I suggest you to collect literature related to your topics mainly the Cambridge university, U.K have done lot of work. based on literature study identify any gaps or limitation or new seismic design method. based on this process, find out the tentative title for your Ph.D or theory ..the Ph.D work is your independent study and need to do by yourself..i am sure you will get new topic by based on above mentioned process..ok all the best for your Ph.D..
Agreed with Dr. Karthigeyan. However, You may consider a topic related to the behaviour of a particular civil structure in dynamic environment, from seismic soil structure interaction point of view.
Mr.Ahmad, i agree with your point and also the main one that you had an advice to start working on a subject by yourself..i too agree with this point but the newness starts from literature only. i already clearly mentioned these points from my earlier message..i am not saying that supervisor role will not be there in Ph.D work, definitely supervisor can help in choosing the topic but scholar should know every moment of his or her work starting from the selection of topic. ok thanks for your view..