Determine the Basic Concepts of Prestressing
In the year 1904, Freyssinet tried to introduce prestresses in concrete to resist stresses developed due to external loads. Later, the concept of prestressing was formulated by Doehring of Germany and Jackson of United States. Mandl and Koenen were the first ones to propose a theory for modelling the behaviour of prestressed members to perform design. Notable work was done by M. Koenen and Steiner in the area of losses of prestress in prestressed members. Dischinger demonstrated the use of unbonded tendons in the year 1928 in the construction of a bridge. The first major use of prestressing in civil infrastructure in the United States was the construction of the Walnut Lane Bridge in Philadelphia in the year 1950. In the last many decades, prestressed concrete has been widely used in the construction of long span bridges, railway sleepers, shell roofs, marine structures, nuclear pressure vessels, water retaining structures, transmission towers and many other structures.