ABSTRACT
Earthquake e x c i t a t i o n as two extreme c o n d i t i o n s ; ( 1 ) u l t i m a t e e x c i t a t i o n of v i b r a t i o n : resonance s t a t e , ( 2 ) u l t i m a t e e x c i t a t i o n of one way loading; impulsive s t a t e . The e f f e c t of v i b r a t i o n e x c i t a t i o n and i t s u l t i m a t e s t a t e s correspond to the f a t i g u e behaviour and f a t i g u e f r a c t u r e of s t r u c t u r a l m a t e r i a l s , members and s t r u c t u r e s . Conversely, i m p u l s i v e e x c i t a t i o n and i t s e f f e c t on s t r u c t u r e s correspond to one way impulsive loading. Between these two opposite extreme c o n d i t i o n s , s t r u c t u r e s w i l l behave a t t h e i r u l t i m a t e s t a t e under earthquake e x c i t a t i o n . E s p e c i a l l y under
Testing of Metals for Structures. Edited by F.M. Mazzolani. © 1992 R I L E M . Published by Taylor & Francis, 2 Park Square, Milton Park, Abingdon, Oxon, 0X14 4RN. ISBN 0 419 15810 3
earthquake e x c i t a t i o n s t r u c t u r e s v i b r a t e f o r v e ry few c y c l e s and seem t o s e l e c t the same frequency wave f o r themselves from the random earthquake waves and to resonate, and consequently to amplify t h e i r e f f e c t [ 3 ] .
