Explain the principles behind the finite element method (FEM) and its application in civil engineering operations. Discuss how FEM helps in simulating complex structural behaviors and analyzing the response of various materials under different loading conditions. Additionally, elaborate on the process of discretization involved in FEM and its significance in accurately predicting structural performance. Furthermore, explore the challenges and limitations associated with implementing FEM in civil engineering projects, highlighting the computational complexities and the need for validation against experimental data. Evaluate the role of FEM in optimizing structural designs and enhancing the safety and efficiency of civil engineering operations.