Cranes work on the frame of a building under construction.
An office building is under construction.
Just because cranes work on the building frame construction doesn't mean it is for an office building.
exists x1 x2 x3 x4 x5.(n_frame(x3) & a_topic(x1) & on(x1,x3) & of(x3,x4) & under(x4,x5) & n_construction(x5) & n_building(x4) & n_work(x1) & (x1 = x2) & ne_nam_cranes(x2))
exists p1 x1 x2.(exists x3.(under(x1,x3) & n_construction(x3)) & n_building(x1) & of(x1,x2) & n_office(x2))