A few remarks about and examples of questions

A few remarks about and examples of questions for the exam next Monday A question regarding the Pantheon: Why does it have a cracking pattern like the one shown on the left below? •

answer • A hemispherical dome will develop horizontal tension in the lower part of the dome, the way a hemisphere of Jello made in a bowl will bow out in the lower region (until 52 degrees up, measured from the center point of the dome. • The cracks are widest at the bottom and narrow down to almost nothing at about 52 degrees.

http: //www. achterboschzantman. nl/? portfolio=houten-brug-sneek https: //www. hasslacher. com/de/la-seine-musicale • http: //transsolar. com/de/projects/la-seinemusicale? ct=t(Transsolar_Newsletter_September_20179_7_2017 • La Seine Musicale, Boulogne-Billancourt hess timber

• After being overshadowed by steel and reinforced concrete, wood is on the rise again in large scale construction. • The ‘modern’ use of wood is very different from the historic uses of heavy timber. • Glue lam and cross laminated timber have made large sizes and difficult shapes possible. • Computer driven machinery makes forms possible that were unthinkable before.

How to make a column stand on end? Post-tension it! In a sketch show this principle is used in reinforced concrete construction.

Describe the different roles that are played by the Gherkin’s core columns and diagrid structure in making the building resist the ‘dead’ load of the structure itself, the live load of the occupants, and the lateral loads of winds and earthquakes

Answer to the Gherkin question on the previous slide • Building our cardboard and reed model showed how strong and stiff the diagrid is by nature (even after we removed the core tube and the spacing blocks!) Being double-curved AND triangulated. . this makes sense! • As a result of the stiffness of the diagrid system the core columns only have to bear the major part of the gravity loads (‘live’ and ‘dead’ loads. )

7. Both Structures shown are anti-clastic, doublecurved surfaces. Describe the differences between the structures

• The tensile double-curved roof is in pure prestressed compression. This will guarantee that the roof does not ‘flutter’ in the wind or excessively sag when rain falls on it. • The double-curved reinforced concrete bridge support system acts mostly in pure compression. A beam bridge of this span would be subject to serious bending forces which would require a lot of concrete and reinforcement to counteract.

In the examples below: Positive curvature results in compression and negative curvature in tension. How would these structures perform in a gravity-free environment, like outer space? What consequences would that have for structures out in space?

• In gravity-free space there exists still the mass of objects, but not the continuous pull we feel on earth. So the issue is to hold elements in place (which in daily life in the space station is done using Velcro straps all over the place. ) • But a heavy structure has to be strong enough to resist the impact of another structure hitting it (think of a space station being hit by a docking rocket going too fast. )

Why do these stairs not fall down?

• The adhesion of the mortar to the bricks and tiles of these stairs is able to supply shear strength to the over-all structure. • They can be built by ‘gluing’ the bricks and tiles in place without using scaffolding by using a very sticky lime mortar.

Buildings actually fall over on occasion. . why? • https: //www. youtube. com/watch? v=s. D 6 XSj. B 8 ZMw

Draw a sketch of a building that uses the structural principal at work in the illustrations below

The structures shown are 100 years apart in the days they were built. What has changed in that time with the construction of diagrids?

• Computer analysis and computer driven fabrication make unusual forms possible that would have been beyond the capacity of previous ‘man power’.

The phenomenon of buckling, even in slender stone columns. Failure is without warning and very abrupt, and thus very dangerous.

What is going on here? How would you prevent it? Answer: more material in the slab where it meets the column. . Mushroom head, ‘dropped panel’

The illustrations explain the main four forces and the force-system of bending. In five simple sketches show a structural situation where these forces will be at work