unit 6: building technology in construction topic understand common forms of low-rise construction...

Unit 6: Building Technology in Construction

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.


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.



List 5 examples of each.



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


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?


Forces – Five basic types

Compressionsquashes

Tensionsquashes

Bendingbends

Shearcuts

Torsiontwists

What are they?


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?


Beams

Beams take many different forms. Can you list different 5 types

They must be used so the widest section takes the load.


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


Stabilising StructuresWhy do we need to stabilise structures?

So they won’t collapse


Stabilising StructuresHow do we stabilise structures?

We need to analyse the forces then add additional members to counteract the forces.


Stabilising StructuresTo stabilise structure we use:

Struts – in compressionTies – in tension

Key word: Triangulation


TriangulationExamples of triangulation in daily use


Stabilising StructuresStructural members used in tension don’t

need to be stiff


Stabilising StructuresConsider the different forces on this swing

Each part has to be designed to cope with the particular force acting on it

The bolts supporting the chains are in shear.

Members in Compressionare called?

Members in tensionare called?


Solid/ Mass StructureWalls 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


Cellular Wall ConstructionHow does this work?

Solid/ Mass Structure

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.

These forms of construction can be divided into two types: -1.Cellular2.Cross Wall


• 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.


Cross Wall ConstructionHow does this work?


Monolithic StructuresHow 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



Key term: Monolithic WallsSingle structural elements that form the basis of the building. Typically, walls and floors are monolithic because they support the loads in one direction.

In situBuilding each component on site


Traditional building methods


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?


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.


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.


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.

Framed Structure

What materials could be used for the frame?


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

Framed Structure

What materials could be used for the frame?


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.

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

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

Framed 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.

Surface Structure


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 self-supporting nature, shells are suitable for large clear spans with the minimum of supporting 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.

Surface Structure

unit 6: building technology in construction topic understand common forms of low-rise construction...

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