Page 220 - Advanced Design Examples of Seismic Retrofit of Structures

Example of a Steel Frame Building With Masonry Infill Walls Chapter 4 213

l The wall shall not have any inclination or sagging.
l The maximum length and height of the wall shall not exceed 6.0m and
4.0m, respectively.
Based on the conditions above, the walls in the longitudinal direction of the
building do not meet the requirements for infill panels because their length
exceeds 6.0m. Consequently, other retrofit solutions should be considered to
provide the building with an acceptable lateral-load bearing system. Moreover,
according to ICERIFB [2], the wall in I-1-3 does not meet the infill panels
requirements because the distance from the edge of opening in this wall to either
of the columns in the surrounding frame is located closer to 20% of its length, or
the distance from the edge of opening to either of the beams is less than 20% of
its height.

4.4.1.5 Summary
From the conditions of the building, it can be concluded that the example build-
ing does not have any lateral load-bearing system in the longitudinal direction
because the walls do not meet the infill panels’ requirements; hence, a proper
solution should be considered to provide lateral-resisting system for the struc-
ture. In the transverse direction, the walls, except for a single wall, pass the
requirements for becoming infill panels. As a result, the building may benefit
from these several infill panels in the transverse direction in terms of providing
the building with stiffness and strength if these panels sufficiently tolerate the
actions from their surrounding frame members; these are discussed in detail in
Section “The Results” of this chapter.

4.4.2 Retrofit Solution
Once the need to retrofit a building is determined as noted in the previous sec-
tion, evaluation of the sufficiency of the structural members of the building is
carried out. In addition, retrofit solutions are proposed here for the vulnerable
members.

4.4.2.1 Material Properties
In order to determine the mechanical properties of structural members and con-
nections, it is necessary to determine the yield strength of steel. According to
ICERIFB [2], when the expected strength of the material is required, it can
be determined based on the lower-bound material properties multiplied by a fac-
tor of 1.1. In the example, the lower-bound yield strength of steel is 240MPa,
hence the expected yield strength of steel (F ye ) is 264MPa.