Contents Page
Introduction--------------------------------------------------------------------------3
Types of bridges------------------------------------------------------------------- 4
Suspension bridge---------------------------------------------------------------- 4-5
Beam bridge------------------------------------------------------------------------ 5
Arch bridge-------------------------------------------------------------------------- 6
Advantages and disadvantages of bridges--------------------------------- 7
Health and Safety Legislations ------------------------------------------------ 7
Conclusion--------------------------------------------------------------------------- 8
References/sources of information-------------------------------------------- 8
Introduction
Bridges are an arrangement made for crossing to provide passage in the areas where, we have problem of crossing from one side to the other side for example rivers, valleys railways or roads without closing the way beneath them. Bridges are built to provide passage for different purposes may be for road, pedestrian, a canal, a railway or pipeline.
Main purposes of bridges are for carrying the road traffics or other moving loads over a depression or obstruction for instance channels, roads or railways
Looking into types of bridges. To highlight their uses, where do they use, in what type of foundation each is best to be used and the purpose of using them for different distance in span. There are several types of bridges for example, Suspension Bridges, an Arch Bridges, Truss Bridges, Beam Bridges, Cable Stayed Bridges and Cantilever Bridges. Encyclopaedia Britannica Kids, (2012) “truss bridge: bridge” available at: http://kids.britannica.com/elementary/art-88577/There-are-six-basic-bridge-forms Accessed on: 14th December 2013
The main types of bridges that are commonly built: Suspension Bridges, an Arch Bridges and Beam Bridges. The reasons these been used more often, because they are more suitable for many type of foundation and can be cheaper in cost to build.
Types of Bridges
Introduction to the different types of bridges
Ø suspension bridge
Ø beam bridge
Ø arch bridge
Why do we build different types of bridges?
We use different types of bridges because each of different types can hold weight in different ways and the distance that they can cover in single span.
The three types of bridges are:
Suspension Bridge
Firstly, two tall towers are constructed in suspension bridge for the cables to be attached to it. Then huge cables are used to suspend the roadbed, which ranges from one end of the bridge to the other end. The cables are attached by two towers and also, secured by anchorages at the each end to enable the cables to hold the weight of the bridge. The cables which hold the load on suspended bridge to the anchorages at the each end are imbedded in a solid rock or in a huge concrete blocks
To resist bending and twisting, most suspension bridge use truss system beneath the roadway
The towers needs to be firmly imbedded in earth and the foundation must be well constructed to ensure it stand against the forces which cable transfer to tower and then carry forces directly into earth where they imbedded.
Beam Bridge
A beam bridge is a solid horizontal structure, which set on two supports and one placed at each end of the bridge. A simple beam bridge is flat across and supported by two ends.
Beam Bridge designed to stand against the forces that act on the beam when load put on the bridge. When load pressed down on the beam the top edge which is under compression pushes together and the bottom of the beam which is in tension tends to stretches. The structure of the beam is significantly vital and it needs to be extremely strong to ensure that it doesn't bend under the weight of itself and the added weight of the moving load like traffic, water, pedestrians or train passing over it.
Arch Bridges
An arch bridge is a horizontal curved structure which has an abutments on each end of it. The purpose of the abutments on each end is to keep the end of the bridge from spreading outward, because along the curve of the arch to the abutment is where the weight of the load is carried outward.
The main problem the arch bridge have is that, it is always under compression. This is because the load of the deck is pushed outward alongside the curve of the arch towards the abutments. When the curved arch is increased in high or rise it causes the vertical load to have a horizontal thrust.
Arch bridges have great natural of strength and have been around for thousands of years. In the past they were built with stone or brick, but in the modern world we use reinforced concrete or steel. Arch bridge can span up to 244 meter.
Advantages and Disadvantages
Types of bridges
Advantages
Disadvantages
· strong and can hold a lot of weight
· can span 2134 meters away than any other types of bridge
· can span long without creating flow restrictors beneath
· suitable for over wide rivers or valleys
· Some access below require during construction
· Expensive to built
· time
· useful for short span
· On the long distances the beams are placed on piers
· Strong and can hold a lot of weight, because now a days they are built of reinforced concrete with more support of piers
· Good for short span
· Always under tension
· Only span up to 77 meters in a single span
· Time
· Beam bridges are extremely expensive when long spans required due to the number of piers are required to hold long beam.
· More construction materials needed.
Arch Bridge
· Cheaper than other types, with local building materials such as stone and brick or reinforced concrete.
· Wider spans can be build
· Always under compression
· Span only 244 meters
· It use a lot of materials, even for short spans.
Health and Safety Legislation
Health, safety and welfare rules and regulation must be considered all the time, when undertaking any work on the site. Warning signs need to be posted around site to inform the surrounding area to inform people of what your activities on the site. The health, safety and welfare legislations are established and passed by the parliament to protect and reduce injuries and incident at work.
Site manager’s responsibility if to ensure everyone on the site follows the legislations and wearing personal protective equipment (PPE) at all the time, while they are on the site to avoid injuries and incident. Also, Site manager’s responsibility is to record any injuries or incident that happens on the site.
Project manager need to make regular visits to the site, to ensure everything on the site are following smoothly and accurately.
Bridges has helped us of providing passage from areas where, we have problem of crossing from one side to the other side for example rivers, valleys railways or roads.
Different types of bridges are used in civil engineering world for different purposes. Reasons for using different types of bridges, because each type can cover span in different distance and each can hold weight in different ways.
Bridges have been used for around thousands of years and they developed in time by time. Bridges have an essential role in our life for proving access from place to other places where is obstacle of crossing.
References and source of information
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