{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,2]],"date-time":"2025-11-02T11:19:39Z","timestamp":1762082379902,"version":"build-2065373602"},"reference-count":41,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2022,12,30]],"date-time":"2022-12-30T00:00:00Z","timestamp":1672358400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Buildings"],"abstract":"<jats:p>The seismic performance of a structural frame system can be enhanced by strengthening the RC beams\u2019 critical zones. In this paper is presented an experimental study on the improvement of the beam behaviour, subjected to an alternative cyclic procedure which considers the gravity loads reflecting the real demands on the beams\u2019 critical zone. Two strengthening solutions are presented: unbounded post-tension (PT) tendon strengthening to increase resistance and limit residual deformations, and unbounded post-tensioning with jacketing of the RC beam with unidirectional fibre mat reinforced grout (UFRG) to limit compression damage, improving section confinement, thus delaying concrete crushing and buckling of longitudinal reinforcement. The original UFRG material was developed within this study, to apply as a small thickness jacketing material for strengthening RC structures. The main idea was that the steadiness provided by preplacing continuous fibre mats into the mould reduced the fibres\u2019 segregation tendency during the high-performance grout pouring and allowed for the optimisation of their percentage and alignment, attaining a higher tensile strength. The experimental response of the tested Specimens is presented and evaluated through performance parameters that are properly discussed and adjusted to the alternative cyclic procedure. Finally, theoretical predictions are presented, and an adjustable multilinear model is proposed to estimate the strengthening solution\u2019s response.<\/jats:p>","DOI":"10.3390\/buildings13010095","type":"journal-article","created":{"date-parts":[[2023,1,2]],"date-time":"2023-01-02T04:51:22Z","timestamp":1672635082000},"page":"95","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Innovative Seismic Strengthening Techniques to Be Used in RC Beams\u2019 Critical Zones"],"prefix":"10.3390","volume":"13","author":[{"given":"Rita","family":"Gi\u00e3o","sequence":"first","affiliation":[{"name":"CERIS, Civil Engineering Department, Lisbon Superior Engineering Institute, Polytechnic Institute of Lisbon, ISEL\/IPL, 1959-007 Lisbon, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5864-551X","authenticated-orcid":false,"given":"V\u00e1lter","family":"L\u00facio","sequence":"additional","affiliation":[{"name":"CERIS, Civil Engineering Department, NOVA School of Science and Technology FCT NOVA, 2829-516 Caparica, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7708-6995","authenticated-orcid":false,"given":"Carlos","family":"Chastre","sequence":"additional","affiliation":[{"name":"CERIS, Civil Engineering Department, NOVA School of Science and Technology FCT NOVA, 2829-516 Caparica, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,12,30]]},"reference":[{"key":"ref_1","unstructured":"Comit\u00e9 Europ\u00e9en du B\u00e9ton-F\u00e9d\u00e9ration Internationale du B\u00e9ton (CEB-FIB) (2003). 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