2024 Webinars

NHERI@UC San Diego Webinar #3: Larry Nuss
March 15, 2024

Presentation Title:
Concrete Dam Concepts and the Need for Large Scale Shake Testing

Presenter Bio:
Larry retired from the Bureau of Reclamation on December 31, 2011 with 36 years of experience in the design, structural analyses (static, thermal, and seismic), dam safety, risk analysis, and security of concrete dams (gravity, arch, spillway, and buttress dams). He formed Nuss Engineering, LLC on January 20, 2012. He has been a Consultant Review Board Member on projects in Panama, Australia, New Zealand, Turkey, Canada, USA with Tennessee Valley Authority, Bureau of Reclamation, Corps of Engineers, New Brunswick Power, FortisBC, Brookfield, Hydro Quebec, Federal Energy Regulatory Commission, Xcel Energy, Southern California Edison, Panama Canal Authority, Trust Power (New Zealand), AGL Hydro (Australia), EnergiSA (Turkey), HDR, Stantec/MWH, Hatch, AECOM, Shannon & Wilson, Kleinfelder, Intertechne (Brazil), Hatch, Schnabel, DLZ, and Tonkin & Taylor (Australia). He has taught classes in the United States, Japan, India, South Korea, China, and Brazil. He has a Master of Science, University of Colorado, Boulder, Colorado, in Civil Engineering in 1978. He is currently licensed as a Professional Engineer in the State of Colorado and a Practicing Professional Engineer, New Brunswick, Canada.

In 2008, he had procured $3,000,000 from Homeland Security to perform a large-scale shake concrete dam test at the UCSD. The test was to be a 15-foot-high model of Morrow Point Dam with foundation and reservoir. On the day we were going to announce the project, the financial crisis hit, and all eye-mark funding was stopped by Congress. The project died.

Concrete dams are massive structures. There are over 85,000 dams (all types) in the USA. Worldwide, concrete dams have performed very well during earthquakes but have never been subjected to the Maximum Credible Earthquake. There have been small scale shake table tests of concrete dams, but the similitude requirements of small-scale tests are difficult to obtain. "Real" concrete needs to be used in the shake table models and not some synthetic substitute to achieve proper similitude requirements. This is the reason why large-scale testing would be much better. The goal is to progressively test the large-scale models to failure. Engineers in the dam's industry only postulate seismic Potential Failure Modes of concrete dams as concrete dams have not failed during an earthquake. Large-scale testing would provide a means to validate and calibrate the dynamic advanced finite element analyses being performed for the dams.

Webinar #3: Larry Nuss



NHERI@UC San Diego Webinar #4: David Mar
May 7, 2024

Presentation Title:
IT13: Nurture Design Creativity and Innovation

Presenter Bio:
David Mar is the founder of Mar Structural Design, in Berkeley California. He has practiced over thirty years, after receiving his BS and MS at U.C. Berkeley. His practice is known for creativity and innovation, especially in the areas of performance-based design. The firm’s portfolio includes numerous examples of seismically resilient rocking self-centering systems, as well as spine retrofit systems. He was the Project Technical Director of FEMA P-807, Guidance and Recommendations for the Evaluation and Retrofit of Multi-Unit Wood-Frame Buildings with Weak First Stories. David is the Chair of PUC Issue Team 13.

This webinar will present the work of the BSSC’s Provisional Update Committee, Issue Team 13. IT 13 is tasked with exploring ways to Nurture Design Creativity and Innovation and facilitate the design of novel seismic systems, while ensuring safety. The initial work product is a Behavior-based Design Method, intended to directly utilize non-linear behavior, explicit mechanisms, capacity design, and so forth. It is to be less complicated than an alternative means of compliance, and thus avoid the necessity of peer review and non-linear response-history analyses.

It is also intended to be less opaque than the Rules-based prescriptive code design process. While the method is preliminary, and in the proof-of-concept stage, it synthesizes several important design topics. If a designer proposes a novel lateral system, he/she would test it with the following six steps:

  1. Select a suitable set of global strength-ductility requirements, that would be safe against collapse, for a specific hazard. This is a Universal R-Cd Design Space, that would allow more options than the recognized code systems. This proposed design space builds on non-linear static methods and would be benchmarked with FEMA P-695.
  2. Establish the system’s mechanism, using capacity design. This includes requirements to ensure that a SDOF simplification is suitable and reliable. This step is the linkage from global non-linear demands to local non-linear component demands.
  3. Account for the potential of increased local ductility demands due to both plan and vertical irregularities.
  4. Characterize the non-linear components (fuses/plastic hinges) using ASCE 41 as a catalog of tested non-linear elements with defined strength, and deflection limits.
  5. Allow and design for stable foundation nonlinearity, such as from rocking and so forth. Iterate until the system is strong and tough enough to be reliably safe.
  6. Explicitly check the deflection compatibility of the gravity systems.

The webinar will present the concepts underlying the Design Method, as well as various studies being used to develop the details and limitations of the method.

Webinar #4: David Mar