sf free dhighrises june08

7/29/2019 SF Free DHighRises June08

1/3STRUCTURE magazine June 200838

EXTRUDERS

ortho angler slider(parallel)

pipe(perpendicular)

ROTORS

(bulging) rotor hyperboloid

FREE-SHAPERS

merger sweeper

Modeling Software and High-Rise ShapingMany non-orthogonal high-rises are designed to be iconic to

pinpoint urban projects, cities, regions, and even countries on theglobal map. Generally their aades are curved, or unusually shaped,or esthetic reasons, and sometimes to improve the building peror-mance. Complexity o abricating and constructing superstructuresand aades, increases with the geometrical complexity. Remarkably,

repetition o elements is losing importance. Various major projectsdemonstrate the economical easibility o large-scale applicationo non-standard products. The relative ease by which one can nowdesign, allows rapid shape development and quick generation o digi-tal data on components and their production.High-rise shaping is strongly related to the modeling tools that archi-

tects have available. Non-orthogonal building shapes traditionally aredrawn by repeating oor suraces upwards into a 3-D composition byapplying the sotware commands Copy, Move and sometimes Rotate.Subsequently, aades are generated around the oors.

Integration of digital technologies into thevarious stages of building development rapidly

increases the variety of high-rise volumes. A scheme has nowbeen developed to classify the various building shapes. As shaping largely

follows the modeling tools that architects have available, this scheme isbased on those tools as well. Consequently, no knowledge of mathematicalformulae is required to describe the complex curved faades. Transforminga shape is simple, but the structural consequences are considerable.

By Dr. Karel Vollers

Figure 1: The CAD-tool shape scheme.

As shown in Figure 1, standardized shape names have been developeby the author to describe the specifc groups and variations o shapesFor instance, building volumes with upward repetition o oor

without scaling or rotation, are called Extruders. Variations on thbasic orthogonal volume are introduced by inclining the line alon

which oors are moved upwards and by bending the line. As thoors are multiplied upwards, a rotation can be added, turning thvolume into a twister. The basic twister has a constant rotation aroun

a vertical axis. Thus all oors stay identical and aades on each ooare repeated. Though repetition generally iadvantageous, oten now the rotation is varieand the volumes additionally are tapered. Suchvarying adds identity and indicates tharepetition o elements loses importance. Nonstandard elements get aordable, owing tdigitizing o all stages o building developmenRotors are generated by rotating a line arounan axis. When axis and line both are vertical, Cylinder results.

TRANSFORMERS

bender scaled

rotor

tordocarver

TWISTERS

twister angledtwister

slidingtwister

Figure 2a.

Figure 2b.

Figure 2c.

Figure 2d.

Figures 2a, b, c, d - CCTV,Beijing (by OMA); DancingTowers, Dubai (by ZahaHadid); RAK Convention

And Exhibition CentreRas Al Khaimah, Dubai(by OMA); Torre Agbar,Barcelona (by Nouvel).



Free-shapers and Transormers are at the ore-ront o recent building developments. Dataprocessing or orm generation, and subsequentlyproduction, in recent years is eased by scriptingor adopting parametric modeling procedures.In such sotware, shapes are described by rela-tions between their composing elements. Someprograms instantly provide data, such as onoor surace changes when, during the design,a building volume is bent sideways. The shapesdescribed in the system can all be generated by

parametric modeling. Transormers are volumesthat have been transormed either as a whole,or in part. Carvers are sculpted by deducting oradding parts that are described by intersections

with other parts.In an Angler, identical oors are stacked under

a fxed angle. An angler can consist o straightsegments leaning in dierent directions (Figure

2a). When the inclination angle varies, or whenbuilt o straight segments interconnected bybent segments, it is called a Slider. Sliders canoverlap to achieve a more rigid structure, shortentrafc routes and provide alternative fre-escapes.

One o the Figure 2b sliders or stability in acorner rests on another slider. This additionallyenables elevator shats to vertically continue.A Rotor is a building volume created byrotating a line around a vertical axis. When thisline is a semi-circle with its ends on the axis, aGlobe results. Holes are carved in the globe oFigure 2c. Rotational building models can bevaried easily by manipulating the curve that isrotated. The Figure 2dtower seems a rotor, butis a Transormer with elliptical oor plans. Sucha volume can be drawn with solid modelingsotware by frst stretching a globe upwards and

then squeezing it horizontally over one axis.Such transorming turns it into a Scaled rotor.A twister has twisted aades that repeat on alloor levels (Figure 3a). The twisting superstruc-ture in the aade o the Figure 3b twister has

wide columns with vertical sides. They repeatupward, shited sideways and maintaining anoverlap. The zone between outer structure andat recessed glass aades provides sunshadedbalconies. The inward old o one aade givesthe tower an orientation.As the number o aades around a twister grows,the shape resembles more a cylinder. This can

allow or arranging a circle o vertical columnsbehind the aade. With vertical columns there isno torque on the structure. Tapering implies lessvertical repetition, but this in Figure 3cand 3dtwisters is compensated by horizontal repetition:6 aades and 5 wings respectively.

A tordo is a transormed volume, with at least corner moved out rom the orthogonal structgrid. It thus has one or more twisted aades. Tmullions o the Figure 3etordo connect to paravertical structural walls. All components o twisted aades are dierent.Freely curved glass panes have as yet not b

produced on a scale ft or high-rise. Thereotwisted suraces were replaced by cylindrsuraces or were tessellated (by approximating curving shape with at triangular panes). Just

the underside o a set o stairs, a twisted surcan be approximated by at vertical and horizosuraces. Stepped twisters are built o stepped aades. The Figure 4aStepped hybrid twister stepped suraces that connect around a cylindeWhen oors are movedupwards and sideways,along a curving axis, aSlider results. By addinga rotation, it becomes aSliding twister. Whenthe 3D axis is a helix, thevolume is named a Heli-

cal twister. Helical twist-ers can adjoin, intersector merge, depending ontheir positioning andproportions (Figure 4b).

Overlapping can pro-vide a vertical zoneor elevator shats. TheDubai Towers (Figure4c) are Tapered slidingtwisters. Their loorplans scale down, whilemoving upward and

rotating along a doublecurved axis. This curva-ture o the axis is vary-ing, and chosen suchto result in pleasinglycurved aade contours.The vertical structuralcores stay within theoctagonal oor plates.

Where oors are very ec-centric to the core, highatria are made to reducestructural loads.

Figure 3a.

Figure 3b.

Figure 3c.

Figure 3d.

Figure 3e.

Figures 3a, b, c, d, e - Turning Torso, Malm (by Calatrava);Infnity Tower, Dubai (by SOM); Fordham Spire, Chicago (byCalatravea); Gazprom, Petersburg (by RMJM); Ocean HeightsOne Residential Tower, Dubai (by Aedes).

Figure 4a.

Figure 4c.

Figure 4b.

Figures 4a, b, c - ModeGakuen Spiral Tower,Nagoya (by NikkenSekkei); Cobra Towers,Kuwait; Dubai Towers,Dubai (by TVS).

continued on next p



Figure 5a. Figure 5b.

The increasing use o non-standard elements in twisted acades impliesthat such geometry is not applied or economic gain by repetition,but or ease o construction. While twisted aades are double curved,the straight oor ends and aade transoms are easier to measure andrealize than curved elements would be. The repetition o lines on such

shapes helps understanding the geometrical build-up. The incliningcontours add a notion o movement to the shape depending on thedegree o rotation, torquing associates with slow and lazy, to painuland strangling.When the sequence o applied manipulations is not obvious, thevolume is called a Free shaper (Figure 5a). The sinuous balustrades andlouvers o the Figure 5b buildings are single-curved. Buildings withprotruding elements that make the aades seem double curved, areclassifed in the special category Slicers. Figure 5cshows a canyon-likecut-out. The reely curving aade juxtaposes the box-like overall shape.

The glass industry has or many yearbeen lagging behind in developinproduction acilities or such glassI this project is executed with reelcurving insulated glass panes, it will ba major breakthrough.With architects getting accustome

to sotware modeling tools, new shapeare emerging. All pictured buildings ithis article, except maybe the CobrTowers, are in the process o beinbuilt, or are fnished. They are a minopart o what is being realized globallyMany more will arise when reelcurved panes become more aordable

Development o production acilities or reely curved glass is speedinup. An aluminum curtain wall raming system or such aades iavailable: the Alcoa/Kawneer AA100Q-Twist system.Education on the geometrical aspects o complex geometry building

is highly eased by the recently published bookArchitectural Geometr

(Pottman, et al). It elaborates in a very accessible way on the varioutopics that architects and product designers come across whenmodeling on their computer. The CAD-tool shape scheme connectto the descriptions and names used in the book. A ew years ago, manshapes described in the scheme would have seemed mere theoretical now many have been built, and in variations. New modeling tools annew computer based structural calculations will bring new shaping ohigh-rises.

Dr. Karel Vollers is assistant professorof Product Development at DelftUniversity of Technology, Berlageweg1, 2628CR Delft, The Netherlands.He post-graduated in 2001 cum laudeat Delft University on the thesis Twist&Build, which was then publishedas a book. He specializes on realizingfreely curved facades, and developedan adjustable mould for bending freelycurved glass and, with Alcoa/Kawneer,an aluminum framing system. He may

be contacted [email protected].

Figure 5c.

Figures 5a, b, c - Tour Phare, Paris (byMorphosis); Slinky Twins, Paris (by PCA);Opus, Dubai (by Zaha Hadid).

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rmation,visitwww.STRUCTUREmag.org

Images Courtesy o OMA, Zaha HadidArchitects, HSB/Calatrava, SOM, ADSStudio, RMJM, Aedes, Nikken Sekkei,Brian Gassel//TVS, Morphosis, andPCA Architects.

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ReferencesVOLLERS, K.J., Morphological schem

o second-generation non-orthogonahigh-rises, CTBUH 2008 Dubai Congress Proceedings

POTTMANN, H., ASPERL, A., HOFERM., KILIAN, A., Architectural GeometryBentley Institute Press, 2007, ISBN 978-0934493-04-5

sf free dhighrises june08

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