Title:
Statistical Process Control of Fiber-Reinforced Concrete Precast Tunnel Segments
Author(s):
C. Pleesudjai, D. Patel, K. A. Williams Gaona, M. Bakhshi, V. Nasri, and B. Mobasher
Publication:
Materials Journal
Volume:
121
Issue:
2
Appears on pages(s):
127-140
Keywords:
Bootstrap Method; fiber-reinforced concrete; flexure; lining; precast; quality control; statistical process control; time-series control process; tunnel segment
DOI:
10.14359/51740373
Date:
4/1/2024
Abstract:
Statistical process control (SPC) procedures are proposed to
improve the production efficiency of precast concrete tunnel
segments. Quality control test results of more than 1000
ASTM C1609/C1609M beam specimens were analyzed. These
specimens were collected over 18 months from the fiber-reinforced
concrete (FRC) used for the production of precast tunnel segments
of a major wastewater tunnel project in the Northeast United
States. The Anderson-Darling (AD) test for the overall distribution
indicated that the data are best described by a normal distribution.
The initial residual strength parameter for the FRC mixture,
f D
600, is the most representative parameter of the post-crack region.
The lower 95% confidence interval (CI) values for 28-day flexural
strength parameters of f1, f D
600, and f D
300 exceeded the design
strengths and hence validated the strength acceptability criteria set
at 3.7 MPa (540 psi). A combination of run chart, exponentially weighted moving average (EWMA), and cumulative sum (CUSUM) control charts successfully identified the out-of-control mean values of flexural strengths. These methods identify the periods corresponding to incapable manufacturing processes that should be investigated to move the processes back into control. This approach successfully identified the capable or incapable processes. The study also included the Bootstrap Method to analyze standard error in the test data and its reliability to determine the sample size.