Abstract:
Generally the building frames are analysed by Response
Spectrum Method. Some of the modal combination rules used in Response Spectrum Method which has been suggested in ASCE-4-86 i.e. ASCE Standards on seismic analysis of Safety Related Nuclear Structures and Commentry on Standards for Seismic Anaysis of Safety Related Nuclear Structures are SRSS (Square Root of sum of the squares), Grouping, Ten per cent, Double sum. All these modal combination rules and CQC (Complete quadratic combination) have been evaluated in this thesis.
To account the responses from the three earthquake components calculated separately the spatial combination followed in this thesis are :
(i) SRSS
(ii) 1R1 + 0.4R2 + 0.4R3
(iii) 0.4R1 + l.0R2 + 0.4 R3
(iv) 0.4R1 + 0.4R2 + 1. 0R3
For evaluating the above mentioned rules three buildings of different configuration have been analysed by Response Spectrum Method using above modal combination rules and by A Time-history
Analysis. The results by Response Spectrum Method have been compared with the results by Time-history Analysis considering the later as standard.
