Loads


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Loads

 

(in structural mechanics), force actions that produce changes in the stress-strain state of the components of buildings and structures. The following loads are distinguished according to the nature of their changes over time: static loads, whose place of application, direction, and intensity are assumed in calculations to be independent of time or to change so slowly that the resulting forces of inertia may be disregarded, and dynamic loads, whose magnitude, direction, and site of application change so rapidly that forces of inertia must be taken into account in calculations.

Static loads are divided into constant (or dead) loads, which in calculations of any given system are assumed to have constant action (the empty weight of structures, ground pressure, and so on), and intermittent (or live) loads, which may or may not be taken into account in calculations, depending on their significance for the structure in question. Intermittent loads are in turn divided into short-term traveling loads, which change their position (loads resulting from the congregation of people on the floors of buildings or from automobiles and trains on the spans of bridges), and long-term fixed loads (for example, the weight of stationary equipment and of racks and bins in warehouses).

The following loads are distinguished according to the nature of application to the body on which they act: concentrated loads, which are applied to a very small area (point), and spread loads, which are applied to an entire surface (line) or part of it. Spread loads are characterized by the intensity—that is, by the limiting ratio of the magnitude of the resultant load, distributed over a given surface or line, to the magnitude of the area or line on which it is acting, if the latter tends toward zero. A spread load of constant intensity is said to be uniformly spread. A spread load whose points of application occupy an entire surface or section is called a continuous, or distributed, load.

In calculations of structures by the method of limiting states, a distinction is made between rated loads, which are established by design standards and correspond to the conditions of normal use of the structure, and design loads, which are determined with reference to possible deviations from conditions of normal use of the structure. In cases of simultaneous action of several loads, the least favorable design load combination is determined; it corresponds to the critical value of the force or displacement arising in the elements of the structure or installation.

REFERENCE

Stroitel’nye normy ipravila. Part 2, sect. A, ch. 11: “Nagruzki i vozdeistviia: Normy proektirovaniia.” Moscow, 1962.

L. V. KASAB’IAN

References in classic literature ?
Very well," said the Abyssinian, "I promise, and even if there be but five loads you shall have your freedom; but until the gold is in my possession you remain a prisoner.
While Werper dreamed of freedom and the unmolested enjoyment of the fortune in his stolen pouch, and Abdul Mourak lay awake in greedy contemplation of the fifty loads of gold which lay but a few days farther to the south of him, Achmet Zek gave orders to his lieutenants that they should prepare a force of fighting men and carriers to proceed to the ruins of the Englishman's DOUAR on the morrow and bring back the fabulous fortune which his renegade lieutenant had told him was buried there.
The fitful bursts of sleet had changed into a steady rain and the horses had heavy work even without a load behind them.
I know how to load a pistol now; do you know how to load a pistol, Keller?
And running still, Kama groaning on top the load, and Daylight leaping at the gee-pole to avoid going under the runners of the flying sled, they arrived at Dyea by the sea.
A Waggoner was once driving a heavy load along a very muddy way.
Buck watched them apprehensively as they proceeded to take down the tent and load the sled.
You've got a right smart load as it is," said one of them; "and it's not me should tell you your business, but I wouldn't tote that tent along if I was you.
She shook her head decidedly, and Charles and Hal put the last odds and ends on top the mountainous load.
As they swung on the turn the sled went over, spilling half its load through the loose lashings.
Half the load and twice the dogs, if they ever expected to reach Dawson, was what was said.
I kept my piece in my hand still without firing, being willing to keep my charge ready, because I had given the Spaniard my pistol and sword: so I called to Friday, and bade him run up to the tree from whence we first fired, and fetch the arms which lay there that had been discharged, which he did with great swiftness; and then giving him my musket, I sat down myself to load all the rest again, and bade them come to me when they wanted.