| Popis: |
Creep is an inherent property of concrete materials, and an accurate prediction of creep-induced prestress is critical in designing a prestressed concrete structure. The comparison of codes or specifications of different countries on concrete structures was performed in this study. A basic model of prestress loss caused by creep was first deduced from a simple engineering model, and then the derived model was compared with the calculations obtained by different codes. Results show that the overall fundamentals and considerations of these codes are similar. Among these codes, the formulas specified by the Chinese Codes, European Code (DD ENV 1992-1-1), and AASHTO Code (AASHTO LRFDUS-5-M) were similar to the concrete aging formula, while the ACI Code (ACI 209R-92), Australian Code (ACI 209R-92), and Canadian Code (CSA-S6-06) depended more on empirical coefficients obtained via experiments. In the calculation example, the value of creep coefficient directly affected the calculating result of prestress loss. By comparing of the creep models adopted in Code for Design of Concrete Structures (GB50010-2010), European Code (DD ENV 1992-1-1), ACI Code (ACI 209R-92), and Railway Code (TB10002.3-2005). The effects of input parameters on calculation of creep coefficient were discussed in details. This study revealed the appropriate conditions using different codes. |
