Effects Of The Frequency Ratio On The Earthquake Response Of Equipment-Structure-Soil Interaction System

Researches show that under the action of earthquake,the equipment and structure in equipment-structure system work together,and there is a complex dynamic interaction between them.The natural frequency is an important parameter that can reflct the dynamic characteristics,the change of the relative frequency between the equipment and the structure will inevitably effect the dynamic response of them.Moreover,the researches on the dynamic response of equipment-structure system,considering the effect of the location of the equipment,the type of the connection,and the soil-structure interaction,remain to be further studied.Therefore,the time-history analysis method is used to analyze the effect of equipment-structure frequency ratio on the dynamic response of equipment-structure system,when the equipment is located on the different floor of the structure,the connection between the equipment and the structure is different and considering the soil-structure interaction.The main points and related research achievements are as follows:(1)Based on the assumption of rigid foundation,the equipment-structure model with equipment anchored to different floors of the structure was established respectively,and the differences in the dynamic response between the equipment and the structure were analyzed from the perspective of frequency ratio.In the vicinity of ? = 1,obvious resonance phenomenon occurs between the equipment and the structure,and the shearing force of the equipment increases significantly,but the relative displacement is not sensitive to the resonance effect.Due to the reaction of the equipment to the structure,the dynamic response of the structure is obviously reduced.In addition,the magnitude of the dynamic response of the equipment and the severity of resonance effects between the equipment and the structure are gradually reduced as the floors decrease.(2)Based on the rigid connection between equipment and structure,the equipment-structure system model with flexible connection between the equipment and the structure is further established,and the effect of the type of the connection between the equipment and the structure on the dynamic response of the equipment and the structure is analyzed.It is found that the natural frequency of the equipment is decreased after using the flexible connection.The deformation of the equipment is mainly concentrated at the support,and the equipment itself is mainly in the translational motion.The dynamic response of the equipment is reduced,and the equipments in the resonance zone have the most obvious decrease in different frequency ratio cases;the dynamic response decreases most obviously during the strong earthquake.However,the dynamic response of the structure has no obvious change with the change of frequency ratio.(3)The analysis of the equipment-structure-soil interaction system in which the equipment is connected rigidly to the top of the structure shows that the natural frequency of each step of the main structure is significantly reduced the resonance frequency ratio is significantly decreased,and the equipment may resonate with the high-order modes of the structure.The dynamic response of the equipment-structuresoil interaction system is closely related to the seismic stage,the frequency ratio between equipment and structure and the the spectral characteristics of the seismic wave.Therefore,the establishment of a complete model of equipment-structure-soil interaction is of great significance for the safety of equipment and structures under earthquakes.