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[SEAOC] Tiltup Retrofit Anchors

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** Reply to note from IBMMAIL(I1720810) 02/21/96 11:03pm                        
>  From: CarlS95(--nospam--at)aol.com                                                        
>  Subject: ìSEAOC? Concrete Anchors in Tilt-Ups                                
>  I'm looking for opinions, friendly or otherwise:  Are expansion-type         
>  anchors, such as Hilti Kwik-Bolt II, appropriate for out-of-plane anchors in 
>  the wall-to-roof connection to retrofit existing, pre-1971, concrete tilt-up 
>  buildings?  The configuration would consist of concrete anchors drilled      
>  through the wood ledger, and connected to the wood joists with Simpson       
>  holdowns or similar hardware.                                                
                                                                                
Carl,                                                                           
We are applying an approach which I feel comfortable with- on new               
retrofit anchors, we are using strictly epoxy-grout anchors. Our                
experience with any type of expansion anchor that relies on friction to         
retain it in the concrete is that they fail under dynamic (seismic)             
loads well below their static capacity. Furthermore, we have noticed            
that most manufacturers allow a large amount of anchor displacement to          
occur in testing, and as long as it is 'holding', use the ultimate              
pullout value, regardless of anchor displacement. This is not acceptable        
under dynamic conditions of load reversal.                                      
                                                                                
On existing buildings fitted with expansion anchors in the roof to wall         
connection, if the calculated load based on the Division 91 criteria is         
well below the LARR allowable value (use judgement, but 50% of allowable        
should be a clear case), we are approaching on a case-by-case basis,            
approval of the existing anchors by calculation.                                
                                                                                
                                                                                
                                                                                
                                                                                
.bc THONLE                                                                      
                                                                                
Thomas D. Honles, S.E.                                                          
DWP Energy Services Structural Engineering  (213)367-0006                       
Vines:thonle@pdc_csess_struc@ladwp          (213)367-0066 Fax                   
Internet E-Mail: usdwpydp(--nospam--at)ibmmail.com                                           
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