Exercise 3. Read and translate text A. Text A. The post and lintel (part 2)

Text A. THE POST AND LINTEL (part 2)

Wood, being a fibrous material, resists tensile stresses well, as does wrought iron and modern steel, and beams of these mate­rials can span significant distances. The ten­sile forces along the bottom of a beam for along the top of a cantilever are determined by the length of the span and the load placed on the beam. It happens so that eventually, given a span and a load sufficiently great, the tensile strength of the material will be exceeded. The beam will crack at the bottom or deform along the top (or both) and will collapse. Stone and solid concrete, being crystalline materials, have less tensile strength than fibrous wood, and a wooden beam over a given span can carry a load that would crack a stone beam carrying the same load. Of course, the stone beam starts out being far heavier by itself.

The solution, in beams of concrete, which has great com­pressive strength, is to place something within the concrete that will take the tensile forces. This was done by the Romans, as well as in modern times, by placing iron (and now steel) rods in the formwork into which the liquid concrete is then poured. The result is reinforced concrete. The steel is placed where the tensile forces accumulate — on the bottoms of beams and at the top of cantilevers. The Greeks also faced this problem. The central opening of the gateway to the Akropolis in Athens, the Propylaia, built 437-32 B.C., had to accommodate the passage of pairs of sacrifi­cial oxen with their handlers; the result was a span of 18 feet (5.5 meters), far too great for a solid block of marble that also had to carry the roof. The solution adopted by the architect, Mnesikles, was to hollow out the beam to reduce its own weight (it still weighed eleven tons) and to place iron bars along the top of the beam, tо carry the weight of the marble blocks above. In this unique instance, the iron bars are at the top of the beam, not the bottom, where they would be expected. Even so, over the centuries cracks developed in this lintel beam.

Exercise 4. Translate the words:

wood, beams, span(v., n.), crack, deform, exceed, top, collapse, force, rod, formwork, opening, roof, reduce, accommodate, accumulate, solution, determine, opening.

Exercise 5. Choose the right translation from A to B:

A: resist, span, crack, deform, formwork, reduce, pour, bar, rod, fibrous, liquid.

B: пролет, уменьшать, растрескиваться, стержень, брусок, жидкий, противостоять, деформировать, лить, опалубка, волокнистый.

Exercise 6. Are these meanings correct or incorrect? Correct the mistakes:

expect – предлагать

develop – развивать

determine – уменьшать

reduce – определять

solution - решение

crack – перекрывать

span – растрескиваться

formwork – брусок

resist – противостоять

pour – лить

Exercise 7. Translate the following word combinations:

fibrous material, tensile strength, wrought iron, modern steel, tensile stress, wooden beam, carry a load, compressive strength, iron rod, reinforced concrete, face the problem, solid block of marble, iron bars.