Our group does research in structural engineering, focusing on the impacts of extreme events on structures and communities, at the University of Colorado Boulder. Please explore this site to see what we are working on, find recent publications and contact us.
We have written some blogs in English and Spanish about housing characteristics that can be made safer in Puerto Rico.
Please check them out here: https://www.colorado.edu/lab/gpo/publications/blogs. Contact Briar Goldwyn (briar.goldwyn@colorado.edu) or Cole Velasquez (cole.velasquez@colorado.edu) if you have questions.
This month we celebrate Hailey Rae Rose and Maria Jose Echeverria, who both passed their comprehensive exams and advanced to candidacy. Congratulations!
Hailey Rae, Prof. Liel, Maria Jose
Some of our group enjoying Boulder mountain views: Firaol, Hailey Rae, Prof. Liel, Maria Jose and Lianne
Abbie Liel joined Emily Guglielmo, Jessica Mandrick, Cherylyn Henry and Jennifer Goupil in a presentation on ASCE 7-22 New and Updated Hazards at the 2020 Virtual Structural Engineering Summit. Abbie updated the attendees on new design ground snow loads currently being balloted for ASCE 7-22.
Panelists at session on ASCE 7-22 New and Updated Hazards.
Check out this video from the NIST Virtual Symposium where Professor Liel talked about Dustin Cook’s work (in collaboration with colleagues at Texas A+M). Our work starts 30 minutes in.
We’re managing to find ways to spend time together :-)
Hike at Wonderland Lake: Polly, Briar, Hailey-Rae, Professor Liel, Dustin, Janice, Professor Liel’s daughter, Maria Jose
PhD student Lianne Britto successfully passed her PhD preliminary exam this month. Nice work, Lianne!
Congratulations to Casie Venable, who yesterday successfully defended her doctoral work entitled Post-Disaster Housing Safety: Mis(Alignments) between Household Perceptions and Engineering Assessments.
Casie also has a paper recently published in the journal Sustainability on household perceptions of post-disaster housing reconstruction. (https://lnkd.in/dX-E86i)
PhD Candidate Casie Venable has an article recently published online in Sustainability.
How residents perceive housing safety affects how structures are designed, built, and maintained. This study assesses the perceptions of housing safety through a survey of over 450 individuals in communities that received post-disaster housing reconstruction assistance following 2013’s Typhoon Yolanda, and that were potentially vulnerable to earthquakes. We analyzed how housing design factors, post-disaster program elements, personal characteristics, and hazard type and exposure influenced safety perceptions. Overall, individuals were most concerned with the safety of their roofs during hazard events and perceived their houses would be less safe in a future typhoon than a future earthquake. Housing material significantly impacted safety perceptions, with individuals in wood houses perceiving their houses to be the least safe. Individuals living in areas more exposed to hazards also perceived their houses to be less safe. Being relocated after the typhoon, witnessing good or bad practices during reconstruction, and prior disaster experience also significantly influenced perceptions of housing safety. These results are used to make recommendations on how implementing organizations can most beneficially intervene with program factors to improve local understanding of housing safety
In January and February, 2020, our research team traveled to the Philippines and Puerto Rico. Here are some photos that give a sense of what we did and what we learned.
Abbie Liel, graduate student Casie Venable, and local research assistant Darlyn Diang completing household interviews in Cogon, Eastern Samar, Philippines
Transitional wooden shelter destroyed in Typhoon Ursula in Eastern Samar, Philippines
Abbie Liel examines a house collapsed by Typhoon Ursula. We determined the cause of failure to be failure of the column-foundation connection. The roof collapsed onto the rest of the house.
Graduate student Casie Venable and local research assistant Kristhyl Tunggolh interview a resident in Eastern Samar, Philippines
Professors Amy Javernick-Will and Abbie Liel, discussing a roof demonstration at a school in Humacao, Puerto Rico
Graduate Research Assistant, Polly Murray, looking at locally available materials in a hardware store in San Juan, Puerto Rico.
Dr. Sattar, an alum of our group, was recently named a Housner Fellow by the Earthquake Engineering Research Institute. Congratulations, Siamak!
Dr. Sattar, Research Structural Engineer, NIST
Dr. Jakub Valigura’s paper about hybrid-sliding-rocking columns has been accepted by the Journal of Structural Engineering. The paper is entitled “Seismic Repair Assessment of Hybrid-Sliding-Rocking Bridge Columns through Integrated Experimentation and Expert Panel Solicitation.”
Dr. Mohammad Salehi, a recent graduate from Texas A & M, also has a new paper on “Effect of Major Design Parameters on the Seismic Performance of Bridges with Hybrid Sliding-Rocking Columns”, which is forthcoming in the Journal of Bridge Engineering. This paper looks at key design variables and their influence on performance.
Observed damage at the bottom segment of the original column after each test.
Ph.D. student Hailey-Rae Rose successfully completed her preliminary examination. She is working on experimentation related to seismic pipe failures.
Also, Ph.D. candidate Polly Murray passed her comprehensive exam. Polly’s dissertation is tentatively titled “Evaluation of reinforced concrete structures for improved seismic performance, with consideration of reparability and informal construction methods”.
Ph.D. student Hailey-Rae
Congratulations, Eric! Eric’s thesis is entitled “Effectiveness of Mitigation Strategies for Wastewater-Injection-Induced Seismicity for Reducing Seismic Risk”. Please contact him (eric.johnson-2@colorado.edu) for a copy if you’d like to read it before it is posted here.
Eric, defending his thesis over zoom. Since we couldn’t be physically together, he provided his audience with a cherry cookie recipe to bake before the defense!
You can find the post here.
We’ve had a number of papers recently accepted. I’ve posted abstracts and the manuscripts here, before they appear online.
Authors: Jakub Valigura, Abbie Liel and Petros Sideris
This paper investigates the impacts of the column system on bridge life-cycle costs in high seismic areas. It focuses on hybrid sliding-rocking (HSR) columns, which are an accelerated bridge construction (ABC) technology. The authors conduct a life-cycle cost assessment, quantifying costs of bridge construction and potential earthquake damage and subsequent repairs, as well as the cost of bridge closure time due to construction or repairs. Two prototypical modern seismically-designed bridges are considered, each designed with both conventional RC and HSR columns. Construction costs of HSR columns are higher. However, drift demands on the HSR columns are generally lower, damage is less severe and costs of repairing the columns are greatly reduced. Moreover, construction times are about 80% quicker for HSR columns, and repair times are reduced relative to conventional construction. The results suggest advantages in most cases to the HSR column system, reducing construction time and expected costs and time for seismic repairs sufficiently to counteract the increase in upfront construction costs. The benefits of the HSR, and by extension other ABC column systems, are particularly significant for highly trafficked bridges in high seismic areas, but hold for a wide range of input assumptions.
The paper will be published in Structure and Infrastructure Engineering.
Please contact Jakub Valigura with questions.
Median benefits of competing system in terms of direct costs over construction, seismic repair/failure stages and entire life cycle for two prototype bridges.
Authors: Bridger Baird, Abbie Liel and Robert Chase
The rise in the number of anthropogenic small to moderate magnitude earthquakes in the central United States raises questions about the damageability of the built environment in such events. This study examines the performance of modern light-frame wood buildings, including single, multi-family and commercial construction, in earthquakes with moment magnitude of 3 to 6, using dynamic analysis of buildings models subjected to ground motions recorded in past induced events in North America. We focus on first onset of damage, e.g., wallboard or wallpaper cracking, nails popping out. The results show that earthquakes with magnitude less than 4-4.25 are unlikely to cause damage to modern construction. However, moderate magnitude events can cause damage over a wide geographic area (more than 30 miles from the earthquake epicenter, or 40 or more miles from a wastewater injection well). These results can be used to suggest setback distances between injection wells and certain neighborhoods or facilities, and magnitude thresholds for post-earthquake inspections.
The paper will be published in Earthquake Spectra.
Please contact Abbie Liel with questions.
Spatial footprint of damage from an injection site in (a) assuming an earthquake may occur up to 12 miles from the well for damage threshold B, and (b) assuming an earthquake occurs up to 3 miles from the well for damage threshold B and C.
Authors: Balaji Paramasivam, Shideh Dashti and Abbie Liel
The effectiveness of a new liquefaction mitigation strategy is investigated experimentally for newly constructed shallow-founded structures: an in-ground gravel-rubber (GR) panel wall system. The goal was to limit the negative consequences of liquefaction in terms of permanent seismic deformation, while benefitting from the positive consequences of liquefaction in terms of base isolation. The influence of GRs was systematically evaluated on the seismic performance of a layered liquefiable deposit in the far-field and near two different model structures. The structures represented the key properties of a 3-story building (A) on a 1 m-thick mat foundation and a 9-story building (B) with a 1-story basement. The performance of Structure A with GRs was also compared with a similar structure without mitigation and with conventional mitigation strategies that either enhanced drainage alone (e.g., prefabricated vertical drains) or increased shear stiffness around the foundation’s perimeter (e.g., structural walls). Test results showed that the GR wall system could greatly improve the overall seismic performance of short-period structures like A, but may be detrimental to long-period structures like B. The GRs below Structure A effectively isolated the total system, reducing average and differential settlements below the foundation (although not necessarily to acceptable levels), while also reducing the seismic demand transferred to the superstructure, a combination rarely observed by conventional mitigation strategies. The same GR system under Structure B experienced greater seismic moments and shear stress, inducing large shear deformations in soil that led to this structure’s significant rotation and flexural deflection. The foundation continued to rotate even after shaking due to P-Δ effects, resulting in its overturning failure. These results show that GR systems can be quite effective for low-rise structures, but additional reinforcement may be necessary to reduce foundation tilt. Use of such mitigation measures under taller and heavier structures must be accompanied with great caution. Despite their practical limitations, evaluation of GR panel walls may guide future developments of combined, economical, and sustainable mitigation strategies that improve the overall performance of the soil-structure system.
This paper will be published in the Journal of Geotechnical and Geoenvironmental Engineering.
Time histories of foundation settlement and rotation for all structures. Settlements and rotations of BGR during Joshua-H are shown up to 12 s, at which time overturning failure occurred in this structure. The foundation rotation scale in figures c and d is different between -0.01 to 0.03 and 0.03 to 0.07.
Casie is a 2019 USAID/OFDA Graduate Fellow in Humanitarian Shelter and Settlements. She presented for a group of humanitarian professionals on her work- in a world with COVID-19 this was all done virtually on 3/19/20. Well done, Casie!
PhD student Briar Goldwyn presented on “The Influence of Reconstruction Modality, Social Capital, and Community Satisfaction on Willingness to Participate in Resilience-Building Activities” at Construction Research Congress in Phoenix.
Zach Bullock successfully defended his PhD on Wednesday, March 11. His dissertation is entitled: “A Framework for Performance-Based Evaluation of Liquefaction Effects on Buildings”. Congratulations, Zach!
Zach, with his three co-advisors: Profs. Porter, Dashti and Liel
Post-defense celebrations.
Ph.D. student Polly Murray and M.S. student Eric Johnson presented posters at the 2020 National Earthquake Conference. Polly’s poster addressed a framework for assessing reparability of reinforced concrete buildings (pollybmurray@gmail.com); Eric’s poster addressed mitigation of induced seismicity (eric.johnson-2@coloraado.edu).
Eric Johnson and Polly Murray.
Check out this link to a video produced by the CU College of Engineering