Experimental Study And Numerical Simulation Of RC Slabs Strengthened With BFRP And CFRP

Externally bonded fiber reinforced plastic (FRP) materials are widely used for rehabilitating, retrofitting and strengthening reinforced concrete (RC) elements and structures in recent decades. Because of the wide application of reinforced concrete slabs in engineering structures, study on FRP reinforced concrete slabs has a strong appeal to the researchers. As a result of high tensile strength and elasticity modulus, light weight, excellent corrosion resistance etc., carbon fiber reinforced plastic (CFRP) is widely used in various kinds of structural strengthening engineering projects. Basalt fiber reinforced plastic (BFRP) is an inorganic fiber material with good heat-resistant, acid-resistant, chemical properties stability, as well as fine physical and mechanical performance. Compared with CFRP, BFRP has higher elongation and its price is 50% lower than that of CFRP, so it is widely focused by lots of engineers and technicians on its application to engineering.Based on-site test study of RC slabs strengthened with CFRP and BFRP, this paper obtained the respective reinforcing effects of BFRP and the reinforcing effects were compared with that of CFRP. The experimental program is made of flexural tests carried out on four square two-way reinforced concrete slabs (3000×3000×90 mm3) on-site. Four slabs including two slabs strengthened with BFRP, one slab strengthened with CFRP and one slab without strengthening were tested. The internal steel reinforcement is a 8 mm diameter bar grid spaced at 15 cm in x-and y-directions. The concrete cover thickness is about 20 mm. The effects of loads on mid-span deflection, distribution of stresses around the steel bars at the top and bottom of slabs were analyzed.The analysis modal of finite element method, the constitutive relations of materials, elements selection of concrete, reinforced steel bar and FRP are recommended in this paper. The finite element model of two-way slab strengthened with CFRP were established based on related experience data. The nonlinear analysis under different strengthening conditions were carried out. The calculative results were compared with experimental results, which have good consistency. Based on the research above-mentioned, the calculation results of strengthened slabs with different bar space were obtained. The results show that the effect of CFRP's spacing play an important role on slab strengthened with CFRP. Some advices about the spacing of CFRP were given.