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  1. A Bi-Hazard Fragility Curve Development for the Assessment of Kagay-an Bridge in Cagayan de Oro City DR. MICHAEL B. BAYLON,D.Litt.PICE, SEAD, IABSE, ISHMII Civil Engineering Department, College of Engineering Polytechnic University of the Philippines
  2. The Team: XU • Nikki Amores • Garnelo Cupay • Alexander Christian Doong Legaspi • Paul Gilbert Legaspi • Isaiah Alisteir Sudayan Cabanaz • Prof. Dexter Lo
  3. Aerial view of the Kagay-an Bridge connecting the Rodelsa Circle and Barangay Carmen
  4. Background • The Philippine archipelago frequently experiences numerous natural disasters such as severe tropical storms, earthquakes, and sometimes volcanic eruptions. • As defined by the United Nations International Strategy for Disaster Risk Reduction (UN-ISDR, 2004), disaster is the disruption of the normal functioning of a society which leads to serious damages and losses to human lives, properties, economy, and to the environment. • It also exceeds the capacity of the affected communities to cope up with the damages. • Earthquake and flood events are the predominant natural disasters in the Philippines and they, given their frequent recurrence, make the country highly vulnerable.
  5. The Anao-aon Bridge after the magnitude-6.7 Surigao del Norte Earthquake the country had also experienced strong earthquake events in the past such as the magnitude-6.7 Surigao del Norte Earthquake last February 10, 2017. The communities in the surrounding provinces were severely affected, and according to National Disaster Risk Reduction Management Council (2017), the earthquake was an Intensity VII (Destructive) earthquake. Infrastructures such as the Anaoaon Bridge in Surigao City collapsed.
  6. The Kagay-an Bridge during Severe Tropical Storm (STS) Vinta last 2017 On the other hand, flooding is defined as the overflowing of the water level in bodies of water such as rivers and creeks which leads to an inundation of a usually dry area of land. Severe Tropical Storm (STS) Vinta, internationally known as STS Tembin, had wreaked havoc in Misamis Oriental last December 2017 – inundating several municipalities and cities. In the midst of the event, the flood threatened to overflow the Cugman Bridge, a highway bridge in Cagayan de Oro City. Rappler (2017) reported that the bridge is no longer passable at that time due to a crack from the severe flooding
  7. Objectives To determine the level of performance of the Kagay-an Bridge when subjected to flood and seismic events. More specifically, the study targets to: 1. To determine the physical and structural design specifications of the Kagayan Bridge in order to create its digital structural model; 2. To determine the design spectral acceleration, and the force due to wave velocity; 3. To determine the structural capacity of the Kagay-an Bridge when subjected to different seismic and wave loads; 4. To produce the fragility curve of the Kagay-an Bridge subjected to flood and seismic events.
  8. Conceptual Framework
  9. Ground Motion Data (time history)
  10. Seismic fragility analysis • There are different analysis techniques and methodologies that can be used in assessing the seismic capacity of structures. • For instance, Zhang, Acero, Conte, Yang, and Elgamal (2004) utilized the performance-based earthquake engineering (PBEE) methodology to assess the Humboldt Bay Middle Channel Bridge. • Whereas, Tehrani and Mitchell (2012) conducted a seismic performance assessment on bridges in Montreal using Incremental Dynamic Analysis (IDA) method. • These and other seismic fragility analyses are represented as either Damage Probability Matrix (DPM) or Fragility Function. • On the other hand, Taghipour and Yazdi (2015) utilized two techniques, the nonlinear static (Pushover) analysis and the nonlinear dynamic analysis on a
  11. Seismic fragility curves • Seismic fragility is the probability of damage to a structure given a certain earthquake intensity. • Seismic fragility curves graphically represent the estimated structural performance of the bridge structure during earthquakes. Fragility Curve of a Bridge as a Function of Peak Ground Acceleration.
  12. Flood fragility analysis • Lee J., Lee Y., Kim H., Sim, and Kim J. (2016) proposed a methodology for deriving flood fragility curves by means of structural reliability analysis with the failure modes defined as excessive demands of the displacement ductility of a bridge under increased water pressure from accumulated debris and structural deterioration.
  13. Research Design
  14. Research Design
  15. The Kagay-an Bridge during rush hour. (Photo was taken by Kaye Quiblat)
  16. The Bridge Model
  18. Flood Fragility Curves
  19. Flood Fragility Curves
  20. Flood Fragility Curves
  21. Flood Fragility Curves
  22. Flood Fragility Curves
  23. CONCLUSION • According to HAZUS® – MH 2.1 by FEMA, when the bridge piers reached a 10% probability of having a “Moderate Damage”, the city’s engineers and other concerned officials should temporarily close the bridge and are required to conduct a thorough inspection on the bridge piers, specifically on the locations where the critical hinges are. • This could happen to Kagay-an Bridge if Cagayan de Oro City experiences an earthquake with PGA of 0.8g (the PGA of Great Hanshin Earthquake in Kobe, Japan) along its longitudinal axis, and 1.2g along the transversal axis.
  24. CONCLUSION • Through quantitative-probabilistic approach, the flood fragility curves of Kagay-an Bridge pointed out that when water velocity increases, there is a higher probability that the bridge will experience damage due to flooding. • Also, it does not matter if the flood depth reaches the full height of the columns because if the water only has a velocity of 0-15 m/s, the probability of “Moderate Damage” in the bridge piers is less than 10%. • Therefore, flood cannot significantly damage the Kagay-an Bridge unless the water reaches a velocity higher than 20 m/s, which is very unlikely. • This stands true since the past flood events of Typhoons Sendong and Vinta in Cagayan de Oro City can attest that, even though their flood depths reached the bridge deck of Kagay-an Bridge, the bridge did not fail or experienced any damage because the water velocity of these flood events is less than 16 m/s.
  25. RECOMMENDATION • Using the fragility curves, structural threshold values are determined which can be used in structural health monitoring, that is, the bridge has preventive measures when time comes.
  26. RECOMMENDATION… • “A study on the numerical modeling of Kagay-an Bridge with application of Fibre-reinforced Geopolymer Composites” • “Performance based assessment of Fibre-reinforced Geopolymer Composites applied to Kagay-an Bridge: A multi-hazard fragility analysis approach”
  27. REFERENCES • Lee, Jaebeom, Lee, Young-Joo, Kim, Hyunjun, and Sim, Sung-Han (2016). Flood fragility analysis for multiple failure modes of bridges by finite element reliability analysis. The 2016 Structures Congress (Structures16). • Amores, N., Cabanaz , A. S.,Cupay, G. A., Legaspi, A. C. D., Legaspi, P. G., Isaiah (2019) Flood and seismic fragility curve analysis of Kagay-an bridge in Cagayan de Oro City. Undergraduate Thesis. Xavier University. CDO • Baylon, M.B. (2017) Developing fragility curves in seismic assessment of bridge. Lambert Academic Publishing: Berlin Germany
  28. THANK YOU FOR LISTENING. Dr. Michael B. Baylon FB: Emby Binoe