Post-Fire Characteristics of Concrete Beams Reinforced with Hybrid FRP Bars

Kostiantyn Protchenko , Elżbieta Danuta Szmigiera

Abstract

One of the main concerns of experimental and numerical investigations regarding the behavior of fiber-reinforced polymer reinforced concrete (FRP-RC) members is their fire resistance to elevated temperatures and structural performance at and after fire exposure. However, the data currently available on the behavior of fiber-reinforced polymer (FRP) reinforced members related to elevated temperatures are scarce, specifically relating to the strength capacity of beams after being subjected to elevated temperatures. This paper investigates the residual strength capacity of beams strengthened internally with various (FRP) reinforcement types after being subjected to high temperatures, reflecting the conditions of a fire. The testing was made for concrete beams reinforced with three different types of FRP bars: (i) basalt-FRP (BFRP), (ii) hybrid FRP with carbon and basalt fibers (HFRP) and (iii) nano-hybrid FRP (nHFRP), with modification of the epoxy matrix of the rebar. Tested beams were first loaded at 50% of their ultimate strength capacity, then unloaded before being heated in a furnace and allowed to cool, and finally reloaded flexurally until failure. The results show an atypical behavior observed for HFRP bars and nHFRP bars reinforced beams, where after a certain temperature threshold the deflection began to decrease. The authors suggest that this phenomenon is connected with the thermal expansion coefficient of the carbon fibers present in HFRP and nHFRP bars and therefore creep can appear in those fibers, which causes an effect of “prestressing” of the beams.
Author Kostiantyn Protchenko (FCE / ICE)
Kostiantyn Protchenko,,
- The Institute of Civil Engineering
, Elżbieta Danuta Szmigiera (FCE / ICE)
Elżbieta Danuta Szmigiera,,
- The Institute of Civil Engineering
Journal seriesMaterials, ISSN 1996-1944
Issue year2020
Vol13
No5
Pages1-15
Article number1248
Keywords in English fiber-reinforced polymers; FRP bars; HFRP; fire resistance of FRP; beams reinforced with FRP; fire testing of FRP reinforced members; nano-HFRP bars
ASJC Classification2500 General Materials Science
DOIDOI:10.3390/ma13051248
URL https://www.mdpi.com/1996-1944/13/5/1248
Languageen angielski
File
materials-13-01248.pdf 10 MB
Score (nominal)140
Score sourcejournalList
ScoreMinisterial score = 140.0, 16-06-2020, ArticleFromJournal
Publication indicators WoS Citations = 0; Scopus Citations = 0; Scopus SNIP (Source Normalised Impact per Paper): 2017 = 1.285; WoS Impact Factor: 2018 = 2.972 (2) - 2018=3.532 (5)
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