2. The model of a two-story building shown in Figure 2. The girders are assumed to be rigid, and the columns have flexural rigidities EI and EI2, with negligible masses. The stiffness of each column can be calculated from 24Eli h for i=1,2 3 = m, h = h = h, and EI = EI2 = EI, find the natural Assume that m = 2 m, m2 frequencies and mode shapes of the building frame. Ans: 3.7495 3" 9.0524 mh mh F2(t)- El m2 m F(t) El Figure 2 El2 h2 h El