Structural elements

Warming-up

1. What is the function of beams?

2. What are the earliest examples of the usage of beams?

Read the text and say what materials were used for the construction of beams; what material is used now?

BEAMS

Already in the early 3'^d millennia ВС, in Zozer's tomb complex at Saqqara blocks of stone were being deliberately shaped for use as ceding beams instead of just used as found. The Ш that their undersides were cut to a rounded form suggests an even earlier use of cut timber, probably palm logs.

This is to be expected, since timber is easier to cut and transport. Apart from its inferior durability, it is also a more appropriate material because the structural action of a beam involves internal tension as we 1 as compression. Besides, timber, stone, has a tensile strength along the grain to match its compressive strength. With stone there was only one possibility - the use of metal reinforcement at the bottom to improve

the tensile weakness..

Iron beams became structurally important elements only in the late 18^th century with the widespread introduction of cast iron.

Reinforced concrete became a highly versatile structural material, since the strength of the concrete, the overall geometry of the element, and the quantity and placement of the reinforcement rods were all under the designer's control.

Vocabulary...............................................

deliberately — умышленно, нарочно

ceiling — потолок

to suggest — предполагать

log — бревно

inferior — худший (по качеству)

durability — прочность, стойкость

appropriate — подходящий

to involve — включать, вызывать

compression — сжатие

grain — (зд.) волокно

along the grain — по направлению волокна

versatile — многосторонний, гибкий

/. Choose the tight adjective.

1. Cut timber, probably... logs were used as ceiling beams.

a) palm b) oak c) sequoia

2. The structural action of a beam involves...tension as well as
compression.

a) external b) internal c) overall

3. Metal reinforcement at the bottom was used to improve the...
weakness of stone.

a) tensile b) earlier c) compressive

4. Reinforced concrete became a highly... structural material.

a) different b) versatile c) expensive

5. The... geometry of the element was under the designer's control.

a) descriptive b) fundamental c) overall

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