On the occasion of the MIDAS Customer Day, Thursday 22 November 2018, Gruppo Ingegneria Torino was amongst the winners, selected from a shortlist, of the MIDAS MODEL COMPETITION 2018.
In particular, a project was presented for the seismic upgrading of a building intended to house the management offices of a production plant in the Turin area, on behalf of an important multinational operating in the design, production and maintenance of components and systems for civil and military aeronautics.
Specifically, GIT has addressed the study of the solution of static-structural consolidation of the building complex for the purposes of seismic safety in compliance with current regulations.
Summary description of the state of affairs.
The complex is made up of 8 statically independent and modular rectangular buildings, which are substantially identical in all their basic construction aspects (dimensions and reinforcement of pillars and beams, dimensions and reinforcement of floors, etc.); they differ only in marginal architectural aspects such as masonry bands at full height and under windows, window frames, positioning of doors, etc., which, however, still constitute elements of evaluation for the purposes of dynamic behaviour in the seismic phase. In addition to the 8 blocks, there is a further building no. 9, which differs in size, located at the eastern end of the entire block.
Seismic Criticality and Safety Indices.
On the basis of previous FEM analyses, and subsequent refined FEM analyses, the latter carried out following a campaign of investigations on materials and construction details, some criticalities of a seismic nature emerged, which can be activated according to different Safety Indexes.
Attention was therefore focused on the predominant aspect that strongly conditioned the consolidation approach: the width of the full-height joints separating the individual blocks.
These joints had a free distance of between 2.5 cm and 4.0 cm, values that are well below the displacements that the structures, with a height above ground of about 16.00m, would have during an earthquake. A very low safety index is estimated for this criticality related to the “hammering” phenomenon.
The consolidation approach was geared towards the following principles/interventions:
- Substantial maintenance of the current static scheme with longitudinal and transversal frame, even if with different degrees of constraint, providing adequate additional strength and ductility to the resistant elements such as foundations, columns and beams.
- Control of stressing interactions between adjacent blocks and then FEM analysis of the entire building complex integrated with special “link” elements in correspondence with the joint ridges at all three deck levels. These elements are designed to simulate devices such as “shock transmitters” to allow long duration displacements and low excursion speed such as thermal deformations, and on the other hand, to transmit actions of impulsive character such as shears exclusively in the longitudinal direction, leaving “free” the internal translational constraint in the transverse direction.