PSI - Issue 64

Yago Cruz et al. / Procedia Structural Integrity 64 (2024) 732–739 Yago Cruz / Structural Integrity Procedia 00 (2019) 000 – 000

737

6

Focusing on the tendency line of both graphs, it can be observed that one point deviates notably more than the others; this coincides with one of the test zones (grid 7). It is possible that in the area where grid 7 is located there is a singular case that moves this point away from the correlation line. On the one hand, the propagation of the ultrasonic waves may be affected by a steel bar or any other phenomenon that interferes with the data acquisition, which would explain an excessively high propagation velocity. On the other hand, the mismatch may be due to an incorrect reading of the sclerometer because of surface roughness or moisture content. Therefore, the deviation of this singular point from the trend line is calculated. In view of the error made and in order to obtain an even more accurate correlation, it is decided to remove the point relative to grid 7 from the correlational study frame, thus obtaining the correlation equation corrected.

Fig. 5. (a) Linear regression graphic without grid 7; (b) Polynomial regression graphic without grid 7.

By eliminating the grid point 7, it is observed that the polynomial regression gives a better result than the linear regression. In this case, the R² value for the polynomial regression is 0.94 compared to 0.89 for the linear regression, so the equation (equation 1) chosen that best represents the correlation is that of the 2 degree polynomial regression. = −1.79 2 + 177.38 − 143.55 (1) 3.2. BIM model The BIM model management software used to create the 3D model, in this case, is Revit. From the measurements and sketches made on site, the structure is modeled by assembling different structural elements; such as floors, walls, stair flights, railings, beams and columns. Each of these elements belongs to a different Revit family. Predefined software families are used for the stairs, beam, landings, wall, and columns, and the parameters of these elements are adjusted to reflect the real geometry of the case study. However, for the handrail it is necessary to create the family from scratch in Revit. This is due to the complexity of the geometrical shape, both of the distribution of the railings and balusters and of the attachments of the handrail to the wall or staircase. For the staircase nosing it is also necessary to create the family from scratch in order to achieve the correct offset from the stair riser. In addition, it is necessary to create the different types of materials that make up the structure. The elements that compose the BIM model are named with an identifier to facilitate their recognition and the corresponding material is associated to each one, leaving a record of the manufacturing materials (types of concrete and steel used). With all the pathological information collected in the experimental campaign, different data collection "cards" are created in order to have a better access to all the information. These cards allow a control of the different pathologies. In addition, the information collected during the structural health analysis is associated to the model. To simplify the detection of the damages of the structure, they are represented in the BIM model properly located with all the information related to the damage correctly classified. The representation is similar in shape and dimensions to the