Using Artificial Fractal Tree Roots in Construction Design
I have a habit of constantly analyzing “the way things are done” and then thinking about “ways that they could be done better.” Lately, I have found myself thinking a lot about trying to maximize the transmission of loads thru commonly built structures. My thinking is that if one could somehow maximize the absorption, dispersion, or transmission of loads thru structures…that these efficiencies would lower construction costs, improve structural integrity, and perhaps allow us to rethink some of current “out of the box mainstream construction recipes.”
One of the things that I always try to do when I think about things like this is to simply look at everything around me and try to find existing examples that “fit the need.” This “look” includes just about everything from looking at natural forms (biomimicry) to browsing different technologies on the internet.
What originally prompted me to begin this research was the idea of improvements in bridge design and construction. After looking at endless pictures of bridges on the internet and reading about the advantages and disadvantages of each type I decided to try and come up with some sort of new arched bridge design.
After deciding on focusing my designs around an arch, my next challenge was to somehow minimize the use of construction materials, but at the same time optimize the transmission of forces from the top deck, to the arch, and then down to the ends of the arch. While there are quite a number of different ways to construct arched bridges, I was looking for streamlining the construction process via making bridge assemblies more modular and also looking for alternative ways to transmit loads throughout the structure. Most all of the designs that I came across employed only some of the features that I was looking for.
While driving down the road one day, I was still thinking about how one could use arches and somehow do a better job of transferring forces throughout the structure. I looked out my window and saw a few trees. I thought to myself, “trees?” Wow, you know if you think about it, their root systems do a fantastic job of transferring loads in a great many ways.
Think about this. You can plant a tree in loose sand and the root system will grow into this loose sand and prevent the tree from tipping over. How many trees just “up and fall over?” Even in severe storms the root systems of trees do a wonderful job of keeping trees standing.
The next challenge was, OK…so roots are great at transferring loads, but how could you ever integrate them into modern construction methods without going thru great pains or introducing a lot of cost? The answer is quite simply that roots are fractal in nature. This means that you can simply construct different root sizes and join them all together to form a “root system.”
The picture up by the title illustrates how to create roots out of arches or out of triangles. Both arches and triangles are notorious for the strength that they provide. What is interesting about the two roots shown in this picture is that while they both appear to be quite complex, they are very simple in that they these artificial root systems are made from only four different sizes of roots.
The secret to the root system’s strength lies in its ability to disperse loads from a focused area like a tree trunk down to all of its roots and into the earth. The manner in which this gets accomplished suggests that “for artificial root systems” you do not have to embed roots into solid building materials like concrete to achieve the same effect. I.e. you could put your roots into any material that is somewhat firm and achieve similar results. Perhaps a lighter material like foam could be used. Perhaps a balance between the roots and supporting medium could be struck whereby each material compliments the strength characteristics of the other.
The picture below shows how upside down roots could transfer surface loads directly to multiple arch-root segments. The lower arched modular root segments could perhaps be encased in a modestly firm foam-like material? The upper portions of the upside down roots would probably have their roots encased in a rigid material like concrete. Perhaps flat concrete panels that have their undersides dotted with holes that match up with the fractal root patterns could be placed over the upper roots to lock everything into place?
The picture below provides a broader view of how surface areas might be supported by arches and roots beneath them. Perhaps the hollow areas between the surface and arches might be filled with foam to add stability?
A few final words about the drawings and this blog entry. I don’t plan on patenting any of the “fractal root ideas.” I simply wanted to share these ideas, drawings, and thoughts with people that might have an interest and/or see some value in them. There are a lot of new composite materials out there that would probably be well suited towards creating modular, lightweight, bridge construction systems like the one discussed here. The physical characteristics and features of fractal roots can be altered in virtually limitless ways. The designs used to illustrate core concepts on this page are somewhat exaggerated for ease of illustration.
Finally, before ending this article, I just wanted to leave a few links that illustrate some innovative new concepts:
- Advanced Infrastructure Technologies – These folks are developing some really nice composite bridge systems. This link is to a video on their site that shows how they are using composite arch segments to build bridges.
- Civil Engineering (The Online Magazine of The American Society of Civil Engineers) – This link is to an article that describes how some folks in China are using “rooted caissons” to support an approach span on the side of a river.
- University of Delaware (Hillman Composite Beam) – This link is to a very interesting PDF document about Hybrid-Composite Railway Bridge Girder Fabrication, Testing, and Analysis.