Topic Today’s Objective Understand common forms of low-rise construction currently used for domestic and commercial buildings. Today’s Objective Identify and explain different forms of structure.

Topic Issue Assignment 1! Understand common forms of low-rise construction currently used for domestic and commercial buildings. Issue Assignment 1! Assignment Title Criterion covered Site Investigations, Foundation Design and Substructure P1, P2, P3, P4, M1, D1

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.

Types of structural systems List 5 examples of each.

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

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 What are they? Compression squashes Tension squashes Bending bends Shear cuts Torsion twists

A cantilever beam is supported at one end only. 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 Structures Why do we need to stabilise structures? So they won’t collapse

Stabilising Structures How do we stabilise structures? We need to analyse the forces then add additional members to counteract the forces.

Stabilising Structures To stabilise structure we use: Struts – in compression Ties – in tension Key word: Triangulation

Examples of triangulation in daily use

Stabilising Structures Structural members used in tension don’t need to be stiff

Stabilising Structures Consider 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 tension are called? Members in Compression are called?

Solid/ Mass Structure Walls carry out two functions. What are they? Provide support (being load bearing) 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

Solid/ Mass Structure These forms of construction can be divided into two types: - Cellular 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.

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.

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

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

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.

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?

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?

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.

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

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.

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.

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. ETFE