Page 241 - Advanced Design Examples of Seismic Retrofit of Structures

234 Advanced Design Examples of Seismic Retrofit of Structures

where:
Q UF ¼force-controlled action caused by gravity loads in combination with
earthquake forces; and
J¼force-delivery reduction factor, greater than or equal to 1.0, taken as the
smallest DCR of the components in the load path delivering force to the com-
ponent inquestion.Alternatively,valuesof Jequalto2.0fora high level ofseis-
micity,1.5foramoderatelevelofseismicity,and1.0foralowlevelofseismicity
shall be permitted where not based on calculated DCRs. In any case where the
forces contributing to Q UF are delivered by components of the seismic-force-
resisting system that remain elastic, J shall be taken as 1.0. In this example, this
factorisconservativelyassumedtobe2.0;thisisbasedonthefacttheconsidered
building is located in Tehran, which has a high level of seismicity.
In this example, the load combinations based on Eq. (4.29) are used for force-
controlled actions:

Q UF ¼ 1:1Q D +0:44Q L 0:41Q EX aðÞ
Q UF ¼ 1:1Q D +0:44Q L 0:41Q EXP bðÞ
Q UF ¼ 1:1Q D +0:44Q L 0:41Q EXN cðÞ
Q UF ¼ 1:1Q D +0:44Q L 0:50Q EY dðÞ
Q UF ¼ 1:1Q D +0:44Q L 0:50Q EYP eðÞ
Q UF ¼ 1:1Q D +0:44Q L 0:50Q EYN fðÞ
(4.29)
Q UF ¼ 0:9Q D 0:41Q EX gðÞ
Q UF ¼ 0:9Q D 0:41Q EXP hðÞ
Q UF ¼ 0:9Q D 0:41Q EXN iðÞ
Q UF ¼ 0:9Q D 0:50Q EY jðÞ
Q UF ¼ 0:9Q D 0:50Q EYP kðÞ
Q UF ¼ 0:9Q D 0:50Q EYN lðÞ
For the columns at the corners of the building where the two orthogonal
lateral-force-resisting systems coincide, the concurrent multidirectional seismic
effects must be considered. These components of the building shall be designed
for combinations of forces and deformations from separate LSP analyses per-
formed for ground motions in X and Y directions as follows:
(a) forces and deformations associated with 100% of the design forces in the X
direction plus the forces and deformations associated with 30% of the
design forces in the Y direction; and for
(b) forces and deformations associated with 100% of the design forces in the Y
direction plus the forces and deformations associated with 30% of the
design forces in the X direction. Other combination rules shall be permitted
where verified by experiment or analysis.

Acceptance Criteria
Deformation-Controlled Acceptance criteria for deformation-controlled
actions in components shall satisfy Eq. (4.30):

mκQ CE > Q UD (4.30)