Question 13.10: A steel framed building shown in Figure 13.46 is fitted with...
A steel framed building shown in Figure 13.46 is fitted with ADAS device at the junction of braces with the beam. It is subjected to a sinusoidal ground motion. Illustrate the effect of ADAS device.
In the present example, the frame and the ADAS device were modeled in
ETABS (CSI, Berkeley). Period of the frame was 0.1 sec. The ADAS device was modeled using the panel zone between the beam and the brace and assigning a nonlinear plastic Bouc – Wen link. The nonlinear stiffness was taken as 500 kN/m and the yield strength was taken as 10 kN with 5% strain hardening. Yield exponent was taken as 2.0. The frequency of the sinusoidal ground motion was taken as 2 Hz.
The frame was analysed without the ADAS device and again with the ADAS device.
The forces in the steel braces and columns are shown in Table 13.7
Table 13.7 Frame Forces Without and With ADAS Device
| Particular | Without ADAS Device | With ADAS Device |
| Lateral displacement (mm) | 3.35 | 11.3 |
| Brace axial force (kN) | 174 and 168 | 11.5 and 3.0 |
| Column shear (kN) | 43, 53 and 42 kN | 145, 180 and 139 kN |
| Panel zone shear (kN) | NA | 5.5 |
| Panel zone deformation (mm) | NA | 11.3 |
(There are 2 braces and 3 columns)
It can be seen that there is redistribution of forces among columns and braces due to the presence of ADAS device. Steel braces develop little axial force due to ADAS device which helps prevent their buckling. Energy is dissipated by the ADAS device.