Analysis of time-dependent internal forces with conventional computer programs
The procedure discussed in this chapter can be used to solve timedependent problems of common occurrence in practice. As an example, con¬ sider the effects of shortening, due to creep and shrinkage, of a prestressed floor supported on columns constructed in an earlier stage. Analysis of the effect of differential shortening of columns in a high-rise building provides another example; the compressive stress and the change in length due to creep are commonly greater in interior than exterior columns. Bridge structures are frequently composed of members (segments), precast or cast-in-situ, made of concrete of different ages or of concrete and steel (e.g. cable stays). The precast members are erected with or without the use of temporary supports and made continuous with cast-in-situ joints or with post-tensioned tendons. In all these cases, the time-dependent analysis can be done by the application and the superposition of the results of conventional linear computer programs.