Assessment of Existing Bridges using Partial Safety Factors Calibration Methods

Numerous bridges in Croatia, as well as around the world, are currently approaching their designed service life of 50 or 100 years. They are designed according to previous codes with much lower actions, so an evaluation of their load-bearing capacity is necessary. At the European level, there is still no specific standard that would help engineers in assessment of existing structures, while the application of standards for new structures is too conservative. In this article, the assessment of two reinforced concrete bridges on the Croatian national road is presented using two methods for calibrating partial safety factors proposed in fib Bulletin 80. These are the design value method (DVM) and the adjusted partial safety factor method (APFM), which use a specified reliability index and reference period to determine a reduced value of the partial safety factor, which is then used to determine the design value of action and resistance. These methods are used to evaluate the load-bearing capacity of bridge superstructures exposed to dead load and traffic. The used methods are compared with the Eurocode for new structures and conclusions are drawn.