About This Project
Reinforced concrete structural walls are used in many buildings to resist forces due to earthquakes. If you live anywhere on the west coast of the U.S., chances are you're in a building that utilizes a concrete structural wall right now. Earthquakes in recent years in Chile and New Zealand show that these walls often fail prematurely. Our research aims to investigate the use of small steel and polymer fibers mixed in with the concrete to improve the performance of such structural walls.
Ask the Scientists
Join The DiscussionWhat is the context of this research?
Reinforcing concrete with fibers dates as far back as 1900. Only in recent years, however, have fiber reinforced concrete composites been developed that balance efficient use of fibers and strength in a way that makes using this material practical for large-scale applications such as buildings or bridges. One such composite, which was developed at UC Berkeley, called Hybrid Fiber Reinforced Concrete, or HyFRC, utilizes both steel and polymer fibers to control cracks on the macro- and microscopic scales. Previous tests subjecting bridge columns to shaking representative of a large earthquake have proven HyFRC's potential to reduce damage. We would now like to investigate how this material performs when used in the critical sections of a structural wall subjected to earthquake loading.
What is the significance of this project?
While the protection of lives in a major earthquake is of paramount concern when designing a building, the impacts can be much farther reaching. Significant damage, even if it does not lead to collapse of a building, can put a structure out of commission for a significant period of time. For businesses this could mean large revenue losses, or for buildings such as hospitals there would be even worse consequences. Demonstrating that the use of HyFRC improves the performance of structural walls would have both social and economic implications -- leading to buildings that are both safer for the occupants and require less repair in the event of a large earthquake.
What are the goals of the project?
Specimens representative of the critical section of a structural wall called the Boundary Element will be constructed with identical reinforcing steel configurations using both typical concrete and HyFRC. These "dogbone" specimens will be tested under cyclic load reversal in order to investigate:
- How damage in the concrete accumulates throughout the tension and compression cycles
- Behavior of the steel reinforcing bars embedded in the concrete
- Ultimate failure mode(s) of the boundary element
- Verification and calibration of computational models
Budget
Sensors and gauges - Most of the behavior of the concrete and steel is not visible to the naked eye, either because the amount of displacement is so small, or because it's occurring inside the concrete. These sensors allow us to capture every aspect of the response in order to quantify the performance of each specimen.
Steel Reinforcement - Each specimen in this study will be built to comply with current building codes which requires a certain amount of steel reinforcement.
Steel and Polymer Fibers - Because it's not much of an experiment without them!
Machine and Electronics Technicians - Sadly, the university won't let me play with 500,000 lb actuators, cranes, or forklifts on my own (which I think is a travesty), so I'll need to pay some qualified individuals to help me out with those things.
Meet the Team
Team Bio
Let me take you back to my fifth grade science fair, an opportunity for most kids to build a volcano or power a lightbulb with a potato. Not the case for Ian Williams. No, instead I decided that it would be fun mix concrete with various recycled plastics to test alternative forms of reinforcement. (FYI, the plastic mesh bags that oranges come in work pretty well.)
Fifteen years after that fateful science project and my excitement for concrete research has only increased. So much so that I decided to pursue a PhD in structural engineering, and when I discovered what was being done with fiber reinforced concrete at UC Berkeley I knew I had found the right research topic. My current areas of research are in fracture, computational modeling, and environmental effects of fiber reinforced concrete. When I'm not in the lab you'll most likely find me bouldering in Tahoe or Yosemite, or out on my bike searching for some hole-in-the-wall restaurant.
Ian D Williams
Let me take you back to my fifth grade science fair, an opportunity for most kids to build a volcano or power a lightbulb with a potato. Not the case for Ian Williams. No, instead I decided that it would be fun mix concrete with various recycled plastics to test alternative forms of reinforcement. (FYI, the plastic mesh bags that oranges come in work pretty well.)
Fifteen years after that fateful science project and my excitement for concrete research has only increased. So much so that I decided to pursue a PhD in structural engineering, and when I discovered what was being done with fiber reinforced concrete at UC Berkeley I knew I had found the right research topic. My current areas of research are in fracture, computational modeling, and environmental effects of fiber reinforced concrete. When I'm not in the lab you'll most likely find me bouldering in Tahoe or Yosemite, or out on my bike searching for some hole-in-the-wall restaurant.
Additional Information
Video of a typical concrete compression test
Video of HyFRC compression test. Note the highly ductile response, with no explosive failure of the material.
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