The wood is placed in two layers on top of each other. Can be twisted unless the corners are rigid.
The wood is placed in two layers on top of each other.
Stabilized by means of two cables in the diagonals. One of them will always tighten if the square twists.
Triangle that tilts to the rear.
Charnier joints are used, so the bars don’t acquire bending moments.
Hard to achieve a head height that is large enough without the construction being too big.
Triangle with one right angle. One of the sides tilts out of the plane (on each side of the two other).
Still hard to achieve a head height that is large enough without the construction being too big.
Easier to achieve a head height that is large enough.
The two top sides are in the same plane, the bottom side is in another plane.
Triangle that takes up space under the walking level of the bridge.
Still two different planes.
The part that sticks out in the top has no structural effect, but can work as a railing.
Triangle that is broken/transformed to avoid the line along the top. Pin joints / charnier. Not stable on its own.
Triangle that is broken/transformed in the top, but now in one plane. Is to be seen as part of a truss on one side of the bridge.
Cables are introduced to keep the fold stable.
Spatial triangle structure (three-sided pyramid).
Stable when it’s affected by a force from the top, so the cables tighten.
Is not stable in the base, it needs for instance a cable-cross. It is possible to replace some of the bars with cables.
Now with a stabilizing cable cross at the base.
Two of the bars are replaces by cables (if more elements are connected, every other element is in tension and every other is in compression).
The base of the pyramid is tilted upwards.
The dead load of the lower triangle and the live load will keep the cables in tension if the outermost triangle is fixed.
The triangle in the middle is removed.
The shape of the element is simpler, but the head height will be too small.
An extra triangle is now introduced instead. The cables are now in tension independent of the live load. It is a challenge to create a good joint with four pieces of wood, without cutting away too much wood in the ends (so the wood will be weak).
The structure can be continued all the way around the walking area, so it can be seen from the bottom.
Experiment with a bar that stretches out two of the cables. A little too complex / unclear.
Still a bar that stretches out some of the cables to make the square stable. Now a simpler and more symmetric geometry. The intention is to connect elements with a cable at the base point of each element, keeping the “floating” bar.
An attempt to create a larger head height inside the element with an umbrella-like structure. Not as clear in its structural appearance as the previous one.
Now with a “platform”, so the pedestrians don’t have to walk through the structure. The “floating” bar still remains, but once again the structural appearance is not so clear (too many extra elements without a direct structural necessity.
Back to nr. 16, which is the most clear geometry. A minor change has been made, as the floating bar now extends higher above the square than below (again to make more head height and refine the proportions.
Two of the bars are on top of the other two, which creates a hierarchy in the square. The upper bars will carry the walking area.
If more elements are connected, it is possible to replace the side bars with cables.
The floating bar is thicker than the other pieces of wood, emphasising the compression force in the bar. A t-cross turns up as the elements share one piece of wood when they are connected.
Experiment where some of the vertical bars are tilted to the side. Creates a more dynamic structure, but also a more confusing and messy view through the bridge. The structure is perhaps more suitable for a larger bridge structure, but the progress/sequence is better.
Another model showing the t-joint. A bolt goes through all three pieces of wood (a wooden stick symbolizing a metal bolt). The cable joints are moved to the side of the upper bar.
Half of the bridge built with the new joint. No sloping verticals. The proportions are furthermore slightly changed from model nr. 23 (a little less of the structure is placed under the walking area).
3D drawings that show different slopes of the columns (here seen from the end of the bridge). I have experimented with both the sideway placement of the sloping columns and amount of slope. I have chosen to go on with the last one (see explanation by nr. 32).
Final bridge. Due to the thorough use of cables the bridge has a light expression. The experience and perspective along the bridge is important, and the slight tilt of two of the columns is an important part of this. The amount of sloping is carefully balanced so the overall system is tight and does not start to fall apart. The system has to be evident, and the modest slope ensures, that all five elements seem to be connected properly.