Inspection and evaluation of bridge structures for earthquakes risk

The 2017 Earthquake Source and Hazard Map Update in 2017 showed a significant change to the previous earthquake map. An increase in the number of active faults and high magnitude earthquake events indicates an increased potential for earthquake risk. The availability of qualified seismic manual is a must to support the direction of government policy in the provision of infrastructure, especially roads and bridges in a sustainable manner. This study aims to determine the value of the vulnerability of existing bridges against earthquakes and alternative reinforcement that can be done. The reinforcement philosophy is based on performance, similar to the philosophy used in the design of new bridges. Performance criteria are examined using earthquakes with a probability of exceeding 7% in 75 years. Performance criteria are determined based on the level of importance and remaining life of the bridge service. An example of a case study was made by examining and evaluating a prestressed girder bridge located in the earthquake zone 4 of the Jakarta area. Analysis and evaluation of bridge capacity is made using the SAP 2000 program. The 3 (three) dimension model is used to calculate the effect of 3 (three) structural dimensions on the dynamic behavior of the bridge. Earthquake input is made in the form of spectra response according to SNI 2833-2016. For earthquake loading in the X and Y direction the g/R scale factor is used (9.81/5), which is 1.96. The basic shear capacity of the column is calculated according to SNI 2833-2016 which consists of the shear capacity of the contribution of the concrete section and reinforcement. Based on the analysis, it was obtained that the column sliding capacity was 1333.3 kN. The value of the capacity is greater than the ultimate shear load of 519.07 kN so it can be concluded that the sliding capacity of the column still meets the earthquake load so that no structural reinforcement is needed.