1. Unified Workflow for Structural Assessment Across Hazards and Typologies (2021-2023)
Researchers: Mohammad S. Alam, Tracy Kijewski-Correa, University of Notre Dame; David Prevatt, University of Florida, Khalid Mosalam, University of California, Berkeley, Ian Robertson, University of Hawaii, and David Roueche, Auburn University.
To speed up its initial operationalization, the Structural Extreme Events Reconnaissance (StEER) developed a family of Fulcrum mobile Apps for structural assessment on an as and when necessary basis in responses to Hurricanes Harvey, Irma and Maria, adopting a Direct Quantification of Component Performance (DQCP) approach that readily maps to HAZUS-quantifiable damage states. These efforts evolved into a trio of apps to assess buildings, other structures, and hazard intensity, all for wind storms/hurricanes with a pilot app for seismic hazards. Unfortunately, the segmentation of structures by class as well as by hazard has resulted in an evolving library of apps that is more difficult to manage across a growing user base and continues to segregate the hazard community, erecting barriers to multi-hazard assessments. Thus the focus of this project is to develop a structural assessment workflow that is (i) unified across hazards and structure classes, (ii) seamlessly integrates observations of structure and hazard context in one user-friendly mobile application, (3) transitions away from proprietary Fulcrum apps toward Natural Hazards Engineering Research Infrastructure (NHERI)-standard platforms, and (iv) complements the current DQCP approach with a more in-depth expert Forensic Load Path Evaluation (FLPE).
1. Development of WebGIS-based Tool for Probabilistic Damage and Restoration Modeling of Wastewater Systems (2021-2022)
Researchers: Jaehoon Jung, Mohammad S. Alam, Barbara G. Simpson, Andre R. Barbosa, Oregon State University; Nishant Paruleker, Bureau of Environmental Science, City of Portland, Oregon.
The project objective is to develop a framework for probabilistic seismic damage, loss, and restoration modeling of wastewater systems incorporating all relevant sources of uncertainty (e.g. model parameter uncertainty, model class uncertainty) and correlation (e.g. material correlation, spatial correlation of pipe damage) as opposed to traditional assessment studies that rely on median fragility of pipes and no consideration for correlation in pipe damage. The proposed framework was applied to a case study wastewater backbone system of the City of Portland, OR under multiple Cascadia Subduction Zone (CSZ) earthquakes and local M 6.8 Portland Hills fault earthquake scenario. A WebGIS-based Pipeline Damage Estimation Tool was also developed as a part of the project to estimate seismic damage assessment of pipes under ground shaking and ground deformation hazard.
Figure 1. Pipeline Seismic Damage Estimation Tool (Alam and Jung 2022)
2. Defining Appropriate Fragility Functions For Oregon Lifelines (2019-2020)
Researchers: Mohammad S. Alam, Barbara G. Simpson, and Andre R. Barbosa, Oregon State University
A comprehensive taxonomy and database of region-specific fragility functions appropriate for Oregon were solicited by a research cooperative of Oregon-based lifeline providers under the auspice of Cascadia Lifelines Program (CLiP). Objectives included: (i) identify available and missing fragility functions suitable for Oregon lifelines, (ii) evaluate the quality of the collected fragility functions, and (iii) provide recommendations where refinement is needed for future fragility function development studies. To this end, a comprehensive literature review and expert solicitation was conducted and a fragility database was structured using a hierarchy of lifeline systems (electric power systems, water and wastewater systems, and transportation systems), hazards (earthquake, tsunami, etc.), and fragility function attributes (development method, probabilistic distribution, damage states, and other relevant metadata like infrastructure description, and source reference). As a second phase of the project, a Python-driven Fragility Function Viewer web application was developed using Pandas and Dash to enable easy access to the database. The web application allows one to select, visualize, search, compare, and export fragility functions in the database. The database and web application may prove useful to utility managers to assess risk and make informed decision about their facilities.
Figure 2. Fragility Function Viewer for Cascadia Lifelines Fragility Database (Alam et al. 2021, Alam et al. 2022)
3. Performance-based Earthquake-Tsunami Engineering (2015-2019)
This research focuses on the development of a probabilistic structural fragility and risk assessment framework for coastal structures prone to cascading earthquake-tsunami multi-hazards. The research was the focus of Dr. Alam's Ph.D. dissertation and entails three part study aimed at understanding the performance of coastal structures under extreme events, such as, earthquake only hazard, tsunami only hazard, and earthquake-tsunami multi-hazards. To achieve the research objectives, a variety of tools were used, such as physics-based high fidelity finite element models (FEMs), implementation of new phenomenological material models, uncertainty quantifycation methods, and advanced statistical methods.
3a. Earthquake-only hazard: Incorporating model class uncertainty in probabilistic seismic demand and loss assessment
Researchers: Mohammad S. Alam and Andre R. Barbosa, Oregon State University; Fabio Romano, Maria Zucconi, and Barbara Ferracuti, Niccolo Cusano University, Italy; Marco Faggella, Sapienza University of Rome, Italy.
For earthquake-only hazard, we developed probabilistic formulations for incorporating model class uncertainty, which relates to the use of multiple structural analysis models to predict the physical response of structural systems, in probabilistic seismic demand assessment (PSDA) and probabilistic seismic loss assessment (PSLA) of structures. We developed a FEM approach to estimate the response of unreinforced masonry (URM) infilled reinforced concrete (RC) frame buildings accounting for infill-frame interactions and probable column shear failure using OpenSees. Model parameter and model class uncertainty were propagated using Latin Hypercube sampling (LHS) method. Using a modern code-designed 6-story URM infill RC frame building as an application example, we illustrated the paramount importance of considering model class uncertainty arising from the use of multiple FEMs in drift hazard demand, repair cost and life-cycle annualized loss of structures using the results of large number of nonlinear response history analyses (NRHAs) ran in high-throughput computing facility HTCondor at Oregon State University (OSU) and using SP3 web-tool.
Figure 3. Mean annual rate of excedance of (a) drift hazard and (b) repair cost of URM infilled RC frame building for different infill strut model classes (Alam and Barbosa 2018, Romano et al. 2020).
3b. Tsunami-only hazard: Parameterized tsunami fragility function development accounting for structural member failure
Researchers: Mohammad S. Alam, Andre R. Barbosa, Michael H. Scott, Daniel T. Cox, Oregon State University; John, W. van de Lindt, Colorado State University.
For the tsunami-only hazard, we developed a probabilistic framework for deriving physics and simulation-based parameterized tsunami fragility functions, accounting for structural member failures and presence of breakaway opening. In this work, we developed FEM approach in OpenSees that is capable of accounting for presence of breakaway opening and structural member failure, which have been identified as two important parameter a effecting tsunami performance of buildings based on tsunami reconnaissance. Using the framework and FEMs, we developed parameterized scalar vector-valued tsunami fragility functions for a modern code designed school building and showed how the use of scalar vs vector-valued tsunami intensity measure a effects tsunami damage prediction.
Figure 4. Parameterized tsunami fragility surface for RC frame building (a) as a function of inundation depth and momentum flux, and (b) as a function of inundation depth, flow velocity, and inundation depth-flow velocity interaction (Alam et al. 2018).
3c. Earthquake-tsunami multi-hazard: Multi-hazard earthquake-tsunami structural risk assessment framework
Researchers: Mohammad S. Alam, Andre R. Barbosa, Michael H. Scott, Daniel T. Cox, Oregon State University; John, W. van de Lindt, Colorado State University.
For the earthquake-tsunami multi-hazard, we developed a probabilistic framework to assess the structural risk of coastal structures prone to cascading earthquake-tsunami multi-hazards. As a part of this study, we designed three design variants (earthquake only design, earthquake-tsunami design with single column size, and earthquake-tsunami design with multiple column size) of a 4-story and an 8-story special moment-resisting frame (SMRF) reinforced concrete (RC) buildings as per ASCE 7-16 and ACI 318-14 provisions. Using NRHA results of advanced three-dimensional (3D) FEMs of these buildings in OpenSees, which were conducted in a three-phase simulation comprising earthquake phase, free vibration phase, and tsunami phase, we developed several scalar and vector-valued earthquake-tsunami fragility functions. These fragility functions were then used with a site-specific probabilistic earthquake and tsunami hazard analysis (PSTHA) results at three potential building sites within a coastal community to illustrate geospatial variation of the structural risk of the design variants ( Figure. 4) for the earthquake only hazard, for the tsunami only hazard, and for the earthquake-tsunami multi-hazard.
Figure 5. Collapse risk of buildings at different locations of the (a) study area of Seaside, OR, for (b) earthquake-only hazard, and (c) for tsunami-only hazard (Alam 2019, Alam et al. 2019).
4. Collaborative research- Probabilistic hazard, damage, and resilience assessment of coastal communities (2017-2019)
4a. Probabilistic seismic and tsunami hazard assessment framework (PSTHA)
Researchers: Hyoungsu Park, University of Hawaii; Daniel T. Cox, Mohammad S. Alam, and Andre R. Barbosa, Oregon State University
In this work, we presented a framework for probabilistic hazard assessment for the multi-hazard seismic and tsunami phenomena originating from a single fault source, which allows the consistent estimates of seismic and tsunami intensity measures (IMs) for a given coastal community. Using the full-rupture earthquake and tsunami event along the Cascadia Subduction Zone (CSZ) and the framework developed, we assessed site-specific c seismic and tsunami hazard for the city of Seaside, OR, which is a coastal community prone to high seismic and tsunami hazard.
Figure 6. (a) Cascadia Subduction Zone (CSZ), site-specific (b) seismic [PGA and Sa(T=0.3s)] and (c) tsunami hazard [h and hu ]maps for the City of Seaside, OR for tsunamigenic earthquakes in CSZ (Park et al. 2017).
4b. Probabilistic seismic and tsunami damage assessment framework (PSTDA)
Researchers: Hyoungsu Park, University of Hawaii; Mohammad S. Alam, Daniel T. Cox, and Andre R. Barbosa, Oregon State University
In this work, we presented a framework for probabilistic damage assessment of built-environment due to both earthquake shaking and tsunami inundation from tsunamigenic earthquake events at a coastal community. In this study, we utilized PSTHA results with fragility functions from HAZUS-MH earthquake and tsunami module to evaluate the combined impacts of earthquake and tsunami through a stochastic approach that accounts for the accumulated damage due to seismic shaking and subsequent tsunami inundation, for the case study area of Seaside, OR.
Figure 7. Structural damage probability maps for complete damage state for (a) earthquake ground shaking, (b) tsunami, and (c) combined earthquake-tsunami hazard at the City of Seaside, OR due to 500 year tsunamigenic earthquakes in CSZ (Park et al. 2019)
4c. Probabilistic decision support framework for community disaster resilience assessment
Researchers: Sabarethinam Kameshwar, Louisiana State University; Daniel T. Cox,Andre R. Barbosa, Mohammad S. Alam, Oregon State University; Hyoungsu Park, University of Hawaii; Karim Farokhnia and John W. van de Lindt, Colorado State University.
In the final study we developed a probabilistic decision support framework for community resilience planning under multiple hazards using PSTHA , PSTDA tools, and performance goals based guidelines such as the Oregon Resilience Plan (ORP) and the National Institute of Standards and Technology (NIST) Community Resilience Planning Guide (CRPG). Using the framework developed, we assessed the effects of decision support options such as selection of hazards, resilience goals, and mitigation (ex-ante) and response (ex-post) strategies to identify measures that can improve infrastructure performance to meet community de ned resilience goals for the case study area of Seaside, OR.
5. Experimental testing- Experimental investigation of wave-induced (tsunami, hurricane wave and surge) pressure, forces, and debris impact on coastal structures (2017-2021)
5a. Tsunami-like wave-induced lateral and uplift pressures and forces on elevated coastal structure considering flow shielding and channeling and debris impact.
Researchers: Andre R. Barbosa, Daniel T. Cox, Mohammad S. Alam, Glen Galant, Pedro LomonacoOregon State University; Andrew O. Winter, Krishnendu Shekhar, Michael R. Motley, Marc O. Eberhard, Pedro Arduino, Gregory R. Miller, University of Washington.
A 1:10 scale physical model of a two-story elevated coastal building supported on piles was constructed in the Large Wave Flume of Hinsdale Wave Research Laboratory (HWRL) at Oregon State University and tested under tsunami-wave loading for three scenarios: (i) an isolated elevated structure case where no neighboring structure is present; (ii) with the presence of one or two neighboring structures arranged in five structural layout configurations meant to be representative of generic prototypical rectangular buildings in subsections of a coastal community; and (iii) isolated structure impacted by multiple debris in different debris configurations. These experiments lead to development of a dataset of measured pressures and forces acting on an isolated elevated coastal structure, assessments of the effects of flow shielding and channeling on pressure and forces exerted on the neighboring elevated coastal structure, and conceptual evaluation of the tsunami debris field impact and damming forces on elevated coastal structures qualitatively and quantitatively, under unbroken and broken tsunami-like long waves.
Figure 9. Large scale elevated structure experimental setup for tsunami-like wave loading: (a) isolated elevated structure, (b) elevated structure with neighboring structures (here setup as concrete block), and (iii) isolated elevated structure under tsunami-like wave driven multiple debris impact and damming (Alam et al. 2020, Winter et al. 2020, Shekhar et al. 2020)
5b. Physical and numerical modeling of damage of light-frame wood residential building due to hurricane waves and overland surge.
Researchers: Daniel T. Cox, Andre R. Barbosa, Sean Duncan, Mohammad S. Alam, Pedro Lomonaco, Oregon State University; Hyoungsu Park, University of Hawaii; Caileen Yu, University of California, Berkeley; Sungwon Shin, Dayeon Lee, Hanyang University, South Korea
1:6 scale physical models of an on-grade and an elevated light wood-frame coastal buildings were constructed in the Large Wave Basin of Hinsdale Wave Research Laboratory (HWRL) at Oregon State University and tested under hurricane wave and surge loading with regular waves of varying water depths and wave heights to simulate typical wave/surge conditions resulting from landfall hurricanes on low-lying barrier islands. The two specimens were tested under increasing surge and wave conditions until collapse and progressive damage was monitored using LiDAR. Uplift pressure, forces, and acceleration data were gathered. Besides the hydrodynamic tests, several in-air free vibration, ambient vibration, and forced-vibration tests were performed for dynamic characterization of the building specimens. The experimental data gathered were used for system identification, damage progression correlation, and developing uplift pressure distribution formulation.
Figure 10. Large scale coastal wood-frame residential building experimental setup for hurricane wave and surge loading: (a) sheathing removal during a wave trial, (b) damage progression monitoring using point cloud data, and (iii) forced vibration testing for dynamic characterization of the specimen (Dan et al. 2021, Barbosa et al. 2021, Duncan et al. 2021, Alam et al. 202x).