Probabilistic Models for Prototype Testing

The strength of series-produced or mass produced structures is often correlated because of workmanship or material strength correlation (e.g., steel from the same heat or lumber from similar species grown in the same region). A model of correlation is used to select load factors in design based on prototype testing so as to yield structures with a prescribed reliability. Correlation is usually disregarded in practice. It is found, however, that the correlation in structural resistance is significant and can produce important savings if taken into account. This is illustrated in the design example of an industrial building. In this example the best strategy is to test only one prototype, in agreement with common practice.