RESEARCH ON THE LIMIT RATIO OF HEIGHT TO WIDTH FOR BASE-ISOLATED STRUCTURE WITH THE RUBBER BEARINGS CONSIDERING THE VERTICAL EARTHQUAKE ACTION

Through interlaminar shear model with the multi??degree of freedom, the equation of motion was established for base??isolated structure with the rubber bearings, considering the earthquake action in horizontal and vertical directions. The simplified formula for the calculation of the limit ratio of height to width was derived. The influence of vertical earthquake action on the limit ratio was analyzed, in consideration of the factors such as sites and earthquake intensity. The research shows that the influence of vertical earthquake action on the limit ratio of height to width is large in rigid site, which can be increased with an increase in seismic intensity and the peak value of the vertical acceleration. So, the influence of vertical earthquake action on the limit ratio of height to width for base??isolated structure is not ignored in high earthquake intensity zone and rig id site.