structural

The explosion caused little structural damage to the office towers themselves.

Although the round arch was used by the ancient peoples of Mesopotamia several centuries before our common era, it was most fully developed by the Romans, who perfected the form in the 2nd century b.c.e. The arch has many virtues. In addition to being an attractive form, it enables the architect to open up fairly large spaces in a wall without risking the building's structural sound­ness. These spaces admit light, reduce the weight of the walls, and decrease the amount of material needed. As utilized by the Romans, the arch is a perfect semicircle, although it may seem elongated if it rests on columns. It is con­structed from wedge-shaped pieces of stone that meet at an angle always per­pendicular to the curve of the arch. Because of tensions and compressions inherent in the form, the arch is stable only when it is complete, when the top­most stone, the keystone, has been set in place. For this reason an arch under construction must be supported from below, usually by a wooden framework.

Pointed Arch and VaultWhile the round arch and vault of the Romanesque era solved many prob­lems and made many things possible, they nevertheless had certain draw­backs. For one thing, a round arch, to be stable, must be a semicircle; therefore, the height of the arch is limited by its width. Two other difficulties were weight and darkness. Barrel vaults are both literally and visually heavy, calling for huge masses of stone to maintain their structural stability. Also, the builders who constructed them dared not make light-admitting openings in or around them, for fear the arches and vaults would collapse, and so the interiors of Romanesque buildings tend to be dark. The Gothic period in Europe, which followed the Romanesque, solved these problems with the pointed arch.

Usually, we expect to see that certain social changes are brought about by the development of agriculture, structural changes in the society like rapid population growth, different social classes.

Today let’s begin to look at structural engineering in the Space Age.

A structural invention had to be made before the physical limitations of stone could be overcome and new architectural forms could be created.

In earlier times it was necessary to design structural systems suitable for the materials that were available, such as wood, stone, brick.

By adjusting the osmotic pressure so that the cells are always fully inflated, the plant is able to withstand great pressure before snapping, so Spartinas may look like simple marsh grass, but they are really a wonder of chemistry, physics and structural engineering that allows them to survive and even thrive in an environment in which most plants will wilt and die within hours.

The arch is among the many important structural breakthroughs that have characterized architecture throughout the centuries.

The resulting adaptations to dry land include some structural features that arose early in plant evolution; now these features are common to virtually all land plant.

A structural invention had to be made before the physical limitations of stone could be overcome and new architectural forms could be created.

The resulting adaptations to dry land include some structural features that arose early in plant evolution; now these features are common to virtually all land plant.