Methodology for Repair and Strengthening of Historical Monuments Damaged due to Man-Made and Natural Disasters V. Sendova, P.Gavrilovic Institute of Earthquake Engineering and Engineering Seismology, IZIIS University "Ss. Cyril and Methodius", Skopje, Republic of Macedonia ABSTRACT: Presented in the paper shall be the systematic approach and methodology for repair and strengthening of historic monuments damaged due to man-made and natural disasters. Particular attention shall be paid to measures for taking actions in the three key phases: emergency measures, planning and measures after disaster and long term protection of historic monuments, defined on the basis of long years of activities of IZIIS and its experience in the field of protection of historic monuments in seismically active regions in the world. Emphasis shall be put on damage classification and identification within the frames of the first phase - emergency actions. The technical aspects, particularly the aspect of structural repair and strengthening shall be presented within the maxim of "minimal intervention - maximum protection". KEYWORDS: Repair, strengthening, man-made disaster, natural disaster, conservation, protection

1 INTRODUCTION

Disasters are untimely events which cause damage, often widespread. They can be divided into two categories: natural ones, (wind, hurricanes, typhoons, tornadoes, heavy rain, landslips, avalanches and earthquakes) which cannot be prevented but can be anticipated and man-made disasters, (war, terrorism including bomb threats, technological and chemical accidents like gas explosions, release of harmful matter, etc.) which are preventable, but with unpredictable extent of damage that they might cause should they occur.

The territory of the Balkan Peninsula and hence the territory of Republic of Macedonia has unfortunately been characterized by high level of technological and natural hazards in the past and at present. It is a fact that long world wars have often been waged and started in this area. Also, all the Balkan countries are situated in one of the seismically most active regions in Europe characterized by occurrence of strong devastating earthquakes.

On the other hand, this has been an area of development, existence and parishing of many different civilizations, peoples and cultures starting from the prehistoric times until now. Material evidence, first of all in the form of architectonic structures of a sacral nature, exist today in traces and archaeological localities from the classical period, but also in fragments or entire buildings and complexes dating back to the time of the Byzantine culture and the Medieval times. Presently registered and put under the protection of the Law in our country are a total of 154 medieval churches and monasteries. Being located in a region of high natural and technological hazard, these monuments have often been exposed to climatic and human devastating factors including the effect of the earthquakes.

Within the theme of interest of this Workshop, a question is raised as to whether the consequences of the armed clashes are so specific that they should be separately treated. Are or are not the consequences from war devastations similar or the same as the consequences from earthquakes and catastrophic fires as far as the cultural heritage is concerned? We might certainly find some differences in the consequences because the causes are different, i.e., the forces destroying the cultural heritage are different. However, when damage or destruction of cultural historic monuments is considered, the reason does not play a primary role anymore. The consequences are the same and so are the problems and the activities for repair and/or strengthening, conservation and restoration of the cultural historic monuments.

2 BEHAVIOUR OF HISTORIC BUILDINGS AND THEIR PROTECTION

Historic buildings are those that have been entirely functioning regarding their purpose for over a century. As such, they deserve special attention due to their individual historic, architectonic, documentary, economic, social and even political or spiritual value.

Historic buildings were constructed by use of traditional materials characterized by high compressive strength in respect to the low tensile strength and low deformability capacity, constituting in that way structural systems with a limited capability of sustaining dynamic effects. They were dominantly designed as rigid and massive forms that best sustain vertical loads and are much less resistant to the horizontal ones. Gravity effects, accompanied by human activities and natural catastrophes have induced severe damage to cultural heritage in the past. The extent of damage to the historic buildings can be very high not only due to the insufficient seismic resistance, high stiffness of the structure and brittleness of the material but also the ravages of time and the decreased bearing capacity due to insufficient maintenance in the period between two disasters.

Since the beginning of the XX century, traditional techniques and typology of construction that had varied very slowly throughout the centuries, have been rapidly replaced by modern methods. Today, new materials (concrete and steel) dominate in the whole world so that the art and culture of construction from the past is slowly starting to vanish. New materials have increasingly been applied even in restoration of historic monuments. Such a practice has particularly found a fertile ground in conditions of necessary urgent interventions, whereat new techniques and synthetic materials have been promoted. The quality and results from these materials have often been emphasized without knowledge on their durability, chemical compatibility with the existing masonry and reversibility.

Such an approach to intervening on historic structures, without efforts to preserve as much as possible the primary structure and the materials has often been inappropriate, producing additional unwanted effects. The fact that these structures survived through many disasters in the past does not guarantee that they shall survive through future disasters either. Damage induced by natural phenomena like earthquakes or human intention, good or bad, may prevent the structures sustain future disastrous effects. Imposed as a need is development and establishment of a general, scientifically based methodology of conservation, restoration, repair and strengthening of individual types of structures pertaining to the cultural heritage, located in regions of high level of natural and technological hazard.

3 WHEN DISASTER STRIKES

In the case of damage to the structures of the cultural historic heritage due to natural or technological catastrophes, it is necessary to divide the measures to be taken for reduction of the consequences into three phases:

(I) emergency measures and action during the disaster (II) planning and measures after disaster (III) long term protection of historic monuments.

I. Emergency Measures and Action (during the disaster)

The three main activities within this phase are:

1. Quick inspection of damage: - quick inspection of the damaged monument with identification and classification of the

damage; - labeling or transportation of all movable cultural property; - coordination of the work of conservators, architects and engineers; - evaluation of extent of damage to the monument.

2. Temporary actions for protection of as much cultural property as possible: - temporary consolidation of the monument structure if necessary, - immediate protection against weather,

- fire fighting, prevention of damage due to penetration of water and prevention of looting of works of art,

- cooperation with local civil and military authorities as soon as possible.

3. Disaster damage in depth assessment

The objective of the methodology and procedure for disaster damage assessment is to present a uniform procedure for examining and reporting on damage of buildings, establishment of database on disaster effects and to present a methodology for analysis of damage and estimation of economic losses. The primary purpose of these procedures and methodology is to assure an adequate volume of data for the following needs of the community and national authorities:

To reduce incidents of death and injury to occupants of the buildings which have been weakened or seriously damaged

To obtain appropriate information on the magnitude of the disaster in terms of number of usable, damaged and dangerous buildings

To assure a database for uniform estimation of economic losses for development of appropriate rehabilitation programme and assistance in reconstruction and development of the affected region

To provide data for planning and organizing of a civil defense system in elaboration of plans of rescue operations after disasters, training of staff, and organization of supplies

To record and classify damages for planning and performance of repair and strengthening of damaged buildings

To identify the principal elements of damage and develop vulnerability relationship for different categories of buildings in planning and performance of short- and long-term actions for reduction of disaster consequences.

Damage and usability classification according to the damage level is carried out based on a detailed damage description and according to the presented categories.

Because of the specific treatment of the historical monuments, a special form for damage assessment for immovable cultural property is created, (enclosed Form 1). This special form contains all the specific characteristics and parameters which are of basic importance for classification of damage and usability and extrapolation of these data for economic loss analyses. For classification of this kind of structure it is necessary to have specially trained team of specialists. Each damage inspection team should be composed of minimum three members: structural engineer, architect conservator and technician. Their duties are: inspection of the building, completing of the inspection form, preparing daily, weekly and final reports, taking photographs and collection of information about the building e.t.c. All the basic data sets should be transferred to the computer center immediately after their completition and analyzed for the first presentation.

Post-disaster damage evaluation should be organized with implementation of systematic methodology and rapid procedure in order to establish basic information for the local and national authorities for decision making and undertaking of economically justified and technically consistent measures for reduction of disaster consequences in a uniform manner.

II. Planning and measures after disaster

The main activities within this phase are:

1. Data collection on the damage and damage assessment for each damaged monument, 2. Preparing of the survey documentation for each damaged monument, 3. Establishment of priorities and decision making for the program of restoration, repair and

strengthening, 4. Setting up of multidisciplinary teams to propose projects for repair, reconstruction and

strengthening of damaged monuments. Extensive knowledge has been gathered worldwide for the last thirty or forty years in which period historic monuments have been given adequate attention and treatment at both scientific and academic

level, in research approaches and legislation. However, It is only that a team of experts from different profiles, (engineers, architects, archaeologists, art historians, conservators and other), each of them being completely competent for their profession, but sufficiently flexible to accept the arguments of the others, can successfully protect a historic structure. One of the main tasks and problems in repair and/or strengthening in the process of reconstruction and protection of historic monuments is to answer the question as to how far we should go as to the level of safety on one hand and the extent of the intervention on the other. For that reason it is necessary to state some definitions (officially adopted or to be officially adopted) which are in use:

A monument is a structure having an important "cultural value" so high that it is necessary to guarantee its preservation, generally with its architectural, typological and material characters;

A historical building is a building of an urban area, which has a "cultural value" as a whole (historical urban area), while a single building is not a monument. This means that preservation concerns the general character of the construction techniques typical in the whole area.

The sites of monuments must be an object of special care in order to safeguard their integrity and ensure that they are cleared and presented in a seemly manner. The work of conservation and restoration carried out in such places should be inspired by the general principles of conservation.

The conservation and restoration of monuments must have recourse to all the sciences and techniques which can contribute to the study and safeguarding the architectural heritage. Conservation. Architectural conservation generally refers to the combined actions exerted in the

protection, stabilization, repair and restoration of a monument or part thereof. Documentation and planning for the conservation methodology are important aspects of architectural conservation.

Restoration. The term restoration usually implies returning a building or site to what is understood to be its earlier or original appearance. Restoration often implies major intervention to the surviving architectural fabric of a structure, in order to recreate the original finishes and appearances. The quality of restoration is usually critically dependent upon a thorough understanding of a monument through detailed historical research and both above- and below - ground archaeological investigation.

Consolidation. Consolidation refers to minimal strengthening and supporting of structures and building fabrics which are about to fail. Generally it implies the use of new material. The term consolidation can be applied to the conservation of a specific material such as stucco or stone, or to work on a larger scale such as structural consolidation.

Stabilization. Stabilization refers to minimal repair and conservation, avoiding the use of visible new materials when possible.

Anastylosis. The process of reconstructing a collapsed structure, or the careful dismantling and rebuilding of a structure using modern technology. Anastylosis, or reconstruction is dependent upon craftsmen experienced in stone construction and upon the knowledge and skills of the conservation team.

Repair. The term "repair of structures" means elimination of damages suffered by structural elements and the structure as a whole without changing the bearing capacity of the structure from structural aspect.

Strengthening. Strengthening means increasing of the bearing capacity and/or deformability of the structure.

No intervention. For various reasons, the wisest course of action in a conservation project may be to do nothing at all. Occasionally, it is best to leave a site or part of a site undisturbed for a future generation, at which time conservation technologies and other abilities may have improved.

The decisions for repair and strengthening of a historic structure should be thoroughly clarified and justified in advance because of the existence of some unusual aspects (compared to modern structures) that have to be taken into account. This is because historical buildings are quite complicated structures whose behaviour has still not be clarified to a sufficient depth. The difficulties and the complexity of the problem are due to, first of all, the mode in which they are constructed as well as the disturbance of their authenticity in the course of their existence. Historical buildings are constructed of traditional natural materials by using techniques primarily based on experience and skill resulting into a variable quality of construction. Special attention was paid to the geometry and the aesthetic appearance of the structure and much less thought was given to the structural integrity. After

disastrous effects of fires, earthquakes, wars or different reconstruction and consolidation works, the original structural systems were often enlarged or even completely changed.

It is more than evident that a "methodology" is necessary as an approach prior to "methods" as a technique. We should strongly oppose the idea of existence of a "Code for Historical Buildings and Monuments" and support the idea of a "Guide", "Recommendations", "Resolutions", "Charter", etc. This is so because "Code" is "Law" and the monuments have been constructed in compliance with different laws through centuries. Unification of these laws shall therefore lead to negation of the monuments.

The methodology for repair and strengthening of monuments and historical buildings in the process of their protection should encompass the following: Definition of expected natural and technological hazard; Definition of soil conditions and dynamic behaviour of soil media; Determination of structural characteristics along with the bearing and deformability capacity of

existing structures (on the basis of investigation of built-in materials, structural elements and structural system);

Definition of criteria and development of a concept for repair and/or strengthening; Design of structural methods, selected techniques, materials and types of excitation; Determination of the response of repaired and/or strengthened structures and verification of their

seismic stability; Definition of field works, execution and inspection.

Although the above stated seems to be the "normal procedure" - it is the only way of providing high quality in full compliance with specificities belonging to other fields. Of course, this task is much more than simply listing of what is to be done since it requires a lot of knowledge and efforts.

Materials: The key for selecting materials and techniques is classification of repair and strengthening techniques into two main categories: reversible and irreversible. In selecting materials to be used in reversible interventions, there are usually only a few limitations. However, the materials used in irreversible interventions do impose two additional limitations: compatibility of new with old materials and their durability.

Repair and Strengthening Methods: If the analysis of existing structure proves that the structure has a sufficient bearing and deformability capacity, taking of measures for its repair shall be sufficient enough. In case the analysis proves that the bearing and deformability characteristics of the structural elements are not sufficient enough, depending on the vulnerability level, the strengthening should be done to increase the strength of the existing structure and its deformability. In local and/or global strengthening of structures of historic structures, numerous methods and techniques are used:

To achieve structural integrity and joint behaviour of structural elements, the most commonly used procedure is to incorporate horizontal steel ties into the existing masonry (at the top of the existing walls in order to be made invisible - churches and mosques), incorporate reinforced concrete belt courses or reinforced concrete slabs into structures where possible - structures in old towns.

To improve the bearing characteristics of the walls and the columns, several techniques are used: injection of masonry, injection with jacketing, incorporation of vertical reinforced concrete columns, or even incorporation of new reinforced concrete walls (in the structures of the old towns). The injection technique, the material to be used, i.e., the pressure under which the prepared mixture will be injected are selected depending on the size, the position and the shape of the cracks. Irreversibly covering of the existing masonry reduces jacketing usage to internal walls or walls which are not of a particular importance for the historical building, mainly in strengthening of structures in old towns. Vertical reinforced concrete belt courses are used to increase the ductility of the considered element.

The techniques of strengthening of the foundation structure mainly consist of extending the proportions of the foundation and their connection to the vertical elements, modifying the foundation structure and consolidating and improving of the characteristics of soil conditions.

Although there is a similarity between historical buildings and historical monuments, there also exist differences. Historical buildings usually present shear wall masonry structures that are basically non-ductile. The problem of interaction between the "old" and the "new" materials and/or elements that arises in their strengthening requires experimental verification of all techniques that have so far been developed, (injection, grouting, jacketing, confining, base isolation). Since historic monuments

are also masonry structures, same basic principles and requirements hold for them also, but are specific. The characteristic structural entity, the variability of the built-in materials, the complex history of successful modifications done in the past, as well as the degree of deterioration, makes each historic monument a case for itself. Therefore the basic principle of minimal intervention maximal protection and/or preservation of the monument's identity should be adopted.

III. Long term protection of historic monuments (before next disaster)

The activities within this phase are:

1. Execution of already made decisions for repair, strengthening or reconstruction of the damaged monuments in the previous phase,

2. Documentation of the performed repair, strengthening or reconstruction of certain monument, 3. Taking all the necessary measures for disaster preparedness, (documentation, recording,

knowing the risk, town planning, disaster planning, emergency preparation, maintenance, inspections, public education, professional training e.t.c.)

4. To keep pace with the development of new materials and technologies and their application. The activities to be carried out in the field of long term protection of historical buildings and monuments impose the need for selective and complex investigations of materials, techniques, including of new technologies for repair and strengthening, as a prerequisite for development of corresponding methods and their application in practice.

A Guide for Protection of Historic Buildings, Monuments and Sites at national level with incorporation of the national strategy and policy has to be prepared and should be strictly connected with the national policy, expected earthquake activities, national economic potential and general National Code requirements.

CONCLUSION

Undoubtful is the importance of the historic monuments, the admiration and respect that they arouse in the modern world as the only testimony of human existence, creation and achievements in the past. The present civilization has therefore a moral and legal obligation as well as the duty to protect, as better as possible, the cultural heritage in order to preserve it in its authenticity for the present and future generations.

As professionals working in the field of protection of cultural heritage, we mustn't allow that either the globalization process or any other social, political, economic or technological process take place in the world, ignoring the genesis of development of the human environment and the achievements of the human civilization in its course.

REFERENCES

Fielden B., Between two earthquakes. Joint publication ICCROM and GCI, 1987.

Gavrilovic P., Sendova V., Ginell W. Seismic Strengthening and Repair of Byzantine Churches. In: Journal of Earthquake Engineering, Imperial College, London, Vol 3, No.2, pp:199-235, 1999.

Gavrilovic P. Historic Buildings and Monuments. State of the art report. National Conference of Earthquake Engineering, Ankara, 1997.

Proceedings of the International Course on Prevention Measures for the Protection of Cultural Property in Earthquake Prone Regions, ICCROM-IZIIS, Skopje, 1985.

Proceedings of the 1st International Seminar on Modern Principles in Conservation and Restoration of Urban and Rural Cultural Heritage in Seismic-Prone regions, Skopje, 1988.

Sendova V. Seismic Strengthening and Repair of Byzantine Churches in Macedonia. Doctoral dissertation, IZIIS, Skopje, 1998.

US/Yugoslav Workshop for Protection of Historic Buildings and Monuments, Petrovac 1985, YU.

Inventory of damage FORM 1

DAMAGE ASSESSMENT FORM IMMOVABLE CULTURAL PROPERTY

1. Name of Monument

Reference Number

Century of Construction 12 13 14 15 16 17 18 19 20 2. Archaelogical site Religious monument Urban group of Buildings Habitation Fortified urban area Public building Monastery / monasteries Rural group of buildings

Building serving an economic purpose

Isolated monument Military architecture (fortified)

Ethnological structure Building serving technical

purpose Monument to the struggle

for national liberation

3. Location

Overall Floor Space (m2) Condition Before Disaster

Community Basement Good Town Ground floor Medium Place 1 Poor Address 2 Category of

Monument Land register no. 3 Owner 4 Protection Agency Total 4. Damage Caused by the Disaster Destroyed Heavily

Damaged Damaged Slightly

Damaged Intact

Chimney(s) 5. Degree of Danger Covering Repair feasible Structure Repair impossible Dome(s) Vault(s) Status of the Monument Ceiling(s) Unchanged Wooden floor structure Changed Other floor(s) Not retained Bearing wall(s) Nonbearing wall(s) EMERGENCY Arch(es) ACTION Column(s) Staircase(s) Foundations 6. Outline Plan of the Belfry / belfries Monument and Minaret(s) Principal Dimensions Architectural decoration Photographs and Iconostasis indication of damage Mural painting(s) (attach plans)

7. Structural Characteristics Type and quality of building components

8. Description of Deformation and Structural Damage

9. Emergency Action Proposed

10. Repair Program Proposed

Total demolition Demolition(s) Bearing wall(s) Belfry/belfries, minarets Partial demolition Chimney(s) Nonbearing wall(s) External plastering Temporary covering Covering Arch(es) Internal plastering Shoring Timber structure Columns Preservation External scaffolding Dome(s) Piers Restoration Internal scaffolding Vault(s) Beam(s) Protection of mural

paintings Ceiling(s) Wooden floor(s)

Staircase(s) Geomechanical exploration

Protection of architectural decoration

Other floor(s)

Foundation(s)

11. Damage Classification and State of Usability of the Building I. Usable, serviceable

IA - class 1 intact except superficial damage (green category)

IB - class 2 no structural damage II. Temporarily unusable

IA - class 1 structural damage (yellow category)

IB - class 2 heavy structural damage III. Unusable

IA - class 1 very heavy structural damage (red category)

IB - class 2 partial or total collapse 12. Estimated Cost of Repair

1. Value of the building before the disaster:

m2 x denars = denars. 2. Cost of restoring the building to its pre-disaster condition (structural repair):

m2 x denars = denars. 3. Total cost of repair (consolidation):

m2 x denars = denars. 13. Notes Members of the Commission Photographic Coverage Number of negatives Photographer Copyright Owner Place Date

Methodology for Repair and Strengthening of Historical Monuments Damaged due to Man-Made and Natural DisastersV. Sendova, P.Gavrilovic

ABSTRACT: Presented in the paper shall be the systematic approach and methodology for repair and strengthening of historic monuments damaged due to man-made and natural disasters. Particular attention shall be paid to measures for taking actions in the t1 INTRODUCTION2 BEHAVIOUR OF HISTORIC BUILDINGS AND THEIR PROTECTION

3 WHEN DISASTER STRIKESI.Emergency Measures and Action (during the disaster)II.Planning and measures after disasterMaterials: The key for selecting materials and techniques is classification of repair and strengthening techniques into two main categories: reversible and irreversible. In selecting materials to be used in reversible interventions, there are usually onl

Repair and Strengthening Methods: If the analysis of existing structure proves that the structure has a sufficient bearing and deformability capacity, taking of measures for its repair shall be sufficient enough. In case the analysis proves that the bear

Inventory of damageFORM 1DAMAGE ASSESSMENT FORMIMMOVABLE CULTURAL PROPERTYCategory of MonumentProtection AgencyStatus of the MonumentMonument andPrincipal DimensionsProposed