Issue 29

L. Facchini et alii, Frattura ed Integrità Strutturale, 29 (2014) 139-149; DOI: 10.3221/IGF-ESIS.29.13









 

 

k mx t 

k cx t 





 

kg

x

z

, g z x

,

k k

  , 

 

 

k z t 

k x t 

 

 

(11)







h x z

1

  ,

  , x 

  x t h x z    ,

x 

k zz  



h

,



k

1

2

   k E k .

Figure 9: Response   x t evaluated for

  k x t .

Figure 10: Sensitivity of the response

Moreover, a further differentiation with respect to k gives the equation of motion of the second derivative of BW response to the earthquake, as follows:                                 1 2 2 2 11 12 22 1 2 , 2 , 1 , 2 , , , , , , 2 , , , , , , , , kk kk kk kk k k kk kk k k k k k k k kk kk mx t cx t kg z g z z t x t h x z x t h x z x h x z z x t h x z x h x z x z h x z z h x z x h x x x z z                                            (12)

146