CN110763563A - Research method of FRP rib bonding slippage relation based on Poisson effect - Google Patents

Abstract

The invention discloses a research method of FRP rib bonding slippage relation based on Poisson effect, which comprises the following steps: a. selecting and cutting FRP rib materials; b. mounting an anchoring end on the FRP rib; c. pouring and molding the ECC to obtain a bonding sliding test piece; d. sticking a piezoelectric ceramic sensor; e. pasting an intelligent aggregate sensor; f. installing a base plate, a drawing instrument, a pressure sensor and a clamping piece anchorage device; g. placing the bonding slippage test piece on a tensile testing machine; h. connecting the piezoelectric ceramic sensor and the intelligent aggregate sensor with a data acquisition card; i. starting a drawing instrument and applying prestress; j. keeping the drawing instrument applying prestress on the FRP rib material, and starting a tensile testing machine to load so as to perform a bonding slippage test; k. and establishing a bonding slip constitutive relation based on consideration of the Poisson effect and the shear hysteresis effect of the FRP reinforcement. The method can be effectively applied to the bonding and sliding test of the FRP rib material, and the test result is good in accuracy.

Description

A Research Method of Bond-slip Relationship of FRP Bars Based on Poisson Effect

technical field

The invention relates to the technical field of civil engineering, in particular to a research method for the bond-slip relationship of FRP bars based on the Poisson effect.

Background technique

FRP bars have excellent mechanical properties such as light weight, high strength and high durability, and are widely used in marine concrete and structures. The composition of FRP bars includes fiber bundles and matrix, which are co-stressed with concrete or other matrix through surface friction and mechanical occlusal force. However, the surface of FRP reinforcement is easy to peel off under the action of shearing force and is relatively weak, so the bonding relationship between FRP reinforcement and concrete or other substrates is different from that of ordinary reinforcement.

In addition, the FRP bar does not yield during the stress and deformation process, which is brittle failure and has a large amount of failure deformation. Therefore, there is an obvious Poisson effect in the tension process of the reinforcement, which results in a certain degree of debonding between the FRP reinforcement and the concrete, which reduces the bond strength. In addition, during the bond-slip test of FRP bars, 5 times the anchorage length has a shear hysteresis effect, which affects the accuracy of the test results, that is, it must be optimized by reducing the anchorage length.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a research method for the bond-slip relationship of FRP bars based on the Poisson effect, which can effectively It is suitable for the adhesion and slip test of FRP bars, and the test results are accurate.

In order to achieve the above object, the present invention is achieved through the following technical solutions.

A research method for the bond-slip relationship of FRP bars based on the Poisson effect, including the following steps, specifically:

a. Select the FRP bar and cut the FPR bar according to the length required for the tensile testing machine test;

b. FRP reinforcement installation anchor end;

c. The ECC is cast and formed through the template to obtain the adhesive slip specimen: the ECC is cast and formed on the periphery of the FRP bar, and the anchorage length between the ECC and the FRP bar is twice the diameter of the FRP bar;

d. Paste the piezoelectric ceramic sensor on the adhesive-slip specimen: paste the piezoelectric ceramic sensor on the surface of the FRP bar of the adhesive-slip specimen, and the piezoelectric ceramic sensor is located under the ECC;

e. Paste the smart aggregate sensor on the bond-slip specimen: Paste the smart aggregate sensor on the ECC surface of the bond-slip specimen, and the pasting position of the smart aggregate sensor is at the height center of the ECC;

f. Install the backing plate, puller, pressure sensor, and clip anchor on the adhesive slip test piece: Set the backing plate, the puller, the pressure sensor, the clip anchor, and the pad on the periphery of the FRP bar in sequence. The plate, the puller, the pressure sensor, and the clip anchor are located between the ECC and the upper anchoring end, respectively. The backing plate is placed on the upper surface of the ECC. The drawing instrument is installed on the upper surface of the backing plate. Between the clip anchors, the clip anchors anchor and clamp the FRP reinforcement;

g. Place the adhesive slip test piece after installing the backing plate, the puller, the pressure sensor and the clip anchor on the tensile testing machine, and the tensile testing machine clamps the upper anchor end and the lower anchor end;

h. Connect the piezoelectric ceramic sensor to the transmitting end of the data acquisition card, and connect the intelligent aggregate sensor to the receiving end of the data acquisition card, and the data acquisition card is connected to the computer; at the same time, the pressure sensor is connected to the computer;

i. Start the puller and apply prestress to the FRP bar;

j. Keep the puller to apply prestress to the FRP bar, and start the tensile testing machine for loading at the same time to carry out the bonding slip test. During this process, the same signal is still selected to excite the piezoelectric force acting on the FRP bar. At this time, the piezoelectric ceramic sensor vibrates and generates stress waves. The stress waves propagate in the FRP bar, the interface between the FRP bar and ECC, and in the ECC. The smart aggregate sensor receives the stress wave and receives the signal amplitude at different times. value and frequency shift difference to judge the damage degree of the interface between FRP bar and ECC;

k. Establish a bond-slip constitutive relation based on consideration of Poisson effect and shear hysteresis effect of FRP reinforcement.

Wherein, in the step b, the upper end steel pipe is set on the periphery of the upper end of the FRP reinforced material, and the inner wall of the upper end steel pipe and the upper end of the FRP reinforced material are filled with expansion cement, and the expansion cement layer is formed after the expansion cement solidifies, and the inner side of the upper end steel pipe The expansion cement layer and the upper steel pipe together form the upper end anchoring end of the FRP reinforcement; the lower steel pipe is set around the lower end of the FRP reinforcement, and the inner wall of the lower steel pipe and the lower end of the FRP reinforcement are filled with expansion cement, and the expansion cement forms after solidification. The cement layer, the expansion cement layer inside the lower end steel pipe and the lower end steel pipe together constitute the lower end anchoring end of the FRP reinforcement.

Wherein, in the step d, the piezoelectric ceramic sensor is pasted on the surface of the FRP reinforced material of the adhesive slip test piece through 502 glue.

Wherein, as in the step e, the smart aggregate sensor is pasted on the ECC surface of the adhesive slip test piece through 502 glue.

The beneficial effects of the present invention are as follows: a method for researching the bond-slip relationship of FRP bars based on Poisson effect according to the present invention, which includes the following steps: a. Selecting FRP bars and testing them according to the requirements of the tensile testing machine Cut the FPR bar to length; b. Install the anchoring end of the FRP bar; c. Cast the ECC through the template to obtain the adhesive slip specimen: ECC is cast and formed on the periphery of the FRP bar, and the anchorage between the ECC and the FRP bar is The length value is twice the diameter value of the FRP bar; d. Paste the piezoelectric ceramic sensor on the adhesive-slip specimen: paste the piezoelectric ceramic sensor on the surface of the FRP bar of the adhesive-slip specimen, and the piezoelectric The ceramic sensor is located under the ECC; e. Paste the smart aggregate sensor on the adhesive-slip specimen: paste the smart aggregate sensor on the ECC surface of the adhesive-slip specimen, and the pasting position of the smart aggregate sensor is located on the ECC surface. Height center position; f. Install backing plate, puller, pressure sensor and clip anchor on the adhesive slip test piece: Set the backing plate, drawing instrument, pressure sensor, and clip on the periphery of the FRP bar in sequence The anchor, the backing plate, the puller, the pressure sensor, and the clip anchor are located between the ECC and the upper anchoring end, respectively. The backing plate is placed on the upper surface of the ECC, and the drawing instrument is installed on the upper surface of the backing plate. Between the puller and the clip anchor, the clip anchor anchors and clamps the FRP bar; g. Place the adhesive slip specimen after installing the backing plate, the puller, the pressure sensor, and the clip anchor. On the tensile testing machine, the tensile testing machine clamps the upper anchoring end and the lower anchoring end; h. Connect the piezoelectric ceramic sensor to the transmitting end of the data acquisition card, and connect the intelligent aggregate sensor to the receiving end of the data acquisition card, data acquisition The card is connected to the computer; at the same time, the pressure sensor is connected to the computer; i. Start the drawing instrument and apply prestress to the FRP bars; j. Keep the drawing instrument to apply prestress to the FRP bars, and simultaneously start the tensile testing machine to load, In this process, the same signal is still selected to excite the piezoelectric ceramic sensor acting on the FRP bar. At this time, the piezoelectric ceramic sensor vibrates and generates a stress wave. The stress wave is applied to the FRP bar, The interface between the FRP bar and ECC and the propagation in the ECC, the intelligent aggregate sensor receives the stress wave, and judges the damage degree of the interface between the FRP bar and the ECC according to the difference in the amplitude and frequency shift of the received signal at different times; k. The establishment is based on the consideration of FRP Bond-slip constitutive relationship between Poisson effect and shear hysteresis effect of reinforcement. Through the design of the above steps, the present invention can be effectively applied to the adhesion and slip test of FRP bars, and the accuracy of the test results is good.

Description of drawings

The present invention is further described below with reference to the accompanying drawings, but the embodiments in the accompanying drawings do not constitute any limitation to the present invention.

FIG. 1 is a schematic structural diagram of the adhesive slip test piece of the present invention.

Figure 2 is a schematic diagram of the structure of the adhesive slip specimen after installing the backing plate, the puller, the pressure sensor, and the clip anchor.

Included in Figure 1 are:

1——FRP bar 2——ECC

31 - upper end steel pipe 32 - lower end steel pipe

4——Backing plate 5——Drawing instrument

6 - pressure sensor 7 - clip anchor

8 - Piezoelectric ceramic sensor 9 - Smart aggregate sensor.

Detailed ways

The present invention will be described below with reference to specific embodiments.

A research method for the bond-slip relationship of FRP bars based on the Poisson effect, which includes the following steps, specifically:

a. Select FRP bar 1 and cut the FPR bar according to the length required for the tensile testing machine test;

b. FRP reinforcement 1 installs the anchoring end;

c. The ECC2 is cast and formed through the template to obtain the bonding slip specimen (as shown in Figure 1): ECC2 is cast and formed on the periphery of the FRP bar 1, and the anchorage length between ECC2 and the FRP bar 1 is the value of the FRP bar. 1 double the diameter value;

d. Paste the piezoelectric ceramic sensor 8 on the adhesive-slip specimen: paste the piezoelectric ceramic sensor 8 on the surface of the FRP bar 1 of the adhesive-slip specimen, and the piezoelectric ceramic sensor 8 is located below the ECC2;

e. Paste the smart aggregate sensor 9 on the adhesive-slip specimen: Paste the smart aggregate sensor 9 on the surface of the ECC2 of the adhesive-slip specimen, and the pasting position of the smart aggregate sensor 9 is at the height center of the ECC2 ;

f. Install the backing plate 4, the drawing instrument 5, the pressure sensor 6, and the clip anchor 7 on the adhesive slip specimen (as shown in Figure 2): Set the backing plate 4, The pulling instrument 5, the pressure sensor 6, the clip anchor 7, the backing plate 4, the pulling instrument 5, the pressure sensor 6, and the clip anchor 7 are respectively located between the ECC2 and the upper anchoring end, and the backing plate 4 is placed on the ECC2. On the upper surface, the drawing instrument 5 is installed on the upper surface of the backing plate 4, and the pressure sensor 6 is located between the drawing instrument 5 and the clip anchor 7, and the clip anchor 7 anchors and clamps the FRP bar 1;

g. Place the adhesive slip test piece after installing the backing plate 4, the puller 5, the pressure sensor 6, and the clip anchor 7 on the tensile testing machine, and the tensile testing machine clamps the upper anchorage end and the lower anchorage end;

h. Connect the piezoelectric ceramic sensor 8 to the transmitting end of the data acquisition card, and connect the intelligent aggregate sensor 9 to the receiving end of the data acquisition card, and the data acquisition card is connected to the computer; at the same time, the pressure sensor 6 is connected to the computer;

i. Start the drawing instrument 5 and apply prestress to the FRP bar 1, and the pressure sensor 6 is used to obtain the prestress;

j. Keep the puller 5 to apply prestress to the FRP bar 1, and start the tensile testing machine for loading at the same time to carry out the bonding slip test. During this process, the same signal excitation is still selected to act on the FRP bar 1. At this time, the piezoelectric ceramic sensor 8 vibrates and generates a stress wave. The stress wave propagates in the FRP bar 1, the interface between the FRP bar 1 and ECC2, and in the ECC2. The intelligent aggregate sensor 9 receives the stress wave and transmits the stress wave. According to the difference of received signal amplitude and frequency shift at different times, the interface damage degree of FRP bar 1 and ECC2 is judged;

k. Establish a bond-slip constitutive relation based on consideration of the Poisson effect and shear hysteresis effect of FRP bars.

It should be explained that, in step b, the upper end steel pipe 31 is set on the periphery of the upper end of the FRP bar 1, and the inner wall of the upper end steel pipe 31 and the upper end of the FRP bar 1 are filled with expansive cement, and the expansive cement is solidified to form an expansive cement layer. , the expansion cement layer inside the upper end steel pipe 31 and the upper end steel pipe 31 together form the upper end anchoring end of the FRP bar 1; the lower end steel pipe 32 is set on the periphery of the lower end of the FRP bar 1, and the inner wall of the lower end steel pipe 32 and the lower end of the FRP bar 1 Expansion cement is filled between them, and the expansion cement layer is formed after the expansion cement solidifies. Among them, the purpose of the present invention to set the upper end anchoring end and the lower end anchoring end on the FRP bar 1 is: the lateral force of the FRP bar 1 is brittle failure, and the upper end and the lower end of the FRP bar 1 are directly clamped with a tensile testing machine fixture. The FRP bar 1 is crushed, and directly clamping the upper and lower anchor ends by the tensile testing machine can effectively avoid directly clamping the FRP bar 1, so that the FRP bar 1 can be effectively clamped and protected. Avoid pinching the FRP bar 1.

In addition, in step d, the piezoelectric ceramic sensor 8 is pasted on the surface of the FRP bar 1 of the adhesive-slip test piece by 502 glue; and in step e, the smart aggregate sensor 9 is pasted on the adhesive-slip test piece by 502 glue ECC2 surface of the piece.

Also, in step c, in the process of the FRP bar bond-slip test, the anchorage length between the 5 times the anchorage length ECC2 required by the traditional specification and the FRP bar 1 is 5 times the diameter of the FRP bar 1. Twice the shear force hysteresis effect, which affects the accuracy of the test results; and the use of 2 times the anchorage length between ECC2 and the FRP bar 1, the anchor length value is twice the diameter of the FRP bar 1, which can reduce the influence of the shear force hysteresis effect. Makes bond slip results more accurate.

Based on the above situation, it can be seen that through the design of the above steps, the present invention can be effectively applied to the adhesion and slip test of the FRP bar material 1, and the test results are accurate.

The above contents are only preferred embodiments of the present invention. For those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific embodiments and application scope. limits.

Claims (4)

1. a research method based on the bond-slip relationship of FRP bars based on Poisson effect, is characterized in that, comprises the following steps, concrete: a. Select the FRP bar (1) and cut the FPR bar according to the length required for the tensile testing machine test; b. FRP reinforcement (1) install the anchoring end; c. The ECC (2) is cast and formed through the template to obtain the adhesive slip specimen: the ECC (2) is cast and formed on the periphery of the FRP bar (1), and the anchorage between the ECC (2) and the FRP bar (1) The length value is twice the diameter value of the FRP bar (1); d. Paste the piezoelectric ceramic sensor (8) on the adhesive slip specimen: paste the piezoelectric ceramic sensor (8) on the surface of the FRP bar (1) of the adhesive slip specimen, and the piezoelectric ceramic sensor ( 8) Below the ECC (2); e. Paste the smart aggregate sensor (9) on the bond-slip specimen: Paste the smart aggregate sensor (9) on the surface of the ECC (2) of the bond-slip specimen, and the smart aggregate sensor (9) The pasting position of is located at the height center position of ECC (2); f. Install the backing plate (4), the puller (5), the pressure sensor (6), and the clip anchor (7) on the adhesive slip test piece: Set the pads on the periphery of the FRP bar (1) in sequence Plate (4), puller (5), pressure sensor (6), clip anchor (7), backing plate (4), puller (5), pressure sensor (6), clip anchor ( 7) They are respectively located between the ECC (2) and the upper anchoring end, the backing plate (4) is placed on the upper surface of the ECC (2), the puller (5) is installed on the upper surface of the backing plate (4), and the pressure sensor ( 6) Located between the puller (5) and the clip anchor (7), the clip anchor (7) anchors and clamps the FRP bar (1); g. Place the adhesive slip test piece after installing the backing plate (4), the puller (5), the pressure sensor (6), and the clip anchor (7) on the tensile testing machine, and the tensile testing machine clamps the upper end Anchoring end, lower anchoring end; h. Connect the piezoelectric ceramic sensor (8) to the transmitting end of the data acquisition card, and connect the intelligent aggregate sensor (9) to the receiving end of the data acquisition card, and the data acquisition card is connected to the computer; at the same time, connect the pressure sensor (6) ) connected to the computer; i. Start the puller (5) and apply prestress to the FRP bar (1); j. Keep the puller (5) to apply prestress to the FRP bar (1), and start the tensile testing machine for loading at the same time to carry out the bonding slip test. During this process, the same signal excitation is still selected to act on the FRP. The piezoelectric ceramic sensor (8) on the bar (1), at this time, the piezoelectric ceramic sensor (8) vibrates and generates a stress wave, and the stress wave is in the FRP bar (1), FRP bar (1) and ECC (2) ) interface and the ECC (2), the intelligent aggregate sensor (9) receives the stress wave, and judges the interface damage between the FRP bar (1) and the ECC (2) according to the received signal amplitude and frequency shift difference at different times. degree; k. Establish a bond-slip constitutive relation based on consideration of (1) Poisson effect and shear hysteresis effect of FRP reinforcement. 2. A method for researching the bond-slip relationship of FRP bars based on the Poisson effect according to claim 1, characterized in that: in the step b, a peripheral wrapping on the upper end of the FRP bar (1) The upper end steel pipe (31), the inner wall of the upper end steel pipe (31) and the upper end of the FRP reinforcing bar (1) are filled with expansion cement, and the expanded cement layer is formed after the expansion cement solidifies, and the expansion cement layer inside the upper end steel pipe (31) and the upper end steel pipe (31) The upper end anchoring end of the FRP bar (1) is formed together; the lower end steel pipe (32) is set on the periphery of the lower end of the FRP bar (1), and the inner wall of the lower end steel pipe (32) is connected to the lower end of the FRP bar (1). Expansion cement is filled therebetween, and an expansion cement layer is formed after the expansion cement solidifies, and the expansion cement layer inside the lower end steel pipe (32) and the lower end steel pipe (32) together form the lower end anchoring end of the FRP reinforcing bar (1). 3. A method for researching the bond-slip relationship of FRP bars based on the Poisson effect according to claim 1, characterized in that: in the step d, the piezoelectric ceramic sensor (8) is pasted on the Adhesion to the surface of the FRP bar (1) of the slip specimen. 4. A method for researching the bond-slip relationship of FRP bars based on Poisson effect according to claim 1, characterized in that: in the step e, the smart aggregate sensor (9) is pasted on the Adhesion to the ECC(2) surface of the slip specimen.

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