Fire Threat to Stones of Historic and Cultural Heritage Buildings

Many historic buildings are made with stone structures. In addition to the various benefits that this type of material, which is diversified by composition, aggregation and geometry according to historical periods and geographical areas, it must be remembered that exposure to fire constitutes in most cases an important vulnerability. Even recently, several cases of fire have highlighted the importance of designing from fire, in buildings belonging to the cultural heritage, building elements to which adequate attention is not always paid.

Plan and section of the Guarini Chapel in Turin, where the Holy Shroud is kept. The Chapel has been severely damaged by the fire on April 11, 1997.
Plan and section of the Guarini Chapel in Turin, where the Holy Shroud is kept. The Chapel has been severely damaged by the fire on April 11, 1997. Two thirds of its marble structural stones were damaged by the heat. he complex structure of the dome of the Chapel of the Holy Shroud, severely damaged by the fire of 1997, that was rebuilt using stones taken from a quarry opened for the occasion. The opening of the new quarry was due to the need to replace the numerous stone elements destroyed by the effects of the fire or no longer able to perform their load-bearing function. (image from Wikipedia

The case of the fire that seriously damaged the chapel that housed the Holy Shroud in Turin, on April 11, 1997, can be considered iconic in this regard. For its restoration it was necessary to open the quarry near the place from which at the time the stone material with which the supporting structures had been made had been extracted (see reference, page 25) . Among other things, the individual blocks had been designed and installed with techniques of which the memory had been lost and which forced the restorers to a specific study.

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Performance based approach and fire protection of historic buildings

wooden beams inside ceiling of baroque church in Rome
wooden beams inside ceiling of baroque church in Rome

The strategy of protection of historical building against fire risk is different from almost any other type of building. In the most of case, the objective of fire protection, in fact, is preserving occupants of buildings or the their structure.  Sometimes the concern is both. In the case of fire protection of historical buildings, preservation must find solutions that are consistent with the particular needs of the building: such goal needs freedom e cannot be achieved with prescriptive approaches, which have been developed with the typical building in mind.

The most common gap of prescriptive systems, when applied to heritage buildings, in that they do not work well in unique buildings, when the possible solutions are constrained. Frequently encountered constraints include aesthetic objections to:

  • the degree of compartmentation required in the regulations;
  • the inability to meet egress requirements such as the required number of exits or maximum travel distances;
  • The frequent impossibility in installing active fire fighting systems

When these situations occur, designers usually use the equivalency provisions included in most prescriptive regulations. But such provisions normally have been studied for specific occupancy types and must be continually recalibrated as the prescriptive requirements evolve.

In this situation, performance-based regulations allow to meet conservation needs with safety standards provisions.

Explicit goals and objectives for life safety and historic preservation can be applied to performance solutions. Hazards and safety deficiencies should be identified in order to determine compliance options that satisfy safety objectives, respecting historical/aesthetical features. Solutions can be selected from traditional, prescriptive solutions or performance analysis approaches. Using such method, it’s fundamental that all parties involved in the construction understand the significant features that are to be preserved.

Other issues of paramount importance in dealing with fire safety of cultural heritage is the need for special care during:

  • work projects when the structure is particularly vulnerable. When there are temporary collections of combustibles and construction equipment as well as operations that can represent sources of ignition not normally present. Ceilings and walls may be open for repair, exposing combustible structural elements and void spaces that might allow a fire to spread throughout the structure. Existing fire protection equipment may be disabled or removed as a part of the work.
  • special events that may bring large occupant loads, consumption of alcohol that may impair these occupants, and catering or special food preparation activities that can involve additional quantities of combustibles and ignition sources. All activities at special events need to be evaluated and precautions taken to avoid threats.

Did Rome’s Colosseum suffered a post earthquake fire in 271 A.D.?

Colosseum simulation of coaction stress distribution
Image showing the simulation of coaction stress distribution in the Rome’s  Colosseum according the Prof. Enzo Cartapati (Sapienza University of Rome), which presentated a study on the effects of the 217 A.D. earthquake and its possibile connection with a fire that damaged in the same period the monument 

In 217 A.D. Rome’s Colosseum was slightly damaged by a fire. Since Rome is built in a seismic area and there is an earthquake reported during September 217 A.D. ,Rome Univerity  La Sapienza’s Professor Enzo Cartapati has studied the possibility of a fire event due to the seismic event.

Together with Maurizio Cerone, Prof. Cartapati has conducted a structural analysis of Colosseum’s stone columns, in order to understand if actually the fire occurred after the seismic shock.

The presentation of such work, presented during the April 11th 2003 Conference “Integrating Historic Preservation with Security, Fire Protection, Life safety and Building Management Systems”,  can be downloaded from this website:

Cartapati-Cerone_Colosseum

Impacts of Fire on Stone-Built Heritage

Spalling Fire is one of the major threat to stone-built cultural heritage and this    paper is a review of the existing research into fire damage on building  stone. From early research based on anecdotal evidence of macroscopic  observations, scientists have moved on to develop various techniques  for approaching the investigation of fire damage to stone (high-    temperature heating in ovens, lasers, real flame tests), different aspects    of the damage that fire does have been learned from each, developing    understanding of how microscopic changes affect the whole.

This paper, published on the Journal of Architectural Conservation seeks to highlight the need for a greater awareness of the threat that fire poses (and the need to take precautionary measures in the form of fire-suppression systems), of the immediate effects, and of the long-term management issues of natural stone structures which have experienced fire.

Journal_Architectural_Conservation_15_2_47-58