Random Simulation Analysis Of Structural Response And Optimal Design Of Vibration Reduction Under Random Excitations

At present,most of the research and codes for engineering structures focus on the impact of earthquake and wind load on the structure.The random simulation analysis of dynamic response of structures under random load is of great significance to seismic and wind resistance design.The vibration reduction design of engineering structures has always been an important research direction of civil engineering structures.Although the vibration reduction technology of engineering structures has a long development history,the research on the optimal design of the location and quantity of vibration reduction devices(such as viscoelastic dampers)in the vibration reduction design of structures under random loads is not common.Therefore,the main research content of this paper is to carry out the random simulation analysis of structural seismic response and wind-induced response,as well as the optimal design of damping device in structural damping design.The specific research work is arranged as follows:In Chapter 2,artificial seismic wave simulation and structural seismic random simulation analysis based on unit impulse response are carried out.Firstly,the explicit time-domain expressions of single degree of freedom and multi degree of freedom dynamic systems based on unit impulse response are derived.Then,the explicit time-domain expression of single degree of freedom system is applied to solve the ground motion equation of ground motion random model.Then,taking advantage of its ability to quickly solve the response,the artificial seismic wave with specified strength and the artificial seismic wave consistent with the code response spectrum can be simulated efficiently through iteration.Finally,the explicit timedomain expressions of the simulated artificial seismic wave and the response of multi degree of freedom dynamic system are applied to the structural seismic random simulation analysis.Numerical examples show that:(1)based on the existing ground motion model and the explicit time-domain expression of unit pulse,the artificial seismic wave with specified strength and the seismic wave consistent with the code response spectrum can be simulated efficiently(2)The explicit time-domain method(ETDM)based on unit pulse combined with mode superposition method has sufficient accuracy and high efficiency in structural seismic random simulation analysis,and can be used for seismic time history analysis of large structures.In Chapter 3,the random simulation analysis of wind resistance of structures under wind load is carried out.Firstly,the dynamic equation of the structure under wind load is decoupled by mode decomposition method,and the motion equations of multiple single degree of freedom systems are obtained.Then,the explicit time-domain expression of wind-induced vibration response is derived by using the explicit time-domain method based on unit pulse and mode superposition method.Finally,the explicit time-domain expression is used to analyze the windinduced random simulation of the structural wind-induced vibration response.Through a numerical example,it is verified that the explicit time-domain method based on unit pulse has great advantages in calculation efficiency,and the analysis results are reasonable and reliable.The fourth chapter studies the optimal design of damping device in the damping design of frame structure.Firstly,taking the viscoelastic damper as an example,the dynamic response analysis equation of the structure with viscoelastic damper is derived.Then,the explicit timedomain expression of structural dynamic response sensitivity is derived by using the explicit time-domain method based on unit pulse and mode superposition method.Then,taking the reduction rate of random response of the structure and the utilization rate of viscoelastic damper as the evaluation and analysis indexes of vibration reduction effect,the vibration reduction optimization design of the structure under random load is studied.Finally,through two numerical examples,the optimal design of the number and position of vibration damping devices is studied.The analysis results show that the optimal design of the number and position of vibration damping devices is of great significance to improve the vibration damping effect and cost control.Finally,all the research contents of this paper are summarized,and the future research and development direction is prospected.