foundation week3
TRANSCRIPT
-
7/30/2019 Foundation Week3
1/24
-
7/30/2019 Foundation Week3
2/24
2. FOUNDATIONS
By- Kokebe Yifru -Adama University Department of Civil Engineering & Arc- 20010/2011
-
7/30/2019 Foundation Week3
3/24
2. FOUNDATIONS2.1 Introduction2.1 Introduction| All engineered construction resting on the earth
must be carried by some kind of interfacingelement called a foundation.
| The foundation is the part of an engineeredsystem that transmits to, and into, theunderlying soil or rock the loads supported bythe foundation and its self-weight.
-
7/30/2019 Foundation Week3
4/24
2. FOUNDATIONS2.1 Introduction2.1 Introduction
| The term superstructure is commonlyused to describe the engineered part of the
system bringing load to the foundation, orsubstructure.
-
7/30/2019 Foundation Week3
5/24
2. FOUNDATIONS
A building has two basic parts A building has two basic parts|| SubSub --structurestructure|| SuperSuper --structurestructure
| A FOUNDATIONFOUNDATION is a part of a building whichis in direct contact with the ground to support
the weight of the building and other loads andtransmits the loads to underlying soil or rock.
What are the Loads on a building?What are the Loads on a building?
-
7/30/2019 Foundation Week3
6/24
2. FOUNDATIONS
-
7/30/2019 Foundation Week3
7/24
2.2 FUNCTION OF
FOUNDATION
-
7/30/2019 Foundation Week3
8/24
2.2 FUNCTION OF
FOUNDATIONFoundations have the following purposes:
1.
Even distribution of load of the structure over alarge bearing area so as to bring the intensity
of loading within the safe bearing capacity of the foundation soil .
2. To Load the bearing surface at a uniform rate soas to prevent unequal settlement
-
7/30/2019 Foundation Week3
9/24
2.2 FUNCTION OF
FOUNDATIONpurposes:-
3 . For Lateral stability of the structure
4. For Provision of level and firm bed
5. To Increases the stability of the structure asa whole.
-
7/30/2019 Foundation Week3
10/24
2.3 ESSENTIALREQUIREMENTS OF GOOD
FOUNDATION
-
7/30/2019 Foundation Week3
11/24
2.3 ESSENTIAL REQUIREMENTS OFGOOD FOUNDATION
Good Foundations:Good Foundations: --
1.1.
Shall be constructed toShall be constructed to Sustain the loadsSustain the loads
( dead & imposed ) and to( dead & imposed ) and to transmittransmit
to the subto the sub
soil safely.soil safely.
2.2.
The base shouldThe base should be rigidbe rigid to prevent differentialto prevent differentialsettlements.settlements.
-
7/30/2019 Foundation Week3
12/24
2.3 ESSENTIAL REQUIREMENTS OFGOOD FOUNDATION
Good Foundations:Good Foundations: --
3. Should be taken sufficiently deep to3. Should be taken sufficiently deep to guard theguard thebuildingbuilding
against damage or disaster caused byagainst damage or disaster caused by
swelling or shrinkage of the subswelling or shrinkage of the sub --soil.soil.
4. Should be erected in an exact position & well4. Should be erected in an exact position & well
built tobuilt to withstand unexpected naturalwithstand unexpected natural
calamitiescalamities ..
-
7/30/2019 Foundation Week3
13/24
2.3 ESSENTIAL REQUIREMENTS OFGOOD FOUNDATION CONT
The selection of foundation type depend onThe selection of foundation type depend on
a number of factors which include:a number of factors which include:
|| Nature of the soilNature of the soil|| Size and weight of the structureSize and weight of the structure|| Variation of ground water level Variation of ground water level
(due to season); and(due to season); and|| Building lawsBuilding laws
-
7/30/2019 Foundation Week3
14/24
2.4 TYPES OF FOUNDATION
-
7/30/2019 Foundation Week3
15/24
2.4 TYPES OF FOUNDATION
Foundations may be broadly classifiedFoundations may be broadly classified
|| Shallow foundations, andShallow foundations, and|| Deep foundations.Deep foundations.
|| A foundation A foundation isis ShallowShallow if its depth is equal to orif its depth is equal to orless than its width.less than its width.
|| Deep foundationsDeep foundations , the depth is greater than its, the depth is greater than itswidth. (width. ( TerzaghiTerzaghi ))
-
7/30/2019 Foundation Week3
16/24
-
7/30/2019 Foundation Week3
17/24
SHALLOW FOUNDATIONSSHALLOW FOUNDATIONS CONT..Type of SF from the design point of viewType of SF from the design point of view
1)1) CombinedCombined
footingfooting2)2) SpreadSpread
footingfooting
|| Strip Footing for wallStrip Footing for wall|| Pad FootingPad Footing --isolatedisolated
for columnfor column
3)3) StrapStrap footingfooting4)4) MatMat
foundationfoundation
-
7/30/2019 Foundation Week3
18/24
SHALLOW FOUNDATIONSSHALLOW FOUNDATIONS
CONT..1)1)
CombinedCombined
FootingFooting
Reinforced concrete combinedfootings carry more thanone column load .
Are often Rectangular or trapezoidal(for unequal load) in plan view.
1)1)
Combined footingCombined footing
-
7/30/2019 Foundation Week3
19/24
SHALLOW FOUNDATIONSSHALLOW FOUNDATIONS CONT..
2)2) SpreadSpread
footingfooting
(open trench foundation)(open trench foundation)
a)a)
Strip Footing for wallStrip Footing for wall| Used for load-bearing walls.| Are usually long reinforcedconcrete members of uniformwidth and shallow depth.
-
7/30/2019 Foundation Week3
20/24
SHALLOW FOUNDATIONSSHALLOW FOUNDATIONS CONT..
2)2) SpreadSpread
footingfooting
b) Pad Footingb) Pad Footing --isolated for columnisolated for column| ~ Spread footings are often square in plan view,
are of uniform reinforced concrete thickness, and
are used to support a single column load locateddirectly in the center of the footing.
-
7/30/2019 Foundation Week3
21/24
SHALLOW FOUNDATIONSSHALLOW FOUNDATIONS CONT..
3) Strap3) Strap
footing (cantilever footing)footing (cantilever footing)
If two independent footings of twocolumns are connected by a beam| May be used where the distanceb/n
the columns is so great that
a combined footing is not used.| And, Near property lineN.B-
strap beam does not remain in
Contact with soil. But, serve to transferthe column loads with equal and uniformsoil pressure under both footings.
-
7/30/2019 Foundation Week3
22/24
SHALLOW FOUNDATIONSSHALLOW FOUNDATIONS
CONT..
4)4) MatMat
foundationfoundation| A large and thick reinforced
concrete foundation, often of uniform thickness, that isContinuous and supports
the entire structure.
| Suitable where the ground
conditions are very poor andbearing capacity of the soil is
so low that individual spread
footings can not be provided.
-
7/30/2019 Foundation Week3
23/24
FOUNDATIONSFOUNDATIONS
Assignment
1. Name the different types of foundations you
recommend under different situations and thesoil. Explain them briefly. (max 10 pages)
Summary
By Group 2
-
7/30/2019 Foundation Week3
24/24
Thank You!!