| The bottom frame masonry structure is composed of the bottom frame and the upper masonry.The bottom frame space is large and masonry space is smaller,Therefore,it is widely used in urban construction in our country.However,the overall stiffness of the structure is not uniform,and the seismic performance is poor.A new isolation layer is installed between the masonry and the frame mentioned above,which is formed the isolation structure between layers of masonry and the seismic response of the structure is analyzed by the direct integration method of state equation and SAP2000.The main research work is as follows:(1)The vibration equation of the base isolated structure with n floor of bottom frame is obtained.It is concluded that the damping ratio of the isolation bearing is more than 0.2,and the frequency ratio of the upper and lower structure should not exceed 0.8;(2)The vibration equation of the seismic isolation of the bottom frame masonry structure is solved,The direct integration method of state equation and the traditional forced decoupling method are given,At the same time,the two results are compared and analyzed,It is found that the forced decoupling method has less error in the first and two order vibration response of the structure,but the error of higher order vibration response is larger;(3)The seismic response analysis of masonry structure with bottom frame is carried out by using the direct integration method of state equation,and which is analyzed by SAP2000,At the same time,the two results are compared and analyzed,It is found that the forced decoupling method has less error in the first and the secondly order vibration response of the structure,but the error of higher order vibration response is larger;(4)For the isolated structures with 3 floors and 2 floors bottom frame,the three dimentional finite element modes are researched.The seismal response of the two structures modes indicates that the bottom frame may be designed to 3 floors in the structure. |
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