Fragility-Based Seismic Safety Assessment of a Randomly Scoured Bridge

Subject Areas : Structural Engineering

Ali Raoof Mehrpour Hosseini ¹ , Mehran Seyedrazzaghi ^{2 *} , Nasser Shamskia ³

1 - Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran
2 - Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran
3 - Department of Civil Engineering, Qazvin Branch, Islamic Azad University, Qazvin, Iran

Received: 2023-11-06 Accepted : 2024-02-27

Keywords: Bridge, Earthquake, Multi-hazard, Safety assessment, Scour,

Abstract :

River bridges are constantly subjected to hydraulic hazards, which may not cause immediate damage but can lead to erosion over time, creating conditions that can cause damage. The scour is time-dependent and can gradually alter the stability of the structure against lateral loads. The support conditions of a bridge can degrade due to scouring, which can increase its vulnerability when it faces unpredictable lateral loads such as floods or earthquakes. Bridge safety assessment depends on various factors, including the nature of the earthquake that may occur, the soil type at the construction site, and the formation of cavities around foundations, among other factors. This study has generated a framework to assess the bridge model when subjected to multiple hazards, including earthquake and scour. The framework considers the depth of random scour in the bridge's foundations to quantify the impact of various factors, including the occurrence of seismic pulses during near-field earthquakes and the internal friction angle of the soil. The study examined how various factors impact the random patterns of non-uniform and uniform scour in different foundations of a bridge model. The results indicate that the bridge model is more susceptible to damage during an earthquake with pulse-type behavior. Additionally, the angle of internal friction in soil-pile interaction affects the probability assessments of fragility analyses.