Reliability based safety level evaluation of Turkish type precast prestressed concrete bridge girders designed in accordance with the load and resistance factor design method

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2010
Argınhan, Oktay
The main aim of the present study is to evaluate the safety level of Turkish type precast prestressed concrete bridge girders designed according to American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) based on reliability theory. Span lengths varying from 25 m to 40 m are considered. Two types of design truck loading models are taken into account: H30S24-current design live load of Turkey and HL93-design live load model of AASHTO LRFD. The statistical parameters of both load and resistance components are estimated from local data and published data in the literature. The bias factors and coefficient of variation of live load are estimated by extrapolation of cumulative distribution functions of maximum span moments of truck survey data (Axle Weight Studies) that is gathered from the Division of Transportation and Cost Studies of the General Directorate of Highways of Turkey. The uncertainties associated with C40 class concrete and prestressing strands are evaluated by the test data of local manufacturers. The girders are designed according to the requirements of both Service III and Strength I limit states. The required number of strands is calculated and compared. Increasing research in the field of bridge evaluation based on structural reliability justifies the consideration of reliability index as the primary measure of safety of bridges. The reliability indexes are calculated by different methods for both Strength I and Service III limit states. The reliability level of typical girders of Turkey is compared with those of others countries. Different load and resistance factors are intended to achieve the selected target reliability levels. For the studied cases, a set of load factors corresponding to different levels of reliability index is suggested for the two models of truck design loads. Analysis with Turkish type truck models results in higher reliability index compared to the USA type truck model for the investigated span lengths.
Citation Formats
O. Argınhan, “Reliability based safety level evaluation of Turkish type precast prestressed concrete bridge girders designed in accordance with the load and resistance factor design method,” M.S. - Master of Science, Middle East Technical University, 2010.