STRUCTURAL INTERVENTIONS TO MONUMENTAL BUILDINGS

Transcription

1 STRUCTURAL INTERVENTIONS TO MONUMENTAL BUILDINGS DOCTORAL THESIS (SUMMARY) DOCTORAL CANDIDATE: BULBUK MARTIN-ŞTEFAN SCIENTIFIC COORDINATOR: Prof. Dr. Eng. ILDIKÓ BUCUR The doctoral thesis deals with the topic of structural interventions on monumental buildings and is mainly based on a series of actual structural interventions of the author s, on certain historic or architectural monuments of our national heritage. His experience is supported by deep theoretical studies and considerations. We all know that nowadays we emphasize the process of restoring and rehabilitating built heritage, as the most valuable component of the history of national, European and world culture. We must say that all interventions on monumental buildings are unique if we take into account the degree of deterioration of the structural subassemblies and the needs of functional rehabilitation of a particular objective. All structural interventions on such monumental buildings must assure resistance and stability at least equal to the original one, or even higher, in order to acquire new and modern functions, asked by their further use for the benefit of the society. They also have to comply with well determined rules concerning their structural and architectural originality and authenticity. Assuring such resistance and structural stability needs, acquiring new modern comfort functions, and maintaining authenticity as a whole and in details (regarding architecture, materials, or technologies) cause difficulties to specialized planners, as well as to execution engineers and specialists. However, given the extremely important cultural aim, the solution to technical problems until the fulfillment of the objective must weigh the same.

2 The present doctoral thesis follows the path of achieving this desideratum, the author hoping to help the specialists involved in the rehabilitation of monumental structures and contribute to the theory and practice of the process of saving built heritage. In order to provide the theoretical and normative framework necessary to the specialists in interventions on monumental structures, the author presents in the first chapter the theoretical bases and the doctrines of protecting built heritage. In this chapter we present the definitions and the main principles of monument protecting. We refer to the situation of national heritage, including cultural and historical settlements that need urgent interventions in order to be partially or totally saved. Further on we presents the Romanian and international legislation in this respect and the list of the UNESCO world heritage in Romania. The author further underlines the present trends and the opportunity of studying about structural interventions on monumental buildings. In the second chapter the author makes a historical retrospective of the relation function-form-structure, which is necessary in order to know the cultural and historical periods of the evolution of the national, European and world built environment. We go back to the history of architecture and building techniques. We present the cultures of archaic periods, ancient architecture, the architecture of the Middle Ages until the new era, and the architecture of the 20th century and provide many specific examples and their authors. We consider it necessary to know the architectural styles, as well as structures, materials and technologies used in the past and at present in order for the specialist to be able to distinguish among the different historical steps of certain structures or buildings, which were built successively in different styles, with different characteristics. Chapter three is a description and classification of the types of masonry according to the structural subassemblies they are part of. We insist on horizontal subassemblies, namely masonry floors and vaults, as well as on their execution technologies. We further present a series of binders used during the historical periods when such structures were common, as well as the most important consolidation solutions applied to these structures. Here are some of them: the use of certain stays, of cast or plaster coatings, concrete steel belts and the system of embedded and tied fittings (Brutt-Saver).

3 Chapter four presents the general criteria of preserving and rehabilitating built heritage. We enumerate and present preservation methods, the general scheme and the rehabilitation methodology by diagnosis and structural therapeutics. We deal with the opportunity of approaching the issue of rehabilitation and the conceptual models in this respect. We also present the rehabilitation-endurance binomial, which has to be permanently under the specialist s attention during design and execution. In the fifth chapter we present the general issues of structural interventions, the issue of authenticity and adaptation to modern comfort demands. The author presents a classification of structural interventions according to the degree of intervention on the original structure. We describe and give examples of the following: consolidation interventions without modifying the original structure; consolidations that modify the structure, but use structural elements compatible with the original structure; indirect consolidations, using additional structural elements or subassemblies, but preserving the originality of the structural form; structures in the case of which modern functional necessities impose adding new buildings, which will be integrated as well as possible in the ancient whole (see the tables ). In this chapter we also present 10 case studies of consolidation and rehabilitation, executed by the author. The consolidation and rehabilitation solutions are described in details and accompanied by pictures taken on the site during execution. Every single case presents a new constructive solution, which may serve to solve similar cases in the future. The consolidations of masonry vaults, by taking over the dead and service load by an additional floor executed above them, may allow maintaining the original vaults and saving the possible mural paintings on them. Consolidating wooden floors by drawing them back to their original positions using special technologies, without demolition and reconstruction, as well as consolidating the buildings they are part of is an approach that may save important and imposing monumental buildings from being destroyed or replaced by new fake constructions. The consolidation of historical roof structures and the reparatory reconstruction, with original materials, of the vaults of monumental buildings, by the original applied technologies, are important achievements that may serve as examples for further similar interventions in the case of other building with similar deficiencies.

4 . Table 5.1 Strengthening, preserving the original structure Case Deficiency Strengthening solution Masonry vaulted structure Precarious technical Theater of Turda, Romania state of the masonry Partial covering with reinforced [ pillars and arches of the concrete using Pozzolanic cement basement Masonry vaults Orăştie, Romania [ Cracks on the masonry vaults and arches Covering with reinforced concrete using Pozzolanic cement Alternative solution of strengthening Bohemian brick vaults Cracking of the arches and vaults Brutt Saver system: embedded steel spirals fixed with special mortar

5 Table 5.2 Strengthening, adding compatible structural elements Case Deficiency Strengthening solution Arch and vault structures Horizontal displacement of the supporting structural element Metallic tie-rods of convenient type Multi-storied building masonry Lateral displacements of the external walls, damage of the elevation wall Joining girder at the level of the slab and foundation Mine railway bridge Continous beam of reinforced concrete Bălan, jud. Harghita Unacceptable vertical deflections and cracks in the middle of the span Strengthening with special tie-bar system

6 Table 5.3 Indirect strengthening providing additional bearing structure Case Deficiency Strengthening solution Saint Michel Church, Cluj Insufficient lateral stiffness of the The Gothic vaults are hung on a The Gothic vaults of the supporting walls, lateral supplementary slab system lying on sanctuary displacements the perimeter walls Masonry arches and vaults Basement of Theater, Turda Precarious technical state of the masonry Composite slab of reinforced concrete and steel deck on metallic beams Masonry vaults, basement of the Palace of Justice, Odorheiu-Secuiesc Cracks and breaks, detached bricks, important vertical displacements Additional reinforced concrete slab on metallic beams Timber slab with ornamental ceiling, Palace of Justice, Odorheiu- Sec. Great and evolutive deflection of the slab, cracks in the ornamental plastering of the ceiling Lifting girder of reinforced concrete with its additional supporting timber structure

7 Table 5.4 Rehabilitation by adding new blocks to the building, functional improvement Case Palace of Justice, Odorheiu-Secuiesc New staircase of reinforced concrete, steel and glass Emplacement of the new block of the staircase between two old blocks of the building Interior view ortotrop staircase Good taste rehabilitations, by adding new parts, architecturally and structurally suitable, and by assuring functionality and the necessary modern comfort are examples to follow when designing and executing similar interventions. Chapter six is an execution guide, drafted for those involved in the process of rehabilitation and structural consolidations of monumental buildings, and it contains a series of recommendations regarding structural interventions necessary to executants. It contains a methodology of identifying historic buildings. We present tables containing the building characteristics for the Gothic, Baroque and Eclectic era. It also introduces the notion of rehabilitation category, according to the designer s and executant s involvement in the structure of the buildings to be rehabilitated. Further on, the guide presents in details the necessary and compulsory achievement steps of the rehabilitation process of the buildings erected on the construction site. Chapter seven contains some conclusion of the author. Chapter eight contains mentions about the author s original contributions. In the end, as a conclusion of the above mentioned, the guide offers the author s general recommendations, based on the experience gained throughout the execution years spent on our country s construction sites, regarding structural interventions to monumental buildings.