مهندسی عمران شریف (Aug 2020)
بررسی آزمایشگاهی تأثیر مقدار و آرایش میلگردهای طولی و عرضی در تیرهای بتنی پیش تنیده تحت خمش
Abstract
The recent changes in urban communities and consequently the need for thinner strong concrete structures has caught researchers' attention. Structural performance characteristics such as ultimate loads, maximum loads, and ductility along with formation and propagation of cracks in prestressed concrete beams have been studied by many researchers. In this paper, an experimental study was carried out to investigate the effect of amount and arrangement of non-prestressed longitudinal and transvers bars on improving the performance of six prestressed concrete beams with identical geometry and concrete properties under static loads. Cracking strength, formation and propagation, ultimate load carrying capacity and ductility of beams were determined. Unbonded post-tensioning is applied to 7-wire strand tendons with Grade 270 and diameter of 0.5in that are positioned with constant eccentricity within the beam. The test results indicate that adding non-prestressed reinforcement to concrete beams generally has a significant effect on properties of prestressed concrete beams such as ultimate load, maximum load, ductility and pattern of crack formation and propagation and also have a significant reduction in brittleness and showed better ductility. The response of beams significantly depends on the method of confinement by transverse reinforcement and also the distribution of longitudinal reinforcement.
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