Prestressed concrete works by introducing compressive stress into the concrete before it is loaded. This is achieved by using high-strength steel cables or wires, known as tendons, which are embedded in the concrete. The tendons are tensioned, or stretched, to create a compressive force in the concrete. This compressive force helps to counteract the tensile stresses that occur in the concrete when it is loaded.

In his book, "Prestressed Concrete Design and Construction," Fritz Leonhardt provides a comprehensive guide to the design and construction of prestressed concrete structures. The book, which is now available in PDF format, is a valuable resource for engineers, architects, and students who want to learn about the principles and applications of prestressed concrete.

Prestressed concrete is a type of concrete that has been subjected to compressive stress before it is loaded, which helps to improve its strength and durability. The concept of prestressed concrete was first introduced in the early 20th century, and since then, it has become a widely used construction material in the building industry. One of the pioneers in the field of prestressed concrete is Fritz Leonhardt, a German engineer who made significant contributions to the development of prestressed concrete design and construction.