Frictional non rocking seismic base isolator for structure seismic protection (fnsi)

Abstract

Frictional Non Rocking Seismic Base Isolator For Structure Seismic Protection (FNSI) is a seismic protection isolator installed under foundations or columns of a building or other structure. FNSI separates a building or other structures from ground seismic motions and passes slight fraction of seismic forces to the superstructures so that the superstructure protected from earthquake induced damages. FNSI consists of three main parts, a Sliding Hammer fixed into ground, a Rotating Anvil, RA, and a Hook fixed to the superstructure, wherein contacted moving surfaces are so smooth for effective isolation. Seismic motions shake the sliding hammer which imitates ground motions and causes RA to rotate around center of the Hook convex or concave, and to simultaneously vibrate in vertical direction. RA movements cause the isolated superstructure to move vertically and slightly horizontally where the vertical vibrations can be accommodated by increase in material strength when responding to short term loading.

I claim 
     
         1 . frictional non rocking seismic base isolator for structure seismic protection or FNSI which is installed between a structure and ground, so that earthquake motions transferred only through the FNSI to the structure, comprises,
 a) a sliding hammer (SH) which is a disk has top smooth concave surface and bottom flat surface fixed to ground,   b) a rotating anvil (RA), which is 2-convex, arrangement connected rigidly through a cylindrical neck, wherein bottom convex of the arrangement has similar radius to the sliding hammer concave, and is large enough so that it, normally, does not slide over the sliding hammer due to horizontal forces affect the bottom convex, due to horizontal reaction forces created partially or completely at the peripheries of the contacted surfaces of the SH and RA, and wherein the other top convex of the arrangement has comparatively smaller radius, and wherein the arrangement situated between the upper face of the SH concave and the lower face of an upside down concave fixed centrally at bottom of,   c) a hook which is a disk, has flat surface at the top, and wherein the upside down smooth concave has a radius similar to top small convex of the RA, so that the RA small convex fits into the hook concave and can rotate around its own center which is, normally, coincide with the center of the hook upside down concave and wherein the hook upside down concave is connected rigidly and centered at the bottom of the hook disk which is connected to the structure isolated by the FNSI.   
     
     
         2 . another embodiment of the FNSI as defined in  claim 1 , wherein the RA bottom convex has 2 or more different vertical radii, wherein a central part of the bottom convex has a radius equals to the radius of the SH and the other surrounding parts of the bottom convex have gradually and slightly smaller radius than SH to allow increasingly widening tapered space between the SH and the bottom convex of the RA. 
     
     
         3 . a third embodiment of the FNSI as defined in  claim 1 , wherein the RA has convex-concave arrangement connected rigidly through a cylindrical neck, wherein bottom convex of the arrangement has similar radius to the SH concave and the bottom convex of the RA is large enough so that it, normally, does not slide over the SH, due to horizontal reaction forces created partially or completely at the peripheries of the contacted surfaces of the SH and RA, and the top concave of the arrangement has comparatively smaller radius than SH radius, and wherein the hook has bottom upside down convex fits into the top concave of the RA, and the upside convex is connected rigidly to and centrally to the bottom of the hook disk which supports and connected to the structure, which is isolated by the FNSI. 
     
     
         4 . a fourth embodiment of the FNSI as defined in  claim 1 , wherein the RA has convex-concave arrangement connected rigidly through a cylindrical neck, wherein the bottom convex of the RA has 2 or more different vertical radii, and wherein a central part has a radius equals to the radius of the SH and surrounding parts have gradually and slightly smaller radius than SH to allow increasingly widening tapered space between the SH and the bottom convex of the rotating anvil, and wherein the bottom convex of the rotating anvil is large enough so that it does not slide over the SH, due to horizontal reaction forces created partially or completely at the peripheries of the contacted surfaces of the SH and RA, and wherein the hook has upside down convex fits into the top concave of the rotating anvil wherein the small radius of the top concave of the rotating anvil increased gradually and slightly towards the edges of the small concave to allow for tapered space with the convex of said hook and wherein the convex of the hook is connected rigidly and centered at the bottom of the hook disk which has a flat top surface to support and connect to the structure which is isolated by the FNSI. 
     
     
         5 . a method to protect structures from earthquakes, or other sources of vibrations, by using the: FNSI as defined in  claim 1 ,  2 ,  3  or  4  by placing the FNSI between the structure and ground, normally under columns or foundations, one FNSI under each column or foundation, wherein, normally, no other connection between the structure and ground other than the FNSIs. 
     
     
         6 . A method to operate each FNSI as defined in  claim 1 ,  2 ,  3  or  4  wherein any movement of the SH due ground movement in an earthquake, results in rotating the RA around the center of its top small convex or concave, simultaneously with moving up vertically which causes the structure to vibrate, mostly, vertically instead of rocking horizontally, due to high smoothness of the contacting surfaces of the SH, RA and Hook convex or concaves and due the Rotation of the RA around the center of Hook bottom convex or concave, which does not coincide with the center of SH which. 
     
     
         7 . The RA as defined in  claims 1 ,  2 ,  3  and  4 , normally, does not move when wind forces affect the isolated structure by means of FNSI, wherein the wind pushes, normally, horizontally, the structure, which pushes the Hook, which pushes the top convex or concave of said RA, which pushes the bottom convex which touches the SH concave completely or partially, and the SH reacts, normally, with horizontal forces which are almost equal to the wind forces, and the reaction forces of the SH are, normally, not initiated if the wind forces less than frictional forces between the SH and the bottom convex of the RA. 
     
     
         8 . The RA as defined in  claims 1 ,  2 ,  3  and  4 , stays, normally, at the lowest location of the SH concave when the SH is not exited by a ground motion, wherein the gravity loads of the structure act on the SH via the RA contacted surfaces, and wherein the SH reacts with equal forces to the normal to surface components of the gravity forces, and the tangential components of the gravity forces push the RA downwards towards the lowest point of the SH, and wherein the fractional forces resulted from the normal components of the gravity forces acting on the SH concave, are normally very small because of the high smoothness of the contacted surfaces of the SH concave and RA convex.