This thesis is the outcome of my research activities as a university researcher, first at the Institute for Mechanics of Materials and Structures (IMWS) of Vienna University of Technology (TUWien), and then at Material- Technology Innsbruck (MTI) of the University of Innsbruck (UIBK). It would have been an impossible task without the support of the following individuals and organizations. First of all, I want to thank my wife Qiong and my daughter Weina, who have always supported me during my doctoral studies. I would like to thank Prof. Herbert A. Mang whose knowledge, patience and enthusiasm in research have encouraged me to pursue my research career in Austria. I am very thankful to Dr. Matthias Zeiml, who always guided me in my research. His deep understanding of fire-loaded concrete, both experimentally and numerically, always inspired not only me but also our whole research group. I wish to thank Prof. Roman Lackner, who guided me from the macroscopic world to the microscopic universe. His knowledge in plasticity has helped me to pass the jungle of the strong discontinuity embedded approach (SDA) and stress locking, and to find the way to numerical analysis of fracture of concrete. Many thanks are due to Dr. Christian Pichler, who provided me with a code for multiscale homogenization of early-age concrete and explained the guidelines for working with this code. I am very grateful to my former colleagues Dr. Aram Amouzandeh and Dr. Thomas Ring of Vienna University of Technology, who shared a big office at the laboratory of IMWS with me for two years. I could always turn to them when I could not solve my problems. Special thanks go to Prof. Josef Eberhardsteiner and Associate Prof. Bernhard Pichler, who made me focus on my timetable and work efficiently. Regarding administrative support, I would like to thank: Mag. Martina Pöll, Ms. Gabriele Ostrowski, and Ms. Astrid Schuh from IMWS and Ms. Sabine Riml from MTI. I gratefully acknowledge financial support by the China Scholarship Coun- I cil and by the Austrian Ministry for Transport, Innovation and Technology (bm.vit) within the KIRAS-project (Austrian security research program) 813794 "Sicherheit von Hohlraumbauten unter Feuerlast" (-Safety of underground structures under fire loading-). Last, but not least, I appreciate the selfless help from the research group of MUMPS (MUltifrontal Massively Parallel sparse direct Solver), which allowed me to use their compute program for my work. Without their solver, all simulations would take at least five times longer.