Experimental study and numerical prediction of the bond response of NSM CFRP laminates in RC elements under sustained loading

Gómez, Javier; Barris, Cristina; Jahani, Younes; Baena, Marta; Torres, Lluís

doi:10.1016/j.conbuildmat.2021.123082

Cited by 13 publications

(10 citation statements)

References 27 publications

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“…All tests were performed using a direct pull-out shear configuration. The test set-up for the sustained loading tests consisted of adapting the set-up applied in the instantaneous characterization of the NSM CFRP-concrete joint [11] by using a steel lever arm with a magnifying factor of 8.3 (Figure 2a). For the PSL tests, the instantaneous characterization set-up was used (Figure 2b).…”

Section: Test Set-up and Instrumentationmentioning

confidence: 99%

“…The details of each experimental series are listed in Table 2, i.e., where the cycle function (steady for constant objective temperature and cyclic for 24 h-periodical temperature cycles), whether the specimens were preconditioned (or not) before loading, the objective temperature in the climate chamber, the temperature measured on the specimen's surface, the temperature measured inside the NSM groove (attached to the CFRP) and the duration of the test are presented. In the experimental series S1 (previously presented in Gómez et al [11]) and S2, specimens were tested under steady temperatures, while in series S3 and S4, trapezoidal and triangular 24-h temperature cycles, respectively, were applied (Figure 3). Experimental series S3 was split into two different steps.…”

Section: Sustained Loading Experimental Seriesmentioning

confidence: 99%

“…The effect of sustained loading in NSM CFRP strengthening systems was experimentally evaluated in Emara et al [10] and Gómez et al [11] for room conditions. In both Appl.…”

Section: Introductionmentioning

confidence: 99%

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Sustained Loading Bond Response and Post-Sustained Loading Behaviour of NSM CFRP-Concrete Elements under Different Service Temperatures

et al. 2021

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Nowadays, one of the foremost procedures for strengthening concrete structures is the Near-Surface Mounted (NSM) technique. This paper presents an experimental study on the effect sustained loading and different service temperatures (steady and cyclic) have on NSM Carbon Fibre-Reinforced Polymer (CFRP)-concrete bonded joints and their post-sustained loading load-slip behaviour. Four experimental campaigns using eight NSM CFRP-concrete specimens were performed by employing two different service load levels (15% and 30% of the ultimate load) and combining two groove thicknesses (7.5 and 10 mm) and two bonded lengths (150 and 225 mm). Two steady state temperatures (20 and 40 °C) and two cyclic service temperatures (ranging between 20 and 40 °C) were programmed. The slip obtained was proportional to the sustained load level. Furthermore, higher slips were registered for specimens under higher mean temperatures in the cycle. After 1000 h of sustained load testing, the specimens were tested under monotonic loading until failure (post-sustained loading tests). In general, the ratio between the post-sustained loading ultimate load and the instantaneous ultimate load was close to the unity, although some differences were perceived in series S2 (steady 37.7 °C) with a mean increase of 6.3%, and series S3-B (cyclic temperature ranging between 24.6 and 39.2 °C) with a mean reduction of 9%.

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Section: Test Set-up and Instrumentationmentioning

confidence: 99%

Section: Sustained Loading Experimental Seriesmentioning

confidence: 99%

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Sustained Loading Bond Response and Post-Sustained Loading Behaviour of NSM CFRP-Concrete Elements under Different Service Temperatures

et al. 2021

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“…Extensive studies about the short-term behaviour of NSM FRP strengthened beams have been carried out [ 4 , 5 ]. However, little attention has been paid to its performance under sustained load despite this action might affect its mechanical performance [ 6 , 7 ]. The same limitations exist under high temperature conditions [ 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

Performance of Linear Mixed Models to Assess the Effect of Sustained Loading and Variable Temperature on Concrete Beams Strengthened with NSM-FRP

Perera

Torres

Díaz

et al. 2021

Sensors

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Although some extended studies about the short-term behavior of NSM FRP strengthened beams have been carried out, there is a lack of knowledge about the behavior of this kind of strengthening under sustained loads and high service temperatures. Electromechanical impedance method formulated from measurements obtained from PZT patches gives the ability for monitoring the performance and changes experienced by these strengthened beams at a local level, which is a key aspect considering its possible premature debonding failure modes. This paper presents an experimental testing program aimed at investigating the long-term performance of a concrete beam strengthened with a NSM CFRP laminate. Long term performance under different levels of sustained loading and temperature conditions is correlated with EMI signatures processed using Linear Mixed-effects models. These models are very powerful to process datasets that have a multilevel or hierarchical structure as those yielded by our tests. Results have demonstrated the potential of these techniques as health monitoring methodology under different conditions in an especially complex problem such as NSM-FRP strengthened concrete structures.

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“…The flexural and shear behaviors of RC beams strengthened with NSM-FRP under static loading conditions have been widely studied in the literature. However, although several studies have been performed regarding the combined effects of sustained load and temperature on the bond response of NSM-CFRP laminates in concrete elements [ 4 , 5 , 6 , 7 ], studies devoted to the global response of the strengthened structure under those same conditions acting simultaneously are practically nonexistent. This paper presents an experimental study to examine the long-term performance of a RC beam strengthened with NSM-FRP and subjected to a sustained load in conjunction with changing temperatures.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Impact of Sustained Load and Temperature on the Performance of the Electromechanical Impedance Technique through Multilevel Machine Learning and FBG Sensors

Perera

Torres

Díaz

et al. 2021

Sensors

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The electro-mechanical impedance (EMI) technique has been applied successfully to detect minor damage in engineering structures including reinforced concrete (RC). However, in the presence of temperature variations, it can cause false alarms in structural health monitoring (SHM) applications. This paper has developed an innovative approach that integrates the EMI methodology with multilevel hierarchical machine learning techniques and the use of fiber Bragg grating (FBG) temperature and strain sensors to evaluate the mechanical performance of RC beams strengthened with near surface mounted (NSM)-fiber reinforced polymer (FRP) under sustained load and varied temperatures. This problem is a real challenge since the bond behavior at the concrete–FRP interface plays a key role in the performance of this type of structure, and additionally, its failure occurs in a brittle and sudden way. The method was validated in a specimen tested over a period of 1.5 years under different conditions of sustained load and temperature. The analysis of the experimental results in an especially complex problem with the proposed approach demonstrated its effectiveness as an SHM method in a combined EMI–FBG framework.

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Experimental study and numerical prediction of the bond response of NSM CFRP laminates in RC elements under sustained loading

Cited by 13 publications

References 27 publications

Sustained Loading Bond Response and Post-Sustained Loading Behaviour of NSM CFRP-Concrete Elements under Different Service Temperatures

Sustained Loading Bond Response and Post-Sustained Loading Behaviour of NSM CFRP-Concrete Elements under Different Service Temperatures

Performance of Linear Mixed Models to Assess the Effect of Sustained Loading and Variable Temperature on Concrete Beams Strengthened with NSM-FRP

Analysis of the Impact of Sustained Load and Temperature on the Performance of the Electromechanical Impedance Technique through Multilevel Machine Learning and FBG Sensors

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