Calibration of the design code for concrete structures

The presented study deals with the development of design code for reinforced concrete and prestressed concrete beams, slabs and columns. The major steps in the code calibration procedure include the development of load and resistance models. It is assumed that the available load models are adequate. Therefore, the main focus of this study is the verification of resistance models. A considerable database is gathered on material strength: ordinary concrete, lightweight concrete, high-strength concrete, reinforcing steel, and prestressing steel. The test results were provided by industry and they are analyzed to determine the cumulative distribution functions and other statistical parameters. It is observed that there is a considerable improvement in quality of materials during the last 20-30 years, and this results in an increased reliability of structural components. The reliability analysis is performed to determine the reliability indices for components designed according to the current code (ACI 318-99). Based on the results, the target reliability indices are selected. New load and resistance factors are recommended based on closeness to the target reliability index.