RU53776U1 - BENCH FOR TESTING REINFORCED CONCRETE ELEMENTS FOR A SLIDING EXCENTRED SHORT-TERM DYNAMIC COMPRESSION - Google Patents

Abstract

A useful model may find application in dynamic testing of reinforced concrete samples. The technical result consists in creating a stress-strain state characterized by the simultaneous action of bending moments of two planes and compressive longitudinal force during short-term dynamic loading. To accommodate the ends of the reinforced concrete element, the stand contains supporting elements mounted on the power floor, in the cutouts of which the rollers are installed, in one of the supporting elements - motionless, and in the other - with the possibility of horizontal movement. There are metal plates on the rollers. To create short-term impacts, the stand contains a loading device in the form of a pile rig, the masts of which are equipped with a load limiter, and a loading beam. To create bending moments of two planes on either side of the loading device, two additional traverses are installed on additional supports. The rotation of the reinforced concrete element is carried out due to the releases of its reinforcement, passed through oval holes made in one of the additional traverses. The compressive load is supplied by means of a jack located at the other end of the reinforced concrete element between it and the second additional traverse, which is solid, as well as cords fixed by the ends to additional traverses.

Description

The utility model relates to testing equipment, namely, machines for testing samples for oblique eccentric compression.

An analogue of the claimed device is a testing machine for dynamic tests of reinforced concrete elements for impact load using the energy of a falling load, presented in the collection: Impact: Eff. Fast Transient Loadings: Proc. 1 ^st Int. Conf.Eff. Fast Transient Loadings. Lausanne, p. 37-65. Article title: Constitutive modeling of concrete under impact loading (Impact ratios for concrete). Authors: John. R., Shah SP The machine includes a loading device consisting of a concrete base, columns, load, load drive, an electro-strain gauge force sensor, a strain sensor, an acceleration sensor, a speed sensor and an optical measuring unit connected to a computer. This machine provides bending testing of reinforced concrete elements. At the same time, it is not possible to compress the element with longitudinal compressive force. Test reliability is enhanced by automatically calculating bending stresses and strains.

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

Also known installation for testing beams presented in the journal "Concrete and reinforced concrete" No. 5, 1969, S. 29. The installation consists of support and loading saddles, rigidly mounted on the power floor, supporting grips, loading shoes, swivel bracket,

rotary traverse, detachable traction with coupling, spring dynamometer (force meter) of roller bearings, support joints, rollers, loading traverse. This installation allows you to study the operation of reinforced concrete elements with oblique bending, but does not allow you to create oblique eccentric compression in the reinforced concrete element.

The closest device adopted for the prototype is a stand according to the patent of the Russian Federation for utility model No. 48225. This device contains: support elements mounted on the power floor, additional supports located on both sides of the loading device, additional traverses installed on these supports; cords, the ends of which are fixed in additional traverses, three metal plates, rollers, loading traverse, load meter and jack. The loading device is made in the form of a pile rig, the masts of which are equipped with a load limiter. One roller is placed motionless in the cutout of one support element, the other in the cutout of the second support element with the possibility of horizontal movement, two metal plates are placed on the rollers, and the third is fixed on the outlets of the reinforced concrete element. Traverses are made with holes for skipping releases of reinforced concrete element reinforcement. A jack is installed between the third metal plate and the additional traverse. Supports for additional traverses are made with the possibility of adjusting their height. This setup allows testing reinforced concrete elements for oblique eccentric short-term dynamic tension, but does not allow investigating the operation of the element when bending moments of two planes occur and the action of longitudinal compressive force, which, as shown by theoretical studies, in some cases, occurs during the operation of reinforced concrete structures (reinforced concrete columns industrial buildings).

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 compressive 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 beam, rollers, two metal plates to accommodate the ends of a reinforced concrete element, a force meter, additional supports located on both sides of the loading devices, additional traverses installed on these supports, cords whose ends are fixed in additional traverses 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, while one roller is stationary in the cutout of one of the support elements, and the second is in the cutout of the second support element with the possibility of horizontal movement, with one metal plate mounted on a stationary roller, the other is on the moving one. It is also common that one additional traverse is made with oval holes for skipping the outlets of the reinforcement.

Unlike the prototype, the stand has two, not three, metal plates, which are located on rollers in the places of support of the reinforced concrete element. At the same time, only one of the additional traverses has openings for passes of releases of the reinforcement of the element, and the second is solid, while the jack is located between the additional traverse and the reinforced concrete element itself and rests against the traverse.

In special cases, supports for additional traverses in the stand are made with the possibility of adjusting their height, and the stand is equipped with an insurance system to limit the deflection of a reinforced concrete element installed at a distance of its maximum allowable deflection.

With oblique eccentric compression in the reinforced concrete element, bending moments arise in two planes and longitudinal compressive force. Since the jack is located directly between the reinforced concrete element and the additional traverse, abutting against it, since its wall is continuous (without holes and outlets of reinforcement missing in them), the test bench allows you to create a longitudinal compressive force with the help of a jack, additional traverse and a tie system passed through holes in additional traverses. Moments in two planes are created by rotating the test element by a certain angle, by skipping the valve outlets into oval holes in an additional traverse located on the other side relative to the jack, and applying a transverse dynamic load using a pile driver.

The insurance system is designed to avoid damage to measuring instruments.

The utility model is illustrated by drawings. Figure 1 shows a General view of the test bench; figure 2 is a front view of it, figure 3 is a top view, 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 supporting elements 4, 5. The design scheme is a hinged beam. To do this, on each of the supporting elements 4, 5, rigidly fixed to the force floor 1, there is a roller, respectively 6, 7. On one of the supporting elements 4, the roller 6 moves freely in its cutout, and on the other supporting element 5, the roller 7 is stationary. Metal plates located on casters on which mounted

reinforced concrete element, not shown. To create a compressive load in the experimental sample 2, the outlets of the reinforcement 8 are provided. These outlets 8 are passed through the oval holes in the metal traverse 9, and then anchored behind it. Traverses 9, 10 are mounted on height-adjustable additional supports 11, 12 (Fig. 1). Between the traverse 10 and the reinforced concrete sample 2, a hydraulic jack DG-25 13 is placed, which is connected to the oil station and creates a compressive longitudinal force. Through metal traverses 9, 10 cords 14 with a total length of three meters were passed. Each strand 14 is fixed to the traverses 9, 10 (Fig. 3) on both sides using nuts 15, to ensure the immobility of the additional supports 11, 12. A loading traverse 17 with an insurance system 18 is laid on the experimental sample 2 through metal gaskets 16 (Fig. 2). The insurance system 18 is made to avoid damage to the measuring instruments. It restricts the movement of the sample 2 and the traverse 17 located on it. The insurance system 18 is installed at a distance of the maximum allowable deflection from the experimental sample 2. A special plate 19 is fixed to the traverse 17 for installing the force meter 20, which will record the impact force (Fig. 4). The dynamic lateral load is created using the pile driver 21, by impact. The base of the pile machine 22 is rigidly fixed through the streams of the power floor 23. On the pile driver 21 at a predetermined distance using a winch, a load is fixed 24. To limit the movement of the load 24 after impact on the masts of the pile machine 21, limiters 26 made of metal are fixed through a rubber gasket 25 . They are secured with a bolt and nut 27.

First, with the help of a jack 13, a compressive 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 24 of the pile rig 21. The rotation of the sample 2 is achieved by skipping the outlets

reinforcement 8 through special oval holes in the traverse 9, which allow the experimental sample 2 to move vertically, and horizontally impose a connection. Moreover, in the experimental sample 2 there are bending moments of two planes and a longitudinal compressive force. The mass of the load 24 can be adjusted by adding metal plates 28. The force of the impact is also regulated by increasing or decreasing the height of the fall of the load 24.

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

Claims (3)

1. A test bench for testing reinforced concrete elements for oblique eccentric short-term dynamic compression, containing support elements mounted on the force floor, rollers, one of which is fixed in the cutout of one of the support elements, and the other with the possibility of horizontal movement in the cutout of the second support element, two metal plates to accommodate the ends of the reinforced concrete element, one of which is located on a stationary roller, and the other on a movable, loading device in the form of a copier, the masts of which are equipped with a load limiter, a loading beam, two additional traverses mounted on additional supports on both sides of the loading device and one of which is made with oval holes for passing releases of reinforcement of the reinforced concrete element, tie rods fixed with ends on the corresponding additional traverses, a load meter and a jack, characterized in that the second additional crosshead is solid, and the jack is placed between it and the reinforced concrete element and abuts against reverse. 2. The stand according to claim 1, characterized in that the supports for additional traverses are configured to adjust their height.
3. The stand according to claim 1 or 2, characterized in that it is equipped with an insurance system to limit the deflection of a reinforced concrete element installed at a distance of its maximum allowable deflection.