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Modelling of the “tangent” cast-in-place segmental cantilever construction is more difficult in terms of preparation of input data. All cantilever nodes must be again connected by means of finite elements at the beginning of construction. This time however, the nodes cannot be formed by segment elements because in the time of the first segment installation, other segments are not yet cast. Therefore, auxiliary elements must be defined and these must be installed at the very beginning of construction (global time 0 (zero)), see Fig. 13a. The cross-section is thus transformed to a general cross-section, an imaginary zero section-stage is defined that is formed by a steel element of minimal possible dimensions (in order not to affect the sectional stiffness). Considering a different time of casting (stage 1 of cross-sections), number of section types must be increased similarly to the project described in Fig. 13.
In the second construction stage, casting of segment 1 is modelled by the change of appropriate cross-section from stage 0 to stage 1, see Fig. 13b. Similarly to “precise levelling”, the fresh concrete of the first segment cannot be subject to dead load for the same reason. Therefore, the dead load of the first segment is applied only in the time of prestressing of the first segment, see Table 4. Once again, a set of point loads can be used to model the real dead load. Subsequent construction stages can be seen in Fig. 13 and Table 14.
For better understanding, Fig. 14 shows the deflection of a half of the symmetrical structure calculated after segment 4 has been stressed in the time of 1000 days after the two cantilevers have become monolithic in the joint. The deflection curve is again smooth except the break in the point of attachment of the cantilever to the closing joint.
