Page 257 - Advanced Design Examples of Seismic Retrofit of Structures

250 Advanced Design Examples of Seismic Retrofit of Structures

(A) (B)

(C) (D)
FIG. 4.15 Retrofit details of the vulnerable columns. (A) Existing 2UNP18PL22x1. (B) Retrofitted
2UNP18PL22x1. (C) Existing 2UNP18PL16x1. (D) Retrofitted 2UNP18PL16x1 [12a].

Steel columns under combined axial tension and bending stress shall be con-
sidered deformation-controlled and shall be evaluated using Eq. (4.35):

T M x M y
+ + 1:0 (4.35)
m t T CE m x M CEx m y M CEy
where:
m t ¼value of m for the column in tension based on Table 5.11 (in Chapter 5
of this book);
T¼tensile load in column; and
T CE ¼expected tensile strength of column computed in accordance with
Eq. (4.36).

Q CE ¼ T CE ¼ F ye A c (4.36)
where:
A c ¼area of column; and
F ye ¼expected yield strength of the material.
As can be seen, except for three columns, all columns meet the acceptance cri-
teria. In order to retrofit the vulnerable columns, welded steel plates are used in
accordance with the details shown in Fig. 4.15.

Shotcreting of the Infill Panels in Transverse Direction
There are different methods to improve the seismic performance of infill walls
in order to improve the in-plane and out-of-plane performance; these methods
include installation of FRP strips on the infill wall and using cementitious