3. Mixed frames with triangulations

3.1 Mixed frames with centered bar triangulations

According to Eurocode 8, the dissipative elements of a dissipative mixed triangulation frame must be steel diagonals. Non-dissipative structural elements, such as columns or beams, can be steel or composite.

The reasons are as follows:

• mixed diagonals would contribute to overloading the beams and columns in the situation before buckling of the diagonals, which is contrary to the economics of the project;

• no information is available on the cyclic behavior of mixed diagonals, and it is therefore not possible to define it in a simple approach as is done for steel diagonals alone