Page 222 - Advanced Design Examples of Seismic Retrofit of Structures

Example of a Steel Frame Building With Masonry Infill Walls Chapter 4 215

b 10:6 545 545
p
INP240 ! B ¼ 10:6cm,t ¼ 1:31cm ! ¼ ¼ 8:09 p ffiffiffiffiffi ¼ ffiffiffiffiffiffiffiffiffiffi ¼ 10:6
t 1:31 F y 2640
Q CE ¼ ZF ye ¼ 410:27 2640 ¼ 10:8 ton m

Flexural and Shear Strength of Columns As can be seen in Table 4.4, six
types of columns are used in the building. The method of determination of
the flexural strength of column sections is similar to that for the beam sections
which was presented in Section “Flexural Strength of Beams.”
According to ASCE 41 [1], the shear strength of columns, Q CE , shall be
computed in accordance with Eq. (4.10).

Q CE ¼ V CE ¼ 0:55F ye d c t p (4.10)

where d c ¼column depth and t p ¼thickness of column web.
Since the column sections are made of double profiles with discontinuous
welding, none of the column sections satisfies the compactness requirements,
hence their flexural strength is determined in accordance with Eq. (4.9).
In the following, an example of a 2UNP180+2PL160 10 column is pre-
sented for checking the flexural and shear strength of the section. The expected
flexural and shear strengths of all the column sections in the example building
are presented in Table 4.4.
3
3
2
2UNP180 + 2PL160 10 ! A ¼ 87:92cm ,S x ¼ 559:7cm ,S y ¼ 598:2cm ,
A w ¼ 31:94cm 2
5 5
Q CEx ¼ S x F b ¼ 559:7 0:6 2640 ¼ 1478 toncm
3 3
5 5
Q CEy ¼ S y F b ¼ 598:2 0:6 2640 ¼ 1579 toncm
3 3
Q CE ¼ V CE ¼ 0:55F ye d c t p ¼ 0:55 2640 31:94 ¼ 46ton

Lower-Bound Values of Strength
Axial and Flexural Strength of Columns The axial strength of columns, Q CL ,
shall be computed in accordance with Eq. (4.11).

Q CL ¼ P CL ¼ 1:7F a A (4.11)

2
KL 1 0:5β F y
if C c ! F a ¼
r F:S: