CN103335897A - Concrete creep test apparatus and method - Google Patents

Abstract

A loading device and method for a concrete creep test of the present invention solves the problems of the existing concrete creep test device such as high cost, large site occupation, complicated operation, and poor loading stability, and is formed by three steel beams. A loading base and a set of two-stage levers, the two-stage levers include a primary lever steel beam and a secondary lever steel beam. Its beneficial effect is that by adopting the two-stage lever loading structure, compared with the single-stage lever test device commonly used at present, the lever loading efficiency of the creep test can be greatly improved, and the length of the loading lever can be shortened, and the volume of the counterweight and the weight can be reduced. The size of the test site can also reduce the requirements for installing lifting equipment, and it can also save the construction of a large-volume concrete base test platform.

Description

A concrete creep test device and method

technical field

The invention belongs to the technical field of civil engineering and relates to concrete creep test technology, in particular to a loading device for concrete creep test and a creep test method thereof.

Background technique

Concrete creep test is an important material test work in the field of civil engineering. The test content is mainly to determine the creep characteristics of concrete by applying a long-term constant load to the concrete specimen and measuring the growth of its compressive strain with time.

The requirements of the concrete creep test for the loading equipment are: stable load, no need to adjust the load after loading or the number of load adjustments is as small as possible, large loading range, simple operation, accurate and convenient measurement and reading, little influence by temperature/humidity, and small size wait. Due to the limitation of technical conditions, it is relatively difficult to have a loading device that satisfies the above requirements at the same time. The current creep test loading devices can be roughly divided into four types: lever type, spring type, spring lever type and hydraulic type. Among them, the hydraulic loading device is expensive and its application is very limited. The spring-type and spring-lever-type test devices are loaded by springs, which are easy to operate and small in size. However, the long-term compression deformation of the concrete specimen will cause the spring to unload, which will cause changes in the applied test load. Therefore, regular testing is required during the test. Adjust the pressure on the concrete specimen. To a certain extent, this greatly increases the complexity of the experiment. At the same time, the load adjustment needs to be carried out according to the actual measured value of the concrete specimen load, so the measurement error will affect the accuracy of the loading, and then affect the reliability of the test results.

The lever loading device is a creep loading device that is widely used at present. The natural counterweight is amplified by a steel beam and pressed on the concrete specimen. One end of the lever device is connected with the large-volume reinforced concrete base platform through a steel strand, and the other end is hoisted with a weight. The device has simple principle, convenient processing, stable loading, and no need for multiple adjustments during the test. However, in order to obtain the load required for the test (usually hundreds of kilonewtons), there are usually problems such as large counterweights, long levers, large concrete volume of the floor platform, and large floor space.

Contents of the invention

In order to solve the problems of the existing concrete creep test device such as high cost, large site occupation, complicated operation and poor loading stability, the present invention proposes a loading device and method for concrete creep test.

In order to achieve the above object, the technical solution of the present invention is: a concrete creep test device, which is characterized in that it includes three steel beams, and the steel beams are arranged in layers in space to form a loading base and a set of two-stage Lever, the two-level lever includes a first-level lever steel beam and a second-level lever steel beam; wherein, the loading base steel beam and the first-level lever steel beam are used for installing concrete specimens, and the loading base steel beam and the first-level lever steel The first ends of the beams are aligned and connected together by the first connection assembly, the second end of the loading base steel beam is set with ground counterweight, the secondary lever steel beam is aligned with the second end of the base steel beam, and connected by the second The components are connected, the second-level lever steel beam is pressed to the second end of the first-level lever steel beam through the pressure-transferring hinge support, and the second end of the second-level lever steel beam is provided with a test counterweight.

Further, the steel beams all adopt double channel steel section, including the first channel steel and the second channel steel, the openings of the first channel steel and the second channel steel are arranged oppositely, and also include the connecting plate between the channel steel, There are anchor holes on the connecting plate located at both ends of the channel steel, which are used for anchoring the connecting components.

Further, the connecting assembly includes a finish-rolled threaded steel tie rod and an anchor, and the finished-rolled threaded steel tie rod passes through the anchor hole of the steel beam, and is connected to the steel beam by the anchor.

A concrete creep test method is characterized in that comprising the following steps:

a. Site selection and leveling of the foundation;

b. Place the base steel beam on the foundation, and place the ground counterweight at the second end of the base steel beam;

c. Install the concrete specimen on the steel beam of the loading base, install the first-level lever steel beam parallel to the steel beam of the loading base above the concrete specimen, and align the first end of the first-level lever steel beam with the first end of the steel beam of the loading base , and are connected by connecting components;

d. The second end of the first-level lever steel beam is provided with a pressure-transmitting hinge support, and a second-level lever steel beam parallel to the first-level lever steel beam is installed above the pressure-transmission hinge support. end is aligned with the second end of the steel beam at the loading base and connected by a connection assembly;

e. Install the test counterweight at the second end of the secondary lever steel beam.

Further, the counterweights are reinforced concrete ballasts.

Beneficial effects of the present invention: the concrete creep test device of the present invention adopts a two-stage lever loading structure, compared with the currently commonly used single-stage lever type test device, it can greatly improve the lever loading efficiency of the creep test, and shorten the loading lever The length, reducing the volume of the counterweight and the area of the test site can also reduce the requirements for installing lifting equipment, and can also save the construction of a large-volume concrete base test platform.

Description of drawings

Fig. 1 is the schematic diagram of the test device structure of the embodiment of the present invention;

Fig. 2 is the schematic diagram of the steel beam structure of the embodiment shown in Fig. 1;

Fig. 3 is a sectional view of the steel beam shown in Fig. 2;

Figure 4 is a schematic diagram of the structure of the pressure transmission hinge support.

Explanation of reference signs: steel beam 11, first channel steel 111, second channel steel 112, connecting plate 12, anchor hole groove 13, scale 14, connecting component 21, finish-rolled threaded steel bar 211, anchor 212, transmission Compression hinge support 22, pressure bearing shaft 221, steel backing plate 222, limit rod 223, ground counterweight 31, pre-buried tunnel 311, test counterweight 32, concrete specimen 4.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

As shown in Figure 1, a kind of concrete creep test device of body embodiment,

Including three steel beams 11, the steel beams are arranged in layers in space to form a loading base and a set of two-stage levers, that is, the three steel beams 11 are located in the same vertical plane parallel to each other, distributed according to different heights, and It is stipulated that from bottom to top, the loading base steel beam, the first-level lever steel beam and the second-level lever steel beam. The two-stage lever includes a primary lever steel beam and a secondary lever steel beam; wherein, a concrete specimen 4 is installed between the loading base steel beam and the primary lever steel beam, and the concrete specimen 4 is the tested concrete To test the concrete specimen, the steel beam of the loading base is aligned with the first end of the first-level lever steel beam, and connected together through the first connection assembly 21, the second end of the steel beam of the loading base is provided with a ground counterweight 31, and the second end of the steel beam of the second-level lever The beam is aligned with the second end of the base steel beam and connected through the second connection assembly 21. The secondary lever steel beam is pressed to the second end of the primary lever steel beam through the pressure transmission hinge support 22, and the secondary lever steel beam The second end of the test counterweight 32 is established. In this embodiment, the counterweight is realized by pouring concrete piers. Since the ground counterweight 31 needs to press through the second end of the first lever beam, a pre-embedded pipe 311 is required in the ground counterweight 31 so that the connecting assembly 21 can The connection between the first lever beam and the third lever beam is realized through the counterweight.

As shown in Figures 2 and 3, the steel beams 11 all adopt a double channel steel section, including a first channel steel 111 and a second channel steel 112, and the openings of the first channel steel 111 and the second channel steel 112 are placed oppositely. It also includes a connection patch 12 between the channel steels, the first channel steel and the second channel steel are connected together through the connection patch 12, wherein the connection patch plates at both ends of the channel steel have anchor holes for connecting components anchoring.

In order to reduce the difficulty of opening holes, a certain gap can be reserved between the two channel steels when the first channel steel and the second channel steel are spliced together, so that the finished rolled threaded steel bars 211 of the connection assembly 21 can pass through. The size of the gap is also determined by the diameter of the finish-rolled rebar pull rod 211 that is used to connect and fix. In order to make the device of this embodiment have adjustment space during the loading test, the anchor hole is set as an anchor hole groove 13, that is, the anchor hole groove 13 as shown in FIG. The groove-shaped through hole opened in the direction of the lever arm (it can also be the groove-shaped through hole reserved when two pieces of channel steel are spliced together). In this embodiment, in order to make the adjustment of the load more rapid and accurate, there is also a scale 14 on the anchor hole 13 for indicating the position of the anchor on the lever steel beam, which is used to assist in quickly adjusting the load to meet the requirements.

As shown in Fig. 1, Fig. 2 and Fig. 3, this embodiment also provides a connection assembly 21, which includes a finished-rolled threaded steel tie rod 211 and an anchor 212, and the finished-rolled threaded steel bar tie rod 211 passes through the steel beam The anchor hole is anchored with the lever beam 11 through the anchor.

As shown in Figure 1, Figure 2, Figure 3 and Figure 4, in order to improve the accuracy of load loading, the concrete creep test device of this embodiment includes a pressure-transmitting hinge between the second lever beam and the concrete specimen 4 Seat 22 also transmits pressure through a pressure-transmitting hinge support 22 between the second lever beam and the third lever beam. The pressure-transmitting hinge support 22 includes a pressure-bearing shaft 221 and a steel backing plate 222, the steel backing plate 222 is a flat steel sheet, the pressure-bearing shaft 221 is a round steel, and the steel backing plate is located on opposite sides of the pressure-bearing shaft , are in contact with the pressure-applying surface and the pressure-receiving surface respectively, and the function is to make the force more uniform. The pressure bearing shaft is located between the steel backing plates, and its function is to make the force-applying object and the force-receiving object a line contact, thereby ensuring that the load calculation of the lever pressure is more consistent with the theoretical calculation value and reduces the system error. In order to prevent the structure from being unstable due to the rolling of the pressure bearing shaft, the pressure transmission hinge support of this embodiment further includes limit rods 223 , and the limit rods 223 are respectively welded on both sides of the pressure bearing shaft to prevent the pressure bearing shaft from rolling.

In combination with the above-mentioned concrete creep test device, the present embodiment further provides a concrete creep test method, which is characterized in that it includes the following steps:

a. Site selection and leveling of the foundation;

b. Place the base steel beam on the foundation, and place the ground counterweight at the second end of the base steel beam;

c. Install the concrete specimen on the steel beam of the loading base, install the first-level lever steel beam parallel to the steel beam of the loading base above the concrete specimen, and align the first end of the first-level lever steel beam with the first end of the steel beam of the loading base , and are connected by connecting components;

d. The second end of the first-level lever steel beam is provided with a pressure-transmitting hinge support, and a second-level lever steel beam parallel to the first-level lever steel beam is installed above the pressure-transmission hinge support. end is aligned with the second end of the steel beam at the loading base and connected by a connection assembly;

e. Install the test counterweight at the second end of the secondary lever steel beam.

The counterweight is a concrete pouring block.

The concrete creep test device and test method of the above embodiments solve the problems of the existing concrete creep test device or the cost is too high or the site is large, the construction is complicated, and the loading is unstable by adopting the structure of multi-stage lever loading. Compared with the single-stage lever-type test device with stable loading and low cost, the length of the lever used for loading is greatly reduced. Requirements for heavy equipment are reduced, significantly reducing the cost of concrete creep tests and improving loading efficiency.

The above descriptions are only specific implementations of the present invention, and those skilled in the art will understand that various modifications, substitutions and changes can be made to the present invention within the technical scope disclosed in the present invention. Therefore, the present invention should not be limited by the above examples, but should be limited by the protection scope of the claims.

Claims (10)

1. A concrete creep test device, is characterized in that, comprises three steel beams, and described steel beam is arranged in layers in space, forms a loading base and a cover of two-stage lever, and described two-stage lever comprises one-stage Leverage steel beams and secondary lever steel beams; among them, the loading base steel beam and the first level lever steel beam are used to install concrete specimens, the loading base steel beam is aligned with the first end of the first level lever steel beam, and passes through the first end of the first level lever steel beam A connecting component is connected together, the second end of the loading base steel beam is provided with a ground counterweight, the secondary lever steel beam is aligned with the second end of the base steel beam, and is connected through the second connecting component, and the secondary lever steel beam passes through the transmission The pressure hinge support is applied to the second end of the first-level lever steel beam, and the second end of the second-level lever steel beam is provided with a test counterweight. 2. A kind of concrete creep test device according to claim 1, is characterized in that, described steel girder all adopts the cross section of double channel steel, comprises the first channel steel and the second channel steel, the first channel steel and the second channel steel The openings of the two channel steels are arranged opposite to each other, and also include connecting panels between the channel steels, wherein the connecting panels at both ends of the channel steels have anchor holes for anchoring the connecting components. 3. A concrete creep test device according to claim 2, characterized in that there is a gap between the first channel steel and the second channel steel. 4. A concrete creep test device according to claim 2, characterized in that, the anchor hole is an anchor hole groove, and the anchor hole groove is a groove-shaped opening along the direction of the lever arm on the connecting plate. through hole. 5 . A concrete creep test device according to claim 2 , characterized in that, the anchor hole has a scale for indicating the position of the anchor on the lever steel beam. 6 . 6. A concrete creep test device according to claim 1, characterized in that, the connecting assembly comprises a finished-rolled threaded steel bar and an anchor, and the finished-rolled threaded steel bar passes through the lever steel beam anchor hole, And use anchors to connect with steel beams. 7. A concrete creep test device according to any one of claims 1-6, characterized in that, a pressure-transmitting hinge support is included between the second lever beam and the concrete specimen, and the The pressure transmission hinge support includes a pressure bearing shaft and a steel backing plate. The steel backing plate is a flat steel sheet, and the pressure bearing shaft is a round steel. The steel backing plate is located on both sides of the pressure bearing shaft and is in contact with the pressure application surface and the pressure bearing surface respectively. . 8. A concrete creep test device according to any one of claims 1-6, wherein a pressure-transmitting hinge support is included between the second lever beam and the third lever beam, and to transmit pressure. 9. A concrete creep test method is characterized in that comprising the following steps: a. Site selection and leveling of the foundation; b. Place the base steel beam on the foundation, and place the ground counterweight at the second end of the base steel beam; c. Install the concrete specimen on the steel beam of the loading base, install the first-level lever steel beam parallel to the steel beam of the loading base above the concrete specimen, and align the first end of the first-level lever steel beam with the first end of the steel beam of the loading base , and are connected by connecting components; d. The second end of the first-level lever steel beam is provided with a pressure-transmitting hinge support, and a second-level lever steel beam parallel to the first-level lever steel beam is installed above the pressure-transmission hinge support. end is aligned with the second end of the steel beam at the loading base and connected by a connection assembly; e. Install the test counterweight at the second end of the secondary lever steel beam. 10. A concrete creep test method according to claim 9, characterized in that, said counterweights are reinforced concrete ballasts.

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