4800
4800
4065
87050
64000
164715