Shear strengthening of continuous reinforced concrete T-beams using wire rope units

Abstract

A simple unbonded-type shear strengthening technique for reinforced concrete beams using wire rope units is presented. Ten two-span reinforced concrete T-beams externally strengthened with wire rope units and an unstrengthened control beam were tested to failure to explore the significance and shortcomings of the developed unbonded-type shear strengthening technique. The main parameters investigated were the type, amount and prestressing force of wire rope units. All beams tested failed owing to significant diagonal cracks within the interior shear span. However, beams strengthened with closed type wire rope units exhibited more ductile failure than the unstrengthened, control beam or those strengthened with U-type wire rope units. The diagonal cracking load and ultimate shear capacity of beams with closed-type wire rope units were linearly increased with the increase of vertical confinement stresses in concrete owing to the prestressing force in wire rope units, while those of beams with U-type wire rope units were little influenced. It was also observed that average stresses in closed-type wire ropes crossing diagonal cracks at ultimate strength of beams tested were far much higher than those in U-type wire rope units, showing better utilization in case of closedtype wire ropes. The shear capacity of beams with closed-type wire rope units is conservatively predicted using the equations of ACI 318-05 for shear modified to account for the external wire rope units. A numerical formula based on the upper bound analysis of the plasticity theory is also developed to assess the load capacity of continuous T-beams strengthened with wire rope units.Comparisons between measured and predicted shear capacities showed that the coefficient of variation obtained from the mechanism analysis is less than that from the modified ACI 318-05 equations. In addition, the predictions by the mechanism analysis for beams with closed-type wire rope units are in good agreement with test results, regardless of the value of stresses used for the calculation of energy dissipated in wire ropes.

Wire Rope Flexural Bonded Strengthening System on RC-Beams: A Finite Element Simulation

“…The measured axial load capacities of all strengthened columns were higher than the predictions obtained from ACI 318-05, indicating that the ratio of the measured and predicted values increased with the increase of the volume ratio of wire ropes and flange width of T-shaped steel plates. Yang et al (2009b) also tested a series of reinforced concrete continuous T-beams externally strengthened with unbonded wire ropes and concluded that the ultimate shear capacity of beams strengthened with closed-type wire ropes increased with the increase in the amount and prestressing force of wire ropes, whereas that of beams with U-type wire ropes was little influenced by the amount and prestressing force of wire ropes. Wire ropes were also previously tested as flexural strengthening materials, and it was shown that if the stiffness of wire ropes was not improved, their contribution was suboptimal (Haryanto, 2011;Atmajayanti et al, 2013;Galuh, 2015).…”

On the Performance of Steel Wire Rope as the External Strengthening of Rc Beams With Different End-Anchor Types

“…its high tensile strength. A series of previous studies on reinforced concrete beams strengthened with steel wire ropes have shown very promising results [8][9][10]. In Indonesia, the use of steel wire rope as a strengthening material was first studied by Haryanto [11]; this study showed that the flexural strength of reinforced concrete Tbeams in the region of negative moment increased via a bonded strengthening system and a ratio of 2.03 was obtained.…”

Flexural behaviour of RC beams strengthened with prestressed steel wire ropes polymer mortar composite

“…Previous investigations have been conducted to study the flexural behaviour of RC beams strengthened with prestressed steel wire ropes. Kim et al (2007) and Yang et al (2009) adopted wire rope units to enhance the shear strenghth of RC beams. It was observed that the shear strength of the strengthened beams was significantly increased, and the higher the initial prestressing force in wire rope units, the higher the shear strength obtained.…”