■ Numerical Model Development

A reliable seismic risk assessment requires an accurate and efficient simulation of infrastructure systems. The accurate and efficient simulation is the most fundamental task in seismic vulnerability assessments. For this, the research team developed the numerical modeling technique of components and systems, which are compatible with governing failure modes, through the model validation with experimental data. For the component level, the research team developed the numerical model of  structural components with different failure modes. For the system level, the research team developed the numerical model of a scaled three-story frame performed by a shaking table test and the numerical model of a real long bridge using sensor data recorded during historical California events. 

Selected Publications

• Yoon Jae Kim, Chang Seok Lee, and Jong-Su Jeon* (2025). Model parameter estimation for hysteretic behavior simulation of FRP-jacketed reinforced concrete columns. Earthquake Engineering & Structural Dynamics; 54(6): 1657–1677, May 1.

• Yewon Park, Chang Seok Lee*, and Jong-Su Jeon (2024). Hysteretic model parameters for seismic performance assessment of cyclically degraded reinforced concrete columns. Soil Dynamics and Earthquake Engineering; 179: 108519, April 1. 

• Sergei Shturmin, Chang Seok Lee, and Jong-Su Jeon* (2023). Lumped plasticity model for simulating the inelastic earthquake response of CFT columns. Journal of Constructional Steel Research; 211: 108196, December 1 .

• Chang Seok Lee and Jong-Su Jeon* (2021). Adaptive hysteretic model for reinforced concrete columns including variations in axial force and shear span length. Earthquake Engineering & Structural Dynamics; 50(15): 4001–4031, December 1.

• Muhammad Haseeb Alvi, Chang Seok Lee, and Jong-Su Jeon* (2021). Model development and seismic performance evaluation of rectangular reinforced concrete columns with short lap splices in existing building frames. Engineering Structures; 245: 112922, October 15.

• Chang Seok Lee, Yewon Park, and Jong-Su Jeon* (2021). Model parameter prediction of lumped plasticity model for nonlinear simulation of circular reinforced concrete columns. Engineering Structures; 245: 112820, October 15.

• Jong-Su Jeon, Sujith Mangalathu*, and Sang-Youl Lee (2019). Seismic fragility curves for California concrete bridges with flared two-column bents. Bulletin of Earthquake Engineering; 17(7): 4299–4319, July 1.

• Karthik Ramanathan, Jong-Su Jeon*, Behzad Zakeri, Reginald DesRoches, and Jamie E Padgett (2015). Seismic response prediction and modeling considerations for curved and skewed concrete box-girder bridges. Earthquakes and Structures; 9(6): 1153–1179, December 11.

• Jong-Su Jeon, Ji-Hun Park*, and Reginald DesRoches (2015). Seismic fragility of lightly reinforced concrete frames with masonry infills. Earthquake Engineering & Structural Dynamics; 44(11): 1783–1803, September 1. 

• Jong-Su Jeon*, Abdollah Shafieezadeh, Do Hyung Lee, Eunsoo Choi, and Reginald DesRoches (2015). Damage assessment of older highway bridges subjected to three-dimensional ground motions: Characterization of shear-axial force interaction on seismic fragilities. Engineering Structures; 87: 47–57, March 15.

• Jong-Su Jeon*, Laura N Lowes, Reginald DesRoches, and Ioannis Brilakis (2015). Fragility curves for non-ductile reinforced concrete frames that exhibit different component response mechanisms. Engineering Structures; 85: 127–143, February 15.

• Jong-Su Jeon, Laura N Lowes*, and Reginald DesRoches (2014). Numerical models for beam-column joints in reinforced concrete building frames. ACI Special Publication; 297: 3.1–3.26, March 6. 

■ Fragility Assessment of Long Bridges under Spatially Variable Ground Motions

Differential support motions may have a detrimental effect on the safety of a bridge during strong earthquakes since these motions can induce additional internal forces in the bridge compared to uniform ground motions. To address this challenge, this research has focused on addressing the effect of spatial variability of ground motions on the vulnerability of long bridges and further providing guidelines for the seismic design of the bridges reflecting this effect. Also, the research team plan to further extend this fragility assessment of these bridges in liquefiable soils along with the development of soil-structure interaction models. For example, the research team performed a probabilistic assessment of a cable-stayed bridge subjected to differential support motions and developed the numerical modeling approach for long bridges through the comparison of simulated results with recorded sensor data.

Selected Publications

• Jian Zhong, Jong-Su Jeon, and Wei-Xin Ren* (2018). Risk assessment for a long-span cable-stayed bridge subjected to multiple support excitations. Engineering Structures; 176: 220–230, December 1.

• Jong-Su Jeon*, Abdollah Shafieezadeh, and Reginald DesRoches  (2018). Component fragility assessment of a long, curved multi-frame bridge: Uniform excitation versus spatially correlated ground motions. Structural Engineering and Mechanics; 65(5): 633–644, March 10. 

• Jian Zhong, Jong-Su Jeon*, Wancheng Yuan, and Reginald DesRoches  (2017). Impact of spatial variability parameters on seismic fragilities of a cable-stayed bridge subjected to differential support motions. Journal of Bridge Engineering ASCE; 22(6): 04017013, June 1. 

■ Seismic Damage Assessment of Infrastructure Systems

To facilitate assessment of the seismic vulnerability of structural systems, fragility functions defining the probability of meeting or exceeding a specific limit state given an earthquake intensity level are developed using numerical simulation of structures with a range of configurations and design details; however, a reliable assessment of seismic risk requires appropriate simulation of component failure mechanisms. To achieve this, the research team developed fragility curves for various structural types such as bridges, frames, and pipelines.

Selected Publications

• Minsun Kim, Chang Seok Lee*, Byungmin Kim, and Jong-Su Jeon* (2025). Effect of soil profile-related parameters on seismic performance of ductile reinforced concrete building frames in California. Soil Dynamics and Earthquake Engineering; 190: 109118, March 1. 

• Jiuk Shin and Jong-Su Jeon* (2022). Seismic damage mitigation strategy using an FRP column jacketing system in gravity-designed reinforced concrete building frames. Composite Structures; 279: 114700, January 1. 

• Jong-Su Jeon*, Sujith Mangalathu, Junho Song, and Reginald DesRoches (2019). Parameterized seismic fragility curves for curved multi-frame concrete bridges using Bayesian parameter estimation. Journal of Earthquake Engineering; 23(6): 954–979, July 3.

• Sujith Mangalathu, Jong-Su Jeon*, and Jiqing Jiang (2019). Skew adjustment factors for fragilities of California box-girder bridges subjected to near-fault and far-field ground motions. Journal of Bridge Engineering ASCE; 24(1): 04018109, January 1.

• Sujith Mangalathu and Jong-Su Jeon* (2018). Adjustment factors to account for the effect of bridge deck horizontal curvature on the seismic response of concrete box-girder bridges in California. Earthquake Spectra; 34(2): 893–914, May 1.

• Sujith Mangalathu, Jong-Su Jeon*, Jamie E Padgett JE, and Reginald DesRoches (2017). Performance-based grouping methods of bridge classes for regional seismic risk assessment: Application of ANOVA, ANCOVA, and non-parametric approaches. Earthquake Engineering & Structural Dynamics; 46(14): 2587– 2602, November 1.

• Sujith Mangalathu, Farahnaz Soleimani, and Jong-Su Jeon* (2017). Bridge classes for regional seismic risk assessment: Improving HAZUS models. Engineering Structures; 148: 755–766, October 1.

• Jong-Su Jeon, Eunsoo Choi, and Myung-Hyun Noh* (2017). Fragility characteristics of skewed concrete bridges accounting for ground motion directionality. Structural Engineering and Mechanics; 63(5): 647–657, September 10.

• Jong-Su Jeon, Reginald DesRoches, Taesik Kim, and Eunsoo Choi* (2016). Geometric parameters affecting seismic fragilities of curved multi-frame concrete box-girder bridges with integral abutments. Engineering Structures; 122: 121–143, September 1.

• Do Hyung Lee, Byeong Hwa Kim, Seong-Hoon Jeong, Jong-Su Jeon, and Tae-Hyung Lee* (2016). Seismic fragility analysis of a buried gas pipeline based on nonlinear time-history analysis. International Journal of Steel Structures; 16(1): 231–242, March 31.

■ Earthquake Resilience of Transportation Networks

As significant uncertainties are associated with the factors governing the operational characteristics of bridges following earthquakes, it is important to compute the reliability of transportation networks as a function of bridge fragility. A novel framework for the computation of transportation network fragilities following earthquakes is proposed herein, and the effectiveness of the proposed methodology is demonstrated using a hypothetical bridge network in California, USA. The proposed methodology affords the likelihood of functionality of bridge routes as a function of ground motion intensity. The network fragilities identified by this methodology can aid emergency responders and bridge owners in assessing the availability of possible routes after a seismic event based on the likelihoods of functionality of the routes.

Selected Publications

• Mendgie Chen, Sujith Mangalathu, and Jong-Su Jeon* (2023). Betweenness centrality-based seismic risk management for bridge transportation networks. Engineering Structures; 289: 116301, August 15.

• Mendgie Chen, Sujith Mangalathu, and Jong-Su Jeon* (2022). Seismic reliability assessment of bridge networks considering travel time and connectivity reliabilities. Earthquake Engineering & Structural Dynamics; 51(13): 3097–3110, October 25. 

• Mendgie Chen, Sujith Mangalathu, and Jong-Su Jeon* (2022). Machine-learning-based seismic reliability assessment of bridge networks. Journal of Structural Engineering ASCE; 148(7): 06022002, July 1.

• Mendgie Chen, Sujith Mangalathu, and Jong-Su Jeon* (2021). Bridge fragilities to network fragilities in seismic scenarios: an integrated approach. Engineering Structures; 237: 112212, June 15.

■ Economic Loss and Collapse Risk of Building Frames

The second generation of the performance-based earthquake engineering (PBEE) framework allows for a probabilistic seismic risk assessment of frame buildings through collapse. This framework can be utilized to estimate financial losses in frame buildings. This is particularly important for building stakeholders to allow risk-informed decisions for effective seismic designs and retrofit schemes that minimize such losses in the aftermath of an earthquake. The emphasis of this paper is on the effects of assigned risk category on the seismic risk, including both collapse risk and economic risk, assessed in a probabilistic manner. Here, the collapse risk includes the mean annual rate of collapse that takes account of all possible levels of seismic hazards of interest.

Selected Publications

• Seong-Hoon Hwang, Sujith Mangalathu, Jinwon Shin, and Jong-Su Jeon* (2022). Estimation of economic seismic loss of steel moment-frame buildings using a machine learning algorithm. Engineering Structures; 254: 113877, March 1.

• Sujith Mangalathu, Seong-Hoon Hwang, and Jong-Su Jeon* (2021). Quantifying the effects of long-duration earthquake ground motions on the financial losses of steel moment resisting frame buildings of varying design risk category. Earthquake Engineering & Structural Dynamics; 50(5): 1451–1468, April 25.

• Seong-Hoon Hwang, Jong-Su Jeon*, and Kyungkoo Lee* (2019). Evaluation of economic losses and collapse safety of steel moment frame buildings designed for risk categories II and IV. Engineering Structures; 201: 109830, December 15.

■ Earthquake-Induced Sloshing Effects on Steel Water Tanks Using Computational Fluid Dynamics

In lifeline engineering, liquid-storage structures play irreplaceable roles in the development of a national economy, but many liquid tanks have been severely damaged or collapsed during historical strong earthquakes. Because of the uniqueness of this structure type, failure causes some types of disaster, such as a fluid leakage, fire, or environment pollution. Post-earthquake reconnaissance reports have indicated that liquid sloshing is one of the major causes of serious damage in a tank and the environment during earthquakes. To address earthquake-induced sloshing effects on water tanks, the research team firstly developed the ANSYS computational model of water tanks based on existing results of shaking table tests. Fluid pressures on the tank walls extracted from computational fluid dynamics will be mapped to the walls to perform computational structural analysis in order to estimate the stress and deformation of the water tanks and to ultimately derive their fragility functions. 

Selected Publications

• Tae-Won Kang, Hyun-Ik Yang, and Jong-Su Jeon* (2019). Earthquake-induced sloshing effects on the hydrodynamic pressure response of rigid cylindrical liquid storage tanks using CFD simulation. Engineering Structures; 197: 109376, October 15.

■ Seismic Vulnerability Assessment of Steel Storage Rack Frames

Nonstructural failures have accounted for the majority of earthquake damage in several recent earthquakes. Thus, it is critical to raise awareness of potential nonstructural risks, the costly consequences of nonstructural failures, and the opportunities that exist to limit future losses. Nonstructural components of a building include all of those components that are not part of the structural system. The primary purpose of this research is to identify the sources of nonstructural earthquake damage on rack storage frames and piping systems and to propose seismic retrofit methods for reducing their potential risks. Firstly, shaking table tests for the system level and cyclic load tests for the component level were performed and their numerical models were then developed based on experimental data. Significant damage on nonstructural components are identified in terms of engineering damage states. Finally, their fragility curves will be generated to assess the seismic vulnerability in the system and component level and are used to develop effective and efficient retrofit measures such as dampers and stiffening members.