Abstract
This chapter includes application of recent research on the repair and strengthening of historical structures and provides a structural assessment of five historical mosques in Albania. Apart from visual inspection, terrestrial laser scanner (TLS) data are used to analyze the historical structures. The FEM analysis conducted in SAP2000 aims to investigate the structural behavior of the undamaged model under static and dynamic loads. Stress concentration and mode period results have a considerable difference, which highlights earthquake vulnerability and changes the strategy of possible retrofitting. As a result, possible practical solutions for the structural problems based on previous research and enhancement of the existing structural resistance are suggested.
TopLiterature Review
Protection of cultural heritage has become an emerging problem in recent years. It rises as a necessity for elimination of structural problems or distresses that result from unusual loading and exposure conditions, inadequate design or construction practices. These distresses may be caused from overloading, natural disasters, foundation settlement, deterioration of materials, etc. Some other reasons for strengthening are: correcting design or construction errors, resisting exceptional or accidental loading conditions, increasing tensile, shear, and flexural capacity of structural elements (Islam, 2009).
Key Terms in this Chapter
Schmidt Hammer Test: A non-destructive technique used to determine the compressive strength, surface hardness and penetration resistance of reinforced concrete and masonry structures by measuring the rebound of a spring-loaded mass impacting against the surface of the sample. The hammer hits the surface at a defined energy. The test equipment measures the rebound which is dependent on the hardness of the concrete.
Differential Settlement: Uneven settlement of the soil beneath the foundation of a structure that may lead to “sinking” of different parts of the structure which causes cracks and other structural problems.
Imperfect Geometry: A term used to describe the actual geometric shape of an old building, which has been altered due to external factors such as weathering agents, earthquakes, human interventions, etc. (i.e. distortion of the vertical alignment of the walls).
Terrestrial Laser Scanner (TLS): A digital portable laser-based ranging and imaging system used to provide detailed and highly accurate 3D data rapidly and efficiently for a wide range of applications such as topography, mining, as-built surveying, architecture, archaeology, monitoring, civil engineering and city modelling.
Local Reconstruction “Cucci Scucci”: A restoration technique used when there is a considerable loss of units. It is suggested that the new substituting units to have same material properties as the missing one.
Unreinforced Masonry (URM) Building: A type of building where load bearing walls, non-load bearing walls or other structural and non-structural elements are made of bricks or stones bonded with mortar and it is not braced by reinforcing beams.
Injection: An effective method for repairing or strengthening masonry walls. Fine hydraulic lime grout is applied into cracks, voids and cavities within the masonry by low-pressure injection in some previously drilled holes.
Perfect Geometry: Idealized geometric shape of a structure with perfect alignment of the walls and good connections.
Retrofitting: The process of strengthening older buildings in order to improve global performance (in this case) under seismic action. When dealing with historic structures, a special care must be taken in order to minimize the risk of altering the original architectural and cultural characteristics.