1977. Recommendations for the design of aseismic prestressed concrete structures

At the Fifth FIP Congress in Paris in 1966, the FIP Commission on Seismic Structures presented a document on the general principles of prestressed concrete design for structures resistant to earthquake shocks, in order to provide immediate assistance to designers.

During the Sixth FIP Congress in Prague in 1970, the Commission presented a further report giving design recommendations based on limit state methods developed in the CEB/FIP Recommendations for the Design and Construction of Concrete Structures (1970). The report covered degrees of damage, design requirements, limit states, ductility, column design, and the design of connections and supports.

Since then, the Commission, under the chairmanship of Dr. Eng. S. Inomata, has prepared the three reports presented in this volume.

The first, Recommendations for the Design of Aseismic Prestressed Concrete Structures, considers earthquake loads at two levels of risk: the characteristic moderate earthquake and the characteristic severe earthquake, with the possibility of an even more extreme event—the maximum credible earthquake. In general, limit state design methods are proposed, and design values for loads, material strengths, and prestress are suggested.

The second report contains a series of explanatory comments on the recommendations, while the third report is concerned with the use of unbonded tendons in aseismic prestressed concrete structures.

In earthquake-prone regions in particular, there is considerable debate regarding the necessity of grouting post-tensioned tendons. However, at present, there is insufficient evidence to show that grouted tendons perform better than unbonded tendons in structures subjected to seismic forces. The Commission wishes to emphasise the importance of this issue and to encourage further investigation based on field performance.

This report reviews recent research and design proposals in an attempt to establish a state-of-the-art summary of current knowledge on the use of unbonded tendons. Although no specific design recommendations are presented, it is hoped that this report will assist designers in developing simple and universally applicable design concepts for aseismic unbonded prestressed concrete structures.