How to make a ridge beam 12 m long?

Surely there must be a typical (proven) solution for a long ridge beam.

There is a house made of aerated concrete under a gable roof. Distance from wall to wall between gables 8m, between gables 10m. The angle of slope of the roof ~ 41 degrees, the length of the rafters ~ 5.5 m height in the ridge of almost 5m.

Internal walls do not exist, columns and supports do not want to do.

Question – how and what to make such a long ridge run?

There are three solutions so far:

1) To make a ridge beam out of I-beams 35-40

2) Make a general without ridge beam, the rafters connect pinches at a height of 3m from the floor, in the plane of the roof to let diagonal boards, thus binding the rafters and to prevent longitudinal movement.

3). Make ridge beam in the form of a truss of pipes 50-70mm