Title: Calibration of Service I Limit State for Reinforced Concrete Bridge Deck Designed using AASHTO Empirical Method
Author(s): Dan Su and Hani Nassif
Publication: Symposium Paper
Appears on pages(s): 32-53
Keywords: code calibration; limit state; reinforced concrete deck; crack control
Service I limit state in the AASHTO LRFD Bridge Design Specifications (BDS) is applied for the control of cracking in reinforced concrete elements in order to maintain its normal functionality and to achieve its design life. There are two methods specified in AASHTO LRFD BDS: 1) equivalent strip design method and 2) empirical method. For the empirical method, no exhaustive design calculation are needed and the reinforcement area is obtained as a percentage of the concrete section. However, usually, the reinforcement area designed using empirical method is less than that designed using the equivalent strip method, which could result in shortened service life and excessive crack width. Albeit arching action effects were considered in the empirical method which improves the flexural resistance of concrete deck after cracking, the effects of arching action on crack control of reinforced concrete deck were not studied. In addition, different exposure conditions and different design sections (positive moment vs. negative moment regions) were not considered in the empirical design method. Thus, it is extremely important to investigate and calibrate the Service I limit State for reinforced concrete decks designed using the AASHTO empirical method. In this study, the Service I limit state function is formulated and the load and resistance models are developed. The arching action effects are integrated into the resistance model. Detailed calibration is performed to ensure uniform target reliability will be achieved for different design parameters including exposure conditions, span lengths, deck thickness, and positive moment and negative moment regions.