Serviceability Performance of Prestressed Concrete Buildings Taking into Account Long-Term Behaviour and Construction Sequence

Abstract

A common problem faced by engineers nowadays is the restriction on structural member dimensions due to architectural and spatial concerns. Such restrictions have resulted in the use of high strength concrete in vertical members to reduce sizes, the use of central core walls and peripheral columns to increase window areas, and the use of prestressed floors to increase spans, to name a few. Serviceability problems (e.g. cracking) may, however, arise in the long term. This paper in turn addresses two major issues associated with buildings. Firstly, the differential axial shortening between core walls and columns caused by large differences in stress levels induces additional stresses and strains in horizontal structural members, which are not normally accounted for by traditional design methods. Secondly, the post-tensioning of concrete floors gives rise to additional internal forces induced by several meams such as sequential construction, and secondary “P-δ” effects of the high-strength slender columns. As it is almost impossible to eliminate these secondary effects completely, a series of studies have been carried out to examine their effects on the structural design of these buildings.