إعادة تأهيل البلاطات الخرسانية المتضررة تحت تاثير الأحمال المتكررة باستخدام الألياف الكاربونية

Rehabilitation of Damaged Reinforced Concrete Slabs Subjected to Repeated Loads Using CFRP Sheets

Abstract

This study includes rehabilitation of the damaged slabs subjected to repeated loads using external strengthening. For this purpose, ten two-way reinforced concrete (RC) slabs were constructed and tested under concentrated loads. All slabs are square in shape with the dimensions of )1050 x 1050 x 70(mm. The slabs are internally reinforced with φ8@150 mm steel bars and simply supported on the outer perimeter. Two of these slabs were tested as a reference without external strengthening and subjected to two types of concentrated loads up to failure. The first was subjected to monotonic loads and the second to repeated loads. The remaining eight slabs were divided into two groups. The first group loaded up to 50% of the damage load, and the second loaded up to 75%. Rehabilitation of both groups was done using carbon fiber-reinforced polymers (CFRP) sheets and textile- reinforced mortar (TRM) layers. Then the eight slabs were tested under repeated loads up to the failure point. The test parameters were the type of external strengthening system (CFRP or TRM), the ratio of damage in the slab (50, 75)% of the damage load, and the distribution method of the repair materials (orthogonal or parallel).The experimental results indicate the efficiency of both repair systems in rehabilitating damaged slabs and the superiority of the CFRP system by increasing the maximum load by about (41.25- 88)%, decreasing the final deflection by about (35- 69)%, and improving the structural properties compared to the reference slab. Whereas the use of TRM layers; increased the maximum load by about (9- 21.25)% and reduced the final deflection to about (8- 43.33)%. The best result was when the damaged slabs (at a ratio of 75%) were repaired using the orthogonal scheme in both repair systems (CFRP sheets and TRM layers).