Roman Thrust Roof

By far the commonest covering throughout history is the trussed roof constructed upon a frame composed of triangular sections spaced crosswise at intervals and made rigid in length by beams.

Roman thrust roof.

It exerts the same kind of thrust as the circular arch and must be buttressed along its entire length by heavy walls with limited openings. Viola no ridge at all less overall wood usage etc. It is a form of barrel roof. Pantheon apparently used this iterative technique to evolve structures so it sure ain t new.

The term bathymetry is used to describe underwater relief while hypsometry studies terrain relative to sea level the latin word terra the root of terrain means earth. Terrain or relief also topographical relief involves the vertical and horizontal dimensions of land surface. There are several mechanisms for absorbing this thrust. One is to make the walls exceedingly thick and strong this is a primitive and sometimes unacceptable method.

The old roman designers e g. In physical geography terrain is the lay of the land this is usually expressed in terms of the elevation slope. Roman architects discovered that two barrel vaults that intersected at right angles formed a groin vault which when repeated in series could span rectangular areas of unlimited length. Truss es formerly were principally of wood and were used to cover masonry as well.

One of the important ingredients of the mortar was a volcanic deposit found near rome known as pozzolana which when the concrete had set not only made the concrete as solid as the rock itself but to a certain extent neutralized the thrust of the vaults which formed shells equivalent to that of a metal lid. The weight distribution inherent to the arch means that the thrust is always outwards. The dome exerts thrusts all around its perimeter and the earliest monumental examples such as the roman pantheon required heavy supporting walls. To easily deal with the end wall thrust go to a hip roof and wrap the top with a 1 4 by 1 steel strap.

The romans however do not seem to have recognized the value of this pozzolana mixture for they otherwise provided amply for the counteracting of any thrust which might exist by. The roman s had not conceived of a decorative. Buttress in architecture exterior support usually of masonry projecting from the face of a wall and serving either to strengthen it or to resist the side thrust created by the load on an arch or a roof. From there it is a simple step to a dome.

The 4 535 tonne weight of the roman concrete dome is concentrated on a ring of voussoirs 9 1 metres 30 ft in diameter that form the oculus while the downward thrust of the dome is carried by eight barrel vaults in the 6 4 metre thick 21 ft drum wall into eight piers.