Structural members in concrete bridges and highway - Essay Example

? and Section # of The report signifies the importance of highways and bridges in everyday life of humans. It also explains the various basic elements used in the making of the structure along with the phases the whole project goes through. Furthermore, various examples of successful and failed structure are explained in the report to show the significance of the design and importance of a bridge or a highway. The report covers all the factors involved in making this modern era masterpiece. INTRODUCTION Mankind has always been on the lookout for different means and methods to make sure that its existence on the earth is one with freedom of movement and comfort. The first tool was invented for the very same purpose; also the wheel was one such invention adding to the comfort and time-saving of the human race. Bridges and highways are two such inventions, which have basically added more life to the human age by reducing their time traveling in cars from one place to another. The revolution of highway networks and over-head and over-water bridges have made sure that the time spent on actual work is more than the time spent travelling like in olden days. The report will stress on the significance of these two inventions and different aspects of them which are an essential part of their existence. LITERATURE REVIEW Various literatures have been published in relation with this report. Engineering skills have always been under study as it is an ever evolving subject. Various books had to be studied as a lot of research was needed t fulfill the requirements of the report. Many publications were also linked to find out the modern methods and components used in the building of bridges and highways. The knowledge of components like beams and columns were studied using previous case studies. The examples of bridges and highways which have stamped their existence in the human history had to be found using newspaper publications as modern wonders have not a lot of books written about them yet! The best literature for the report was case studies of failed bridges and highways which gave an insight on the reasons of design failure and the further corrections made due to the failed component or design. CORE MEMBERS There are many elements that have to be understood before the structure of any structure like a bridge or a whole highway can be comprehended. Engineering laws are always based on key elements. Some key elements of both the structures will be explained quite extensively along with the types of bridges which have these elements present in them. Some of those key elements are: Beam This element in the bridge is the horizontal structure which withstands vertical weight known as bending for example gravitational load or load due to wind. Beams in bridges can either be made of reinforced concrete, steel or wood. Any type of beam can be categorized by their profiling. Some of the examples of beams are I-Beam, T-Beam and box beam. Column Column is known to be the vertical structure designed for carrying lateral weight. It is one of the most important components of the bridge. This is the first portion of any bridge that has to be built. The horizontal weights like slabs and beams are placed once the column has been constructed. Foundation Foundation is the lowest layer of support of a structure. It can either be deep or shallow. This is usually the first part of the design when the project is being planned. The phases or implementation will be later discussed in the report. The foundation is the component of the structure which holds the columns on which the beams lie. Therefore it can easily be said that a solid foundation, which has holding capability is the one which is best for any kind of bridge, otherwise the structure can be massively damaged causing human and financial loss. Types of Bridges There are various types of bridges that have been developed over the period of time, when the human brain has evolved with experience in engineering designs. The types of bridges can although be generally described ways they are designed. Some of them will be explained for better understanding of this research paper. Beam Bridge A beam bridge, in layman terms, can be explained like a plank on top of two columns. The modern beam bridge is however far more superior in design and engineering complexity. Modern beams made of either slabs or steel are connected over a number of columns to complete a bridge. Under load conditions, the top surface of this kind of bridge are compressed where as the lower surface faces the force known as tension. The bridge is stabilized by using the compensation of these two forces to each other. Arch Bridge This is generally a bridge which has an abutment at both ends and is in shape of an arch. The weight is distributed mainly at the end of the bridge here the abutment is situated. It is mostly an old design which was used by the Greeks. The bridge is generally small in length, but there are some examples where the long arch bridges have been created by using a number of arches. Suspension Bridge Suspension bridge, in the modern era, is the most used and favored design by engineers. This is due to the fact that it can withstand many natural disrupting factors wind and earthquakes. These bridges are suspended from cables on top of large columns. The oldest and simplest design of such a bridge is one where cables hang and planks are used to form the bridge. The columns or vertical structures are rooted deep in the land or the water this kind f design is specially preferred while making a bridge between valleys or over the river. Movable Bridges These kinds of bridges are the reflection of modern engineering, where the static designs were known to be stable; these designs bring further space usage to the modern world. There are two types of movable bridge, one with the pivot arm or the other which is the sliding door design. Both are especially useful when they are built on rivers and ships and boats have a constant route from underneath them. METHOD OF IMPLEMENTATION Various steps are under-taken for the completion of both, the bridge and a highway alike. A construction company has to set up its goals and designs even before the first brick is laid. The construction steps are explained in detail in this section of the paper Bridge Phases The first step in building a bridge is the preparation which basically includes the study of the fact, that whether a bridge is needed to join the two places or not. Various professionals and agencies are involved in this process before a demand of the construction is generated in front of the decision making authorities. After the study phase comes the design phase, which is the most significant phase in the process of development of any structure or product. The first aspect which is under study in this phase is the geographical requirements of the area, especially which will identify the type of bridge that has to be constructed with most ease, complying with the requirements of the situation. A suspension bridge may not be the best solution in a mountainous area. When the type of bridge is selected, rigorous work of designing the bridge and studying it under different situations through simulations and calculations is done. If the bridge performance is unsatisfactory under this phase, it is never feasible to start construction until the desired results on paper have been achieved. The final phase which is known as the construction phase is the last part of building the bridge. The construction practices differ from bridge to bridge, but some practices are common for all type of bridges. Generally the construction material and machinery are brought to the site and construction is carried out. Different bridges require different material and machinery for the completion of the project. A suspension bridge needs tall tower to e erected; hence machines with tall arms are needed where as concrete bridges need a large amount of reinforced concrete slabs to be laid on the beams which are constructed beforehand. (Alexander, 1916) Highway Phase Like any structure, a highway or a road needs similar steps before its completion. The first step, like always is the planning portion. In this phase a team of experts from all walks of life gather to assess the area, the need and the complications that are present for a certain project. After the feasibility has been completed, the design phase comes under the microscope. In this phase, the map of the road and specially the connection of the highway from existent road are chalked out. If the design goes wrong in the slightest of manner, it will ensure that the hazards of driving on such highway are multiplied. The construction phase of the highway is the last part. This phase has actually evolved as the machinery and equipment used to pave roads have modernized considerably since the earlier highways were built. The best and foremost highways are nowadays concrete highways. Here the topics under the sub heading are discussed. In earlier days, concrete slab made highways showed huge amount of disintegration and peeling away of the surface. A technique of introducing air bubbles was used, hence making the concrete slabs more durable for a longer period of time. The technique used now, is the fast-track concrete pavement in which new paths or the old one, that are reconstructed can be opened to traffic without the usual waiting period if 5-6 days (Austin, 1907). The areas of the highways where heavy load is expected, a new technique known as retrofitting is used. It involves cutting slots and placing in joints across the slotted area and then patching the slot with fast-track concrete mix. This allows a smooth weight transfer of the heavy load from one slab to another (Portland, 2011). Once the highway is complete, certain tests are carried out to check the safety standards of the highway and whether it full-fills the international set-standards or not. STRENGTH AND WEAKNESS OF BRIDGES AND HIGHWAYS This section will render light over some of the examples of successful as well as some disastrous bridge/highway designs. Successful Bridge This bridge, known to be a master piece of modern architecture is the longest bridge over water in the history of bridge making. This bridge is located in the eastern part of China and connects Qingdao city and the Hongdao Island. The design of the bridge is of self suspension type held with cables. It is approximately 43 kilometers long (David, 2011). The main challenge that was crossed while building this bridge was the huge area of water it had to cross to connect the two districts. Also, the effects of earthquakes and water currents have been compensated in the design, giving the bridge strength to stand for a very long time to come. Bridge Failure The perfect example of a failed bridge is Tacoma Narrows Bridge in 1940 in USA. This bridge connected Seattle to Tacoma and disintegrated after 3 days of its opening. This was a suspension bridge and due to the early era, is a prime example of the primitive designs used at that time. The design did not incorporate the wind, which constantly crashed into the structure at relatively high speeds. The normal design was good enough to withstand the weight and everyday use, but the wind factor was the one that brought its downfall. The wind caused vertical oscillations to the structure, and due to the inability to with stand dynamic movement the bridge collapsed (Norbert, 2008) Successful Highway One of the biggest success stories in the history of man-made monuments is the Karakorum highway, connecting not two cities but two countries namely China and Pakistan. The biggest challenge for the construction of this highway was the terrain in which this was built. It was not only mountainous, but snowy weather conditions as well. Extensive help of the military services of both the countries were used to create this masterpiece. It took almost 16 years to complete and is considered to be the highest paved road of the world. The benefit of this road has been the economic growth of both countries due to a trade route built by the sheer skill of the engineering team and their associates. Such projects show the extent of technology and skill level that has been developed over the years (Mumtaz, 2010) Highway Failure The failure of a highway is an epic dilemma as a lot of finances have to be utilized to modify a design after the construction has been completed or even started. Several failures along the lfe-Osu-llesha in Nigeria have been seen. After deep study, it has been found out that the problem is due to the soil used in paving that highway. The soil contains huge amount of talc and hydro mica. The flaky composition of the soil makes it difficult for holding the residues of the soil together. This issue was not highlighted in the planning phase of the project when the soil was being selected. This resulted in many sections of the road swelling and un-usable after not very long of the highway opening. If the study had been done properly, this kind of issue would not have arrived, saving huge amount of finances which now have to go in the project for its repair (Meshida, 2006). CONCLUSION This report can be concluded by describing an analogy in which a bridge/highway is created between two factious towns. The amount of length saved to the community of the two people can be somehow converted in the time saved travelling in their cars on the route when the bridge was not present. It can be safely said that more time of their lives will be saved by this then their actual lives. Such an impact has been brought upon by this simple everyday invention, about which we don’t think about while travelling. A road/highway/bridge has evolved the way man travels. Long journeys which were earlier not possible without aircrafts or boats are now been travelled due the connection made by this smart structural invention by mankind. BIBLIOGRAPHY Alexander ,J. (1916) Bridge Engineering. USA. John Wiley & sons Delatte, N. (2008) Beyond Failure: Forensic Case Studies for Civil Engineers. ASCE Press Eimer, D. (2011) China builds longest bridge [internet]. Available from < http://www.telegraph.co.uk/news/worldnews/asia/china/8248197/China-builds-worlds-longest-bridge.html> [21-11-2011] Khalid, M. (2010) History of KKH. Pakistan. Oxford press Meshida, E. (2006) Highway failure over talc–tremolite schistterrain: a case study of the Ife to Ilesha highway, South Western Nigeria Portland cement Inc. (2011) Concrete pavement: Highways [Internet]. Available from [21-11-2011] Thomas A. (1907) Highway Construction. Technical World Magazine Read More