An-Najah Nationa UnuversityFaculty Of Engineering
Civil Engineering DepartmentNablus-Palestine
Foundation Design of Multy story building
Suprevisors:Dr.Sami Hijawwi
Perpared By:Asmaa Abed-Al Hadi Mardawi
Rasha EstewiMaysoon Sbeeh
2009-2010
Chapter One General definition of the
project
Our project is to foundation design of a residential
building which consists of seven stories.
Chapter two talks about literature review of
Foundations
It’s function is to transfer the load of the structure to the soil on which it’s resting.
A properly designed foundation transfers the load throughout the soil without overstressing the soil.
Thus, geotechnical and structural engineers who design foundations must evaluate the bearing capacity of the soil.
Depending on the structure and Depending on the structure and soil Characteristics, type of soil Characteristics, type of foundation is usedfoundation is used::
1-Raft or mat foundation
Mat foundation is a type of shallow foundation which is used if the soil layer near the ground surface has alow bearing capacity.
the column loads are so large that the sum of the areas of the isolated footings required to support the structure exceed 50%of the total area of the building .
2-Pile foundation
Piles are used to transmit the load to
underlying bedrock or a stronger soil layer.
Piles are used when the soil too weak,
when subjected to horizontal forces… etc,
the cost is more than shallow foundations.
Settlement of foundationSettlement of foundation
The settlement of a structural foundation consists of three parts:
1- Immediate settlement: takes place during application of the loading as a result of elastic deformation of the soil(no change in water content).
2- Consolidation settlement takes place as a result of volume reduction of the soil caused by extrusion of some of the pore water from the soil.
3- Creep or secondary settlement occurs over a very long period of years after completing the extrusion of excess pore water.
Figure below Settlement stages with time.
Chapter 3:Summary of laboratory Chapter 3:Summary of laboratory test resultstest results
Natural moisture content (N.M.C): ranges between 8% - 12.5%.
2 -Liquid limit (L.L): ranges between %31.9 - 50%.
3 -Plasticity index (P.I): ranges between 10.5% - 22%.
4 -Specific gravity = 2.72.5 -Allowable bearing capacity = 2.1
Kg/cm2.
Chapter 4:Chapter 4:Descriptions of loads Descriptions of loads building and its structurebuilding and its structure
The structural system of this building is typical one, consisting of slab, beams, and columns. The slabs are one-way in all floors.Descriptions of loads on the footingDead loadsLive loads
Chapter 5:Loads analysisChapter 5:Loads analysis
Column No.
Dimensionsm
Service loadton
Ultimate load ton
10.4*1.2196248
20.4*1.4452602
30.4*1.4565704
40.4*1.4693876
50.4*1.4292.5363
60.4*1.2194227
70.4*1.2337460
80.4*1.2352.5480
90.4*1.2354482
100.4*0.8309375
110.4*1.2336458
Column No.
Dimensionsm
Service loadton
Ultimate load ton
120.4*1.4559761
130.4*1.4331450
140.4*0.8236276
150.4*1.2319386
160.4*1.2319435
170.4*0.8213256
180.4*0.8140163
190.4*0.8461575
200.4*0.8409506
210.4*0.8216.5273
Chapter 6Chapter 6
Is the Basic part of this Is the Basic part of this project; it handles with the project; it handles with the analysis, design and analysis, design and settlement calculations of settlement calculations of mat, and pile foundationsmat, and pile foundations..
3-D Mat Foundation
Determine the depthDetermine the depth
To determine the depth of the mat we should take the critical loads and positions.
The depth of mat determined by the critical check which is punching shear check.
We found it =120 cm.
Settlement of mat foundationSettlement of mat foundation
from 2.4mm to maximum 33.5mm
Design of pile foundationDesign of pile foundation
1-Estimating pile capacity
The ultimate carrying capacity is equal to the sum of the ultimate resistance of the base of the pile and the ultimate skin friction over the embedded shaft length of the pile, this expressed by :
Qu = QS + QP
2-Determination of the point bearing capacity
For piles in saturated clay in undrained cohesion as our case , the point bearing capacity may be estimated as :
QP = 9 Cu Ap
3-Determination of skin resistance
The formula of skin resistance of the
pile can be expressed as:
QS =∑ {α *P*∆L*cu }
This table presents the proposed This table presents the proposed dimensions of piles and there dimensions of piles and there capacities in (KN)capacities in (KN)..
Diameter/length12 m15m
0.6274 KN236 KN
0.8382 KN384 KN
1499 KN499 KN
We choose Pile diameter 1m and the length was 15 m
Cap dimensionsCap dimensions
The minimum distance between two terraced piles is 3D.
Pile caps should extend at least 150 mm beyond
the outside face of exterior piles.The minimum thickness of pile cap above pile
heads is 300 mm.
The number of piles needed and cap The number of piles needed and cap dimensions are summarized in the table dimensions are summarized in the table belowbelow::
Column No.
Cap Dimensions(m)
No. of piles Pile Size (L,D)
14.4*4.4415*1))
27.4*7.4915*1))
310.4*7.41215*1))
44.4*19.41415*1))
57.4*4.4615*1))
64.4*4.4415*1))
77.4*5.5715*1))
810.4*4.4815*1))
910.4*4.4815*1))
107.4*4.4615*1))
117.4*5.5715*1))
Column No.
Cap Dimensions(m)
No.of pilesPile Size (L,D)
1210.4*7.412(15*1)
137.4*5.57(15*1)
145.5*5.55(15*1)
157.4*5.57(15*1)
167.4*5.57(15*1)
177.4*4.44(15*1)
183.5*5.53(15*1)
197.4*7.49(15*1)
2010.4*4.48(15*1)
214.4*4.49(15*1)
Reinforcement details of piles
The structural design for all piles is:
Pile diameter= 100cm.
Pile gross area=
( π/4()1002 =)7850 cm² .
As min = 0.005Ag = 0.005*7850 = 39.25cm²
Use 12Φ20 mm.
Reinforcement details of Reinforcement details of capscaps* Punching shear check:ФVc=Ф*1.06*√ fc*d*bo (kg,cm)
* Wide beam check: ФVc=Ф*0.93*√ fc*d*b (kg,cm) Ast =ρ * B*d
Settlement of pilesSettlement of piles
Elastic settlement for single pile
Se = Se(1) + Se(2) + Se(3)
Se1: Elastic settlement of pile.
Se2: Settlement of pile caused by the load at the pile tip.
Se3: Settlement of pile caused by the load transmitted along the pile shaft.
Elastic settlement of group of Elastic settlement of group of pilespiles::
Se = S * √(Bg / D)Se(rigid) = 0.93 * Se(elastic)
The following table presents the elastic settlement of group of piles
Length(m)Diameter(mm)
Se(elastic)(mm)
Se(rigid)(mm)
1512.852.65
Consolidation settlement of Consolidation settlement of pilespiles
This table summarized the results of calculation of consolidation settlement of piles:
Column No.
Service load (ton)
Cap dimension
Consolidation settlements of piles(mm)
14+17+212364.4*4.429
1+61964.4*4.425
8+935410.4*4.414
16+7+113377.4*5.521
133317.4*5.520
3+1256510.4*7.420
194617.4*4.425
2040910.4*4.415
24527.4*7.427
181403.5*5.522
52937.4*4.419
103097.4*4.419
153197.4*5.520
46934.4*19.463
Chapter Chapter 66
This Chapter aims to do some comparison ,quantities calculations, discusses the results of the project, and it gives recommendations of what are the proper and most economical type
of foundation for this building.
As a result of the previous analysis of the quantities of concrete and steel needed for the different types of foundation,, we recommend using mat footing instead of the pile footing. The following table summarizes the
comparison:
ComparisonPile footing Mat footing
settlement OK OK
Volume of concrete(m³)
1760 720.237
Weight of steel
8.89ton 0.85 ton/m
