According to the Cultural Heritage Act of 2009, a culture monument is defined as any immovable and movable authentic material testimony of human presence and activity and processes in nature that have scientific and / or cultural value and is of public significance. In the new law, the term “cultural monument” has been replaced by “cultural valuable”.
From 2016 there is also an online map, containing location and data for over 800 buildings, out of a total of about 1700, cultural monuments located in the central part of Sofia. It was prepared by the team of the chief architect of Sofia – Zdravko Zdravkov, with the idea of every interested citizen, to receive information about our cultural heritage in the Bulgarian capital – Sofia.
On top of the location of the houses, there is also information regarding their condition, as well as what fines are imposed on the owners for their lack of care. Up until now, they amount to more than half a million leva /250 000E/. According to other statistics of a metropolitan municipality, 80% of these 1700 buildings are not maintained and become dangerous for the inhabitants, residents and tourists.
The repairs to these buildings must meet the requirement of maximum preservation of the architectural identity. Every project must be agreed with the Institute for Cultural Monuments. In order to achieve the criteria of minimum volume of interventions on the original design, it is necessary to collect as much information as possible about the geometric dimensions of the building, structural elements, the chemical and physic-o-mechanical properties of the building materials, the impacts on which the building is exposed, types, size and causes of current damages and others. Analysis of the collected information can include computational 3D models with crack distribution and computational seismic checks. The goal is to achieve the desired results with minimal interventions only at the critical points of the building.
Good analysis is not an inexpensive task, but it could actually drastically reduce the cost of repair with a significant reduction in the amount of repair work.
There are modern methods allowing minimal interventions that do not affect the appearance of facade elements or the whole building when is required.
An example, so that you can get an overall idea, woule be of an enforcement system that is completely hidden and does not disturb the appearance of the building is the reinforcement with FRP lamellae. The main components of this type of system are reinforcement strips/coating and a matrix. The “bearing” function is borne by reinforcement fibers. The other material serving as a filler that distributes and conveys the tension is called a matrix. Once installed in the masonry joints, they improve the shear strength, vertical and bending strength of the element. A major advantage of this method is the small volume of construction interventions, which is a major factor in the restoration and enhancement of cultural monuments.
This effect can also be achieved by the additional reinforcement of steel rods in pre-cut grooves in the masonry joints. Partial replacement of the existing masonry mortar also contributes to improving the load-bearing capacity of the elements.
Building-in of FRP lamellae is becoming increasingly widespread in the case of the reinforcement of wooden elements. Key factors for the successful application of FRP lamellae are the precise execution of the technological procedures, a good knowledge of the mechanical properties of the materials and the stresses in them. The collaboration of materials with different mechanical properties is a complex engineering task that should be solved by experts with high theoretical and practical training.
In case of lowered mechanical properties of the bonding solution and bricks with irregular shape, the use of networks of high-strength filaments is an efficient and innovative solution. Easy to work and cut, they increase the load-bearing capacity of the wall by storing the stones using Ultra High Strength Steel (UHTSS) or Ultra High Molecular Weight Polyethylene (UHMWPE) ropes. This reinforcement system offers original preservation of the masonry on one side of the element, which makes it particularly effective for high demands on facade elements of cultural monuments.