Offshore structures is a really good topic in structural engineering. Personally, since you want to include FEA wave-structure interaction would be an interesting (and challenging) topic also optimization in FEA methods is another interesting one. Aeroelasticity for wind turbines, wavelet methods are also some good topics. I think you should search for related papers of your interests and see what attracts you more, probably you will come up with a better topic that suits you more.

Composite materials are very popular topic. You can find a lot of research paper in this field. Personally, you can prefer with multidisiplinary topics such as, CFRP, GFRP, Pultrusion, laminate etc.

Seismic retrofit of Steel or RC structures by dampers and base isolators.

Hi Ansaff Ahamed Ashraff

The Best and most used book for undergraduate study is

Structural Analysis

Book by Russell Hibbeler

You can find this book at this link

https://g.co/kgs/eSTcho

Boost your skills in machine learning, particularly function approximation techniques beside whatever topic you are going to pursue.

Progressive collapse of structures during earthquakes...

Effect of warping.