Research On Mechanical Behavior Of Reinforced Concrete Beams Strengthened With Near-surface Mounted High-strength Aluminum Alloy Bars

At present,most of the building structures are ordinary reinforced concrete structures,but as time goes by and the function of external loads,the ordinary reinforced concrete structures unavoidably suffer from a decrease in their load-bearing capacity and durability.Therefore,relevant researchers have investigated use of appropriate new materials and new methods to strengthen reinforced concrete structures in order to enhance their service performance and extend their service life.T7075 series aluminum alloy can be considered as an ideal reinforcement material to strengthen reinforced concrete beams due to its many advantages such as light weight and high strength,good ductility and corrosion resistance.The near-surface mounted reinforcement method is to cut slots on the surface of the beam,embed the reinforcement bar into the beam with binding material,and fill the slot evenly with binding material,so as to strengthen the reinforced concrete beam and improve the mechanical performance of the beam,this reinforcement method has more advantages than externally bonded reinforcement method.Therefore,in this paper,7075high-strength aluminum alloy bars are considered as reinforcement bars,and near-surface mounted reinforcement method is used to strengthen reinforced concrete beams.At the same time,mechanical anchorage measures or carbon fiber reinforced polymer（CFRP）cloth U-shaped wrap anchorage measures are considered to anchor the end of reinforced concrete beams.To test the strengthening effect of T7075 series high-strength aluminum alloy bars on reinforced concrete beams and the influence on their failure modes,this paper combined material engineering and reinforcement engineering,studies 8 simply supported beams（including 1 reference beam and 7 near-surface mounted strengthened reinforced concrete beams）through four point bending monotonic loading test:（1）By displacement control loading,the test data of load,deflection,material strain and crack width of each beam in the loading process are measured under the conditions of different number of reinforcement bars,type of binding material,end anchoring type and cladding number of CFRP cloth,and the variation of each data was analyzed..（2）The failure process,failure mode and failure mechanism of 8 test beams were described.The results of research indicate that aluminum alloy bars near-surface mounted reinforcement can effectively improve the cracking load and bearing capacity of beams,but it needs effective binding materials and reasonable anchorage measures to make aluminum alloy bars play full role in the strength and achieve higher utilization.（3）The influence of near-surface mounted reinforcement with 7075 high-strength aluminum alloy bars on the flexural performance of reinforced concrete structures were analyzed,and the feasibility and superiority of near-surface mounted strengthening reinforced concrete beams were concluded.Based on the calculation theory of ordinary reinforced concrete beams,this paper put forward the ultimate load-bearing capacity calculation formula of beams strengthened with near-surface mounted aluminum alloy bars after the whole process force analysis of test beams,and the feasibility of the proposed formula is verified by MATLAB software.