General Criteria for Nominal Main Bonded Reinforcement

1 General Criteria for Nominal Main Bonded Reinforcement 

It may be expected that concrete adjacent to the outer surface of the vessel will lose moisture at a greater rate than in the general body of the vessel. This moisture gradient through the thickness of the vessel will cause differential drying shrinkage and the tensile stresses, hence, are introduced in the outer surface of the vessel. These stresses are effectively controlled by means of bonded reinforcement. 

In Additional to these tensile stresses, some random tensile stresses are introduced due to differential cooling strains which cannot be covered by analysis constructional stresses locked in, local stress concentration and thermal gradient stresses are some more to be considered while assessing the amount of reinforcement. 

For preliminary disposition of main bonded reinforcement, it is necessary to study carefully the vessel behaviour during elastic and ultimate load conditions and a proposed construction technique. After careful study of the vessel , general criterion for main bonded reinforcement is established. This criterion is indicated in Fig. 8.2. It covers preliminary requirements for general vessel areas and specific haunch and equatorial regions. A tensile stress of 1500 Ib/m (3.45 MN/m ) at working conditions, worse case of 600 psi (4.15 MN/m ) at ultimate load is also considered. 

Check on reinforcement around haunch based on stress concentration figures (principal tensile stresses) with and without fillets is also made, taking zones across the barrel wall and the cap. Four different cases shown in Fig. 8.3 have been taken for analysis, with and without principal compression. These are the stresses for proof pressure case from elastic analysis carried out on computer using program ISOPAR or equivalent. 

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Fig. 8.2 General criteria for nominal main bonded reinforcement...

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