BEHAVIOR OF RC CONTINUOUS SLABS STRENGTHENED BY EXTERNAL PRESTRESSING STEEL STRANDS
Mohamed H. AbuGazia1, Mahmoud El-Kateb2, Tamer Elafandy3 and Amr A. Abdelrahman4 1 TA and MSc. Student, Structural Engineering Dept., Ain Shams University, Cairo, Egypt
2 Assistant Prof., Structural Engineering Dept., Ain Shams University, Cairo, Egypt 3 Associate Prof., RC Dept., Housing and Building National Research Center, Giza, Egypt
4 Prof., Head of Structural Engineering Dept., Ain Shams University, Cairo, Egypt.
ABSTRACT
External prestressing is a post tensioning technique where the prestressing steel tendons are placed outside the concrete elements. It means that the prestressing force is only transformed to the structural element through the mechanical anchorages and deviators. It is one of the widely used methods of enhancing the flexural strength of the Reinforced Concrete (R.C.) slabs. The enormous usage of external prestressing systems to strengthen R.C. continuous slabs needs more researches to have a fully understanding of its
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It’s a very quickly and useful tool to strengthen distressed concrete bridges and also to construct new bridges with considerably higher capacity compared to traditional bridges.
The “Truc de la fare” bridge which was built in France, consisted of prestressed concrete slab with lateral ribs and supported by subtended cables, deviated by steel struts, is a good example for the external unbonded prestressing systems.
Analysis of external prestressed elements is different comparing to the ordinary bonded prestressed elements or even the internally unbonded prestressed elements. It can be attributed to lack of bond between steel tendon and concrete, besides the second order effect that makes a notable reduction in the effective depth of the tendons during
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