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ADDIS ABABA UNIVERSITY
DEPARTMENT OF CIVIL
ENGINEERING
CENG 3103
BUILDING CONSTRUCTION
Instructor – Abraham Assefa (Eng.) Nov. 2009
CEng 3103 – Building Construction
Course Outline
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1. Introduction 5. Building Construction Elements
Foundation and Basement
2. Building Drawings Floors
3. Building Structural Systems Exterior and Interior Closures:
Reinforced Concrete Structures Walls
Stairs
Steel Framed Structures
Elevators
Prefabricated Building Doors and Windows
Systems Roofs
Shell and Dome Structures Finishing
4. Planning of Buildings Damp – Prevention
Fire Places
5. Building Construction Formwork and Scaffolding
Elements Sanitary Systems
6. Health and Safety in Fire and Life Protection
Building Construction Mechanical Systems
Electrical Systems
CEng 3103 – Building Construction
Chapter 5 – Building Construction Elements
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Presentation Outline
5.1 Foundation and Basements
5.1.1 Introduction
5.1.2 Functions of Foundations
5.1.3 Essential Requirements of a Good Foundation
5.1.4 Types of Foundation
5.1.5 Site Investigation and Sub – Soil Exploration
5.1.6 Causes of Foundation Failures and Remedial Measures
5.1.7 Foundation Construction
Setting Out Foundation Trenches
Excavation and Timbering of Foundation
Excavations in Ground with Sub – Soil Water Problems
CEng 3103 – Building Construction
5.1.1 Introduction
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Buildings consist of Sub and Super Structure elements
Sub – Structure or Foundation – is the lower portion of the building,
usually located below ground level, and transmits the load of the
superstructure to the sub – soil
The soil which is located immediately below the base of the
foundation is called the Sub – Soil or Foundation Soil
Since it remains below ground level, the signs of failure of foundation
are not noticeable till it has already affected the building
A foundation should be sufficiently strong to prevent excessive
settlement as well as unequal settlement
Unequal Settlement - might be caused due to weak sub soil, shrinkable and
expansive soil, frost action ground water movement, excessive vibration,
consolidation settlement or slipping of strata
CEng 3103 – Building Construction
5.1.2 Functions of Foundations
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Foundations serve the following purpose:
1. Reduction of Load intensity
2. Even Distribution of Load
3. Provision of Level Surface
4. Lateral Stability
Against Sliding, and overturning due to Wind and EQ
5. Safety against undermining
Against undermining or scouring due to burrowing animals or
flood
6. Protection against soil movements
Special foundations to allow for sub – soil movements
CEng 3103 – Building Construction
5.1.3 Essential Requirements of a Good Foundation
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Foundation should be constructed to satisfy the following
requirements:
1. Foundations shall sustain and safely transmit the Dead and Live
Loads of the Superstructure, in a way that the pressure will not
cause settlement which would impair the stability of the
building or adjoining structures
2. Foundation shall be rigid to avoid differential settlement,
specially when the superstructure load is not evenly distributed
3. Foundations shall be sufficiently deep to guard against damage
or distress caused by swelling or shrinkage of the sub – soil
4. Foundations should be so located that its performance may not
be affected due to any unexpected future influence.
CEng 3103 – Building Construction
5.1.4 Types of Foundation
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Types of Foundations can be classified into two:
A. Shallow Foundation
Spread Footing, Combined Footings, Strap Footings and Mat
Foundation
B. Deep Foundation
Deep strip, rectangular or square footing, Pile Foundation, Pier or
Drilled Caisson Foundation, and Well or Caisson Foundation
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Shallow Foundation
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A. Shallow
Foundation
Spread
Footing,
Combined
Footings, Strap
Footings and
Mat Foundation
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Shallow Foundation
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A. 1 Spread Footing
Will spread the force over
a large area
There are different kinds:
Single Footing
Stepped Footing
Sloped Footing
Wall footing without step
Stepped footing for wall
Grillage foundation
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Shallow Foundation
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Wall footing without step
Stepped footing for wall
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Shallow Foundation
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Grillage foundation – Timber or Steel Stanchion carrying
heavy load in weak bearing capacity soils
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Shallow Foundation
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A. 2 Combined Footing
Support two or more
columns
There are different kinds:
Rectangular
Trapezoidal
Combined Column
Design Criterion – Center
of Gravity of Columns
shall coincide with the
centroid of the footing
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Shallow Foundation
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Combined Footing
for Columns and
Wall
Sometimes it may
be necessary to
provide a
combined footing
for columns and
wall
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Shallow Foundation
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A. 3 Strap/ Cantilever Footings
Strap Footing - If
independent footings of two
columns are connected by a
beam
When the distance
between the columns is wide
and with high bending
moments
Strap beam will not
transfer loads, it will be
assumed to be stiff enough
to result in uniform pressure
under each footing
Border Columns
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Shallow Foundation
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A. 4 Mat Foundation
Mat is combined footing that
covers the entire area beneath
a structure and supports all the
walls and columns.
Used when the bearing
capacity of the soil is low or
when there is a compressible
layer , erratic strata prone to
differential settlement
There are different types
Solid Slab
Beam Slab
Cellular System
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Deep Foundation
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B. Deep Foundation
Deep strip, rectangular or square footing, Pile
Foundation, Pier or Drilled Caisson Foundation, and Well
or Caisson Foundation
Strip, rectangular or square footings come under the
category of deep foundation, when the depth of the
foundation is more than the width of the footing
Well foundations are used in bridge piers
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Deep Foundation
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B. 1 Pile Foundation
Use vertical members made
of steel, timber or concrete
Use skin friction and end
bearing resistance
Adopted when
No firm bearing strata exists
in a reasonable depth
When pumping of sub – soil
water would be too costly or
timbering to excavations too
difficult
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Deep Foundation
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Types of Pile Foundation
End Bearing
Used for multistory buildings to
minimize settlement
Friction
Used in granular soil
Combined End bearing and
Friction pile
Compaction pile
Used to compact loose granular
soil
Don’t carry loads by themselves
and thus can be made of soft
materials
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Deep Foundation
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B. 2 Pier Foundation
Consists of a cylindrical
column of large diameter to
support and transfer large
loads
Difference with pile is method
of construction
Pier foundation uses only
bearing and has shallow depth
When there is a close hard
rock strata and stiff clay
Types
Masonry or Concrete Pier
Drilled Pier
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Deep Foundation
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Masonry or Concrete Pier
Used when a good
bearing stratum exists up to
5m below the ground level
Size and spacing of the
piers depends up on the
depth of hard bed, nature
of overlaying soil and
super imposed loads
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Deep Foundation
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Drilled Caissons or Foundation
piers or just piers
Denote cylindrical foundation
Is a compressed member
Are generally drilled with the
mechanical means
Three Types
Concrete caisson with enlarged
bottom
Caisson of Steel Pipe with
concrete fill
Caisson with concrete and steel
core in steel pipe
CEng 3103 – Building Construction
5.1.4 Types of Foundation – Deep Foundation
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B. 3 Well Foundation (Caissons)
Are box like circular or
rectangular structure which are
sunk from the surface either by
dead load or water to the
desired depth
Larger in diameter to pier or
drilled caissons
Used in bridge piers,
abutments in rivers and lakes,
docks, break water and other
shore structures, pump houses
and water front structures
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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Since foundation are to be based in sub – soils, sufficient
investigation of the sub – soils is a must
Sub – Soil Investigation is carried out for
New Structures
Selection of type and depth of foundation
Determination of Bearing Capacity
Prediction of settlement
Determination of Ground water level
Evaluation of earth pressure against walls, basements and abutments
Provision against construction difficulties
Suitability and degree of compaction of soil
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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Sub – Soil Investigation is carried out for
Existing Structures
Investigation of the safety of the structure
Prediction of Settlement
Determination of remedial measures – Unsafe structure or in case of
detrimental settlement
SITE RECONNAISSANCE
Inspection of the site and study on topographical
features is often helpful
Following features shall be studied: -
Local Topography, excavations, cuttings, quarries, evidence
of land slide, fills, water level and drainage patters
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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SITE EXPLORATION
Objective – to provide a reliable, specific and detailed
information about the soil and ground water conditions for
safe and economic design of foundations
Depth of Exploration
Depth (Significant Depth) shall be up to the level where the
pressure increase will cause settlement or shear failure of
foundations
Depends on the type of structure, its weight, size, shape and
disposition of loaded areas, and the soil profile and its properties
Assumed – One and Half to two times the width (smaller of the
lateral dimensions) of the loaded area
Directions
Isolated Spread Footings – 1.5 times the width
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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Directions
Adjacent footings with clear spacing less than twice the width – 1.5 times the
length
Pile Foundation – 10 to 30 m, or more, or at least 1.5 times the width of the
structure
Base of Retaining Wall – greater of 1.5 times the base width or 1.5 times
the exposed height
Floating Basement – Depth of Construction
Weathering Considerations – 1.5 m in general and 3.5 m in black cotton
soils
Min Depth – 1.5 m
Methods of Exploration
1. Open Excavation
2. Borings
3. Sub – Surface Soundings
4. Geo – Physical Methods
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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Methods of Exploration
1. Open Excavation
Trail pits are the cheapest
methods in shallow deposits
Advantages – Soil Strata
can be observed and samples
(disturbed or undisturbed) can
be conveniently taken
Suitable up to 3m depth
For greater depths and for
excavation below ground
water table, specially in
pervious soils, measures for
lateral support and ground
water lowering is necessary
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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Methods of Exploration
2. Boring Methods
Methods commonly used
Auger boring
Auger and Shell boring
Wash boring
Percussion boring
Rotary boring
A. Auger boring
Used in cohesive and other soft soils above
water table
Operate mechanically or manually
Hand augers are used up to 6m
Two types Spiral or Post Hole
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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2. Boring Methods
B. Auger and Shell boring
Cylindrical augers and shells with
cutting edges at lower end
Hand operated up to 25 m and
mechanized rigs up to 50 m
Suitable for soft to stiff clay, shells
for very stiff and hard clay, and
shells or sand pumps for sandy soils
Small boulders, thin soft strata or
rock or cemented gravel can be
broken by chisel bits attached to
drill rods
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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2. Boring Methods
C. Wash boring
Is fast and simple method for
advancing holes in all types of
soils (except for boulders and
rock)
Steps
Driving a casing with hollow
drilled rod with sharp chisel or
chopping bit
Forcing water under pressure
Resulting in Chopping and
jetting action
Forcing the cutting up ward
and reviewing the color of wash
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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2. Boring Methods
D. Percussion boring
Soil and rock formations are broken by repeated blows of heavy chisel
or bit suspended by a cable or drill rod
Water is added to the hole during boring
Suitable for advancing a hole in all types of soils, boulders and rock
E. Rotary Boring
Very fast method
A drill bit is rotated with firm contact to the bottom of the hole
A water solution of bentonite, with or without admixtures is continuously
forced down
The mud coming up wards bring the cuttings to the surface
Core Boring or Core Drilling – commercial diamond – studded bits
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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Record of Borings
Accurate and explicit
record of borings shall be
kept
Soils/Rock collected shall
be properly preserved
and arranged serially
according to the depth at
which they were found
Boring Chart
Site Plan showing location
of bores
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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3. Sub – Surface Soundings
Sounding methods consist of measuring the resistance of the soil
with depth by a means of PENETROMETER under static and
dynamic loading.
The penetrometer may consist of a sampling spoon, a cone or
other shaped tool.
The resistance to penetration is empirically correlated with some of
the engineering properties of soil, such as density index,
consistency, bearing capacity etc.
Used for general test by experts
Commonly used methods:
Standard Penetration Test
Cone Penetration Test
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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4. Geo – Physical
Methods
Geo Physical methods are used
when the depth of exploration is
very large, and also the speed of
investigation is of primary
importance
Were developed in connection
with prospecting of useful minerals
and oils
Methods
Gravitational Methods
Magnetic Methods
Seismic Refraction Method
Electrical Resistivity Methods
CEng 3103 – Building Construction
5.1.5 Site Investigation and Sub – Soil Exploration
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Choice of Exploration Soil Samplers
Methods Thick Wall
Nature of Ground
Thin Wall
Topography
Cost Mode of Operation
Soil Samples and Open Drive Sampler
Samplers Stationary Piston
Soil Samples Sampler
Disturbed Samples Rotary Sampler
Undisturbed Samples
CEng 3103 – Building Construction
5.1.6 Causes of Foundation Failures and Remedial Measures
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Foundations may fail due
to the following reasons:
Unequal Settlement of Sub
– Soil
Unequal Settlement of
Masonry
Sub – Soil moisture
movement
Lateral Pressure on Walls
Lateral Movement of Sub –
Soil
Weathering of Sub – Soil
due to trees and shrubs
Atmospheric Action
CEng 3103 – Building Construction
5.1.7 Foundation Construction
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Under Foundation Construction,
the following topics will be
reviewed;
Setting Out Foundation Trenches
Excavation and Timbering of
Foundation Trenches
Excavation in Ground with Sub –
Soil Water
A. Setting Out Foundation
Trenches
Is the process of laying down
the excavation lines and
center lines etc on the ground,
before excavation is started
Foundation Layout Plan
CEng 3103 – Building Construction
5.1.7 Foundation Construction
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B. Excavation and
Timbering of
Foundation Trenches
Excavation can be
done either manually
or with equipments
Manually
Equipments
CEng 3103 – Building Construction
5.1.7 Foundation Construction
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C. Timbering of Foundation Trenches
When the depth of trench is large,
or when the sub – soil is loose , the
sides of the trench may cave in
Timbering or Shoring consist of
providing timber planks or boards
and struts to give temporary support
to the sides of the trench
Methods:
Stay Bracing – Firm Soil & 2m
Box Sheeting – Loose Soil & 4m
Vertical Sheeting – Soft & 10 m
Runner System – Extremely Loose
Sheet Piling
CEng 3103 – Building Construction
5.1.7 Foundation Construction
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CEng 3103 – Building Construction
5.1.7 Foundation Construction
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D. Excavation in Ground
with Sub – Soil Water
High water table or
water logged area
Dewatering
Ditches and Sumps
Well Point System
Shallow Well System
Deep Well System
Vacuum Method
Electro – osmosis Method
CEng 3103 – Building Construction
5.1.7 Foundation Construction
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