KTU CE 204 Construction Technology - Module 5

CONSTRUCTION
TECHNOLOGY
Module 5
Fr. Dr. Bennet Kuriakose
Department of Civil Engineering

Syllabus
Tall Buildings – Framed building – steel and concrete frame –
structural systems – erection of steel work – concrete framed
construction – formwork – construction, expansion joints
Vertical Transportation
Stairs – types – layout and planning
Elevators – types – terminology – passenger, service and
goods elevators – handling capacity – arrangement and
positioning of lifts
Escalators – features – use
Ramps
Department of Civil Engg., SJCET Palai 2

TALL BUILDINGS

Tall Buildings - History

Tall Buildings (High Rise Buildings)
• How to define? - there is not precise definition
• At present, tall or high-rise refers to buildings more than few
stories height.
• Emporis Standards defines a high-rise as "A multi-story
structure between 35–100 meters tall, or a building of
unknown height from 12–39 floors.“
• According to the building code of Hyderabad, a high-rise
building is one with four floors or more, or 15 to 18 meters or
more in height.
• Residential high-rise buildings are called „tower blocks‟ /
„MDUs‟ (Multi Dwelling Units) / flats
• Buildings with more than 50 storeys are at present known
as „sky-scrapers‟

Tall Buildings
Challenges
• A building is considered to be tall when the analysis and
design are affected by lateral loads (earthquake, wind etc.),
particularly the sway
• As the height of the building increases, wind plays more
effect.
• The material required for the buildings also increases as the
height is increased, i.e., it has to carry heavy lateral loads
• Tall buildings also brings challenges in geotechnical stability,
firefighting, HVAC systems, accident evacuation…

Tall Buildings
Characteristics of Tall Buildings
1. Building is heavy compared to normal buildings. The soil
properties need to be carefully considered.
2. Tall buildings are surrounded by low-rise podium structures
with lesser loads. This can induce differential settlement
3. Heavy lateral forces – especially wind loads
4. Wind induced vibration can induce fatigue problems.
5. Because of the vibrations, the tall buildings are designed for
dynamics loads
6. If the structure is made up of RCC, creep plays a major
effect
7. Serviceability also plays major effect as wind induced
vibrations will be very high

Structural Systems
Structural system indicates the way with which the building is
so planned that it efficiently handle the lateral loads.
1. Rigid frame structural system
– In rigid frame structure, beams and columns are
constructed monolithically – no rotation happens between
them

Structural Systems
– The lateral stiffness of a rigid frame depends on the
bending stiffness of the columns and beams
– Normally RCC buildings are built as rigid. However, it may
be used in steel construction as well, but the connections
will be costly.
– 20 to 25 storey buildings can be constructed using rigid
frame system.
– Advantages:
• ease of construction
• labors can learn construction skills easily
• construct rapidly
– Burj Al Khalifa which is the tallest structure in the world is
constructed using rigid frame system.

Structural Systems

Structural System
2. Braced Frame Structural System
– braced frames are cantilevered vertical trusses resisting
laterals loads primarily using diagonal members that
together with the girders, form the “web” of the vertical
truss, with the columns acting as the “chords‟‟.
– Bracing members eliminate bending moments developed
in beams and columns.
– used in steel construction
– This system is suitable for multistory building in the low to
mid height range.

Structural Systems

Structural Systems
– it can be repetitive up the height of the building with
obvious economy in design and fabrication.
– However, it might obstruct internal planning and the
location of doors and windows.

Structural Systems
3. Rigid Frame – Infill Wall System (Dual System)
– Infill walls are designed to provide an action similar to
bracings
– Rigid infill walls are provided wherever required in the
frame without openings. The other parts can be provided
with infill partitions.
– Rigid infills need to be provided on all storeys (no storey
can be missed), lest should have soft-storey failure
– Sometime this rigid infills are provided with steel
reinforcement
– Wall-frame system suitable for buildings with storey
number ranges from 40-60 storey

Structural Systems

Structural Systems
4. Rigid Frame – Shear Wall System
• It is a continuous vertical wall constructed from reinforced
concrete wall
• Shear walls withstand both gravity and lateral loads
• It is highly suitable for bracing tall buildings either reinforced
concrete or steel structure. This because shear walls have
substantial in plane stiffness and strength.
• Normally preferred to be provided around lift-well, stair-case
system.
• shear wall structural system can be economical up to 40
stories building structure.

Structural Systems

Structural Systems
5. Core and Outrigger System
• Outrigger are rigid horizontal structures designed to improve
building overturning stiffness and strength by connecting the
core or spine to closely spaced outer columns
• The central core contains shear walls or braced frames.
• Outrigger systems functions by tying together two structural
systems (core system and a perimeter system)
• Practically, Outrigger systems used for buildings up to 70
stories.
• Outrigger system resist the lateral forces very effectively

Structural Systems

Structural Systems
7. Tube System
• This system consists of exterior columns and beams that
create rigid frame, and interior part of the system which is
simple frame designed to support gravity loads.
• It is substantially economic and need half of material
required for the construction of ordinary framed buildings.
• It is used for the construction of buildings up to 60 storeys.
• Types of tube structure system include framed tube
system, trussed tube system, bundled tube system, and
tube in tube system
• massive loads.
• A tube-in-tube system (hull core) is obtained, if the core is
placed inside the tube frame structure.

Structural Systems

FRAMED CONSTRUCTION

Framed Buildings
• Framed structures are the structures having the combination of
slabs, beams and columns to resist the gravity and lateral
loads.
• This can handle heavy lateral loads
• Load path: Slabs  beams  columns  foundation
• Material: concrete or steel
• Tall buildings are always framed

Steel Frame
• The different components cut into required size is brought to
sight and joined.
• Joining – Bolting or Welding
• Advantages:
– Speed of construction
– Inherently ductile
– Does not disturb the surrounding amenities
– No formwork required for frames
• Types:
– Rolled Steel sections
– Light-gauge sections
– Built up
– Pre-engineered

Steel Frame

Steel Erection
• The process of steel structural construction at site is called
steel erection
• Major Tasks in steel erection:
1. Establishing a suitable foundation
2. Lifting and placing the components. (generally cranes
are employed.). To secure the components in place,
bolted connections / spot welds are made
3. Align the structure checking the level, plumb, inclination
4. Final bolting up / Final welding
• Cranes and MEWP (Mobile Elevating Work Platforms) are
used for erection purpose

Concrete Frame
• Types:
– In-situ frames (rigid type frames)
– Prefab (precast construction) frames (partial rigidity)
In-situ cast frame
• Considered to be rigid type frames as cast monolithically
• However, rigidity of joint will only be achieved if the
reinforcement of beam is developed into the column.

Concrete Frame
Prefab Frame
• The beam and column is precast and placed at sight.
• The columns will be equipped with „corbels‟ or „nibs‟
wherever the beams are to be supported.
• In order to have partial rigidity, the beam is connected with
corbel using vertical steel bars and the joint is grouted.

FORMWORK

Formwork (Shuttering)
• When concrete is fresh and in its liquid state it must be
restrained within a mould in order for it to set in its required
shape. Formwork is the term used to describe this mould.
• Formwork cost ~20% of cost for big structures
• Concrete is approximately 2.4 times as dense as water, and
in its liquid state, it imposes considerable forces on the
formwork containing it. Consequently it is necessary to
reinforce the formwork with stiffeners or wailings
• Formwork is eventually removed
after the required time.
• Removal of formwork is known as
stripping
• Stripped formwork can be reused

Formwork
Requirements of good formwork
1. Strong enough to withstand the weight and pressure from
concrete
2. Rigidly constructed to retain its shape upon loading
3. Joints should be tight against leakage of concrete matrix
4. Shall be easily stripped
5. Fixed firmly to the support (ground) so that no settlement
happens

Formwork
Formwork failures…

Parts of Formwork

Taxonomy of Formwork
A. Based on usage
1. Conventional Formworks
– Using timber of plywood
– Time consuming for large
concrete works
2. Flying Form
– Table-type of truss reinforced
forms, lifted to the required level
– Flying form of a whole storey can
be built and is often used for high-
rise buildings
– Increased Speed, efficiency and
accuracy

3. Slip Form (Jack Form)
– Concrete is continuously poured into
a continuously moving form (typically
300 mm / hour)
– Mould will be shallow, as the
concrete is set within, form is moved
up.
– Building silos, chimneys, core-walls
etc.
– Rapid hardening concrete is normally
employed
– A continuous finish is obtained
without cold joints
– Types: (a) Vertical (b) Horizontal
(c) Tapered

4. Prefabricated Formwork
– For preparation of prefabricated modules (ex: stairs,
columns, beams, bridge sections) of large in number.
– Prefabricated formwork for whole storey/house can be
made if it can be replicated several times
– Saves times and workmanship

B. Based on Materials
1. Timber
– Part of conventional formwork
– Can be cut into required size and
shape
2. Plywood
– 18 mm thick plywood is used for
normal applications
– Can be bend if required.
– Chances of bending – to be
stiffened
– Chance warping after continuous
reuseDepartment of Civil Engg., SJCET Palai 38

3. Steel formwork
– Used for all types of formworks –
conventional, slip, flying..
– Fine finish is obtained.
– Easily installed and stripped
– Inherently stiffer than timber
– Do not absorb moisture
4. Aluminium Formwork
– Normally used for prefabricated
type
– Strong and light
– Do not corrode

5. Plastic Formwork
– Glass fibre reinforced plastic
(GFRP) is commonly
employed
– Normally used for
prefabricated type form
– Moulded into required shape
– Will not corrode

Stripping of Formwork

PREFAB CONSTRUCTION

Prefab Construction
• Prefab/ Prefabricated / Precast/ Modular construction is a
method where, the components of the building or structure is
cast at factory, transported to the site and placed.
• Stages: Casting at factory  Curing (accelerated) 
Transportation (by heavy trucks)  erection
• Advantages:
1. Cost of formwork and scaffolding is reduced
2. Construction time is greatly reduced
3. Quality control can be assured – as built in factory
4. Bad weather and environment at site will not be an issue
5. Very thin sections can be cast with precision
6. Reduced redundancy – no much effect for differential
settlement, thermal strains, shrinkage etc.

Prefab Construction
• Disadvantages:
1. Transportation require good transportation and road
services
2. Members to be designed for extra load (handling load)
3. Heavy duty cranes required for erection
4. Lack of monolithic action – less integrity
5. Loss of redundancy – thus reduction is overall stiffness

JOINTS IN CONCRETE

Joints in Concrete Construction
• Buildings will have dimensional deviations due to various
factors (thermal expansion/contraction, differential settlement
etc.)
• Joints are provided to accommodate such differences
without affecting the strength and serviceability of the
building.
Types:
– Construction joints
– Expansion joints
– Contraction joints
– Isolation joints

1. Construction Joints
– Normally provided for ground supported slab (and not for
roof slabs or beams)
– Construction joints are placed in a concrete to define the
extent of the individual placements
– Construction joints must be designed in order to allow
displacements between both sides of the slab

– Types of construction joints:
• Butt-type
• Tongue and Groove type

• Butt with dowels
• Butt with ties

2. Expansion Joints
– To avoid thermal stresses developed in building,
pavement slab or bridges
– For building, one expansion joint is provided per 45 m
length.
– Expansion joints are sealed to avoid water percolation or
to prevent fine substances to fall off.

3. Contraction Joint
– Contraction joints are provided in concrete pavements,
slabs, walls, floors, dams, canal linings, bridge, retaining
walls etc.
– Provided to avoid shrinkage and thermal contraction
stresses
– Contraction joints are designed to develop cracks at the
joint on contraction

4. Isolation Joints
– Completely isolate a component (ex. Slab) from another
component (wall, column etc.)
– Provided to prevent the monolithic action (of two different
materials), thereby reducing the effect due to differential
settlement, thermal expansion etc.

VERTICAL TRANSPORTATION

Introduction
• The various systems that provide means to travel from
storey to storey of a building is known as vertical
transportation.
• Types:
– Stairs
– Ramps
– Elevators
– Paternoster
– Escalators
– Stairlifts

Stairs
• Series of steps arranged to connect floors
• The room or enclosure in which stair is located is called
staircase (stairway)
Components:

Stairs
• Tread: Upper horizontal portion of a
step. Foot is placed on the tread
• Riser: Vertical portion of the step
• Rise: vertical distance between two
successive tread faces
• Going (tread) : horizontal distance
between two successive riser faces
• Flight: series of steps without any
break. Not more than 12 steps in a
flight.
• Landing: Platform provided
between two flights of a stair

Stairs
• Waist: slab supporting stair (RCC)
• Nosing: projecting part of tread
beyond the face of riser
• Handrail: Inclined rail at convenient
height
• Baluster: vertical member
supporting rail
• Newel post: Vertical post placed at
the end of flights to connect the
ends of handrails

Taxonomy of Stairs
A. Based on Profile4
1. Straight Stairs
– (a) single flight (b) multiple flight

Taxonomy of Stairs
2. Quarter Turn (L-type)
– 90 degree turn between flights
3. Half Turn
– (a) dog-legged (b) open-newel (well)

Taxonomy of Stairs
4. Bifurcated stairs
5. Three-quarter turn stairs

Taxonomy of Stairs
6. Continuous Stairs
– No landing and no intermediate newel post
– (a) circular (b) spiral/ helical

Taxonomy of Stairs
B. Based on Material
1. Wood
2. Stone
3. Brick
4. RCC
5. Glass
6. Metal

Taxonomy of Stairs
C. Based on Structural Behaviour
1. Spanning Longitudinally
– Waist slab support on two landing or beam at ends of the
flight

Taxonomy of Stairs
2. Spanning Horizontally (laterally)
– The waist slab span will be in the horizontal direction.
– (a) cantilever (b) both side supported (c) centre supported

Taxonomy of Stairs
3. Folded Plate Stair
– act as a folded plate from one end of the flight to the other

Ramps
• Sloping surface connecting the floors at different levels.
• Facilitate mainly physically challenged people
• Also provided in public buildings for carrying luggage,
baggage etc.
• Provided for parking area for vehicle movement
• Types: (a) straight (b) doglegged (c) curved
• Slope should not be more than 1:15 for manual use (1:16 to
1:20 is preferred)

Ramps
• Slope more than 1:10 will hit vehicle bottom
• The surface of the ramps should be rough-finished
• Handrails are also provided.
• If landing is provided, same slope should be provided on
both flights.

Paternoster
• paternoster lift is a
passenger elevator which
consists of a chain of open
compartments (each usually
designed for two persons)
that move slowly in a loop up
and down inside a building
without stopping.
• Passengers can step on or off
at any floor they like.
• Now, sometime used for
transporting goods from one
floor to other

Elevator (Lift)
• Modified form of paternoster
• Single lift travel up and down – no circulation
• High-speed elevators are used in high-rise buildings which
travel from typical storey levels to other (not necessarily from
bottom floor and top floor – shuttle type)

Elevator Taxonomy
A. Based on Use
1. Passenger Elevators – used for
transportation of passenger
2. Goods Elevators – used for
transportation of goods within the
building
3. Construction Elevators –
temporarily for construction
materials and equipments
4. Service Elevators – for service
persons in a building (food, clothes
etc.)

Elevator Taxonomy
B. Based on Hoisting Operation
1. Hydraulic Elevators
– typically used in low-rise
applications (2-8 story buildings),
and move up and down via a piston
that supports the elevator cab from
the bottom.
2. Traction Elevators
– use ropes that pass over a wheel
attached to a motor that sits above
the elevator shaft. These elevators
are used for mid- to high-rise
applications due to their increased
speeds and maximum traveling
heights.

Elevator Taxonomy
3. Climbing Elevators
– have their own electric or combustion
engines mounted to them.
– Many construction lifts works in this
method
4. Pneumatic Elevators
– move their passenger cabs up and
down by controlling air pressure
within the elevator's chamber.
– This type of application could be
found in residential homes where a
pit and hoist-way would not be
feasible.

Escalators
• An escalator is a type of vertical transportation in the form of
a moving staircase which carries people between floors of a
building.
• It consists of a motor-driven chain of individually linked steps
on a track which cycle on a pair of tracks which keep them
horizontal.
• Escalators are used around the world in places where lifts
would be impractical.
• Advantages:
– Escalators have the capacity to move large numbers of
people.
– They can be placed in the same physical space as a
staircase.

Escalators
– They have no waiting interval (except
during very heavy traffic).
– They can be used to guide people
toward main exits or special exhibits.
– They may be weatherproofed for
outdoor use.
– A nonfunctional escalator can function
as a normal staircase, whereas many
other methods of transport become
useless when they break down or
lose power.

Escalators

Stairlifts
• Attached to the stairs to move differently able/ old people up
or down
• Attached with a chair or wheel chair can be attached.
• Used normally for homes or small apartments – not in public
building
• Can be easily attached to an existing stair case

KTU CE 204 Construction Technology - Module 5

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KTU CE 204 Construction Technology - Module 5