topical advanced design studio 5501, Prof. Pongrantz, FA2013, digital design and fabrication, DDF, College of Architecture, Texas Tech University

DDFvicente carrasco

contents

a 00 fiber reingorced concrete research 3-18

a 00 bc movable molds research 19-22

a 01 hauer building skin 23-24

b 01 2d pattern 25-27

b 02 3d pattern 28

b 03 optimization 29-30

team4 31-32

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a_00 fiber-reinforced concreteThe use of fibers in construction is an old concept with straw and horse hair being used in mortar and mud bricks since the time of the Egyptians.

The modern use of FRC was invented at the end of the 19th century by Ludwig Hatschek. He sought a new roofing material and created a material using portland cement and asbestos, which is known for its fire-proofing and resistance to breaking under ten-sion. The process he developed, called the Hatschek process on Hatscheck machines, is still in use today even though the industry has moved from asbestos to other fibers. He named his product Eternit, which is what FRC is known synonymously as today.

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hatscheck process

A water-based slurry of fibres with ad-hering fine cement particles is formed into a thin layer on the surface of a sieve cylinder. Three such sieve cyl-inders rotate with up to two-thirds of their diameter immersed in the slurry. The parts of the sieve cyliders project-ing out of the slurry come into contact with an endless, continuously moving felt belt. This felt takes up the fibres and the adhering cement particles to form a thin layer of randomly oriented fibres. The still moist fibre layer is trans-ported on the rotating transport belt, has a water reduced by a suction sys-tem and is then transferred to a form-ing roller. This process continues until the required thickness is achieved

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a_00classification according to volume fraction

low volume fraction (<1%)

The fibers are used to reduce shrinkage cracking. These fibers are used in slabs and pavements that have large exposed surface leading to high shrinkage crack. Disperse fibers offer various advantages of steel bars and wiremesh to reduce shrinkage cracks: – (a) the fibers are uniformly distributed in three-dimensions making an efficient load distribution; – (b) the fibers are less sensitive to corrosion than the reinforcing steel bars, – (c) the fibers can reduce the labor cost of placing the bars and wiremesh.

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moderate volume fraction (between 1% and 2%)high volume fraction (greater than 2%)

The presence of fibers at this volume fraction increase the modulus of rupture, fracture toughness, and impact resistance. These composite are used in construction methods such as shotcrete and in structures that require energy absorption capability, improved capacity against delamination, spalling, and fatigue.

The fibers used at this level lead to strain hard-ening of the composites. Because of this improved behavior, these composites are often referred as high-performance fiber-reinforced composites (HPFRC). In the last decade, even better composites were developed and are referred as ultra-high-performance fi-ber reinforced concretes (UHPFRC).

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mechanism

The composite will carry increasing loads after the first cracking of the matrix if the pull-out resistance of the fibers at the first crack is greater than the load at first cracking;

At the cracked section, the matrix does not resist any tension and the fibers carry the entire load taken by the composite.

With an increasing load on the composite, the fibers will tend to transfer the additional stress to the matrix through bond stresses. This process of multiple cracking will continue until either fibers fail or the accumulated local debonding will lead to fiber pull-out .

According to the report by ACI Committee 554 the total energy absorbed in fiber debonding as measured by the area under the load-deflection curve before com-plete separation of a beam is at least 10 to 40 times higher for fiber-reinforced concrete than for plain concrete.

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fibersfiber size

steel fibers

To bridge the large number of microcracks in the composite under load and to avoid large strain localization it is necessary to have a large number of short fibers. The uniform distribution of short fibers can increase the strength and ductility of the composite.

Long fibers are needed to bridge discrete macrocracks at higher loads; however the volume fraction of long fibers can be much smaller than the volume fraction of short fibers. The presence of long fibers significantly reduces the workability of the mix.

When well compacted and cured, concretes containing steel fibers seem to possess excellent durability as long as fibers remain protected by the cement paste.

In most environments, especially those containing chloride, surface rusting is inevitable but the fibers in the interior usually remain uncorroded.

Long-term tests of steel-fiber concrete durability at the Battelle Laboratories in Columbus, Ohio, showed minimum corrosion of fibers and no adverse effect after 7 years of exposure to deicing salt

microcrackmacrocrack

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a_00glass fibers

Ordinary glass fiber cannot be used in portland cement mortars or concretes because of chemical attack by the alkaline cement paste.

Zirconia and other alkali-resistant glass fibers possess better durability to alkaline environments, but even these are reported to show a gradual deterioration with time.

Similarly, most natural fibers, such as cotton and wool, and many synthetic polymers suffer from lack of durability to the alkaline environment of the portland cement paste.

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types of frccompact reinforced composites (cpc)

Researchers in Denmark created Compact Reinforced Composites using metal fibers, 6 mm long and 0.15 mm in diameter, and volume fractions in the range of 5 to 10 %.

High frequency vibration is needed to obtain adequate compaction. These short fibers increase the tensile strength and toughness of the material.

The increase of strength is greater than the increase in ductility, therefore the structural design of large beams and slabs requires that a higher amount of reinforcing bars be used to take advantage of the composite.

The short fibers are an efficient mechanism of crack control around the reinforcing bars.

The final cost of the structure will be much higher than if the structure would be made by traditional methods, therefore the use of compact reinforced composites is mainly justified when the structure requires special behavior, such as high impact resistance or very high mechanical properties

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slurry-infiltrated-fibered concrete (SIFCON)

reactive powder concrete (RPC)

The processing of this composite consists in placing the fibers in a formwork and then infiltrating a high w/c ratio mortar slurry to coat the fibers.

Compressive and tensile strengths up to 120 MPa and 40 MPa, respectively have been obtained. Modulus of rupture up 90 MPa and shear strength up to 28 MPa have been also reported.

In direct tension along the direction of the fibers, the material shows a very ductile response. This composite has been used in pavements slabs, and repair

Investigators in France by adding metal fibers, 13 mm long and 0.15 mm in diameter, with a maximum volume fraction of 2.5%.

This composite uses fibers that are twice as long as the compact reinforced composites therefore, because of workability limitations, cannot incorporate the same volume fraction of fibers.

The smaller volume fraction results in a smaller increase in the tensile strength of the concrete. Commercial versions of this product have further improved the strength of the matrix, chemically treated the surface of the fiber, and added microfibers.

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multiscale-scale fiber-reinforced (MSFRC)

engineered cementitious composite (EEC)

Researchers the Laboratoire Central des Ponts et Chaussees (France) proposed to combine short and long fibers to increase the tensile strength, the bearing capacity, and the ductility).

With this blend, good workability was achieved with fiber volume fractions up to 7%.

One typical combination of fibers is 5% straight drawn steel fibers, 5-mm long and 0.25 mm in diameter, and 2% hooked-end drawn steel fibers, 25-mm long and 0.3 mm in diameter.

The ultra high-ductility of this composite, 3-7%, was obtained by optimizing the interactions between fiber, matrix and its interface.

Mathematical models were developed so that a small volume fraction of 2% was able to provide the large ductility.

The material has a very high stain capacity and toughness and controlled crack propagation

The manufacturing of ECC can be done by normal casting or by extrusion.

By using an optimum amount of superplasticizer and non-ionic polymer with steric action, it was possible to obtain self-compacting casting.

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fibre C by riederThe glassfibreconcrete panels fibreC are large-format thin concrete panels, rein-forced throughout their thickness with glass and are designed for the cladding fa-cades of buildings, and for interior decoration. The fibre-reinforced concrete panels fibreC successfully combine strength, formability, fire resistance, light weight and the authentic appearance of concrete.

Fibrous concrete and its production technology have been well known for over 30 years. This material is used mainly for architectural decoration and special design solu-tions. The dispersion interaction of concrete and glass greatly increases the strength of the material throughout the reinforcement area.

The glassfibreconcrete panels fibreC divided into:

facade concrete panels;interior concrete panels;concrete siding;shaped concrete elements;small architectural forms;items

Glassfibreconcrete panels fibreC are large canvases and calibrated with a flat geometry, which is achieved by over a 4-week production cycle. The technology of production of concrete panels fibreC implies, first of all, a batch of the correct co-lour, and then its placement in a special form with liquid concrete and six layers of fibreglass, of which the four middle layers are woven into a network, while the remain-ing two are placed in random order. After a 28-day production cycle of hardening the fibre-reinforced concrete by surface treatment and additional boards, including water-repellence treatment, the panels gain water-repellent properties.

Each concrete panel fibreC always has an individual character due to a combina-tion of different shades of colour and texture, such as thin strips, smooth shades, small dents, surface cracks and pores. Panels Fibre C are concrete, nothing more and nothing less.

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Glassfibreconcrete panels have a fibre thickness of 8, 10, 13 mm and are available in for-mats of 1200x2500 and 1200x3600 mm when installing the panels using the technology of ventilated facades.

The concrete panels fibreC are a non-combustible material. They have successfully passed fire tests in Russia and are guaranteed against fires at temperatures up to 350 ° C.

Fiber-reinforced concrete panels fibreC are distinguished by:

strength and durabilitylightweight,high fire-resistant properties,resistance to dynamic and climatic influences,frost resistance,a wide range of colours,a variety of options for the surfacean individual look.

greennessRieder has been certified according to ISO 9001 and ISO 14001. The large number of our patents, tests and certificates underscore the enormous innovative force and technical progress of our company and guaran-tee the safety and reliability of our products.

All our products undergo multi-stage testing in accor-dance with international standards (e.g. EN 12467) to ensure the highest product quality. Apart from stan-dardised testing procedures we underscore our high demands on quality through a close co-operation with architects and suppliers, who are integrated into our quality management system. Definition of variation in quality according to the DIN 18202 standard.

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[c] space pavilion by alan dempsey and alvin huanga_00

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The pavilion was is the winning submis-sion for competition hosted by AA’s Design Research Labratory. It called for the use of Fibre C.The basis of the competition was constructability within a tight schedule and budget, simplicity and elegant form, effective use of material, pa-vilion as a continuous extension of furniture to roof structure.

joint detail winning submission

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fibre C-special

fibreC is a high-strength, thin, flexible and mouldable mate-rial and can be used for flat, curved and all kinds of special shapes.

Owing to the unparalleled mouldability of glassfibreConcrete panels, its unrivalled slenderness and the entire production system as such, fibreC can be used for the most extraordinary applications.

The formation of closed corners and curves in one continuous piece and with uniform robustness opens up new perspectives for wall construction and interior design. Formed parts and 2D elements are custom-made to achieve flowing transitions from interior to exterior surfaces and a smoothcovering for edges.

references

http://www.ce.berkeley.edu/~paulmont/241/fibers.pdfhttp://www.profasad.com/fibre-c/http://cspacepavilion.blogspot.com/

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04/2012

Standard

Size Special sizes Dimensional variation length (3.6 m) Dimensional variation width (1.2 m) Diagonal difference up to | over 1.5 m Diagonal difference over 2.5 m | 3.6 m ThicknessThickness tolerance Edge straightness (Level 1) Perpendicularity (Level 1)

Physical characteristics Tolerances facing up to 0.6 | 1.2 m Tolerances facing up to 3.6 m Swelling Shrinkage Bulk density Bending tensile strength Elastic modulus Dead load / Mass per unit area (13 mm)

Building material class Temperature stability

Conductivity

Weather-resistance Water impermeability Heat-rain-alternate test Frost resistance Frost-defrost-alternate test UV-light resistance Hot water resistance Wet storage resistance Fastening visible Fastening not visible Substructure Joint width

2500/1200 mm and 3600/1200 mm on request± 3 mm ± 2 mm ± 3,5 mm | ± 4 mm± 5 mm | ± 6 mm 13 mm ± 1,3 mm ± 0,05 % ± 2 mm/m

± 2 mm | ± 4 mm ± 8 mm 0,384 mm/m 0,737 mm/m 2,0 - 2,42 kg/dm3

> 18,5 N/mm² (MOR) approx. 10.000 N/mm²26 - 31,5 kg/m² 10*10^(-6) 1/˚ k A1 - incombustible according to humidity up to 350˚ approx. 1.000 Joule / (kg * K) lambda: ca. 2,0 W / (m * K)

given given given given light-, UV-colour pigments given given rivets adhesive, undercut anchoraluminium, steel min. 8 mm

EN 12467 EN 12467 DIN 18202 DIN 18202 EN 12467 EN 12467 EN 12467

DIN 18202 DIN 18202

EN 12467, Category 4 DIN 51045 DIN 4102 | EN 13501

EN 12467EN 12467 EN 12467 EN 12467 DIN 12878 EN 12467 EN 12467

Colours

Polar White Ivory Silvergrey Anthracite Liquide Black

Sahara Sandstone Terra Terracotta Venice Green

Surfaces

MA brushed / smooth surface, natural blushing effect FE sandblasted: blasted at higher pressure, surface is rougherFL sandblast

Assembling and Weather Protection

Hydrophobicity

Colour, Design & Surface

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ness for purpose of the panels, are permitted. EN 12467 / Data sheet Exposed concrete 02/2004 [Publisher.:BDZ/DB

* Subject to the particular quotation documentation. The information contained in this document and the technical description of product characteristics and the technical instructions for their use should not be interpreted as a contrcommitment on the part of the manufacturers. Despite careful inspection, no liability can be accepted for the correctness, completeness and topicality of the document. This is par

Reinforcement Edge formation

** MOR: Modus of Rupture; Design values deviate from MOR in accordance with national rules anregulations. National approvals, rules and regulations apply to the calculation of the rated resistance

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a_00bc movable molds research

In the past in order to create curved concrete surfaces, individual molds would have had to been made. This was time consuming and costly. With the advent of 3-D cad design, a better method would have to arise

Flexible form work, specifically pin molds are advantageous for their re-usability. Its cost effective when com-pared to creating individual molds for complex facades or systems.

The idea of flexible form work goes back to Renzo Piano in the 60’s. He made the concept drawing to the right which has adjustable pins and a flex-ible material on top to hold the form.

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single curved moldOne issue that quickly arises from pin mold is that one has to use previously poured and slightly cured concrete sheets. How-ever timing is key since if it is too stiff, cracks can from and it may not settle completely into the desired shape. If the slab is too fresh it runs the risk of the con-crete slumping and getting displaced and also not remaining smooth with the pins.

A simple experiment to figuer out a proper mixture and precure time is to do a single curved panel.

local displacement

mold is too flexible

mold is too stiff

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double curved moldThere are two possible options for a double curved surface, a plate model and strip model.

The best option though is the strip model since in allows for greater flexi-blity without buckling from the plate.

A frame held the supports at a hori-zontal level, to pour the concrete at. This frame could be lowered with a crane to deform the mould.Foam, polyether, was used as a border for the formwork. It fulfilled the function of withstanding the horizontal concrete pressure, but itwas also flexible enough to follow the deformations of the mould.

a_00bc

1. t = 0 min. The mould is ready for the concrete. The mould is horizontal and rests on a plate which is temporary supported. At t = 0 adding water to the mixture, start hardening of the concrete.2. t = 8 min. Pouring the concrete into the mould.3. t = 15 min. Smoothening of the fresh concrete.4. t = 49 min. Lifting the formwork to be able to remove the temporary struts.5. t = 47 min. Deforming of the mould.6. t = 48 min. The end of deformation process. The element has the final shape.7. t = 1 day After one day of hardening the element is removed from the mould.8. t = 1 day The element above its mould.9. t = 1 day The final element on the supporting points.

for more information and in depth testing of mixures and the processes visit:http://homepage.tudelft.nl/6w3a0/FlexibleMouldProject.htm

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a_01 erwin hauer design #5

Compared to Design 4, the molding of Design 5 involves a few extra steps and additional reinforcement for installa-tions that require high load-bearing ca-pabilities. Due to the comibination of structural simplicity and strength and a highly effective interaction with light.

development process

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front elevation

side elevation

plan

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b_01

_section

_rotated views

_assembly

rotated + mirrored

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b_01I was interested in creating a component that would allow for fl exibility. I apporached the human spine and designed an interlocking linear componet with tolleraces allowed for sub-tle pivoting.

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b_02

scale 1’:1”

base design

variation

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b_03I cut out an inverted pyramid from the center of each faceted compo-nent. each pyramid a dif-ferent height as to allow for variation in aperture.

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connection

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team 4

assembly_side assembly_front assembly_perspective

section

31

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fall 2013