Research On Calculation Methods Of Bending Resistance Bearing Capability Of Reinforced Concrete Beams In Service

Suffering physical, chemical and biological action from natural environments, damages have come forth in some used reinforced concrete structures and its bearing capabilities have reduced. For this reduction, the safety of structures will be imperiled and its use life will be influenced. So, the evaluation and prediction of bearing capability of reinforced concrete structures is a impendent issue in civil engineering.Combined with the project Research on Bending Resistance of Bearing Capability Reinforced Concrete Structures in Service of Province funds support, and based on 17 testing beams in site cast, the influence of the reduction of cohesion between steel bar and concrete on ultimate bearing capability of concrete structure is analyzed. For the testing purpose, parts or full of the steel bars are exposed to simulate the influence of cohesion failure degree, failure length and its location on the structures are analyzed, and working principles of the structures after failure are also discussed. FEM is also used to verify the rationality and reliability of the testing results; simulation results and experimental result are consistent.The purpose of the text is to evaluate the bearing capability of reinforce concrete structures after the rust of steel bars, and to appraise properly of the post bearing capability of reinforced concrete structures. Based on the research, the safety of reinforced structures in service and scientific prediction of its residual life can be made, and this will provide bases for further choice of economical and reasonable maintenance schedules. Furthermore, this research will save enormous funds for the country, improve basic funds investment and promote the reuse rate of basic funds. The research also has fundamental bearings on our economic improvement and social development.Focused on the evaluation of bearing capability of reinforced concrete structures in service, some issues below are discussed especially:1. Influence of some circumstances on bearing capability of non-cohesion and half-cohesion reinforced concrete structures;2. Research on calculation methods of bearing capability of reinforced concrete beams after medium rust;3. Research on calculation methods of bearing capability of reinforced concrete beams after severe rust;4. Nonlinear FEM analysis and simulation of reinforced concrete beams;5. Evaluation method of bearing capability of reinforce concrete structures inserviceResult indicates that the influence of cohesion failure length and location between steel bar and concrete on half-cohesion structures is not evident,' however, for non-cohesion structures, this influence is evident. The calculation method of bearing capability of reinforced concrete structures after rust is associated with the rust degree of steel bar, including the reduction of steel bar strength and effective area and the reduction of cohesion capability between steel bar and concrete. In the evaluation process of bearing capability of reinforced concrete structures in service, some structures bearing capability can be made with calculation methods of concrete structures in service, based on practical behavior parameters, rust degree of steel bars and decline of material strength.