Research On Nonlinear Numerical Models And Analysis To Seismic Energy Responses Of Multi-Ribbed Composite Slab Structures

Multi-ribbed composite slab structures (MRSS) is a new structure system that has a good performance in energy dissipation and seismic behavior. From early1990s, the study on MRSS has achieved great progress in theoretical research and engineering application during the past twenty years. Based on pre-stage tests and composition characteristics of MRSS, a reasonable and effective nonlinear numerical analysis model is built. By the means of FEM simulation and theoretical analysis, the seismic displacement and energy responses of MRSS are analyzed. And then the energy-based seismic design method is proposed, which lays a foundation on further research and application of MRSS. The main research contents are as follows:1Research on the nonlinear numerical model of MRSSConsidering the composition characteristics and mechnical behaviors of MRSS, a relatively fine nonlinear finite element model of MRSS under complicated conditions is developed based on general finite element software of MSC.MARC with user-defined material models. The finite element model applies fiber-beam and layered-shell theories and considers the related interface requirements. And its accuracy is verified by the comparison between the numerical simulation results and the experimental data. The proposed numerical model has a bigger application scope and a better precision than existing models for its precise material constitutive relations, suitable element styles and effective interface connections. And the model can be used in the simulation on mechanic behaviors of MRSS under reciprocating loads such as earthquake.2Research on seismic displacement responses of MRSSFor the two assumptions of fixed lateral displacement mode and control by basic vibration mode, the traditional pushover analysis method can not be used in high-rise buildings whose reaction by high-order mode is obvious. The modal pushover analysis (MPA) method can be used in high-rise buildings by multi-mode pushover analysis and combination. In this thesis, the MPA method is applied in analyzing seismic displacement responses of middle-high MRSS by use of pushover algorithm based on multiple point constraints method. The time-history analyses of two12-storey MRSS examples under10seismic waves are completed. The applicability of MPA method in seismic displacement response analyses of MRSS is verified and the calculation method of deformation demand to MRSS members is obtained.3Research on seismic energy responses of MRSSBased on the developed numerical model, the rule on seismic energy responses of MRSS is studied by changing the values of whole coefficient.150elasto-plastic time-history analysis examples of MRSS under10seismic waves are completed. The calculation method of determination to input energy and hysteretic energy (EH) under earthquakes, the distribution and vertical dispersion proportions of EH related to member styles of MRSS are mainly studied. And then the solution of demand to energy-dissipation of each MRSS member is obtained, which is as follows:firstly, the total EH of the whole structure is determined by MPA method, secondly, the EH related to member styles in each floor is obtained by use of proposed formulae derived from time-history analysis results, thirdly, the proportion to EH of each member in each floor is gotten by MPA method, and finally the demand to energy-dissipation of each member is achieved.4Research on energy-based seismic design method of MRSSBased on the fact that the studies on damage mechanism of brick and interface are inadequate, in this thesis, the energy-dissipation capacities of brick and interface are used as safety reserve for their small total energy-dissipation proportion. By applying Park-Ang damage model and member capacity design theory, the problem that the demands of deformation and energy can hardly be used in member design of MRSS is solved. And then the energy-based seismic design method of MRSS is proposed, which is as follows:bearing-capacity design of MRSS, calculation of demands to member deformation and energy, determination of ultimate deformation of member based on Park-Ang damage model with consideration of above safety reserve and member design by using capacity design method. Comparison with time-history analysis results, the method has an adequate accuracy.