Page 188 - Advanced Design Examples of Seismic Retrofit of Structures

180 Advanced Design Examples of Seismic Retrofit of Structures

Design of the New Foundation Based on Code 360 [1], the behavior of foun-
dations is assumed to be force-controlled. As a result, the forces of the linear
analysis are reduced to the corresponding forces related to force-controlled
actions.
Q UD Q UD
Q UF ¼ ¼
m 4
The process of designing the foundation includes the following steps:

(A) Spectral linear dynamic analysis considering simultaneous application
of earthquake components, 100% of the most critical direction of
ground motion, and 30% of the ground motion in the orthogonal axis
under Earthquake-2 and CP performance level. The coefficients of
1.5/4¼0.375 in one direction and 0.3 0.375¼0.1125 in the orthogonal
axis are applied.
(B) The shear story is calculated and applied at the CoM of that story.
(C) The supports reactions are calculated by linear static analysis.
(D) Modeling is done.
(E) To control the foundation adequacy, the out-of-plane shear and flexure
of the section are checked in each direction against the corresponding
capacity.
(F) The vulnerability of the foundation is observed in the strips with the
width of 6–9m all around the foundation of the southern building part,
and also, at the in the strips with a width of 6m at the northern part of
the foundation of the northern building part.
(G) For providing the vulnerable parts with adequate capacity, a layer of con-
crete with the thickness of 70cm having a reinforcement layer at the top
is added to the foundation in those parts.
(H) The capacity of the new section for M Top and M Bot is calculated (see
Fig. 3.42) and is compared with the flexural demands from the envelop
of the loads combinations (see Figs. 3.43 and 3.44).
The details related to retrofit of the foundation are presented in Figs. 3.45 and
3.46. The main steps in the retrofit process of the foundation are illustrated in
Figs. 3.47–3.50.

3.5.2.5 Design of the Added Parts for Filling Diaphragms
Openings
2
As previously noted, there is more than 1200m of opening area in stories 1,
pilot and +1 which have to be filled. In order to keep the loads from filling
these openings to minimum, composite deck system is selected. The 30cm
edges of the existing RC diaphragm are partially demolished by light jackham-
mers, and the steel plates acting as the supports to the steel beams in the new
deck are inserted into these edges. The beams of the composite deck are