New Integrated Knowledge based approachs to the protection of cultural heritage from Earthquake-induced Risk


A Practical Training Program for Conservators of Built Heritage

About the Mosaic Conservation Section

The Bet Sheʽan Conservation Project

Conservation Concurrent with Excavating, Excavator’s Guide
Conservation Engineering in Israel, 1988–2013
Ing. Yaacov Schefer

Is there a subdivision within the field of conservation that relates to engineering? This rhetorical question has been asked more than once and is still being asked today. Isn’t every engineer that is knowledgeable and has the experience and intelligence capable of handling failures or recycling antiquities sites and historical buildings?
Since the practice of conserving built heritage was first begun in the nineteenth century there was a need to address physical, constructive and engineering issues.  Indeed many of the important figures who dealt with built heritage were architects; however, they also took care of the engineering aspects of the conservation. As conservation developed across the world, particularly large-scale interventions at antiquities sites, the recycling of historical buildings for new uses was begun. The architects specialized in the field of building conservation and the technical treatment was turned over to conservators. The latter underwent professional training and specialized courses of study were opened that grant academic degrees in conservation; this is how the field developed in the world and later on in Israel too. There can be no question that teaching the subject in universities greatly improved the level of treatment of historical and ancient buildings, but what developed in the field of conservation engineering? After all, doesn’t every building require engineering intervention? And how, from an engineering aspect, can the high demands of architecture and technical-physical conservation be suitably answered? Few engineers have embarked on a career in building conservation.

In dealing with conservation the field of engineering did not keep pace with conceptual, architectural and technical conservation. Less than twenty years ago ICOMOS established a sub-committee on the engineering of structures for conservation (ISCARSAH). Five years ago a master’s program in conservation engineering was inaugurated in Europe and it is currently the only one in its field, and it is only in recent years that they have begun to offer courses in European universities on the subject of building and site engineering.
Early Approaches to Engineering Intervention at Antiquities Sites
Until the 1990s capable structural engineers provided the engineering solutions required at the antiquities sites and historical buildings; however, at the core of their studies and their specialization were modern buildings made of reinforced concrete and steel. The engineering solutions they provided were in accordance with their training, namely, utiliing reinforced concrete beams or steel beams, concrete foundations or piles, temporary or permanent supports made of wood, reinforced concrete or steel. The safety factors and fundamental planning guidelines were based on the guidelines of framing construction and the appropriate tables for this. The conservation and restoration projects implemented by the British in the 1930s in ʽAkko and Jerusalem were carried out according to construction guidelines for concrete and steel. The antiquities sites that were developed from the 1950s to the early 1990s were also done solely with concrete and steel. For example, these materials were used at the following sites: Bet Sheʽan, Bet Guvrin, the Western Wall, the Southern Ophel, Tel Lachish, Masada and Tel Hazor. Intervention utilizing concrete and steel was done in the historical buildings of the nineteenth century and it is evident in most of these structures today.   

This approach that calls for building the engineering base using reinforced concrete and steel was accepted and still exists because of a number of reasons:
1.The knowledge the engineers have to work with is based on theories they are taught in the engineering schools where the use of reinforced concrete and steel still prevail.
2. Ancient and historical technologies are not taught and the strength and weakness data of the ancient structure are completely ignored.
3.The lack of knowledge and an unwillingness to accept advances in the field of conservation engineering in the world.
The serious consequences of this approach can be seen throughout the world and in Israel. Irreversible harm has been caused to sites and historical buildings to the extent of damage or loss of the site, or enormous costs incurred at the sites in order to remove the concrete and steel and replace them with appropriately engineered stabilization.

The Change of Approach in Conservation Engineering
In Israel the change of approach in conservation engineering began in the 1990s with the establishment of the Conservation Department in the Israel Antiquities Authority. The department’s director at that time, Arch. Giora Solar, took a number of significant initiatives that included adding a conservation engineer to his staff, as well as absorbing new immigrants from the former Soviet Union including engineers and conservators that were educated based on the conservation doctrine. Other factors influencing this change of approach were due to the engineering needs at large projects that were developed during these years and the possibility of receiving professional advice on engineering topics from experts overseas. The components that fostered a drastic change in the approaches to conservation in Israel included: proper utilization of the professional engineering-conservation man-power that mostly came from the large aliyah of the 1990s and teamwork that included engineers, conservators, architects and planners. Although the practice of conservation was a new profession, these created a dynamic of conservation engineering.
The engineer’s work in the conservation, restoration or temporary stabilization of an archaeological and historical site rests on four pillars:
1. Knowledge of ancient and historical construction practices and the typical failures that occur at the sites.
2.A conservation engineering survey. This is a fundamental tool for providing engineering solutions, just as documentation is the basis for conservation and for architectural planning at a site.
3.An environment that “favors” conservation engineering approaches from the side of the customers, the parties involved and the archaeological and planning teams on site.
4. Professional conservation-engineering ethics.

The integration of a number of young engineers who studied in Israel and attended seminars in the country and overseas advanced awareness of the field somewhat; however, the number of conservation engineers is extremely small. The reasons for this stem from the fact that the field is still not taught in engineering schools, the field still does not grab a large market share and there is still insufficient awareness among those requesting the work in Israel – i.e. public and governmental entities – to advance the field of conservation engineering, as is already occurring in some of the European countries.
Changes in engineering approaches will probably occur only after the field is included in the training of engineers. That is to say, only after an entire generation of engineers is educated in the methods of construction and ancient building technologies, about the concepts of conservation, conservation ethics, about the failures and conservation engineering solutions. It turns out in many instances that these are also more cost effective than using modern techniques.

The Survey and the Conservation Engineering Planning
The field of conservation engineering involves office work, as well as field work in which the engineer is involved. The goal of the conservation engineer is to find solutions and offer them for problems before, during or after the implementation of conservation measures or the re-use of the site or historical building. For the most part the conservation engineer is expected to provide quick answers for supporting where required and give alternative solutions and recommendations for the feasibility of the constructive engineering solution. Moreover, it is expected that he will provide alternative solutions and recommendations for an economic-engineering solution, and that the engineering solution will guarantee the “life cycle” of the building after the completion of the stabilization and conservation work.
The basic tools for conserving archaeological sites and historical buildings are the conservation engineering survey and the project’s conservation engineering principles.

The Conservation Engineering Survey. The survey is based on conservation conventions, policy documents and the rules of conservation work in the world. It consists of five sections that take into account all of the constructive and physical engineering knowledge about the site. Naturally, the survey also includes the surveying engineer’s knowledge which is a result of collecting information and years of experience. The survey will usually include: an introduction with the background about the work and the purpose for performing the survey; the construction technology, including laboratory tests of materials; the condition of the constructive engineering and physical conservation, including research, engineering monitoring and different engineering tests; survey conclusions; the survey recommendations and a list of information sources for the survey. The engineering planning of a site or ancient building will commence only after performing a survey, studying the conclusions and recommendations of the engineering surveyor and receiving the customer’s approval for his recommendations. 
Conservation Engineering Planning: Conservation engineering planning consists of constructive engineering planning and physical engineering planning. The surveyor’s recommendations will first be studied from both aspects, and the planning done in light of them will include two components:

1. Engineering conservation principles for a building: salvage work of a building or remains of a building are part of its stabilization and conservation measures. These steps will often serve as a “pilot” for technical engineering conservation methods for the conservation project, and they will be based on conservation principles that should be applied to the engineering work in the building intended for conservation. For example:
-  All work will be based on ancient construction methods and appropriate technologies.
-  The conservation work will be based on stone construction, without any cast elements.
-  The conservation work will be done utilizing lime-based rather than cement-based mortar.
-  All work that is done to remove safety hazards, in the case of temporary supporting, will be done utilizing materials and elements that will not endanger the stabilization and conservation work and future recycling.
-  If new elements are required for permanent supporting, which are also suitable for removing the hazard and for the future, the element will be implemented in accordance with the conservation guidelines of ancient historical buildings such as the engineering guidelines of the ICOMOS International Scientific Committee on Structures (ISCARSAH).

2. Stabilization plan. This plan will be carried out on the basis of engineering conservation principles for a structure and in accordance with the conclusions and recommendations of the engineering survey. The plan will include clear instructions, for example:
-  Engineering solutions will make m

In conclusion, the experience accumulated in treating cultural heritage sites from the standpoint of their physical-engineering, and practicing international standards, principles and ethics in the heritage conservation have led to the development of the field of conservation engineering. However, more effort is required to instill it in the training of engineers and in the practice of the generation of engineers that are at work today.

MAY 2013

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