8. Find synonyms to the following words. Compose your own sentences with them

Склад, гладкий, балка, желоб,паз

9. Make suitable word combinations. Translate them

precast ribbed i-beam hollow lightweight presstressed chanell erection sloped cement inflated i shaped reinforcing shear moment web shop main

core slabs section joists filler units beams equipment grooves mortar joists bars rods rubber tubes cage steel floor

10. Read the text. Find key-words characterizing all types of beams Beams

Precast concrete floor units are at present manufactured mainly in the ollowing different types:

a) Ribbed slabs or channel units;

b) Вeams of hollow core type;

c) I-beam section, with either cast-in-place or precast slab;

d) Inverted I-beam joists with lightweight filler blocks between;

e) Beams assembled from hollow concrete blocks;

f) Precast and prestressed floor units.

Channel Beam.—The type most frequently used in in­dustrial building, warehouses, etc., where a plain ceiling is not required.

For sites where heavy erection equipment is available, several of the channel types are precast in one wider beam with several ribs. The advantage of this is quicker erection and a reduction in the quantity of concrete, its disadvantage being that such units are not so suitable for continuity reinforcement.

Hollow Beam.—The hollow beam with a box cross section gives a smooth and plain ceiling finish immediately after erection.

On the external sides there are sloped grooves provid­ing for a better connection with the neighbouring units when the joints are filled in with cement mortar. Because of the plain ceiling, hollow beams are used mostly for dwell­ings, offices, and such public buildings as schools and hospi­tals. Channel beams are lighter in weight, easier to manu­facture and cheaper.

An important feature in the production of hollow beams is the use of inflated rubber tubes which make dismantling quick, easy, and safe.

I-section.—There are several methods of forming I-shaped joists. In most of them, all reinforcing bars are assembled in advance to form a reinforcing "cage". The shear rods are welded to the moment bars top and bottom. The shear rods are generally round, welded in between the moment bars, making a space between the moment bars. From the manufacturing standpoint this is ideal, since thesizeof the shear-bars may be kept constant and their spacing can be varied according to the need for shear reinforcing. The reinforcement in these joists is well anchored because of the welded connection between web and main steel.

T-section. — The T type is most simple to manufacture, being cast with the flange inverted on the shop floor. But this section should only be applied to roof structures, or to floors in dwellings, etc., where heavy local superloads are never to be expected. For, although the small mortars joint between the top flanges of the two neighbouring sections might secure an equal deformation of loaded and unloaded members at the designed load, it will crack long before the critical load is reached; at that stage each of the loaded members is detached from the other, and there is no cross distribution of the loads.

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