Structural design/Building information model

The main objective of design is to ensure that the structure is capable of performing its function, with the required degree of reliability and with low cost, during the intended design life, which implies that structures and structural elements must be designed, performed and maintained to meet the basic requirements of ultimate strength, functionality, durability and robustness.

The first step of the design process, the most delicate, is certainly the "conception of the structural system". The choice of the construction system and of the structural scheme/system must necessarily take into account:

• nature of the soil,

• implementation / executive aspects,

• aesthetic aspects,

• economic aspects.

The success of the work essentially depends on the conception of the structure, rather than on elaborate calculation processes and improvements.

Then it passes

• the definition of a model for the geometric scheme, for the material and for the loads;

• its resolution (structural analysis), ie the determination of deformations and stresses;

Finally, it runs

• the dimensioning of the structural elements,

• verification of the structural elements, to check that the structure is able to withstand the actions that stress it during its useful life.

BIM applied to structural design

The contemporary design methodology has undergone and will undergo major transformations due to the diffusion of tools that are profoundly modifying the exchange of information between the different subjects involved in the creation of a work.

It all started with the birth of Building Information Modeling, better known as BIM. It is a theoretical approach to process management that can be implemented in several ways. Among all, the currently most widespread one is based on the use of the IFC format as an interoperability standard; that is, this format allows the exchange of the project and all the data connected to it between the various software that manage the entire design process, starting from the design proposal, to move on to the final design, the executive, site management, management costs and does not end with the construction of the work but continues with its management and maintenance over time. It is a shared construction project with integrated information in a format that models both the structure and the entire project history from inception to final demolition.

It allows engineers to work on a single project from anywhere in the world. It condenses an overabundance of information about every detail into a functional format. Facilitates testing and analysis during the design phase to find the best answer to a problem. It simplifies design, simplifies coordination among team members, and facilitates facility maintenance across the entire built environment—and that's just the beginning.

Using a BIM approach, the works are designed, built and managed on time and on budget, the problems encountered during construction are greatly reduced and the building is preserved over time with lower charges and costs.

Due to its position and geographical conformation, Italy is periodically affected by seismic phenomena of various magnitudes. The four seismic hazard zones into which the Italian territory is divided range from zone 1, where the probability of a strong earthquake occurring is high, to zone 4, where the probability is very low.

To prevent any damage caused by an earthquake, it is advisable to carry out anti-seismic interventions on existing buildings. In the case of buildings considered strategic or with a public utility function (for example hospitals, schools and government buildings) such interventions are mandatory.

To establish which are the most suitable anti-seismic interventions, various parameters must be taken into consideration: the type of construction (single-storey or multi-storey), the type of load-bearing structure (masonry, reinforced concrete, wood), the foundations on which the building rests, the seismic zone and the context in which the building is inserted. Equally fundamental for the choice of the intervention is the advice of a competent technician, who conducts the appropriate diagnostic investigations and laboratory tests.

It is also important to distinguish between seismic improvement, aimed at increasing the anti-seismic safety level, and seismic adaptation, which provides for the achievement of the safety threshold required by law, based on the seismic zone in which the building is located.

So let's see what are the main types of anti-seismic interventions:

Consolidation of masonry: structural deficiencies and atmospheric agents can lead to subsidence and therefore make it necessary to reinforce floors and walls (load-bearing and non-load-bearing) through the use of fiber-reinforced plasters with polymeric matrix (FRP), carbon or glass fibres, of mortars and thermosetting resins.
Reinforcement of reinforced concrete or wooden structures: calculation errors during the dimensioning phase, wear and stresses can weaken the wooden and reinforced concrete beams, pillars and columns. For interventions on these structures, carbon fibers prove to be the most used, because they are light and quick to apply.
Structural reinforcement works on the floors: the use of connectors allows a thin slab to be superimposed on the existing structure, often made of concrete with an electro-welded mesh, connected to the existing floor.
Use of anti-seismic devices: energy dissipators are devices that disperse a large part of the energy transmitted to the structure during an earthquake, thus reducing the stresses in the structural elements; the seismic isolators are positioned between the foundations and the elevated structures to decouple the earthquake frequencies from the frequencies of the elevated structure and avoid the occurrence of resonance phenomena; the structural joints, on the other hand, allow the interruption of the continuity of a work and therefore avoid seismic damage to two contiguous areas.
Geotechnical consolidation: the improvement of the foundation soils is just as necessary as the rehabilitation of the structure.