RU48225U1 - BENCH FOR TESTING REINFORCED CONCRETE ELEMENTS FOR A SLIDING EXCENTRED SHORT-TERM DYNAMIC STRETCH - Google Patents

Abstract

Test bench for reinforced concrete elements for oblique eccentric short-term dynamic tension. The utility model relates to test equipment and can be used to test samples for oblique eccentric tension. Support elements are mounted on the power floor, additional supports for the reinforced concrete element, located on both sides of the loading device, additional traverses installed on these supports; cords whose ends are fixed in additional traverses, three metal plates and a jack. The loading device is made in the form of a pile rig, the masts of which are equipped with a load limiter. There are rollers on the supports. One roller is located on one of the supporting elements motionless, and the second in the cutout of the second supporting element with the possibility of horizontal movement. The element was rotated by skipping the outlets of the reinforcement into the oval holes of the additional traverses and anchoring them for the metal plate on one side and for the traverse on the other. The technical result consists in creating a stress-strain state characterized by the simultaneous action of bending moments of two planes and tensile longitudinal force during short-term dynamic loading.

Description

The invention relates to a testing technique, namely, machines for testing specimens for oblique eccentric tension.

An analogue of the claimed device is a testing machine for mechanical testing of tensile materials according to the patent of the Russian Federation for invention No. 2243535, IPC 7 G 01 N 3/08, published 2004.12.27. The machine includes a loading device consisting of a base, columns, a crosshead, a load drive, an electrotensometric force sensor, a passive and active gripper, a strain gauge, an active gripper displacement sensor, a strain measurement unit, a load control unit, and a computer. This machine provides axial deformation of the samples. In this case, when the test samples are stretched, misalignment of the grips may occur. This leads to a spread of test results. In the known machine, the strain gauge is made in the form of two metrologically identical, but mechanically and electrically independent strain gauges connected to the measuring unit. The reliability of the tests is increased by automatically calculating the stresses from the accompanying bending.

However, this test machine does not allow to study the operation of elements in oblique eccentric short-term dynamic tension.

For the prototype adopted installation for testing beams presented in the journal "Concrete and reinforced concrete" No. 5, 1969, S. 29. The installation consists of support and loading seats, rigidly

mounted on the power floor, support clamps, boot shoes, swing arm, swing arm, detachable link with clutch, spring dynamometer (force meter), roller bearings, support joints, rollers, feed beam. This setup allows testing reinforced concrete elements for oblique bending under static loading, but it does not allow investigating the operation of the element in the event of bending moments of two planes and the action of longitudinal tensile forces, which, as shown by theoretical studies, in some cases arise during the operation of reinforced concrete structures.

The objective of the utility model is to expand the range of dynamic research. The technical result, the achievement of which the problem is aimed at, is to create a stress-strain state characterized by the simultaneous action of bending moments of two planes and tensile longitudinal force with short-term dynamic loading.

The problem is solved as follows.

In common with the prototype is that the claimed device contains: supporting elements for a reinforced concrete element mounted on a power floor, a loading device, a loading crosshead, rollers and a load meter.

But unlike the prototype, this device contains:

additional supports for the reinforced concrete element located on both sides of the loading device, additional traverses installed on these supports; cords whose ends are fixed in additional traverses, three metal plates and a jack. The loading device, in contrast to the prototype, is made in the form of a pile rig, the masts of which are equipped with a load limiter, while one roller is stationary on one of the supporting elements, and the second in the cutout of the second supporting element with

the possibility of horizontal movement, with one metal plate mounted on a fixed roller, the other on a movable, and the third mounted on the outlets of the reinforcement of the reinforced concrete element. In addition, the jack is located on one side of the installation, between the metal plate and the additional traverse, and in the additional traverses there are oval holes for passing releases of reinforcement of the reinforced concrete element.

With oblique eccentric tension in a reinforced concrete element, bending moments arise in two planes and a longitudinal tensile force. The test bench allows you to create a longitudinal tensile force using a jack, a metal plate and a system of cords, passed through holes in additional traverses. Moments in two planes are created by rotating the test element at a certain angle, by skipping the outlets of the reinforcement into oval holes in the additional traverses, and applying a transverse dynamic load using a pile driver.

The utility model is illustrated by drawings. Figure 1 shows a General view of the test bench; in figure 2 is a front view, in figure 3 is a top view, in figure 4 is a side view.

The design of the stand is installed on the power floor 1, to ensure rigid fastening. Experimental sample 2, through a metal strip 3 (figure 2), lies on the supports 4, 5. The design scheme is a hinged beam. For this, on each of the supports 4, 5, rigidly fixed to the force floor 1, there is a roller, respectively 6, 7. On one of the supports 4, the roller 6 moves freely in the neckline of the support, and on the other support 5, the roller 7 is stationary. Metal plates located on rollers on which a reinforced concrete element is mounted are not shown in the drawing. To create a tensile load in the experimental sample 2, releases of reinforcement 8 are provided.

the outlets 8 are led through oval holes in the metal traverses 9, 10, and then anchored on one side immediately after the traverse 9, and on the other hand, are passed through the oval holes in the traverse 10 and the metal plate 11 and then anchored. The rotation of the sample 2 is achieved by passing the releases of the reinforcement 8 through special oval holes in the traverses 9, 10, which allow the experimental sample 2 to move vertically, and impose a connection horizontally. Traverses 9, 10 are mounted on height-adjustable additional supports 12.13. Between the traverse 10 and the plate 11 is placed a hydraulic jack DG-25 14, which is connected to the oil station and creates a tensile longitudinal force. Through metal traverses 9, 10 cords 15 with a total length of three meters were passed. Each strand 15 is fixed to traverses 9, 10 on both sides using nuts 16, to ensure the stability of additional supports 12, 13. A loading traverse 18 with an insurance system 19 is laid on an experimental sample 2 through metal gaskets 17. The insurance system 19 is designed to avoid damage measuring instruments. It restricts the movement of the sample 2 and the traverse 18 located on it. The insurance system 19 is installed at a distance of the maximum allowable deflection from the experimental sample 2. A special plate 20 is fixed to the traverse 18 for installing the force meter 21, which will record the force of impact. The dynamic lateral load is created using the pile driver 22, by impact. The base of the pile machine 23 is rigidly fixed through the streams of the power floor 24. A load 25 is fixed to the pile machine 22 at a predetermined distance using a winch. To limit the movement of the load 25 after impact on the masts of the pile machine 22, limiters 27 made of metal are fixed through a rubber gasket 26 . They are secured with a bolt and nut 28.

First, using a jack 14 through the releases of the reinforcement 6, a tensile load is supplied. Then, experimental sample 2 is aged for approximately ten minutes. After this time, a transverse shock is applied. The shock load is created by the mass of the falling load 25 of the pile unit 22. In this case, the bending moments of two planes and the longitudinal force act in the experimental sample 2. The mass of the load 25 can be adjusted by adding metal plates 29. The force of impact is also regulated by increasing or decreasing the height of the fall of the load 25.

To obtain data on the stress-strain state of the experimental sample, a set of standard measuring instruments is used.

Claims (2)

1. A test bench for testing reinforced concrete elements for oblique eccentric short-term dynamic tension, containing support elements mounted on a force floor, a loading device, a loading beam, rollers, a load meter, characterized in that it is equipped with additional supports located on both sides of the loading device, and additional traverses installed on these supports, in addition, it additionally contains cords, the ends of which are fixed in additional traverses, three metal plates and a jack, while one roller is fixedly mounted on one of the supporting elements, the other is in the cutout of the second supporting element with the possibility of horizontal movement, one metal plate is located on the fixed roller, the second on the movable, and the third is fixed to the outlets of the reinforced concrete element, moreover, the loading device is made in the form of a pile installation, the masts of which are equipped with a load limiter, and the jack is located on one side of this installation between the third metal plate and additionally crosspiece, with additional cross-members are made oval apertures for the passage of concrete reinforcement member releases. 2. The stand according to claim 1, characterized in that the additional supports are made with the possibility of adjusting their height.