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