Research On Seismic Design Method Of Multi-storied Multi-ribbed Slab Structure Based On The Pushover Analysis

Based on the study to stress performance analysis of single frame grid from Multi-ribbed Composite Slab (MRCS), this paper describes a new equivalent frame-diagonal strut model of analysis. According to the above model, a model of Multi-ribbed Slab Structure (MRSS) is proposed, which is used for the preliminary seismic performance analysis and appraisement. The proposed MRSS model provides method for the seismic performance appraisement of MRSS under certain seismic intensity. The main study contents of this paper are followed.1. Based on the previous study of unfilled frames, the stress character of single grid frame from MRCS is described. Through the moment of ribbed beam and ribbed column under horizontal load and the stress on the contact surface of frame grid and aerated concrete filling block, the width of equivalent frame-diagonal strut is determined. Based on the stress of concrete blocks on the stress block area, the equivalent unidirectional stress-strain relation of frame-diagonal strut model is proposed, which is deduced from the force-displacement relation of concrete block in the diagonal line. The method provide with basic theory for nonlinear analysis of MRSS.2. According to the FEMA273 requirement, PMM (axial pressure and moment) hinges are set at end frame columns, connecting columns and ribbed columns; M3 (moment) hinges are set at concealed beams and ribbed beams; P (axial pressure) hinges are set at equivalent frame-diagonal struts. A series of hinged rigid bar are proposed in the model for transfer horizontal load from end frame columns to MRCS. The above settings are based on the SAP2000 software setting values to structural member bars. Then, the Multi-ribbed Composite Wall (MRCW) pushover analysis model, also used for the analysis of MRSS, is proposed.3. According to the previous study of a 1/2 ratio multi-storied MRSS building structure, a corresponding pushover analysis model is established. Before the pushover analysis, the plastic hinges locations and numbers are predicted and set by the experiences from previous tests and research findings. After the primary analysis, the nonlinear behavior of structure is predicted again which provides the references for the modifying of plastic hinges locations and numbers. Based the twice analysis, the occurrence sequence of structure member hinge and weak points of building are described, while the force-displacement curve of building top floor is mapped, which are matched with the previous test results. Finally, through the above model research, the seismic performance appraisement method for the multi-storied MRSS building structure is concluded, which is based on the pushover analysis.