Damage to Historical Balconies in View of Building Physics

摘要

The article presents the problem of damage to historical balconies,having other structural or material solutions than the modern ones.Their durability and maintenance aspects comprise a wide spectrum of issues,including repair and renovation methods,selection of new materials for the existing structures and their mutual interaction.The applied solutions must take into account the specificity of the components,their performance in the conditions of external environment,the impact of variable temperatures,both positive and negative ones(including,in particular,zero-crossings),atmospheric precipitation or solar radiation.Particular attention was paid to balconies with steel and ceramic structure,whose technical diagnostics should include,apart from structural analysis,also detailed observations of heat and mass transfer phenomena.The paper presents the results of numerical analyses for two-dimensional models,similar to the actual structure of the historical envelope(both for the original state and after the performed thermo-modernization works)as well as the results of thermographic measurements of one of residential buildings with balconies with steel beams.In the adopted boundary conditions,the local climate was taken into account,based on the data from the nearest meteorological station.The present objective involved the acquisition of qualitative results.The obtained results comprised: the distributions of temperature fields in cross-sections,distribution of heat flux density changes,and temperature values in selected cross-section locations.The research confirmed the expected tendencies in temperature distributions in the envelope,the location of local thermal bridges and the zones of their impact.Further analyses should be continued on the obtained changes in heat flux density,both in the steel beam support node,as well as in the joints and bricks in the adjacent layers.These places overlap with the actual occurrence of loose and weakened mortars in the building walls and in ceramic tiles.In further analyses,simulation programs facilitating the determination of the amount and changes of moisture in time should be applied.