Method of constructing structures with seismically-isolated base

Abstract

A seismically isolated structure and a method of constructing same provide a rigid diaphragm, a plurality of footings each positioned at least partially under the rigid diaphragm, and a plurality of base isolation devices each positioned between a footing and the rigid diaphragm, wherein the rigid diaphragm was constructed in situ above the footings generally below its final elevation. A barrier is positioned between the rigid diaphragm and at least the footings to prevent bonding between the rigid diaphragm and the footings. The barrier, which may be structural or chemical or a combination thereof, may also span between the footings if appropriate.

1 . A method of constructing a seismically-isolated structure having a rigid diaphragm supported on base isolation devices, comprising: 
 providing at least a footing in ground;    positioning a barrier between footings and rigid diaphragm;    Constructing the rigid diaphragm on the barrier;    elevating the rigid diaphragm; and    installing the base isolation devices between the footing and the rigid diaphragm.    
   
   
       2 . A method of construction according to  claim 1 , wherein construction above the rigid diaphragm begins before raising the rigid diaphragm.  
   
   
       3 . A method of construction according to  claim 1 , wherein the footing is positioned within a field of the rigid diaphragm.  
   
   
       4 . A method of construction according to  claim 1 , wherein the barrier includes a tarp.  
   
   
       5 . A method of construction according to  claim 1 , wherein the barrier includes sheets of plywood.  
   
   
       6 . A method of construction according to  claim 1 , wherein the barrier includes a layer of sand.  
   
   
       7 . A method of construction according to  claim 1 , wherein the barrier is chemical.  
   
   
       8 . A method of construction according to  claim 1 , wherein the footing is constructed from concrete.  
   
   
       9 . A method of construction according to  claim 1 , wherein the footing has a recessed formation that receives a lifting device.  
   
   
       10 . A method of construction according to  claim 1 , wherein the rigid diaphragm has a recessed formation that receives a lifting device.  
   
   
       11 . A method of construction according to  claim 10 , wherein the barrier has its recessed formation for the recessed formation of the rigid diaphragm.  
   
   
       12 . A method of construction according to  claim 1 , wherein the rigid diaphragm is formed from concrete.  
   
   
       13 . A method of construction according to  claim 1 , wherein the rigid diaphragm is reinforced with steel.  
   
   
       14 . A method of construction according to  claim 1 , wherein the construction above the rigid diaphragm begins before raising of the rigid diaphragm.  
   
   
       15 . A method of constructing a seismically-isolated structure, comprising: 
 providing concrete footings in ground;    laying a barrier above footings;    constructing a concrete rigid diaphragm above the barrier;    elevating the rigid diaphragm to its final elevation;    constructing above the rigid diaphragm before raising the rigid diaphragm to its final elevation; and    installing base isolation devices between footings and rigid diaphragm.    
   
   
       16 . A method of construction according to  claim 15 , wherein construction above the rigid diaphragm comprises light wood frame construction.  
   
   
       17 . A method of construction according to  claim 15 , wherein the footings are in block form.  
   
   
       18 . A method of construction according to  claim 15 , wherein an upper surface of each footing and ground spanning between the footings form a generally flat surface on which the rigid diaphragm is formed.  
   
   
       19 . A method of construction according to  claim 15 , wherein an upper surface of each footing and ground spanning between the footings form a generally flat surface on which the rigid diaphragm is supported before being raised to its final elevation.  
   
   
       20 . A construction, comprising: 
 a structure having a rigid diaphragm;    a plurality of footings each positioned at least partially under the rigid diaphragm;    a plurality of base-isolation devices each positioned between the rigid diaphragm and a footing;    wherein the rigid diaphragm was constructed above the footings below its final elevation    
   
   
       21 . A construction of  claim 20 , further comprising a barrier positioned between the rigid diaphragm and the footings during construction of the rigid diaphragm.  
   
   
       22 . A construction of  claim 21 , wherein the barrier extends between the footings.  
   
   
       23 . A method of constructing a rigid diaphragm for use in a seismically-isolated structure: 
 providing footings;    providing a barrier on the footings; and    constructing the rigid diaphragm on the barrier.    
   
   
       24 . A method of constructing of  claim 23 , further comprising: 
 forming a generally flat surface on each footings to serve as a supporting surface for the rigid diaphragm as it cures.    
   
   
       25 . A method of constructing of  claim 23 , wherein the barrier is rigid.  
   
   
       26 . A method of constructing of  claim 23 , wherein the barrier is chemical.  
   
   
       27 . A method of constructing of  claim 23 , wherein the barrier is granular.