Page 273 - Advanced Design Examples of Seismic Retrofit of Structures

266 Advanced Design Examples of Seismic Retrofit of Structures

FIG. 4.23 Details of connection of shotcrete bars to the frame members [12a].

beams may be done by adding steel plates on the flanges in order to increase
their flexural capacity.

Evaluation of the Frame Connections
All the beam-column connections in the example building are simple cradle-
type. Because of the age of the building, as-built sketches of connections were
not available. These connections should be able to transfer the shear forces and
flexural moments from the beams to the columns.
As indicated in Section “Shotcreting of the Infill Panels in Transverse
Direction,” steel plates with the length of 1.5a and width of double flange width
of beams plus the width of the column section should be added to the columns
and beams at the corners in order to provide full contact between the infill walls
and the frame members. Based on Section “Evaluation of the Beam and
Columns,” the beams experience a concentrated force P from the infill walls
at the distance of l beff . Accordingly, the fillet welds in the connection are under
shear force P and flexural moment P. l beff . These added plates should be stiff-
ened by triangular stiffeners. As an example for determination of the size of
these stiffeners, the beam A-1-3 on STORY1 is considered. In this bay, the shear
force of 6.74 ton is applied at the distance of 61.4cm. Assuming that four stiff-
eners with the length of 30cm are added with the weld size of 8mm, we have:
P
f v ¼
A
Mc
f b ¼
I