Footings and Connections

Origin of the Study

We initially created a rectangular for our Grid shell. However, it was suggested we make them long, and angular to match the shape of the grid shell.


Besides making it angular, a request was made to add hollow pieces of tubular steel permitting the insertion of a steel rod across and another steel rod hammered to the earth at angle, and a hinge.


The horizontal bracing across will help attach some of the diverse anchors together.   The vertical tubular piece (at an angle) will help us insert a rebar piece that will be buried into the ground for stability.






Characteristics of the Anchors

The anchors were made from rebar.   Each rebar is ½ inch thick.   Aleks did the welding at his house where he has some facilities for welding.

Aleks purchased the initial concrete bags, and later Andres purchased 2 more bags. So, we used a total of three bags of concrete.

Andres also purchased a can of the Rust Oleum © automotive gray primer to paint the rebar footings to match the color of the concrete.  Painting the anchors silver makes them look better next to the structure.

Troy built the concrete forms, and sample grid connectors to show how it would be attached to the grid shell structure.

We were able to make enough time to work either together or separately on numerous tasks.


2 rebar pieces 10 feet long (1/2 inch wide)

1 tubular steel piece (1/2 inch wide) and hollow

Wooden form boards

½ inch wide dowel

Blue Painter’s tape

4 standard size hinges (about 2 inches long)

Plywood pieces (about 2 inches wide)

3 bags of ready to mix concrete.










The Evolution of Our Footings throughout the semester

The footings began as a square or rectangular concrete anchor with the rebar attachments on top.    But later, since our structure is rather circular – we decided to cast the footings with an arch on one side – matching the shape and orientation of the structure.

The four footings produced today would translate into 12 to 16 footings. This is due to the fact that our Grid shell of four points or lines will have four footings on each contact point or line.




A footing is a synonym of an anchor.

A dowel is a round wood rod.

A hinge is a joint that permits solids pivot.

Wooden forms may be made from real wood or less expensive wood composite materials.

A hinge is made of steel.

A ready to mix concrete bag is understood to have sand, aggregate (gravel), stone, and concrete – it does have the recipe for concrete and all you need to do is add the water (about 2 to 4 gallons for every 80 pound bag).



Once we mix our concrete on an orange Home Depot bucket, we can add the mixture to the form with the anchor.


First the anchors are welded along with the tubular steel and the hinges outside of campus.   Then the wood forms are assembled in the wood chop.

Additional pieces of wood were made from plywood to create recess cavity for us to place our hands and assist in the lifting of the anchors.

These additional pieces of wood also were connected to the angular dowel pieces that covered the tubular steel to keep the concrete mixture out of the system.

The anchors will lined up in groups of 3 or 4 at each anchor line will make up for a total of four anchor points in order to support our Grid Shell.   These anchor points The concrete mix is mixed, and poured on the wooden forms.   It takes about twenty-four hours for the concrete to set.



The anchors will lined up in groups of 3 or 4 at each anchor line will make up for a total of four anchor points in order to support our Grid Shell.   These anchor points will be placed at an angle complementing the tension and compression forces that support our Grid Shell.



The design and construction of the footings were made through numerous research, design and pictures that other engineers or Architecture students have done to provide an anchor point to tensile structures, and other grid shells.

We tested it on the 30 ft. Model (at the time our prototype anchor had no hinges), and we produced an extra footing with a hinge as recommended in class for maximum flexibility.

Now, this assembly of 3 footings side by side at each of the 4 line anchor points will be tested this coming week.

Thank you.

Aleks        Andres           Troy

(Footing and Connections Group)



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