Time-dependent internal forces in uncracked structures: analysis by the displacement method - Concrete Structures: Stresses and Deformations - page 165

Figure 5.11 Composite frame of Example 5.3: (a) frame dimension (for cross-
section of member BC, see Fig. 5.8(b)); (b) bending moment diagram
at t 0 ; (c) released structure for analysis of changes of fixed-end forces
in BC.

A conventional elastic analysis is performed for a continuous frame
subjected to the load q , giving the bending moment at time t 0 shown in
Fig. 5.11(b). The moments of inertia of the cross-sections used in the
analysis are 0.4234 m 4 for BC and 0.080 m 4 for the columns. These are
the centroidal moments of inertia of transformed sections, using E ref =

E c ( t 0 ) 30 GPa for all members. The centroid of the transformed sec-

tion at age t 0 for member BC is 1.611 m above the bottom

=

fi bre; hence,