Recently the evaluation of seismic performance of existing buildings has received a great attention. This book contains seven research topics. These topics concentrated in the modelling and analysis of existing RC buildings due to gravity and seismic loads before and after strengthening. Therefore, it is the hope of the author that this book being the first in Sudan, Arab and African universities introduces the evaluation of seismic performance and strengthening of existing reinforced concrete buildings. In addition to that, this book is suitable for undergraduate, postgraduate students, researchers and academics who are involved in the engineering design domains.