Seismic Aspects Regards Overbuilding on Masonry Heritage Buildings

Nowadays, masonry heritage buildings usually experience changes during exploitation. In areas of emphasized seismic risk, in cases of extensions, alterations to the original dimensions, reconstruction (the removal of bearing elements, replacement of materials, introduction of new fittings), or the subsequent erection of properties close by, with a comparison of the foundation levels change of use, refurbishment, extension, or additional building to an existing building. It is necessary to analyze the seismic aspect of such interventions in seismic prone areas. At first, we’ll focus on the legal and technical regulations. For start we’ll look back at UNESCO’s Program on Masonry Heritage, then domestic and regional legal and technical regulations and with all of that we will define the first step of the process. Next step would be a detailed registration of the current condition of the building, and also determining the characteristics of the embedded materials. The load bearing structures of the building must also be accurately identified, with all relevant measurements and, in particular, a description of the building materials and their condition. This includes all detailed maps, plans, and details of the used materials, and especially detailed record of all the damages on the structure. Even at this early stage of investigative works it may prove necessary to secure certain structural elements, or even the entire building, to prevent it from collapsing. As a rule, this requires not only the removal of the outer cladding or even of parts of a wall to determine the depth of cracks but also, if there is any suggestion of subsidence, excavations around the building or to the depth of the foundations. Calculations, based on the planned and current condition of the building, will show whether the strengthening and rehabilitation are needed for the structure. The elements that need reinforcement or conservation can be identified during the initial visit, and provision can immediately be made to take the necessary steps to relieve the load. It is necessary to do all the steps regarding technical regulations, legal regulations, methods of approach, theoretical consideration, methods of calculation, and in the end to determine the needs of that building. Theoretical consideration regarding the determined condition of structure, from all the above aspects, is the next step to be done. This also includes evaluation of the viability of these interventions, based on experience. The most sensitive issue, without doubt, is determining the condition of the foundations. This should be addressed with the utmost care with the general opinion of the building’s stability in mind.