Transcript Unit 6_Blg Tech_2 File

Topic
Understand common forms of low-rise construction currently used for
domestic and commercial buildings.
Today’s Objective
1. Identify and explain different forms of structure.
Unit 6: Building Technology in Construction
Types of structural systems
What are the three main types of structural systems?
•Mass
•Frame
•Shell
These can be either man-made or natural.
List 5 examples of each.
Unit 6: Building Technology in Construction
Types of structural systems
List 5 examples of each.
Unit 6: Building Technology in Construction
Types of structural systems
All structures do one or more of three things. What are they?
• Support to hold something upright and steady
• Span a distance or reach across a gap
• Contain or protect something
Unit 6: Building Technology in Construction
Structures
Structures are built to support a load.
The load may be static or dynamic.
Many structures need to be designed to withstand dynamic loads
even though they spend most of the time supporting static loads..
Why?
Unit 6: Building Technology in Construction
Forces – Five basic types
What are they?
Compression
squashes
Tension
squashes
Shear
cuts
Torsion
twists
Bending
bends
Unit 6: Building Technology in Construction
Beams
Beams are usually supported at both ends. What happens to the top
when it bends? What happens to the bottom of the beam?
A cantilever beam is supported at one end only.
What happens to the top when it bends? What happens to the bottom
of the beam?
Unit 6: Building Technology in Construction
Beams
Beams take many different forms. Can you list different 5 types
They must be used so the widest section takes the load.
Unit 6: Building Technology in Construction
The Challenge
Using one piece of A4 paper construct a beam that will hold a
£1 coin as far out as possible from the table edge.
Materials: one piece of A4 paper
Use a ruler to measure the distance from the table edge
Unit 6: Building Technology in Construction
Stabilising Structures
Why do we need to stabilise structures?
So they won’t collapse
Unit 6: Building Technology in Construction
Stabilising Structures
How do we stabilise structures?
We need to analyse the forces then add
additional members to counteract the forces.
Unit 6: Building Technology in Construction
Stabilising Structures
To stabilise structure we use:
Struts – in compression
Ties – in tension
Key word: Triangulation
Unit 6: Building Technology in Construction
Triangulation
Examples of triangulation in daily use
Unit 6: Building Technology in Construction
Stabilising Structures
Structural members used in tension don’t
need to be stiff
Unit 6: Building Technology in Construction
Stabilising Structures
Consider the different forces on this swing
The bolts supporting the chains are in shear.
Members in tension
are called?
Members in
Compression
are called?
Each part has to be designed to cope with the particular
force acting on it
Unit 6: Building Technology in Construction
Solid/ Mass Structure
Walls carry out two functions. What are they?
1. Provide support (being load bearing)
2. Provide protection ( by means of the external envelope)
What types of building would solid structures be used in?
• For low to medium rise buildings where the
floor areas are not too large.
What materials might be used to build a solid
structure?
• Brickwork
• Block work
• Stonework
• Mass concrete
Unit 6: Building Technology in Construction
Solid/ Mass Structure
These forms of construction can be divided
into two types: 1. Cellular
2. Cross Wall
Cellular Wall Construction
How does this work?
The internal and external walls form cells,
which are the rooms of the building.
This produces a rigid, stable and load
sharing structure.
This is typical of traditional construction.
Unit 6: Building Technology in Construction
Solid/ Mass Structure
Cross Wall Construction
How does this work?
• A series of independent load bearing
walls, known as cross walls, are built
parallel to each other and at right
angles to the front of the building.
• The separating walls carry the loads
whereas the front and back do not so
these can be of light construction
known as curtain walls.
• To make sure that the structure is
stable the floors are rigidly tied to the
cross walls, thus forming a box-like
structure.
Unit 6: Building Technology in Construction
Solid/ Mass Structure
Monolithic Structures
How do they work?
They use concrete as a medium for carrying structural
loads.
They are cast in-situ and are commonly reinforced
concrete.
The walls and in some cases the floors are cast at the
same time, which increases the structural stability of the
building.
Common applications are blocks of flats
Unit 6: Building Technology in Construction
Solid/ Mass Structure
Traditional building methods
Key term: Monolithic Walls
Single structural elements that form the basis of the building. Typically, walls and
floors are monolithic because they support the loads in one direction.
In situ
Building each component on site
Unit 6: Building Technology in Construction
Framed Structure
A framed structure consists of an
interconnected framework of members
having a supporting function.
The protecting external envelope is provided
by cladding or infill walls.
Frames are made from steel, concrete or
timber, which are simply and quickly erected
on site.
Can you give me an example?
Unit 6: Building Technology in Construction
Framed Structure
Framed structures are also known as skeletal or skeleton
construction.
Support is provided by an interconnected framework of members.
Cladding applied to the outside of the framework or infill walls built
between provide protection.
Framed structures are used for a wide range of low to high rise
buildings.
Unit 6: Building Technology in Construction
Framed Structure
The framework may be produced in a
factory for easy and quick assembly on site
using steel, timber or pre-cast concrete.
An alternative is to use cast insitu concrete
for the framework, but formwork is required
to support and shape the wet concrete.
There are three main types of framed
construction .
What are they?
• rectangular
• triangulated
• portal.
Unit 6: Building Technology in Construction
Framed Structure
Rectangular framework
This is the most commonly used form of framed
construction.
It consists of a series of vertical supporting
members, known as columns, which are spaced
apart and tied together by horizontal spanning
members, known as beams.
The framework produced supports the floors, walls
and roof.
What materials could be used for the frame?
Unit 6: Building Technology in Construction
Framed Structure
Triangulated framework
This is a framework that has been
triangulated or based on the shape of a
triangle and it provides a very rigid
structure.
Examples of this framework would be a
trussed rafter in a pitched roof construction
and the grid structure used for large spans
in industrial units
What materials could be used for the frame?
Unit 6: Building Technology in Construction
Framed Structure
Portal frame
These structures have no internal columns
which allow clear internal floor areas and
high storey heights.
The frames may be used alongside each
other to form multi-bay construction.
This consists of a supporting column and
roof beam, rigidly joined together to form
one continuous structural member.
Unit 6: Building Technology in Construction
Framed Structure
Portal framework
They are normally used in pairs bolted
together at their apex.
Portals are spaced and tied by horizontal
members, which also serve as fixing points
for the roof sheeting and wall cladding.
What building types would use portal
frames?
•Warehouses
•Factory units
•Manufacturing plants
Unit 6: Building Technology in Construction
Framed Structure
Shed Structures
Similar to portal frames as they form large
clear internal floor areas, however they
differ in that the span between members is
filled by either braced girders or roof
trusses.
Applications are similar to portal frames
Unit 6: Building Technology in Construction
Surface Structure
These consist of either a thin lightweight material that has been curved or
folded to obtain the necessary strength, or a very thin material that is stretched
over supporting members or medium.
There is a wide variety of forms including shells, vaults, bent or folded plates,
tents and air-supported structures.
Surface structures are commonly made from, timber, concrete, steel, plastic,
canvas or rubber.
Unit 6: Building Technology in Construction
Surface Structure
Shell Roof
These are normally formed using either
cast insitu concrete, or two or three layers
of timber boards.
Because of their lightweight mainly selfsupporting nature, shells are suitable for
large clear spans with the minimum of
supporting structure.
Unit 6: Building Technology in Construction
Surface Structure
Air supported structure
These consist of either a complete skin
which is sealed at ground level and
supported from the inside by compressed
air using an airlock entry system or
alternatively inflated tubes acting as
supporting ribs may be incorporated into
the skin.
These structures are used for warehouses,
sports complexes and exhibition areas.
Unit 6: Building Technology in Construction