Question 13.5: Illustrate the construction of an inelastic response spectru...
Illustrate the construction of an inelastic response spectrum for a ground motion having peak ground acceleration, peak ground velocity and peak ground displacement as 1 g, 90 cm/sec and 60 cm, respectively. Make use of Newmark–Hall amplification factors for 5% damping and 84.1 percentile.
First, the elastic design spectrum is generated as per the procedure outlined
in Section 8.8. The amplification factors for 5% damping and mean + standard deviation on acceleration, velocity and displacement are 2.71, 2.3 and 2.01, respectively. The elastic spectrum is shown in Figure 13.31(a). Next, inelastic response spectrum is generated for a ductility of 1.5, 2, 4 and 6 using the procedure outlined in Section 13.7 and Equations (13.34). There is a transition zone between T_{A} and T_{B}, and between T_{E} and T_{F}. The resulting spectrum on a tripartite graph is shown in Figure 13.31(b).
D^{\prime}=D/\mu (13.34a)
V^{\prime}=V/\mu (13.34b)
A^{\prime}=\frac{A}{\sqrt{2\mu -1}} (13.34c)
