The Use of Flax Fiber-Reinforced Polymer (FFRP) Composites in the Externally Reinforced Structures for Seismic Retrofitting Monitored by Transient Thermography and Optical Techniques

Author(s):  
C. Ibarra-Castanedo ◽  
S. Sfarra ◽  
D. Paoletti ◽  
A. Bendada ◽  
X. Maldague
2020 ◽  
Vol 10 (7) ◽  
pp. 2489 ◽  
Author(s):  
Francesca Sciarretta

This paper presents a study on the potentiality of seismic retrofitting solutions with pultruded Fiber Reinforced Polymer (FRP) profiles. This material can be used in connected frames providing lightweight, corrosion-free and reversible retrofitting of masonry buildings with the moderate requirements of surface preservation. In a hypothetical case study, an experimental program was designed; monotonic shear tests on a half-size physical model of the sample wall were performed to assess the structural performance before and after retrofitting with a basic frame of pultruded Glass Fiber Reinforced Polymer (GFRP) C-shaped profiles, connected to the masonry by steel threaded bar connections. During the tests, the drift, the diagonal displacements in the masonry and the micro-strain in the profiles were measured. The retrofitted system has proven very effective in delaying crack appearance, increasing the maximum load (+85% to +93%) and ultimate displacement (up to +303%). The failure mode switches from rocking to a combination of diagonal cracking and bed joint sliding. The gauge recordings show a very limited mechanical exploitation of the GFRP material, despite the noticeable effectiveness of the retrofit. The application seems thus promising and worth a deeper research focus. Finally, a finite element modelling approach has been developed and validated, and it will be useful to envisage the effects of the proposed solution in future research.


Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2376 ◽  
Author(s):  
Wang ◽  
Petrů

The recent developments of FRP (fiber reinforced polymer) are towards the growth and usage of natural FRP in the field of engineering due to both environmental and economic benefits. Flax fiber is one of the most commonly used natural fibers. One of the critical factors affecting the mechanical behavior of FFRP (flax fiber reinforced polymer) is hygrothermal aging. Some experimental works have been conducted to investigate the effect of hydrothermal aging on static behavior of FFRP. However, fewer efforts have been made to study its damping properties after hydrothermal aging. In this paper, the effect of surface treatment (including alkalization, silanization, acetylation and alkali-silanization) on dynamic mechanical behavior of FFRP under hygrothermal aging is studied. The results show that water resistance and damping properties of FFRP are improved after surface treatment. The acetylation treated FFRP exhibits excellent damping performance among all treated specimens.


2015 ◽  
Vol 2015 ◽  
pp. 1-13
Author(s):  
Yun-Cheul Choi ◽  
Hyun-Ki Choi ◽  
Dongkeun Lee ◽  
Chang Sik Choi

Unreinforced masonry (URM) structures represent a significant portion of existing historical structures around the world. Recent earthquakes have shown the need for seismic retrofitting for URM structures. Various types of strengthening methods have been used for URM structures. In particular, a strengthening technique using externally bonded (EB) fiber reinforced polymer (FRP) composites has attracted engineers since EB FRP materials effectively enhance the shear strength of URM walls with negligible change to cross-sectional area and weight of the walls. Research has been extensively conducted to determine characteristics of URM walls strengthened with EB FRP materials. However, it is still difficult to determine an appropriate retrofitting level due to the complexity of mechanical behavior of strengthened URM walls. In this study, in-plane behavior under lateral loading was, therefore, investigated on a full-scale nonstrengthened URM wall and URM walls retrofitted with two different FRP materials: carbon (CFRP) and hybrid (HFRP) sheets. The test results indicated that both FRP composites were effective in increasing shear strength in comparison with the control specimen. However, better performance was obtained with HFRP compared to CFRP. In addition, an equation for estimating effective strain was proposed, and the theoretical results were in good agreement with the experimental ones.


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