Study On Characteristics Of Museum Floor Wave Under Ground Motion And Subway Vibration

Because China is an earthquake-prone country,the events that damage caused by earthquake to cultural relics are very common.Except for the influence caused by sudden earthquake,it can not be understimated by the long-term impact of urban rail transport on museum cultural relics.Accordingly,reducing the impact of the earthquake and the subway vibration on museum collection of movable cultural relics is very urgent.Actually,the study on the characteristics of the floor wave under the gound motion and subway vibraiton have great value on theory and engineering application.In this paper,finite element model of a museum in Sichuan is first established.The seismic waves and the measured subway vibration waves are used for excitation coincide with site soil condition,and the distribution characteristics of the floor waves in the museum are obtained under the excitation.Then the finite element model of the horizontal isolation bearing and three-dimensional isolation bearing are established to study the law of museum floor waves after horizontal isolation and vertical vibration isolation.Finally,combined with the law of floor waves transmitting in the museum,the factors affecting the floor waves characteristics are analysed and quantitatively studied.The main research work and achievements are as follows:(1)The finite element model of the museum is established in SAP2000.Four seismic waves and four measured subway vibration waves are selected coincide with the site soil conditions for time history analysis.The floor wave acceleration time history of different floor is extracted and Fourier transform is performed to obtain the floor wave spectrum curve.The results show that the floor peak acceleration increases with the increase of the floor number under the excitation of earthquake,and the shape of the floor wave spectrum curve depends on the natural frequency of the main structure.Under the excitation of subway vibration waves,the floor peak acceleration decreases with the increase of the floor number,but the peak acceleration of the top layer increases inversely.The peak of floor wave spectrum is located in the excellent frequency band of the input subway vibration waves,and the vibration at the high frequency is attenuated faster than the low frequency.(2)Finite element model of the museum with horizontal isolation and vertical vibration isolation are established.The time-hisotry characteristics of the floor waves are obtained in terms of horizontal isolation and vertical vibration isolation applied in the museum.Fourier transform is performed to further study the spectral characteristics of floor waves.The analysis shows that the peak acceleration after structural isolation is reduced by 50%compared with the imput seismic wave amplitude.The acceleration of each floor in the supersutrue performs a slight distinction.After the structure is isolated,the corresponding peak frequency of the floor wave spectrum is reduced by 60%?70%.The vertical vibraiton isolation efficiency is between 70%and 80%,and the vertical peak acceleration of each floor is reduced by 50%compared with the original structure.The high frequency component of floor wave spectrum decays faster than the low frequency component in vibration isolation structure.(3)Study on the factors affecting the floor wave characteristics based on a museum in Sichuan.Select the number of museum floors from two to five and select the museum floor span to 4.5m,6m,7.5m and 9m.Subsequently,to study the distribution law of floor waves in the museum under different parameters.The study shows that as the number of floor increases,there is a significant difference in floor peak acceleration at the same floor of the structure.The distribution of floor wave superior frequency shows a new law as the number of floor changes.The distribution of dynamic amplificaiton factors on each floor is relatively discrete in the museum with different spans.As the span increases,the floor wave spectrum curve moves regularly.