Assignment 2 2012Five groups to study

Compressionshortening along the axis

Tension elongation along the axis

Shear shifting across the axis

Torsion rotation about the axis

Bending curvature along the axis

‘force influences/reactions/loads’:For all to read: The value of history in the study of structures by Henri Petrowski

A: In-line forces:

Group 1: Compression

Important: don’t forget buckling

Typical ‘compression element’ in architecture: colonnade.. in humans: toes (ouch!)

The highest building in the world relies on compression in the columns against gravity loads.

(but the most important forces are the overturning forces of wind and earthquake!)

Vault building: all material in compression.

http://www.youtube.com/watch?v=ZrMbt_z14VM&feature=fvwrel

John Ochsendorf, modern formwork-free vault builder at MIT

-------------------------------------------------------------------------------------------------------------------------------

Group 2: tension

Former Philips Headquarters, Eindhoven, Holland ‘Cube’ building Vancouver, Canada

Tensile spiderweb-tensile structure by Frei Otto tensegrity of the human body

Observation/question:

Tension always has a compression component.. does compression always have a tension component?

The straighter the clothesline, the higher the stress..

(in this case there is an extra line to help carry the load..notice the connector..)

Compression-Tension balance

Tensegrity http://www.flickriver.com/groups/tensegrity/pool/interesting/

Group 3: Off-line forces: (shear) Shear

Full scale building shear animation

Punching Shear Maillart’s mushroom columns 1910

Shear wall behaviour in earthquakes:

http://richter.uprm.edu/~jclinton/Lectures/9/9buildings.htm

Group 4: Rotational forces: torsion

--- dis-torsion!

Torsional response to earthquake or winds

Torsional response of a building:

http://cite.iiit.ac.in/vlab/c ITe/media/eerc/Expr8/torsion6.swf

Millau Viaduct in France: Compression and bending in the support pillar and the column on top, pure tension in the cables, torsion and bending in the bridge deck.

http://www.youtube.com/watch?v=HUjAkIAuChk&feature=fvsr

Group 5. Moment related forces: bending

Images above taken from Petroski

Rigid moment resistant joint Pin-connected joint

Part of a Vierendeel truss

Stress distribution in rigid joint Cartagena Building that failed at the rigid joints

Cartagena building: note holes in beams Cartagena building: Very solid foundation structure

Buckling of the web of I beams that were weakened by a test fire.

-----------------------------------------------------------------

Assignment 2 2012

5 groups of students..

1. Research your force-phenomenon in depth by researching and documenting structures/buildings and by producing sketches, diagrams and maybe animations that explain the phenomenon.

a. give historical examples.

b. give examples of the force-phenomenon in different materials.

c. give examples of special joints and methods to deal with ‘your’ force-phenomenon.

2. Make : a physical model that demonstrates your particular force phenomenon in as clear a way as possible.

Every group shall prepare a carefully timed 20 minute presentation of their ‘force phenomenon’ to the class on Wednesday morning Oct 29.

Interesting videos:

Installation of wood floor trusses:

http://www.youtube.com/watch?v=pR_2fumGJEQ&feature=related

Maison en bois construction:

http://www.youtube.com/watch?v=WQrWdvPZhAA&feature=related

Design-construction-flaw :

http://isadikin.com/2007/11/26/designers-pitfall-2-the-deceiving-tube-joint/#more-81

an interesting use of concrete block and cantilevered concrete slabs by Frank Lloyd Wright:

http://blog.archpaper.com/wordpress/archives/45015