The two$-$span bridge shown below is supposed to be built in Columbia, SC in a site comprising stiff soil. The bridge is required to be open to emergency vehicles after a seismic event of a $1000-$year return period. The bridge is supported by two abutments that allow movement in the longitudinal direction and a $3-$column bent at the center. The concrete bent columns are $3ft3ft.$ Use the information provided below to compute the design seismic moment at the base of the columns in the longitudinal direction of the bridge.

Data:

PGA $=0\mathrm{.}161g,S_s=0\mathrm{.}324g,S_1=0\mathrm{.}084g$

Consider the superstructure to be infinitely rigid with a dead weight equal to $8\mathrm{.}5$ K$/$ft$.$

Assume that the columns are fixed at the base

Assume that the pier cap is infinitely rigid.

Assume any missing data.