SU647600A1 - Reinforcement element quality control method - Google Patents

Description

The invention relates to the field of construction and may be used in the manufacture of prestressed reinforced concrete products.

Methods are known for determining the mechanical stresses in a reinforcement that is stressed by means of preheating.

One of them is based on the fact that manufactured reinforced concrete products are selectively subjected to mechanical strength tests, and the quality of the whole batch of products is evaluated according to test results. However, this method does not provide sufficient reliability control of all productsGG |.

The closest technical solution to the proposed is to control the quality of reinforcing elements (rods) in the manufacture of reinforced concrete structures, including heating of reinforcing elements placed in shape stops and measured using voltage sensors in the elements during cooling 2l.

The disadvantage of this method is the inability to measure before

complete cooling of the reinforcing elements, as well as the duration of the installation of resonant sensors on the reinforcing elements and measurements. In addition, product inspection is often carried out selectively. For higher reliability of reinforced concrete products, the diameter of reinforcing elements or their number is chosen with a margin, which leads to a waste of reinforcing steel,

The purpose of the invention is the ycj opemie of the process of controlling and enhancing its exact-, that.

The goal is achieved by the fact that mechanical stress sensors are installed on form supports, and temperature sensors are fixed to reinforcing bars, and the moment of occurrence of stresses is recorded

in the elements and their temporal temperature, the value of which determines the ultimate mechanical stresses in the elements.

Consideration of the process of a paneer {I of mechanical stresses in reinforcing elements shows that the dependence of stresses on time is the following:

. . :) g (1Kh1 (1: to-that)

e

Have

.j-K (i-t.V

tse) - Havisaya functions |.

2 (- zoll rebar element

to;

& y - the distance between the stops form;

flCjfe X, respectively, coeffidi opt for linear extension and model upligosti material reinforcement item; -g. - „-.

K - coefficient characterizing the rate of cooling of the reinforcement;

i - current time;

 the moment of time when Vc K y, that is, when a mechanical stress begins to occur in the reinforcing element;,;, ..,.

TC - temperature of the reinforcing element at the time

t t

TO

Tg is the ambient temperature. : h

The drawing is a graph of dependence. temperatures at cooling (curve 1) and mechanical stress versus time (curve 2) for reinforcing elements made from C 10 grade steel with a diameter of 2–2 mm,

Curve 2 originates from a point, ki on the abscissa axis, at which Vts Eu, that is, from the point corresponding to the origin of the Mechanical - stitches in the element. This moment of time can be fixed, for example, by using electrical contacts, which are installed, between the shape stop and the anchor head of the reinforcing element. The closure of the contact with the reduction of 1Sh {11g eleySh1a to the distance

647.600

between the stops form. is a signal for temperature measurement.

The temperature value at this point in time determines the final mechanical tension yarns that will exist in the reinforcement element of the sandstone, its complete cooling.

For reinforcing elements of different diameters, different values of finite stresses correspond to each temperature value. These dependences are presented in the form of nomograms. Nomograms are also compiled with allowance for corrections for the deformation of the anchor heads and shape stops when the elements are compressed. .

From the measured value of the temperature at which the growth of mechayic stresses began, the final stresses are determined with the help of nomograms, which are established in the reinforcing element after it has completely cooled.

Claims (2)

1. USSR author's certificate No. 351066, cl. q 01 W 33/38, 1968 2. Dtshenko V. T. idr. Measurement of the tension force of reinforcement in the manufacture of prestressed the same. concrete products, M., stroiizdat, G968, p. 54-55. 05 10 15 20 25 50 35 IMUH.