Research Task: West Gate BridgeAssessment Task 1 –  Civil StructuresContributor(s): James Kinsella –  2018 HSC Engineering StudiesSchool: Parramatta Marist High SchoolDate of Publication: 5th   December, 2017Table  of ContentsAppendix A ……………………………………………………………………………11Appendix B ……………………………………………………………………………..11Appendix C……………………………………………………………………………1..2Glossary of Terms……………………………………………………………………………. 13References/Bibliography Select a bridge from the local area and research and detail the historicaldevelopment of the bridge.  Include any facts about the bridge that may be of importance. (Load ratings, historical significance, major upgrades, etc.).SummaryThe West Gate Bridge is a steel cable-stayed bridge in Melbourne, Australia. It spans from the Yarra River, to just north Port Phillip, and is essential as it creates a link between the inner city, Melbourne’s western suburbs, and with the city of Geelong. The main river has a span of 336 metres in length and the height of the bridge from the water is 58 metres. The total length of the bridge is 2,582.6 metres which is the 3rd longest in Australia behind the 3.2-kilometre Macleay River bridge and the Houghton Highway along with the bridge which is considered its “twin” the Ted Smout Memorial Bridge, and is twice as long as the Sydney Harbour Bridge. It is one of the highest bridges in Australia and is right behind the Sydney Harbour Bridge in height. The bridge passes over Westgate Park, a large environmental and recreational reserve created during the bridge’s construction. The bridge carries up to 200,000 vehicles per day. Two years into the construction of the bridge, on the 15th of October 1970, the 112m section between piers 10 and 11 collapsed and fell 50 metres to the ground and water below. Thirty-five construction workers were killed and 18 injured, and still to this day it is Australia’s worst industrial accident. Flint & Neill is a UK based firm of consulting civil and structural engineers and their involvement with the West Gate Bridge starts back in the 70’s at the recommencement of construction, which was a result of a tragic collapse during construction, it was appointed by Redpath Dorman Long to develop a re-erection scheme for the bridge. After a major redesign and a long successful construction, the bridge finally opened in 1978. The bridge was originally built with four lanes of traffic in each direction, and before the upgrade was carrying 160,000 vehicles per day and in need of extra capacity. Even with the existing four lanes of traffic it required an upgrade to 5 lanes, as part of a contract between the State of Victoria, Transurban Infrastructure Management Ltd and Citylink Melbourne Ltd, to join the M1. The upgrade was undertaken by ‘Flint & Neil” in which they had major responsibility for the assessment and strengthening design for the steel bridge, also providing advice when inspecting, operations and maintenance. While also helping with the early designs for improved access. Following a royal commission Construction resumed in 1972, with the bridge being completed in 1978. After 10 years of construction, the bridge, a part of the larger West Gate Freeway, cost $202 million. the bridge was built to carry 40,000 vehicles a day, but volumes are now more than four times the original amount, approximately 160,000 vehicles on an average day. So, there will be another upgrade scheduled soon. Indicate the type of bridge design(s) utilised in the construction of the bridge and detail the origins of that design.Type of bridge DesignThe West Gate Bridge design type is a cable stayed bridge designed by flint Flint & Neill which is a UK based firm of consulting civil and structural engineers. Flint & Neill was established as an engineering consultancy in 1958 and specializes mainly in the design, analysis and building of bridges. OverviewA cable stayed bridge has one or more towers (or pylons), from which cables support the bridge deck. A distinctive feature are the cables which run directly from the tower to the deck, normally forming a fan-like pattern or a series of parallel lines. This is in contrast to the modern suspension bridge, where the cables supporting the deck are suspended vertically from the main cable, anchored at both ends of the bridge and providing support between the  towers.Important ComponentsTake photographs obtained from a site visit of important components ofthe bridge (piers, deck, abutments, etc.).Labelled diagram Stay Cables:The stay cables utilised in the West Gates Bridge structure were constructed from multiple steel wire strands surrounded by a black polyethylene sheath supplied by Flint & Neil. Each  individual  wire strand  was 15.7mm  in  diameter and consisted upon a minimum of seven galvanised steel wires waxed and covered in polyethylene. Polyethylene is an economical and no maintenance corrosion protection material which was cleverly used in the West Gates Bridge Bridge’s construction to prevent corrosion and increase durability.The West Gate Bridge is 2.5km long and is made up of three different structural types: a) composite steel beam and concrete deck approach spans b) pre-stressed concrete box girder viaducts c) Central, cable-stayed steel box girder with orthotropic steel deck section.General Features of the Design:the Melbourne Harbor Trust required a clear width of 304.8m between piers across the river Yarra and a minimum vertical clearance of 51.816m over a 182.88m width. A cable stay and supporting towers in a single vertical plane on the centre line of the bridge, this allowed the bridge to span 2582m because cable stayed bridges have one of the longest possible distance due to its lighter weight. The cables were designed as a trapezoidal box section from the girder with two internal vertical webs, the careful control of steel quality and construction techniques to avoid brittleness in the steal. These safety measures include limiting the thickness of the steel plates and avoidance when possible of transverse welds across  plating subject to tensile stresses. The West Gate bridge was assembled in different parts of panels into the units, called boxes. In the bridge each box was 16.03248 long by 12.77112m wide. Two  such boxes made to opposite hand comprised the full cross-section of the box girder, 25.48128ms wide at the upper flange(flat rim). The use of high strength friction grip bolts for all connections other than those made in the fabrication shop. This also included all the connections in assembling each box as well as all site connections between boxes. When paired with the use of reinforced concrete road deck made to increase the safety properties when connected with the upper flange plate by the use of stud type shear connectors welded to the upper flange plate. The use of a cantilever bracket from the main box girder to extend the overall width of the road, in this case to 34.1376ms overall.Structural Arrangement: The transition curves of the approach viaducts are carried over on to the steel bridge. The actual transition length is from the end up to the joint between boxes 15 and 16, the super elevation of the dock being gradually reduce until the length is at 0. The West Gate Bridge had to incorporate a way of drainage so the build-up of water does not affect the flow of traffic. The boxes on the concave side of the curve has a slight but constant deck curve for drainage purposes, the boxes on the convex side has cross slopes to aid in the quick drainage of the bridge. One of the features of the box girder in the west gate bridge is the relatively thin plates which can be used for the flanges. Such thin plates stabilise the bridge against buckling in compression by the addition of suitable system of stiffeners(Stiffeners are secondary plates or sections which are attached to beam webs or flanges to stiffen them against out of plane deformations).  In the West Gate Bridge it was intended that for the service condition of the concrete deck slab, made to act compositely with the upper flange plating, this contribution significantly helped with stabilisation of the plating. The process of pre-forming was used all over the west gate bridge, the stages of the pre-forming of the concrete were hindered by the by the need to provide steel stiffening ribs sufficient to stabilising those parts of the upper flange which were in compression. It was the failure of the stiffening panels on top of the flange which led to the collapse. The thinnest plating used in the west gate bridge were 1.5ms to 5ms, which was used on the intermediate transvers diaphragms. When the principal dimensions of the bridge had been established and the tender design carried out, in mid-1976 it appears that no serious regard  was given to the many problems that were arising. This is due to the upper flanges crippling under the forces that are acting upon it. Origins of  Cable Stayed BridgeThe modern cable stayed bridges that are present in today’s society were developed after the Second World War and were not entirely a new concept as it was incorporated into some early model suspension bridges such as the Dryburgh Abbey Footbridge (1817) footbridge, The Albert Bridge, London (1873) and the Brooklyn Bridge, New York (1883) to give the deck rigidity. In the twentieth century, early examples of cable -stayed bridges included A. Gisclard’s Cassagnes Bridge (1899) and G. Leinekugel le Coq’s bridge at Lezarddeux in Brittan·(1924). In both bridges the horizontal part of the cable forces is a separate horizontal tie cable, preventing significant compression in the deck.However, it wasn’t till the 1950’s that the first modern cable stayed bridges were built. Two German designers, Franz Dischinger and Fritz Leonhardt, working independently, built the first modern cable stayed bridges: Stromsund Bridge, Sweden (1955) with a 183 metre span and Dusseldorf Bridge, Germany (1957)with a 260 metre span respectively. Thesebridges utilised very few stay cables compared to bridges in today’s society such as the West Gate  Bridge, due to lack of development in materials in the 1950 period. Modern / cable stayed bridge structures tend to use many more cables in order to span the bridge. longer and wider to ensure greater economyMaterials used in the making of the West Gate Bridge:Indicate what type of materials for which the bridge was constructed and discuss reasons why these particular materials were used in this instance.Material  1 – SteelProperties: The most important properties of steel are great formability  and  durability, good  tensile  and yield strength and good thermal conductivity. As well as these important properties one of the  most significant characteristic of steel properties is its resistance to corrosion.Implications within the West Gate Bridge: Each individual cable stay strand is made with high tensile and yield strength steel, meaning that as the bridge is subject to strong tensile forces, and the stay cables are able to resist the force. The really good thermal conductivity property is not necessarily important within the bridges structure as heat is not transferred through the cables. However, steels durability  and  resistance  allows the bridge’s structure  to be very strong and last for years to come.Environmental impacts:  Steel production has a number of impacts on the environment, including air emissions, wastewater contaminants, hazardous wastes, and solid wastes. All of the greenhouse gas emissions associated with steel production are from the carbon dioxide emissions related to energy consumption  which directly relates to climate change.Material 2 – ConcreteProperties : Concrete has a relatively high compressive strength, but significantly lower tensile strength, and  as such is usually reinforced with materials that are strong in tension (often steel). The elasticity of concrete is relatively constant at low stress levels but  startsdecreasing at higher stress levels as matrix cracking develops. Concrete  has a very low coefficient of thermal expansion, and as it matures concrete shrinks. All concrete structures will crack to some extent, due  to shrinkage and tension.Implications within the West Gate Bridge: Both the deck and the towers of the West Gate Bridge are in compression and hence require a high compressive strength material such as concrete to utilize in the structure. Since elasticity is low therefore the bridge is rarely ever subject to any stretching and the bridge’s structure is very solid. Furthermore concretes low Thermal expansion levels means that the bridge has a tendency to not change in shape, area, and volume in response to a change in temperature, through heat transfer.Material 3 – PolyethyleneProperties: Polyethylene is of low strength, hardness and rigidity, but has a high ductility and impact strength as well as low friction. It shows strong creep under persistent force, which can be reduced by addition of short fibres. It feels waxy when touched. Implications within the West Gate Bridge: The stay cables utilized in the West Gate Bridge structure were constructed from  multiple steel  wire strands surrounded by a black  polyethylene sheath supplied  by Flint & Neil. Each individual wire strand was covered in polyethylene as it is an economical and  no maintenance corrosion  protection material which was cleverly used in the Gate Bridge construction to prevent corrosion and increase durability, resulting  in the bridge lasting for  years more to come.Environmental impacts: The fact that polyethylene is durable means it degrades slowly. In addition, burning polyethylene can sometimes result in toxic fumes. Aside from trying to get rid of plastic, creating it can be costly to the environment as well. It takes large amounts of chemical pollutants to createDescribe the effects that the construction of this bridge has had on thequality of local people’s lives both past and present.Describe the effects that the construction of this bridge has had on the quality of local people’s lives both past and present.Influences: PastThe cost to the population to build this bridge was $371 million which servilely impacted the Australian tax payer. At the time of construction, the West Gate Bridge help create thousands of jobs but the public support for the project was soon diminished, after the collapse. The collapse killed 35 workers and injured 218 others, having a wide effect on the community.  It created a way for the population to cross the mouth of port Phillip faster, with the total bridge span of 2.5km the normal trip would have taken just over 5mins.  Influences: PresentThe West Gate Bridge is planned for another major development. The West Gate Tunnel Project give Melbourne a much needed major second river crossing. It will provide an alternative route from the West Gate Freeway to the CBD, making it easier to get to workplaces, universities and hospitals in the city north. The project will slash congestion and travel times, take trucks off residential in the inner west and create thousands of jobs. The West Gate Bridge has created many jobs for the population of Melbourne and has given access to many more commuters AppendixAppendix 1: Stresses on  a Cable Stayed BridgeCritically analyse the photographs for example; stresses, material choice,corrosion protection, etc.?Appendix 2: Statistics of the West Gate Bridge Clearance Height of the west gate bridge Melbourne: 58m Pylon height of the west gate bridge Melbourne: 102m  Length of the west gate bridge Melbourne: 2,582.6MLongest span: 173m Opened: 16th of August 1999


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