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A total of seven underpinning reinforced concrete beams-masonry wall composite components including two combination forms and three tie reinforcement spacing were made and their flexural behaviors were experimentally studied. Deflection, strain of steel bars and concrete, damage mode and bearing capacities of specimens were analyzed. The results show that underpinning reinforced concrete beams and masonry wall can keep good integrity and work together well by use of tie reinforcement. Ultimate bearing capacities of single and double underpinning beams are greater than comparison beam, but the tie reinforcement spacing has no obvious influence on the increase of flexural capacity. On the basis of the constitutive relationships of concrete, brick masonry and basic calculation assumptions of normal section bending bearing capacity, ultimate bearing capacity calculation formula of composite components of underpinning reinforced concrete beams-masonry wall was established and its accuracy was verified by experimental test. [ABSTRACT FROM AUTHOR]

This paper adopts near surface mounted prestressing helical rib steel wire system, using the process of slotting, reinforcing and tensioning helical rib steel wire, filling glue. An experimental study was conducted on 10 RC beams with near surface mounted prestressing helical rib steel wire. The experimental results indicate that this method can improve the overall performance of reinforced concrete beams. The first-crack load, flexural load, ultimate load are increased effectively. With various numbers of helical rib steel wire and prestressing levels, the first-crack load, flexural load and ultimate load can be increased by 72.6%-321.26%, 6. 19%-99.09% and 46.04%-135.27% respectively. This strengthening method can effectively improve the ductility, safety performance and stiffness of reinforced concrete beam. The emergence and development of cracks can be restrained, and the high strength of helical rib steel wire can be fully used. [ABSTRACT FROM AUTHOR]