PSI - Issue 64

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

736

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Table 1. Point cloud properties. Scan

Point density 26,787,988 38,961,876 27,286,469 31,097,358

File size (MB)

A B C D

574 760 581 639

To determine the location and orientation of the reinforcing bars, a Profometer 5 model "S" / "SCANLOG" pachometer from Neurtek was used. The location of bars is carried out on both faces of the wall and on a tread and riser of the stairs. It has been confirmed that the reinforcement has in both cases horizontal bars and vertical bars that run along the entire length of the analyzed element. The depth and location of the bars can be obtained with the pachometer; in this case the diameter of the bars is 16 mm. Data collection information, such as the distance between steel bars or the depth at which they are located, is recorded on data sheets. This process of bar detection is performed before the test with the sclerometer and the ultrasonic equipment to know the location of the reinforcing bars so that they do not interfere in the two subsequent tests to perform the correlational study. The sclerometric and ultrasonic tests are carried out jointly to elaborate a correlational study between them. The sclerometer used is a Schmidt N-type sclerometer from the company Proeti. The ultrasound equipment used, model ETI H0394, is from the same company. For the correlational study, measurements are taken in ten different areas of the staircase wall. The tests are regulated by the UNE-EN 12504-2:2022 standard. For the sclerometer test, it indicates that 9 measurements should be made, properly spaced, and the average of the data obtained in each of the ten different test zones should be calculated. In the same locations the measurement is made by direct ultrasonic transmission to know the propagation velocity. The value given by the ultrasonic meter is the time it takes for the wave to pass through the material. To obtain the velocity, the length between probes, which is the width of the wall (300 mm), is divided by the propagation time measured by the ultrasonic equipment. The average of the rebound index and propagation velocity is calculated for each of the ten locations. Based on the mean values of rebound index and propagation velocity, a graph is created, the abscissa axis of which shows the rebound index and the ordinate axis shows the propagation velocity in m/s. This table is used as the starting point for the correlational study, the objective of which is to obtain an equation that correlates the two control parameters used for the pathological analysis of concrete. A regression of the data is carried out to determine the most appropriate one, which will be the one whose R² is closest to one. Different types of regressions (exponential, linear, logarithmic, polynomial and power) are simulated; however, the regressions with an R² value closest to 1 are the linear regression (R² = 0.68) and the polynomial regression of order 2 (R² = 0.68).

Fig. 4. (a) Linear regression graphic; (b) Polynomial regression graphic.