Reliability based evaluation of seismic design of Turkish bridges by using load and resistance factor method

Yılmaz, Seyit Alp
This study aims to evaluate the safety level of seismic design of Turkish highway bridge pier columns with respect to reliability theory. Evaluation of bridges was performed for four different codes of American Association of State Highway and Transportation Officials (AASHTO). Reliability indices were calculated for AASHTO Load and Resistance Factor Design 2010 (AASHTO LRFD 2010), AASHTO LRFD 2007, AASHTO Standard Specifications of Highway Bridges (LFD 2002) and Turkish modification of AASHTO LFD 2002 (current design code for highway bridges in Turkey). In the scope of project number of 110G093 “Development of Turkish Bridge Design Engineering and Construction Technologies” associated with Middle East Technical University (METU) and Scientific and Technological Research Council of Turkey (TUBITAK) and Turkish bridge design authority General Directorate of Highways (KGM), a new seismic design chapter was proposed based on LRFD provisions. In this study, proposed specifications were also evaluated based on the structural reliability methodology. The statistical data of all components in seismic load demand and column carrying capacity were studied based on both local and international literature to assess the uncertainties. Seismic load demand was calculated with response spectrum analysis of simplified single degree of freedom models of various bridges. Load carrying capacity of pier columns were checked for bi-axial bending combined with axial compression. For that purpose, an algorithm based on Green’s theorem was written for development of the interaction surface adopted from the “Interaction Surfaces of Reinforced – Concrete Sections in Biaxial Bending” (Fafitis, 2001). Reliability index was calculated with numerical Monte Carlo Simulation Method and compared with First Order Reliability Method and First Order Second Moment Reliability Methods.


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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 statis...
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Seismic design and analysis are common practices in bridge engineering which require both knowledge and experience. Technical standards, such as CALTRANS (2010) and AASHTO (2007) provide guidance on the analysis with the methods ranging from Response Spectrum Analysis (RSA) to Time History Analysis (THA). These methods are usually sufficient for obtaining the seismic behavior of common structures and capture the dynamic behavior with decent accuracy. However, this may not be the case for structures which sp...
Citation Formats
S. A. Yılmaz, “Reliability based evaluation of seismic design of Turkish bridges by using load and resistance factor method,” M.S. - Master of Science, Middle East Technical University, 2014.