This book is tailored to the teaching requirements of the Structural Design Principles course for civil engineeringand road, bridge, and river crossing engineering majors in higher education institutions. It references the nationalstandards of the Peoples Republic of China and the current transportation industry standards and design codesissued by the Ministry of Transport. The book provides a detailed introduction to the stress characteristics, design principles, calculation methods, and structural design of various basic components of highway bridge and culvertreinforced concrete structures, prestressed concrete structures, and steel structures.Intended as a primary textbook for students majoring in civil engineering, with a focus on roads,bridges, and river crossings at higher education institutions, this book also serves as a valuable resource for professionals involved in the design,research, construction, and management aspects of bridge engineering within highway andurban construction sectors.