Posts Tagged ‘attractor’

final deformable skin

The following post has to be seen as a continuation and completion of the overall process and especially of the last post. Its content doesn’t represent the intire project but has to bee seen in the context of the previous ones.

PROJECT DESCRIPTION
At the port of Piraeus this tower rises on a very prominent site with a vital surrounding. To resolve the problem of the sleeping giant, this project proposal suggests a deformable skin which creates interactions on different levels between the Piraeus Tower and its context.
Taking the current structure as starting point, surrounding urban hotspots attract parts of the façade to reconfigure. These occurring deformations provoke synergies with the surrounding which allow new happenings and revaluate the whole area.
At one side the skin stretches to provide a roof for the market and its lively atmosphere penetrates the ground floor. On another side the skin allows building a pedestrian bridge across the busy road and creates a stronger relation to the waterfront and the port.
On the plinth the structure covers an open space and grows then upward approximately following the existing structure until it detaches again from the existing to end the tower at its top.
The new stairway climbs up and changes the skin as well. The parametrical creation of the structure which follows the form of the deformable skin undertakes several steps of adaption and optimisation to suit its structural and programmatical needs.
The deformable skin starts its life as a new appearance at the port of Piraeus whose tubular steel structure interacts with its surrounding. The facets are empty or faced with aluminum frames holding different infill panels which will changed over time. The so called “sleeping giant” gets lively and looses its name when people start to occupy the empty space. As the stairway will serve all the stories from the beginning on, the occupants can choose their level as they wish.


OVERALL FLOWCHART


REPRESENTATION in drawings and renderings




visualisation of the market penetrating the Piraeus Tower


visualisation of an interior conected to the staircase


visualisation of the tower in the urban cotext


the following drawing shows the different materialities and how they’re connected with each other


During the final week I was building a model at a 1:5 scale which shows the different aspects of my project. the new structure is attached to the existing and is attracted to the outside to cover and hold the new staircase. The tubular structure and its joints are shown in an abstraction using wooden components.


FILES
GH-file creating the structure in lines
GH-file translating the lines into tubes and adding joints
PDF of the presentation

deformable skin

Considering the project state from the last crit as form finding process, the aim for this crit was to optimize its structure. Several analysis show the strucutre’s weaknesses and strengths. One issue was the maximum span of my structural members and another one consists in the curvature analysis of the deformed surface.




To deal with this optimization idea I first did a quick research in general optimization strategies. Taking them rather as general inputs then as actual algorithms, I came up with my own strategy. The point grid from the form finding process generates several more or less horizontal curves which I first subdivide into segments with the same lenght, which gives a polyline as output. The length can be chosen and in addition there is an option to change the resolution of the polyline following the curve. When the curve’s curvature is higher than a certain value the structural length at that point is only equal the half of the other lengths. The subdivision starts at a given point which consists in the curve’s closest point to the stair attractor and ends by keeping a cerain cap to the starting point.
After the creation of these “horizontal” polylines the neighbours are linked at each point with the two minimal distances. These new “vertical” structural members sometimes have a way too long span to be taken as valuable output. For that reason another subdivision process runs through all of them and subdivides each element taking in account the input value as maximal length. These subdivision points are again linked between each other and sometimes supported by columns standing on the plinth.
Another process at the end consists in bringing the forces down to the ground at certain points.




GH-file

To be sure about the homogeneity of the lengths I ran again an analysis of the structural length.
Image showing the length analysis before the “vertical” analysis:


And after all the optimization processes all is green:


Finally there are a few special moments in the structure. The first consists in the stair leading up to the dissolving top where the structure gives bigger openings at certain points and looks more dynamic.


The pedestrian bridge is suspended from the structure and crosses the road which today separats the port from the tower.


The columns which support the structure above the plinth create a possibility for a public space or restaurant’s outdoor space covered by steel tubes.


As the Piraeus Tower has quite big dimensions, there are many structural joints which hold up the new deformable skin and fix it to the existing concrete structure. But not all joints connect the same number of tubes and all of them come in with a different angle. To deal with this changes and having one system for all the tower the joints have to be adaptive and able to react to each situation. The following joint allows up to seven tubes coming in and each of them can be adapted with two rotation axis. Two steel plates hold the members together and have to be squeezed together. Where the structure is attached to the existing concrete the squeezing is done by the consoles, otherwise a simple screw can fix the joint.


Overview of the structure in elevations and plan:


attractor geometry

To understand better, how my attractor geometry works I’ve produced some images and schemata explaining the different parts of the GH-algorithm.

As I take the existing structure as starting point I introduced its geometry into Grasshopper. The two distinct volumes are drawn separately, as this improves the variability for the further use. Each box is explodet in its six faces which then are subdivided with sliders in both vertical and horizontal direction. The lowest points of the tower volume are eliminated for a smoother deformable skin on the transition from the tower to the plinth. After the subdivisions, all the points are merged together and organized in a way that they can be moved afterwards.

The next step consists in moving the points where they are attracted by an attractor. There are three possible attractor geometries: points, curves and surfaces. For the deformable skin I only used the first two of them, which I’ll explaine here. (A surface as attractor would act the same way as the curves do.)
The moving part is done entirely in a short VB-script. All attractor points are directly put into this component, the curves go first through a curve closest points component and all closest points farther away than the influence radius are culled with a pattern. In addition to all these points there are 5 more inputs: influence radius and force for curve and points and the pointgrid from above. First the curve changes the point grid and then the point geometries refine the deformation.

The influence radius determines which points from the starting point grid are attracted and the force how strong they are moved towards the attractor. Actually the force works as a sort of dumper for the whole attraction.

This VB-script I applied several times, as much as there are urban hotspots. After all deformation happened, the points are taken as curve controlpoints. The organizing of the point collection before moving them allows to have curves going more or less horizontal around the volumes. Of course there are as many curves as there are vertical subdivisions in the beginning – both together from the plinth and the tower (minus the lowest as mentioned above). These curves are again organized in a certain way and then lofted to the final deformed skin.
The following illustrations visualize the different deformations and how they are produced.

- MARKET

- PEDESTRIAN BRIDGE

- STAIRS

- PORT / SEA

- ATHENS / ACROPOLIS

A short overview of the whole GH-canvas

So far the application of a structural solution is produced in a seperate script. But i think it would be better to include this step as well in the deformation part.

response_growing parasite structure

In response to the mid-term crit on the 15th of April 2010 and as continuation of my very first esquisse, I take the following conclusion:
The deformable skin doesn’t cover the whole tower anymore, but rather uses it at certain points as a host. This parasite structure covers the existing structure only where public interaction or attraction would take place. This aims as well to push the idea of phasing the tower’s life and let it change over time. Starting with taking in account the immediate context, interacting wiht it, providing an enclosed safty staircase and a lookout point on the top, the Piraeus Tower will be covered more and more as its value rises and the indoor space gets occupied.

For clarifing reasons the attraction maths and creation of the structure, used in the GH definition, will be reworked and demonstrated in diagrams.

X5_deformable skin

Work in progress layout from the 8th of April:

This layout contains many place holders, which will be replaced for the final presentation. The same for the text which is copied from an earlier blog post to visualize the amount of space needed!

research on attractor geometry and possible forms

Seeking for solutions for my project I tried to look for different possibilities for several aspects of my current state.

  • different attractor geometries using a GH definition -> what happens if the attractor would be a line, curve or even a surface and not only a point as it has been so far?
  • different sizes of the facetting -> larger triangles would need another (smaller) structure for filling up the surfaces, but smaller facetting might need a supporting structure. Both possibilities would be possible, but they need different kinds of detailing and would give a different appereance of the tower
  • analyzing some possible forms I can produce, using the current GH definition

In general I’m inclined to go for the smaller facetting because it gives a smoother appereance and consists in only one structure all over the facade instead of having a main structure and then a kind of filling structure. To avoid a supporting structure for the small facettes, I’ll try to “touch” the existing structure as often as required.
The different attractor geometries – I analysed in a seperate GH file – have to be developed to be used within my project. Concerning the final overall form of the facade, I think I leave this at this point for a while and come back to it, when I know more precisely what I want and for which reasons.

elastic skin

As introduced in the last post the aim of this facade proposal consists in the integration of the tower in the urban context on two levels. Interacting with its surrounding context it brings together places which are today separated by busy roads or visual factors. And changing its form on the top it links to important places whithin a bigger urban context.
The so called attractors transform the existing outline of the tower to achieve the integration of the tower in the city of Piraeus and Athens.
As an exampel you can see in the next image how the skin could link the existing market with the tower’s ground floor to allow more fluidity on this level and bringing together shops on the street with the ones in the building.



As you see in the drawings, the skin doesn’t follow the tower’s outline almost at all. This doesn’t only allow the interaction introduced before, but it also connects the two volumes of the tower and lets them appear as one unity.
The structure, as it is shown now, doesn’t represent the final intention, it is just an approximation of what I’m trying to achieve. Taking the principle of reinforcement from the precedent exercise I tried first to take a main structure (actually the one in the drawings and image above) and then reinforce it where the structure demands it. But while working on our case study, which analyses the growth of lichen, I came up with the idea of combining main structure and reinforcement and taking density as factor for the structure. As I already mentionned I haven’t suceeded yet to build this but in the following images I give an idea of what I’m willing to do. A curfature analysis of the transformed skin should show where more structure is needed and create it with more density at that points. An image of the curvature could be used as image sampler which densifies the structure where a certain colour is shown. Doing so, I could have a more uniform structure which would help the appearance of the tower in its context.

Finally the space between the structural elements can be treated differently. The space can be left open, closed by glasing or even with opaque materials. A possible solution for this could be the following detail, where covering elements are squeezed between metal tubes which go around the structural beams.

skin_deformed by attractors

In the continuation of my first ESQUISSE I translated the attraction idea further.
The main deformation principle is, to take the skin of the existing tower and attract it from different reference points. So far there are two distinct levels of attraction. On the lower part of the tower – around the base – the skin is deformed by places which are in direct interaction with the tower, places where people move from one to another. This deformation integrates the tower in its direct context. It’s not anymore a gigantic lost building in the middle of the urban fabric, but it becomes a part of it.
On the upper level, where the tower is somehow alone due to it’s dimension, the skin is deformed towards important places which can be seen only on this hight overlooking the city. So the tower is not only integrated within the direct context at the base, but as well in the city scale context where the deformation creates visual links between important sites of the City.

Finally the skin will be triangulated into a three dimensional truss which then can be closed or open depending on what is desired on each location. As there might be some structurally critical parts, a new kind of attractor will reinforce the truss at weak places. This last reinforcement step is not yet translated into the design process and can’t be seen in the following images.

The GH file you can get here and also have a look at the VB-component.

two questions

And again, two questions!
Actually what I asked two days ago worked very well, but while continuing with the work I got 2 problems:

  1. I tried to put several attracors into one vb-component. I set the input as list of On3dPoint and then tried to loop the whole script I made as many times as there are attracors in the list. So the idea is that the script runs for the first time with one attracor and puts the moved points into the m0 list which is saved temporarely in the list m1 and then cleared that I can use it again as empty list for the next attracor. Somehow this doesn’t work at all and gives me an error I don’t understand because it is located in line 0 which I couldn’t find!
    I was also thinking about puting the generated lists of moved points after each loop into a listarray, but then I got confused and couldn’t control the list indexes within the listarray anymore.
    see file
  2. The other problem which came up when I wanted to bake the geometry, was that the latter one doesn’t match the GH-geometry. Some triangles are baken very well and the others seem to be quite strange. I tried to define and bake it in many different ways as well as baking the triangle and the offset seperately and then trimming or splitting in rhino. But neither of them worked yet…
    see file

the GH-preview on the left hand side and the baken one in rhino

Would be very nice if you could help me out again! Thanks!

<i>close up of the baked model</i>

x2_CCTV from OMA


To fully understand the following post you can read the last one which introduces the main ideas. X1_CCTVfrom OMA
As a source I used the book CCTV by OMA, A+U, 2005


THE STRUCTURE
The main structure of the CCTV is a continuous grid of diagonal steel beams – called structural diagrid – which cover the whole building. Where the loads are too big, the diagrid is doubled or even quadrubled. In addition to this structure there is a orthogonal structure which consists of vertical load-bearing columns and horizontal perimeter edge beams. These two grids penetrate the concrete slab in a certain distance from the façade. The diagrid is repeated on the outside where it holds the windows in place – this is actually what we see from the outside.


THE 3D MODEL
Taking the interpretation from the last exercice as base, I created a parametrical 3D model in Grasshopper which generates an abstraction of what the CCTV is.
As you move the z- or x-spacing in the model, the diagrid changes its proportions. The width and thickness of both diagrid and reinforcement can be set up individually. Until now the vertical columns and the perimeter edge beam are not really adjustable with parameters but the slabs change their position regarding the z-spacing – one z-spacing contains three floors.
The two intersecting planes generate automatically plan and section and they can be moved either along the z or the x axis. These line drawings are moved out of the 3D model and create a composite drawing with elevation, plan and section as you can see below. Next to this drawing a series of axonometric projections shows the simplified layering of the model.

make2D from baked GH-model

klick on the giff file showing the different layers


THE GH-CODE
download Rhino file
download GH code

To get into the third dimension taking the last GH-file was not really possible, so I started the definition from scratch. The new definition doesn’t build up a line grid in the beginning but it creates a series of rhombi which then are offseted and extruded into volumes. The functions for the attractors remain basically the same but the reinforcement is again a new definition creating another rhombus around each influenced point.
The parametrical model so far is vertical, but I think it won’t be very tricky to move this onto an inclined plane and using its u/v coordinates to define the volumes. Another problem to solve is the overlapping from reinforcement and structure. I tried several ways to avoid it but all of them faild, one is still desactivated in the GH file.
I was also thinking about using this kind of rhombi to apply on whatever surface inspired from David Fanos tutorial. But his base elements stay 2-dimensional and always just share an edge instead of a surface when it would be 3D (offseted).

overview of the GH canvas with explanations

close-up_main structure is generated

close-up_attractors are being set up

close-up_reinforcementis generated around influenced points

close-up_slab and orthogonal grid are generaded

close-up_plan and section are generated