Browsing by Author "Gebre, Abrham"

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    Computer Program for Comparative Study of the Analysis and Design of Slab and T- Girder Bridges
    (Addis Ababa University, 2006-07) Gebre, Abrham; Adamu, Asnake(PhD)
    Ethiopia is one of the mountainous countries in Africa. This topographic condition such as rough terrain, deep gorges of the country; river crossings and other factors aggravate the difficultness of construction of roads in the country without constructing crossways which include culvert and bridges. Thus, Bridges are vital structures required during roads construction. The type of structure in design standard is selected on the basis of openings span in which culverts span 1 to 6m, slab bridge span 6 to 15, and up to 18m with provision, while T-Girder bridge span 10 to 20m, where sometimes span up to 24m. The site visit during this study also reveals that slab bridges up to 12m and T-Girder bridges as low as 9m span have been recorded. This lead to the requirement of the standard to narrow the span gap at the boundary for selecting slab or T-Girder in the range of 10 to 15m spans. In line with this the thesis of this study focused on developing computer program for analysis and design of slab and T-Girder bridges, in due cause solving the design problem of economical spans for slab and T-Girder bridges. A comparative study on the basis of cost of materials is conducted to select and identify the economical span range of slab and T-Girder bridges. The developed program is illustrated using particular example of both slab and T-Girder bridges. The study has come with solution based on the prevailing rates of construction cost to be adopted for design Engineer’s use.
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    Cost Effectiveness of Composite Frames in Condominium Houses
    (Addis Ababa University, 2016-03) Bassa, Bergene; Gebre, Abrham
    Steel-concrete composite construction has gained wide acceptance worldwide as an alternative to pure steel and pure concrete construction. However, this system is a relatively new concept for the construction industry in Ethiopia. Reinforced concrete members are used in the framing system for most of the buildings since this is the most convenient & economic system for low-rise as well as short beam span when columns are closely spaced in buildings frame. However, for medium to wide-spaced column in the buildings frame this type of structure is no longer economic because of increased dead load, less stiffness, span restriction and hazardous formwork. Steel-concrete composite frame system can provide an effective and economic solution to most of these problems in medium to wide spaced column buildings. An attempt has been made in this study to explore the cost effectiveness of steel-concrete composite construction by taking condominium houses currently undergoing in our country for maximum column spacing above which the steel-concrete composite frame structure is cost effective. A cost versus frequently occurred maximum column spacing variation curves along both axes shows that for closely spaced column building frames structures, the conventional reinforced concrete frame system is cheaper than its equivalent steel-concrete composite system. However, this curves show for building frames with column spacing between 9 to 10m and greater than this span along both axes, steel-concrete composite construction has economical advantages than reinforced concrete construction and 9 to 12 and greater than this storeys, again, steel-concrete composite construction has economical advantages than reinforced concrete construction in our country.