Answer
$529.2 \ J$
Work Step by Step
The work required to lift the segment of the chain to the top of the building can be computed as:
$W_{i}=\Sigma_{i=1}^N W_i \approx (3 \Delta y) (9.8) y_i \ ft-lb$
Therefore, the total work done when $\Delta y \to 0$ can be computed as:
$ W=\int_{0}^{6} 29.4 \ y \ dy \\=14.7[y^2]_{0}^{6}\\=14.7 \times 36 \\=529.2 \ J$
