Quantitative Analysis Of Seismic Damage On RC Frame Structures Based On The Energy Input Course Of Seismic Wave

Performance-based seismic design of structures has been discussed as hotspottopic in engineering design area. The determination of seismic performance objectivesis the key to whole structure design on performance-based seismic design. Thequantitative index of damage model is the basic condition for it. In this dissertation,combined with the research project “quantitative analysis of seismic damage on RCframe structures based on the properties of non-stationarity of seismic wave energy”financially supported by National natural science foundation of china (NSFC), severalkey problems are studied according with the energy input course of seismic wave.1． Non-stationarity is the complex characteristic of seismic waves. It can beinterpreted as the inhomogeneous distribution in time and frequency domains. Theinhomogeneous distribution of energy is harmful to structures. Wavelet analysis hasbeen widely applied in simulating earthquake motions and analysis of response toengineering vibration. By using the direct wavelet analysis method, the concept ofmean energy density is set up. Furthermore, the mean energy density and effectiveduration characteristics of ChiChi earthquake in1999for various site conditions andepicentral distances, time history are obtained.2．A mathematical model is carried out to reflect the time varying characteristic ofmomentary input energy. By established the relationship between the time varyingcharacteristic of momentary input energy and the input energy, the maximummomentary input energy, the duration of input energy process, a simplified procedureto develop the simulated deformation history of linear single degree offreedom(SDOF) system is proposed in this paper. The methodology proposed in thispaper is validated using the maximum deformation and cyclic demand spectrum oflinear system. It is found that the simulated deformation response can reflect the maxamplitude of actual deformation and the effect of duration of multi degree of freedomsystem(MDOF).3．In this dissertation, total input energy, maximum momentary input energy andduration of input energy process are taken as three description parameters of inputenergy time histories. The influence of ductility factor of SDOF system and plasticitystatus of MDOF system on the three parameters is investigated according with56earthquake records of4site types and the V/A ratio of ground motions. Based on the three description parameters spectra and ductility factor of structures, a analyticalprocedure is developed for the elastic-plastic three description parameters spectra.4．Based on existing damage models, a new structure seismic damage is definedwhich reflect first excursion failure and cumulative damage failure. Statistics weremade to analyze the association between the content of six parameters which namedinput energy, the maximal momentary input energy, energy growth duration, ductilityfactor, nominal strong vibration times, the ration of maximal momentary input energyand displacement damage, degradation damage on structures, total damage, the rationof displacement damage.5．Using force analogy method, a process is obtained which can estimate the localdamage and the whole damage based on the damage model in this paper. A numericalexample of single-story and single-bay frames shows that injury of plastic hinge inthe course of seismic is the source of frame structure damage. Control of strengthdegradation in the time of reciprocating seismic and reducing the plastic rotationangels in the time of post-earthquake on plastic-hinge region are the keys ofseismic damage on frame structures.6．Based on the mathematical model which reflect the time varying characteristicof momentary input energy, a simple analytical procedure which reflect the timevarying characteristic of dissipation on deformation energy is developed forpush-over analysis of frame structures. The correlation analysis showed that thepush-over analysis based on the time varying characteristic of dissipation ondeformation energy have good accuracy in described the injury three descriptionparameters. By push-over analysis the damage of frame structures can be obtainedinstead of complex dynamic time-history analysis.