I. Знайдіть в кожному ряді слово, переклад якого наданий на початку ряду.

a) середній - 1) adjacent, 2) average, 3) adequate;

b) незначний - 1) neighbouring, 2) necessary, 3) negligible;

100. обмеження - 1) rupture, 2) reinforcement, 3) restraint.

II. Дайте українські еквіваленти наступних сполучень іменників.

pavement temperature, temperature changes, tensile stress, top surface, thickness design purposes, steel reinforcement.

III. Складіть англо-українські пари словосполучень, еквівалентних за значенням.

1. temperature conditions; 2. steel reinforcement; 3. Compressive stress; 4. tensile stress; 5. temperature-frictional stress; 6. tensile strength; 7. average temperature.

1. напруження при стисненні; 2. температурні умови; 3. напруження,

яке виникає від сил тертя при зниженні температури; 4. арматура залізобетону; 5. напруження, яке виникає при розтягненні; 6. середня температура;

7. межа міцності розриву.

TEMPERATURE-FRICTIONAL STRESSES

Stresses are also produced in concrete pavements as a result of the changes in the 'average' temperature of the slab, which cause it to expand and contract. In other words, as the pavement temperature increases or decreases, each end of the slab tries to move away from or toward the slab centre. If cooling takes place uniformly, a crack may occur about the centre of the slab. If expansion is excessive and adequate joints are not provided, then 'blow-ups' may result in adjacent slabs being quite dramatically jack-knifed into the air.

Assuming that adequate widths of joint were provided, the stresses due to 'average' temperature changes could be considered negligible provided that there was no friction between the slab and the supporting soil. In fact, however, considerable friction may be developed between the slab and the soil, with the result that when the slab attempts to expand it is restrained from doing so and compressive stresses are produced at its underside. As the slab contracts the same type of restraint is exerted but this time it results in tensile stresses in the bottom of the slab. It is to be noted that stresses resulting from restraint of this type are only important when the slabs are quite long (say over 100 ft). They are critical only when conditions allow them to be applied when the combined loading and warping stresses from other sources are at their maximum. Since the maximum tensile stress due to frictional restraint only occurs when a slab is contracting and since the warping stresses resulting from temperature gradients are not at their maximum at this time, the net result is that in practice these restraint stresses can usually be neglected when calculating the maximum tensile stresses in a concrete road slab for thickness design purposes.

One further point, which might be mentioned, is that the magnitude of the restraint tensile stresses which are developed is heavily dependent on the temperature conditions prevailing at the time the slab is laid.

Завдання I. Визначте функцію кожної безособової форми, яка зустрічається в тексті.

Завдання II. Розкажіть про дію напруження, яке виникає від сил тертя при зміненні температури.

REINFORCEMENT IN CONCRETE ROAD SLABS

The previous discussion on stress considerations has dealt only with plain road slabs, and no mentions have been made so far of the effects of the introduction of steel reinforcement. The reason for this omission is that at this time there is no acceptable theory on which such a discussion could be based.

Reinforcing steel is, and has been for many years, used in concrete road construction. It should be clear that the term 'reinforcing' i.e. used very loosely indeed in reference to concrete road slabs, as both the amount of steel used and its function are very different from those utilized in 'normal' reinforced concrete building construction. When a bridge, a building or some other such structure is being constructed, the concrete is normally expected to carry only the compressive stresses which are produced, and reinforcing steel is incorporated in the structure to withstand the tensile stresses. The reason for this is that if the relatively low tensile strength of the concrete is exceeded, the result could well be complete collapse of the structure, with perhaps the loss of many lives. With a concrete road, on the other hand, slab 'failure', does not result in any such dramatic happenings since the slab will still be supported. Indeed, if the pavement is on a good foundation the riding quality of the road may be so little affected that the only obvious damage is the aesthetic one of unsightly cracks in the surface. As a result the generally accepted design approach has been primarily to include only sufficient reinforcing steel to minimize the development of cracks and only secondly to regard the steel as tarring any of the tensile stresses.

A practical by-product of this form of usage is that it allows a considerably greater spacing to be used between transverse joints. Examination of the literature on concrete roads shows that in the past there have been considerable differences of opinion as to where and how much of the reinforcing steel should be placed in a concrete pavement. This was primarily due to a lack of understanding of its function in the slab. If tensile stress resistance is the principal criterion, then it is of course logical that two layers of steel should be used, so that one layer is at the top and the other at the bottom of the slab. The function of the top layer of steel is to resist the load and warping tensile stress at the edges and corners at the top surface, while the bottom layer resists the tensile stresses set up at the interior of the underside of the slab.

If only one layer of reinforcement is used and the governing criterion is again resistant to tensile stress, then the layer should be placed near the top of the slab, since it is there that the more critical stresses are induced. Even if it were possible to analyze these stresses exactly, it is doubtful whether in normal road construction the inclusion of sufficient steel in a road slab to completely resist the stresses is justified; not it is necessary from a safety aspect, but it is probably not an economical proposition either, since with modern construction methods additional load carrying capacity could probably be secured at less cost by using additional thickness of concrete than by using relatively large amounts of steel needed to increase the pavement's flexural strength to the same extent. Hence the decision, as has been stated before, to add only relatively small amounts of steel which are necessary to resist crack development at the top of the slab.

Завдання I. Знайдіть речення, які містять інфінітив; визначте його функції. Речення перекладіть.

Завдання II. Підготуйтесь до бесіди про застосування арматури залізобетону при будівництві доріг.

1. Суб’єктний інфінітивний зворот (The Subjective Infinitive Construction)

Модель: ……. N…… V.... Inf.

2. Об’єктний інфінітивний зворот (The Objective Infinitive Construction)

Модель:…… Vact.... N2 Inf.

3. Незалежний дієприкметний зворот (The Absolute Participle Construction)

Модель:

1. ... (with)N...Ving/Ved,N1,...Vf

б) ...N1,...Vf,(with)H...Ving/Ved

Exercises