Research On The Deformation Performance Of Rc Frame Beam

Earthqueke damages and experimental studies indicated that the callapses of buildings were mainly caused by capacity of energy dissipation and plastic deformation of structures cannot meet the requirement. Capacity design can't ensure that the frame structures meet the predictive plastic deformation or ductility requirement, however, performance based design can reach these demand. Therefore, the performance based seismic design theory and method of reinforcement concrete frame structures currently is the forfront research trend of academic and engineering circles, and the performance index is the key point to this kind of design. Thus it is of great practical value to research on the performance index.In order to determine the performance index, 300 RC frame beam models were designed firstly in this paper and elastoplastic pushover analysis was carried out by ABAQUS, which is a 3-dimensional nonlinear analysis software. Based on the calculation results and the results of parameter analysis, the influence of parameters to the deformability of RC frame beams was gave out and the failure modes were classified by shear span ratio and reinforcement ratio. And then, 138 reinforced concrete frame beam models were designed basing on Chinese Codes and analyzed by ABAQUS, according to the calculation results, the influence of shear span ratio and reinforcement ratio to the RC frame beams was analyzed. Based on the curves of bending moment and rotation angle of the 138 calculation models, the rotation angles of each model when it achieves yield load, peak load and limit load respectively were gave out. At last, based on these rotation angles, the performance index applicable to frame beams under different failure modes during small, medium and large earthquakes was presented.The main content of this paper including:1. According to the 20 experimental results of RC frame beams, this paper verified the applicability of ABAQUS damaged plasticity (CDP) model when used to simulate RC frame beams;2. The influence of each important model parameters in CDP model to calculation results was got by parametric analysis, and the reasonable values or range were obtained when used to simulate RC frame beams;3. Three hundreds RC frame beams were designed and elastoplastic pushover analysis was carried out using CDP model and the influence of shear span ratio, reinforcement ratio and stirrup ratio to calculation results was analyzed. Based on the ratio between calculated rotation angles of the plastic region and the whole beam at the limit state, and combining with load -displacement curves, the stress and strain distribution maps of reinforced skeleton frames and concrete, the failure mode of RC frame beams was gained.4. The relationships between calculation results and the ratio of longitudinal rebars with tesion and compression, section size, concrete strength grade were analyzed by modeling a serious of three-dimensional models. Then, shear span ratio and the ratio of longitudinal rebars with tesion were choosed as the variable parameters and 138 RC frame beam models were designed. According to the calculation results, the failure mode of RC frame beams which is suitable for practical engineering was obtained. At last, on the basis of failure modes and displacement angles, the deformation performance index of RC frame beams during medium and large earthquakes was determined.