Timber anti-seismic devices in historical architecture in the Mediterranean area

Abstract

This work investigates the exploitation of a historical timber device used as masonry reinforcement in seismic prevention in the Mediterranean area. Such a technology is realized by means of a three-dimensional timber frame embedded in stone masonry in order to bind together the various structural parts, and contribute to the overall seismic resistance. Very often, such a constructive principle was extended not only to the weakest parts but to the whole building, creating new structural configurations that were able to absorb the effects of seismic ground motions. From Roman times (opus craticium), this system spread all across the Mediterranean area becoming common during the eighteenth century in Italy (Bourbon casa baraccata), in Portugal (Pombaline gaiola), in Turkey (hımış), etc. However, examples of timber devices and frameworks may be found almost worldwide: in the continental northern Europe, including those countries that are usually not subjected to earthquakes, as well as in Central Asia or in Japan, to America and North Africa. A large number of examples are reported to show how some traditional technologies, along with the suboptimal rules of the art, made a robust construction possible. Furthermore, by means of philological criterion and detailed analysis of seismic vulnerability improvement, the knowledge of such a system may allow developing novel designs and specific preservation works that could ensure the structural safety of historical constructions without modifying their main structural configuration. From such a perspective, this study examines the aspects of using diffused timber frameworks with masonry infill that go beyond anti-seismic technology, describes the common constructive features and helps develop guidelines for preservation of such systems.

Mixed Stone-timber Masonry in Traditional Construction: Structural, Architectural and Anti-seismic Features across Europe

“…Such a technology consisted in a timber framework, made of reeds or brushwood fastened tight by means of cordage, that acted as a sort of armour within the stone masonry and allowed to build bearing walls as well as light partitions [3][4]. At every attic level, a long horizontal sleeper-beam was located in order to better distribute the vertical loads and make the usage of shorter vertical columns possible; horizontal and diagonal elements were used to stiffen the whole structure making it crushproof along with distributing the loads in a suboptimal way [5].…”

“…In the eastern Mediterranean area similar solutions are observed from the inner Anatolia to the Balkans and Greece, with slight differences, especially in terms of infill/cladding materials/types. The region of Turkey has experienced frequent seismic events that were easily overcome by the traditional vernacular hımış (figure 5) [5,14]. Typologically, the Turkish traditional architecture is characterized by a ground floor made of stone bearing walls, that are often laced with horizontal runner beams, and the upper floors made of an infill construction: a timber framework and a masonry infill, the hımış precisely, that is sufficiently light to allow the typical bays and jetties overhanging the streets [15][16].…”

Structural Uses of Stone and Timber in The European Historical Construction

“…Such a technology consisted in a timber framework, made of reeds or brushwood fastened tight by means of cordage, that acted as a sort of armor within the stone masonry and allowed to build bearing walls as well as light partitions [3,4] . At every attic level, a long horizontal sleeper-beam was located to better distribute the vertical loads and makes the usage of shorter vertical columns possible; horizontal and diagonal elements were used to stiffen the whole structure making it crushproof along with distributing the loads in a suboptimal way [5] . Figure 1.…”

“…In the eastern Mediterranean area, similar solutions are observed from the inner Anatolia to the Balkans and Greece, with slight differences, especially in terms of infill/cladding materials/types. The region of Turkey has experienced frequent seismic events that were easily overcome by the traditional vernacular hımış [ Figure 5] [5,14] . Typologically, the Turkish traditional architecture is characterized by a ground floor made of stone bearing walls that are often laced with horizontal runner beams, and the upper floors made of an infill construction: A timber framework and a masonry infill, Figure 3.…”

Timber Reinforcements: Local Construction Techniques in Italian Historical Buildings

“…The peculiar vulnerability of masonry structures to shear stresses required such reinforcements. In Italy, after recent earthquakes (L'Aquila 2009 and Amatrice 2016), the rediscovery of such building techniques, in some cases belonging to a sort of forgotten world of knowledge, drove to design alternatives and more sustainable retrofitting interventions for historical buildings [3].…”