The study addresses the complex challenge of assessing the impact of natural hazards on critical infrastructure like road bridges. The GETI index, which quantifies the seismic risk by considering structural, geological, and geotechnical factors, including secondary earthquake effects (soil amplification, liquefaction and landslides) is applied to the Cherry Hill Interchange viaduct near Salt Lake City, Utah, an area with high seismic risk and soft soils. The analysis involved two steps: a literature review and data analysis to assess susceptibility to the different hazards (Level 1), followed by a detailed site response and liquefaction analysis to quantify ground shaking and soil permanent deformations (Level 2). The results were used with fragility curves to estimate damage probability of the viaduct. In the Level 2, a PGA of 0.2 g and lateral displacements of about 3 meters due to liquefaction were estimated for a rare earthquake scenario (2% probability in 50 years). These values indicated a 100% probability of damage to the viaduct, primarily due to lateral spreading, with minimal impact from ground shaking. The study also tested the index’s sensitivity by comparing conditions before and after soil reinforcement executed in the area. After soil improvement, liquefaction was prevented and the updated GETI index showed a 0% probability of high-to-severe damage and only a 4% chance of low damage. This case study demonstrates that the GETI index is a valuable tool for assessing multihazard risks in linear infrastructure and can guide cost-effective mitigation strategies.
Application of a novel geological-geotechnical index for assessing multi-hazard risk in linear infrastructure
Pagliaroli A.;Rollins K.;Brando G.
2026-01-01
Abstract
The study addresses the complex challenge of assessing the impact of natural hazards on critical infrastructure like road bridges. The GETI index, which quantifies the seismic risk by considering structural, geological, and geotechnical factors, including secondary earthquake effects (soil amplification, liquefaction and landslides) is applied to the Cherry Hill Interchange viaduct near Salt Lake City, Utah, an area with high seismic risk and soft soils. The analysis involved two steps: a literature review and data analysis to assess susceptibility to the different hazards (Level 1), followed by a detailed site response and liquefaction analysis to quantify ground shaking and soil permanent deformations (Level 2). The results were used with fragility curves to estimate damage probability of the viaduct. In the Level 2, a PGA of 0.2 g and lateral displacements of about 3 meters due to liquefaction were estimated for a rare earthquake scenario (2% probability in 50 years). These values indicated a 100% probability of damage to the viaduct, primarily due to lateral spreading, with minimal impact from ground shaking. The study also tested the index’s sensitivity by comparing conditions before and after soil reinforcement executed in the area. After soil improvement, liquefaction was prevented and the updated GETI index showed a 0% probability of high-to-severe damage and only a 4% chance of low damage. This case study demonstrates that the GETI index is a valuable tool for assessing multihazard risks in linear infrastructure and can guide cost-effective mitigation strategies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
