Using Operating Characteristic curves to quantify the effect of quality control on geometric properties in structural members: Use case for structural reliability assessments

Quality control has a favourable effect on material properties since quality requirements, as conformity control criteria, encourage producers to deliver high quality products. Previous studies indicate that this effect influences the stochastic models of building material properties — and, ultimately, the safety level of structures. Typically, for every sampling plan an operation characteristics curve (OC-curve) can be derived showing how the plan performs as lots of different quality levels are submitted to it. An OC-curve plots the discriminating capacity of conformity control criteria by establishing a relationship between the probability of accepting a lot and the percent defectives. In structural engineering, the utilisation of OC-curves is well established for the control of certain variables as concrete compressive strength. However, their utilisation for the control of attributes as geometric properties is less common and often neglected. This paper investigates how OC-curves can be derived for the conformity control of geometric properties and further utilisation in structural reliability assessments. This investigation is critical to unlock the potential offered by quality control in the identification and utilisation of existing safety margins during structural design.