دانلود رایگان مقاله انگلیسی نوارهای CFRP برای افزایش عملکرد خمشی تیرهای RC با استفاده از تکنیک تقویت SNSM - الزویر 2018

abstract

Side Near Surface Mounted (SNSM) strengthening technique is among the latest technique introduced recently. In this paper, SNSM carbon fiber reinforced polymer (CFRP) strips strengthening technique is proposed for enhancing the flexural performance of reinforced concrete (RC) beams. A total of seven RC beam specimens were tested: one un-strengthened control specimen, and six specimens strengthened by SNSM-CFRP strips. All beam specimens were tested under four-point bending. Analytical prediction methods were used to verify the experimental results. The load, mid-span, deflection, and strains data were recorded until failure of the specimens. The ductility, stiffness, and energy absorption capacity of the strengthened specimens by CFRP strips were enhanced due to SNSM technique. The results also showed that the SNSM-CFRP strips strengthening technique significantly enhanced the first cracking, yield, and ultimate load capacities up to 153%, 108%, and 147% respectively, compared with that of the control beam. Further, the comparison between the experimental and predicted values shows good agreement.

6. Conclusions

The following conclusions are made based on this study:

The SNSM technique with CFRP strips is effective in improving flexural performance. The yield and ultimate load carrying capacities significantly increased up to 108% and 147%, respectively, compared with the control specimen, mainly based on the number and orientation of the strips and failure mode of the specimens.

The SNSM-CFRP strips significantly enhanced the first cracking and service load up to 153% and 129%, respectively over the control beam specimen, which is very important in the context of serviceability concerns.

The CFRP strips with SNSM strengthening technique significantly improved the service performance of the RC beam specimens by decreasing deflection at various loading phases.

The SNSM-CFRP strips strengthened specimens exhibited excellent ductile behavior due to typical flexural failure mode of the specimens (except S4H). This provides ample warning before failure, and could be regarded as a crucial advantage of the SNSM strengthening technique.

The predicted results of the strengthened specimens showed closer values as that of the experimental results.

The SNSM strengthening technique with CFRP-strips enhanced the stiffness and energy absorption values up to 91% and 161%, respectively, compared with the control specimen.

The use of CFRP as a vertically oriented strips resulted in better flexural performance compared with the horizontally oriented strips, due to its higher bending stiffness.
Further research work is required to investigate the flexural performance of RC beam specimens strengthened with SNSM technique using prestressed CFRP strips.