Construction is widespread all around the world, particularly in Europe. The field of civil engineering is now becoming increasingly oriented to the preservation, consolidation, and strengthening of existing buildings with respect to the design of new buildings. The research in this field is fast growing. In-situ investigations are becoming more and more accurate via non-destructive methods. The geometrical survey is affected by modern technologies such as laser scanner and drone-based photogrammetry. An important part of the research is focused on innovation in strengthening systems. Fibre Reinforced Polymer or Fibre Reinforced Plastic (FRP) consists of an epoxy-based matrix and a non-metallic fibrous sheet. The low viscosity of the epoxy-resin (similar to water) allowed the impregnation of the fibre sheet making two different materials working in a two-phase composite. The matrix protects the fibres from the environment (potentially aggressive from the chemical point of view) and, at the same time, provides adhesion to the substrate, while the sheet has relevant strength in the direction of the fibres and negligible self-weight.

However, FRP has demonstrated drawbacks including the impossibility of application on a wet substrate, poor fire resistance, and poor reversibility. The latter is a crucial issue in the case of masonry building heritage. For this reason, more recently a new type of composites has been considered for structural retrofitting: Fabric Reinforced Cementitious Mortar (FRCM). The main idea consists of substituting the resin with an inorganic-like matrix. A mortar (lime- or cement-based) is more compatible with masonry substrates. On the other hand, mortar cannot impregnate the fibre-sheet because of the relevant viscosity. Thus, an open grid was used (i.e. a fabric). In such a way the mortar passes through the voids and makes the composites. Unfortunately, the amount of fibre per unit volume is reduced, but enough to be effective. When dealing with the problem of global analysis of the structural system, linear methods and nonlinear static methods are the methods that are generally used in common practice. The Finite Element Method (FEM) is now largely processed and many case-studies are evaluated by means of this analysis. In addition, other strategies are available, including limit analysis, simplified methods, FEM macro- or micro-modelling, and discrete element methods (DEM), and are considered with regard to their realism and computer efficiency.

The aim of this Special Issue is to collect studies about the preservation of building heritage including diagnostics, anamnesis, analysis, intervention, monitoring, and the use of new materials and technologies. Original research and review articles are welcome.

Potential topics include but are not limited to the following:

• Heritage: research on the preservation, consolidation, and strengthening of historical construction; case studies including masonry, reinforced concrete, or timber structures
• Composite materials: the use of FRP, FRCM, CRM, or TRM for the structural or energy retrofit, including the characterization of the composite and application on structural elements, e.g. column, arch, vault, beam, floor, truss, etc.
• FEM-analysis: numerical modelling of heritage structures for investigating the seismic vulnerability of damage evolution, and the simulation of laboratory tests
• Analytical modelling: developing new analytical formulas for the proper design of composite-based strengthening
• Durability and creep: the long-term effect of strengthened or un-strengthened structure or composites (alkaline or saline environment and thermal load)
• New materials and technologies: cultural preservation by searching for new composites (e.g. in geo-polymer) or technologies and strategies for cultural heritage sustainability