Testing aerodynamic problems of historical buildings

Due to the shape and uniqueness of historical and listed buildings, which is completely different from the modern building practice, the data recommended by professional literature or standards cannot be used for the calculations of wind load, or can only be used for rough estimation. The exact knlowledge of wind loading on these structures comes especially during reconstruction and preservation into play.

During the inspection of historical buildings, the effect of the wind is important primarily in relation to the roof, the helm roof, the dome and other higher superstructures.

In case of roofing, fastening the outer layer is important, which was done in case of tiled roofs with high slope (generally more than 40°). For sheet metal roofing, the fastening of the edges is important.

In case of historical roofs, it may be subject to a test whether the tilting fillet used near the eaves mitigate (or, as the case may be, amplify) the effect of the wind, and how it affects the dislodgment of the outer layer of the roof.

In order to test these, the local shape coefficients of the roof surface are required.

The assessment of the shape is also important in case of helm roofs. For example: what are the aerodynamic factors for the calculations for baroque towers with wavy elements or the simple pyramidal helm roofs characteristic in the 19th century as well as the intermediate shapes (rhenish helm, turret roof surrounded with four smaller turrets etc.).

It is also an issue how double towers change the aerodynamic environment, which were built for many churches.

In order to protect the helm roof against the tipping effect of the wind, it was lashed to the diagonal beams fitted to the corners of the walled tower structure. This practice was used mainly in case of baroque helm roofs, but it also appeared later. The operation of forge welded or joined wrought iron lashing is worth examining. A global shape factor, applicable to the whole helm roof is necessary for this test.  Please note that there are examples in the 19th century architecture, where the helm roof constitutes a significant part of the height of the tower; an example is the parish church of Bátaszék.

In case of towers, the effect of the (closed or open) bell tower windows on the stability of the tower must be also examined, whether these have a significant effect.

In case of domes, the correlation of the shape, the surface fitting and the structure is also an important issue. A special test in relation to wind may be to examine whether it is a single or multi-layer roof, and what effects it has on the dome and its layers.

Involved researchers and departments

István Sajtos PhD  | BME Faculty of Architecture | Department of Mechanics, Materials & Structures
(in collaboration with the Department for History of Architecture and of Monuments)

Recent publications of BME on the subject

Tóth Zsuzsa, Máté Albert (2011): A soproni tűztorony fa toronysisakjának erőjátéka. [Forces on the helm roof of the Fire Tower of Sopron ] BME Faculty of Architecture, student research project. Supervisors: Dr. István Sajtos , Dr.  Miklós Armuth, Dr. Tamás Lajos, Márton Balczó