Abstract
An experimental study that investigates the behavior of stone slabs strengthened in fixure with near surface mounted (NSM) technique using screw-thread steels and carbon fiber-reinforced polymer (CFRP) bars is presented. A total of ten full-scale stone slabs were tested under a four-point bending loading to investigate the effect of groove dimension, reinforcement ratios, and reinforcement materials on the flexural performance of stone slabs. The test results included failure characteristics, yield and ultimate capacities, deflection of midspan, and cracking behavior of stone slabs. The test results indicate that with the increase of groove height and groove width, cracking load and middeflection decrease by 6.4%–14.18%; however, failure load and middeflection increase by 4.7%–41.2%. Cracking load, failure load, and failure displacement of stone slabs adopting NSM screw-thread steels increased by 10.9%, 167%, and 617%, respectively, under the maximum reinforcement ratios of 0.629% over the control slab without NSM bars. Meanwhile, with the increase of reinforcement ratios, the failure mode transforms from brittle failure to ductile failure. The calculation results of strength are in agreement with the experimental results. Finally, it can be concluded that NSM CFRP bars are more effective than NSM screw-thread steels to improve flexural capacity with the same reinforcement ratios.
Highlights
An experimental study that investigates the behavior of stone slabs strengthened in fixure with near surface mounted (NSM) technique using screw-thread steels and carbon fiber-reinforced polymer (CFRP) bars is presented
Near surface mounted (NSM) screw-thread steels and CFRP bars are emerging as a promising technique widely used for increasing flexural and shear strength of deficient RC members [1, 2] and were extended to unreinforced masonry (URM) walls [3], timber beams [4], and glulam bamboo beams [5] for increasing shear and flexural capacity. e aforementioned research is aimed at the components; for the structures, reinforced concrete frames strengthened with NSM bars were investigated and pointed out that reinforced concrete frames strengthened with NSM bars have a higher ultimate strength. [6]
Bonding mechanisms and pullout test between concrete structures and NSM FRP were investigated in detail [9,10,11]; cyclic loading response of RC beams strengthened in shear with GFRP rods using NSM technique was investigated, and an effective finite element method to model the cyclic response of RC beams was developed [12]
Summary
An experimental study that investigates the behavior of stone slabs strengthened in fixure with near surface mounted (NSM) technique using screw-thread steels and carbon fiber-reinforced polymer (CFRP) bars is presented. Near surface mounted (NSM) screw-thread steels and CFRP bars are emerging as a promising technique widely used for increasing flexural and shear strength of deficient RC members [1, 2] and were extended to unreinforced masonry (URM) walls [3], timber beams [4], and glulam bamboo beams [5] for increasing shear and flexural capacity. Bonding mechanisms and pullout test between concrete structures and NSM FRP were investigated in detail [9,10,11]; cyclic loading response of RC beams strengthened in shear with GFRP rods using NSM technique was investigated, and an effective finite element method to model the cyclic response of RC beams was developed [12]. A comprehensive review of existing research was provided [17,18,19] in NSM FRP reinforcement NSM prestressed reinforcement and design method [20]
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