Abstract
High-strength steel fiber-reinforced concrete (HSFC) and ultra-high strength steel fiber-reinforced concrete (UHSFC) jackets have been proved experimentally to be much more effective with respect to other strengthening schemes in improving the hysteresis performance of existing substandard reinforced concrete (RC) structural members. In this paper, an existing analytical model for the prediction of the shear capacity of RC beam-column joints strengthened with a HSFC or UHSFC jacket is extended to provide design formulation of these innovative HSFC and UHSFC jackets. An authoritative validation of the proposed formulation is also achieved by comparisons of experimental results of 50 beam-column joint specimens with the analytical predictions of the model. Test data used for verification have been collected from the literature based on experimental studies of the authors and other researchers. The merits of the HSFC and UHSFC jacketing technique are also highlighted in the state of practice. Design and application of the proposed fiber-reinforced concrete jackets in deficient existing RC beam-column joints provides a sustainable strengthening technique by contributing to the reduction in the cost and to labor-intensive procedures of common jackets by completely replacing the installation of reinforcement.
Highlights
The acquired experimental results derived from the cyclic loading tests of six exterior reinforced concrete (RC) beam-column joint subassemblages, strengthened using High-strength steel fiber-reinforced concrete (HSFC) and ultra-high strength steel fiberreinforced concrete (UHSFC) jackets, which were tested on previous works of Tsonos [38,39] are used
Bond and adequate anchorage of fiber reinforced polymer (FRP) sheets and strips is a difficult task that has to be faced efficiently since premature debonding FRP failure usually occurs. This common failure mode of such composite materials causes severe and mainly unpredicted reduction in their potential strength. These reasons make the application of HSFC or UHSFC jacketing a promising alternative strengthening technique to upgrade the shear capacity of the beam-column joint region, which requires further attention and investigation
This was fully justified by the low actual shear stress values in the joint region which were lower than half the ultimate joint shear capacity
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The extended analytical model is a significant contribution to the satisfactory designing of innovative, reliable, easy to apply and cost-effective retrofit schemes with fiber-reinforced concrete jackets of high or ultra-high strength that secure the ductile seismic performance of the strengthened structures. For this reason, the acquired experimental results derived from the cyclic loading tests of six exterior RC beam-column joint subassemblages, strengthened using HSFC and UHSFC jackets, which were tested on previous works of Tsonos [38,39] are used. Further validation of the proposed formulation is achieved by comparisons of the analytical predictions of the model with 44 experimental results collected from relative studies of other researchers [17,24,44,45,46]
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