Applications of Statistical Process Control in the Evaluation of QC Test Data for Residual Strength of FRC Samples of Tunnel Lining Segments

Statistical process control procedures are widely applied to improve the production efficiency of industrial products. Application of quality control procedures in monitoring the production, delivery, and construction process are essential, especially when the historical data collected on various projects can be used to gain better insight to the operational procedures. Such information will promote interaction; reduce the liabilities and benefits the owners and suppliers if any of the design parameters that are below the minimum requirement can be identified as soon as possible. The longer time it takes to detect discrepancies in the data, the more the penalty, project delays, and the higher the associated costs to the owners and suppliers. A detailed analysis of the test results of flexural closed-loop control test data conducted in accordance to ASTMC1609 test is conducted for QC requirements of precast segment in tunnel lining project. More than 378 production samples are recorded. The data set contained 1 day (demolding age) and 28 days of molding. The statistical process control and the range of the data are studied in the context of material properties as well as back-calculation of the tensile parameters. The number of parameters evaluated includes flexural strength and deflection at ultimate flexural strength, the residual strength results at L/600, L/300 and L/150. A series of statistical analysis procedures to analyze the correlation of the parameters and addressed the combination of control charts for early detection of spurious shifts in the mean of the test data (out-of-control signal).