Issue 35

W. Xu et alii, Frattura ed Integrità Strutturale, 35 (2016) 481-491; DOI: 10.3221/IGF-ESIS.35.54 481 Effect of steel reinforcement with different degree of corrosion on degeneration of mechanical performance of reinforced concrete frame joints Wu Xu, Liu Ronggui School of Civil Engineering and Architecture, Nantong Institute of Technology (NIT), Nantong, Jiangsu, 226000, China wxlrgwu@163.com A BSTRACT . Beam-column joints which shoulders high-level and vertical shearing effect that maintains balance of beam and column end is the major component influencing the performance of the whole framework. Post earthquake investigation suggests that collapse of frame structure is induced by failure of joints in most cases. Thus, beam-column joints must have strong bearing capacity and good ductility, and reinforced concrete structure just meets the above requirement. But corrosion caused by long time use of reinforced concrete framework will lead to degeneration of mechanical performance of joints. To find out the rule of effect of steel reinforcement with different corrosion rate on degeneration of bearing capacity of reinforced concrete framework joints, this study made a nonlinear numerical analysis on fifteen models without stirrup in the core area of reinforced concrete frame joints using displacement method considering axial load ratio of column end and constraint condition. This work aims to find out the key factor that influences mechanical performance of joints, thus to provide a basis for repair and reinforcement of degenerated framework joints. K EYWORDS . Reinforced concrete; Mechanical performance of joints; Corrosion of steel reinforcement. I NTRODUCTION n China, most framework structures has been degenerated [1]. During construction of old building, core area of building framework joints is usually placed with less or even no stirrup due to the limitation of building science and technology and insufficient understanding on importance of putting stirrup in the core area of framework, which influences quality of old framework joints [2, 3]. Framework joints involving complex force situation can influence overall framework performance. Therefore, studying degradation of mechanical performance of old framework joints is of great and practical significance. It has been found that, steel reinforcement corrosion is the leading cause for function degeneration of old building structure [4]. Besides decrease of mechanical property, performance of steel reinforcement corrosion also includes cracking and even spalling of concrete, weakening of bound stress and decrease of adhesive property. Currently, structure damage or instability induced by corrosion of steel reinforcement in concrete has been one of major issues concerned by the world; it occupies a leading role in factors influencing durability of structure [5]. For building which needs continued construction, steel reinforcement corrosion will further develop and finally result in engineering accidents if no thorough examination and effective treatment are carried out on corrosion condition of steel reinforcement [6]. Hence it is necessary to detect steel reinforcement corrosion and evaluate durability and reliability of corroded component. Research on corroded I