Abstract
The efficacy of post-tensioned metal straps PTMS, wrapped around steel channels anchored to normal reinforced concrete (R.C) beams is tested in increasing the flexural capacity of the beams. For this purpose, nine normal R.C beams with dimensions of 160 mm x 240 mm x 2100 mm are constructed to fail in bending. The location and the number of the straps are considered as the main variable. It is found that using PTMS can enhance the load-carrying capacity of the beam by 29% to 63%. The decisive factors affecting the increase are the location of the straps (at the bottom or sides), shape of the flange and web edges (squared or rounded) and alignment of the flanges (vertical or inclined). A complete guide can be found in the paper as it is a novel method of strengthening beams which can be applied to the beams cast in place with integral slabs.
Highlights
Reinforced concrete beams require strengthening to upgrade their strength, stiffness and ductility capacity which may be required due to design errors, needs for additional load carrying capacity or after an accidental load such as that of an earthquake
Strengthening with Post Tensioned Metal Straps (PTMS) is a novel technique for strengthening structural members developed by University of Sheffield in England and University of Patras in Greece for the first time in 1995 by Frangou et al [1]
Once the channel is constructed in the steel factory and the flanges are bent in right angles, there is a rounded edge inside the channel that makes it impossible to have a full contact with the bottom face of the concrete beam
Summary
Reinforced concrete beams require strengthening to upgrade their strength, stiffness and ductility capacity which may be required due to design errors, needs for additional load carrying capacity or after an accidental load such as that of an earthquake. Imjai [4] tested beams failed in flexure, they used fully wrapped metal straps as a confinement of the beams to enhance flexural strength of the beam, the results of confined and unconfined of the beams are nearly the same but only the ductility is improved. For this reason, it is necessary to develop the method to be used for beams failed in flexure which is the main purpose of this paper. The method is practical and can be used on R.C beams in any frame building
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