Structural reliability analysis of superstructure of highway bridges on China-Pakistan Economic Corridor (CPEC): a case study

Live load models representing truck traffic are the governing factors for the design of bridges. In Pakistan, American Association of State Highway and Transportation Officials-Load Resistance and Factor Design (AASHTO-LRFD) and Pakistan Code of Practice for Highway Bridges (PCPHB) codes are used for the design of bridges. This article presents the reliability analysis of existing bridges of Pakistan for Chinese design trucks which are completely different from Pakistani design truck. Single span and multi-spans bridges are selected on western route of CPEC. Average Daily Truck Traffic data (ADTT) for these bridges was taken from National Highway Authority (NHA). Analysis of bridges is carried out using CSI-Bridge and AASHTO-LRFD, PCPHB and Chinese Codes are used to analyse the bridges. The resultant load effects are extrapolated using non-parametric and linear fit for 75 years return period to carry out the reliability analysis. It is concluded that the reliability index of various bridges is lesser than the target reliability value which is 3.5 in AASHTO-LRFD Code, so the existing bridges are less safe. The probability of failure in single span bridge is maximum using HL-93 truck while in case of multi-span bridges Class-A truck has maximum failure probability.LIST OF ABBREVIATIONSADTT Average Daily Truck TrafficAASHTO-LRFD American Association of State Highway and Transportation Officials - Load Resistance and Factor DesignCDF Cumulative Distribution FunctionCOV Coefficient of VariationCPEC China Pakistan Economic CorridorGVW Gross Vehicle WeightIM Impact loadMDOT Michigan Department of TransportationNCHRP National Cooperative Highway Research ProgramNHA National Highway AuthorityTB-3 Taxila Bridge having three SpansWCB-1 Wah Cantt Bridge having single SpanWGB-6 Wah Garden Bridge having six SpansWIM Weight-In- Motion data