Study on Local Steel Profiles in Steel-Concrete Composite Bridges
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Date
2009
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Addis Ababa University
Abstract
Building a functional transportation infrastructure is a high priority for a nation, particularly for developing country like ours. Currently, the Ethiopian government has given special attention for road construction sector and is to invest billions of dollars. Parallel to road construction, there is also a demand of construction of bridges as most of the existing ones are getting older as they are constructed, during colonization by Italians. Construction of such bridges naturally occupy longer construction time where the time required may be farther exacerbated due to shortage of budget beside having bad construction management practice which is observed in many construction undertakings. Associated with this, the normal day to day traffic flow is affected and causes discomforts to the road users. This problem is serious especially in towns where there is high traffic volume and provision of detours is not simple. Thus, as alternate, steel-concrete composite bridge which obviously shortens the construction time and alleviates the problems with other added advantages is thought in this study. Therefore, in this thesis attempt is being made to compare the usage of locally produced steel profile in steel-concrete composite bridges with the conventional reinforced concrete deck girder bridges cost wise, beside evaluating other merits of such application.
In the thesis work, relevant literatures are reviewed, assessment of availability of local steel profiles for such application has been made to local private and governmental companies that are engaged in manufacturing, supplying and installing of such steel profiles for different engineering purposes. Kality Metal Products Factory, Mesfin Industrial Engineering PLC and Maru Metal Industry are among some whose local products are considered. Accordingly, it is observed that there is local capacity and experience of manufacturing I-section profiles by welding steel metal sheets which are imported from abroad. The practices have been observed with application for buildings, steel bridges and manufacture of vehicle body parts. Thus, the study makes use of these I-section profiles, for design of steel-concrete composite bridge superstructures having span lengths of 12m, 15m, 20m and 24m. For the purpose of comparison, the same span lengths and width of reinforced concrete deck girder bridges are also designed. Finally, based on design out puts, quantities of each item are summarized and using appropriate unit rates, cost analysis and evaluation of the two bridge types is carried out. It is observed that relatively compact and lighter bridge cross-sections can be obtained by using steel-concrete composite structures than the reinforced concrete ones. The steel beams can also be manufactured in workshops prior to the start of the construction and this can reduce the required construction time. Nevertheless, it is concluded that with current market condition and work exposure of metal industries, cost required for steel - concrete composite bridge construction is higher than that of reinforced concrete deck girder bridges of the same span, for spans under consideration. During the study, it is noticed that there are few metal industries that are involved in the manufacturing of steel profiles specially those for steel-concrete composite bridge constructions. So, investors should be encouraged to the sector so that designers could have free choices both in quality and shapes. It is also suggested that as markets are demand driven, consultants and designers should initiate and direct the metal industry by designing steel structures as an alternative. As final recommendation, further studies should be carried out to check feasibility of such constructions in our country in line with the change in development of the metal industry and construction skills, as the time saving by itself is a promising and vital item to be considered in bridge construction.
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Keywords
Local Steel Profiles, Composite Bridges, teel-Concrete