Page 321 - Advanced Design Examples of Seismic Retrofit of Structures

310 Advanced Design Examples of Seismic Retrofit of Structures

where:
P UF ¼axial force in the member computed in accordance with
Section 5.5.5.2;
P CL ¼lower-bound compression strength of the column;
M x ¼bending moment in the member for the x-axis computed in accordance
with Section 5.5.5.2;
M y ¼bending moment in the member for the y-axis computed in accordance
with Section 5.5.5.2;
M CEx ¼expected bending strength of the column for the x-axis;
M CEy ¼expected bending strength of the column for the y-axis;
m x ¼value of m for the column bending about the x-axis in accordance with
Table 5.11; and
m y ¼value of m for the column bending about the y-axis in accordance with
Table 5.11.

5.7.1.2 Force-Controlled Actions
Acceptance criteria for force-controlled actions in components shall satisfy Eq.
(5.30):
κQ CL > Q UF (5.30)

where Q CL ¼lower-bound strength of a force-controlled action of an element at
the deformation level under consideration, which is determined according to
Section 5.7.

Columns
Steel columns with axial compressive forces exceeding 50% of the lower-bound
axial compressive strength, P CL , shall be considered force controlled for both
axial loads and flexure, and shall be evaluated using Eq. (5.31).

P UF M UFx M UFy
+ + 1:0 (5.31)
P CL M CLx M CLy
where:
M UFx ¼bending moment in the member about the x-axis, calculated in
accordance with Section 5.5.5.2;
M UFy ¼bending moment in the member about the y-axis, calculated in
accordance with Section 5.5.5.2;
M CLx ¼lower-bound flexural strength of the member about the x-axis; and
M CLy ¼lower-bound flexural strength of the member about the y-axis.

5.7.2 Nonlinear Static Procedure
5.7.2.1 Deformation-Controlled Actions
Primary and secondary components shall have expected deformation
capacities not less than maximum deformation demands calculated at target