Effect Of Effect On Crack Prevention

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CHAPTER TWO LITERATURE REVIEW 2.1 Introduction Externally prestressed structures, initially developed for bridges, are now becoming popular in bridge construction and strengthening or rehabilitation of existing structures. Comparing with an internal prestressing system, an external prestressing system has some advantages, such as being simpler to construct and easier to inspect and maintain. Prestressed composite beams have been studied by several authors. In this chapter, a review of the research works carried out on external prestressed composite steel-concrete beam is presented. 2.2 Simply supported plate girders 2.2.1 Behavior and strength Two papers to study the behavior of partially prestressed continuous composite beams consisting of a concrete slab supported by a steel beam were presented by Basu et al. (1987) [7, 8]. In these researches, the prestress was introduced in the negative moment regions only . The first paper presented analytical study on the effect of prestressed on crack prevention in the negative moment region and savings in material due to superior structural action. It was concluded that partial prestressing increased the load capacity of the beam by about 20% and eliminated the problem of concrete deck cracking in the negative moment region. It was also concluded that the deflection of the prestressed beam is about thirty percent less than that of the non-prestressed beam. The results of tests on a model of continuous
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