task : @$202$@$\_$#$\_$"What are the fundamental principles governing the behavior of structural materials in civil engineering? How do these principles influence the design and construction of buildings and infrastructure? Discuss the key factors affecting the strength, elasticity, and durability of common construction materials. How do engineers ensure structural integrity and safety while accounting for factors like load distribution, material properties, and environmental conditions? Highlight the importance of material selection and testing in ensuring the reliability and longevity of civil engineering projects."