CN114720290A - Self-reaction force loading device for concrete slab bending test and using method - Google Patents
Self-reaction force loading device for concrete slab bending test and using method Download PDFInfo
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- CN114720290A CN114720290A CN202210357862.4A CN202210357862A CN114720290A CN 114720290 A CN114720290 A CN 114720290A CN 202210357862 A CN202210357862 A CN 202210357862A CN 114720290 A CN114720290 A CN 114720290A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/02—Details
Abstract
The invention discloses a self-reaction force loading device for a concrete slab bending test, which comprises a base and a base fixing pedestal, wherein a left supporting mechanism comprises a left clamp holder and a left clamp holder fixing seat, the left clamp holder is rotatably arranged on the left clamp holder fixing seat, the left clamp holder is provided with a left clamping plate for anchoring the left edge of a test piece, the lower side and the left side of the left clamp holder fixing seat are respectively fixed with a plurality of groups of left vertical springs and a plurality of groups of left horizontal springs, the lower ends of the plurality of groups of left vertical springs are in sliding connection with the pedestal, the left ends of the plurality of groups of left horizontal springs are in sliding connection with a left restraining plate, the left restraining plate is in sliding connection with the pedestal along the left and right direction, a plurality of left hydraulic ejector rods are arranged between the pedestal and the left restraining plate, a loading mechanism is arranged above the pedestal and used for loading the test piece in the vertical direction, and the vertical springs of the clamp holder fixing seat always keep vertical rigidity, The horizontal spring always keeps horizontal rigidity, and the boundary constraint condition of the cutting part of the test piece in the loading and stress process is simulated.
Description
Technical Field
The invention is used in the field of bridge deck member tests, and particularly relates to a self-reaction force loading device for a concrete slab bending test and a using method thereof.
Background
With the continuous development of the infrastructure of China, large and ultra-large bridges are continuously increased and become a crucial part in the infrastructure of China, and in the process of bridge development, the size of the bridge deck is designed to be larger and larger, so that the performance of the bridge deck is difficult to detect. The existing test can not take the whole bridge deck as a test object, the bridge deck is cut along the longitudinal direction, and a plate which keeps the transverse edge to be cut longitudinally is cut out for testing. Therefore, the technical scheme of the application is provided for effectively solving the problem that the real stress of the bridge deck cannot be simulated in the test process.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a self-reaction force loading device for a concrete slab bending test.
The technical scheme adopted by the invention is as follows: a self-reaction force loading device for a concrete slab bending test comprises a base 1, a test piece fixing mechanism and a loading mechanism, wherein the base 1 is of a bilaterally symmetrical structure, the base 1 is fixedly provided with a pedestal 3, a left supporting mechanism comprises a left clamp 4 and a left clamp fixing seat 5, the left clamp 4 and the left clamp fixing seat 5 are horizontally arranged along the front and back direction, the left clamp 4 is rotatably arranged on the left clamp fixing seat 5, two left clamping plates 27 extending rightwards are arranged on the right side of the left clamp 4, and a plurality of left anchoring bolts 26 are uniformly distributed on the two left clamping plates 27 along the front and back direction and used for anchoring the left edge of a test piece 2;
a plurality of groups of left vertical springs 8 are fixed on the lower side of the left holder fixing seat 5, a plurality of groups of left horizontal springs 9 are fixed on the left side of the left holder fixing seat 5, the plurality of groups of left vertical springs 8 and the plurality of groups of left horizontal springs 9 are uniformly distributed along the front and back directions of the left holder fixing seat 5, the lower ends of the plurality of groups of left vertical springs 8 are connected with the pedestal 3 in a sliding manner along the left and right directions, the left ends of the plurality of groups of left horizontal springs 9 are connected with the left restraint plate 14 in a sliding manner along the up and down directions, and the left restraint plate 14 is connected with the pedestal 3 in a sliding manner along the left and right directions;
a plurality of left hydraulic push rods 16 are arranged between the left end of the pedestal 3 and the left side surface of the left restraint plate 14, and the left hydraulic push rods 16 are uniformly distributed along the front-back direction;
and a loading mechanism is arranged above the pedestal 3 and used for loading the test piece 2 in the vertical direction.
Preferably, the left holder 4 is cylindrical, an axial elongated slot is formed in the right side of the left holder 4, left holding plates 27 extending rightward are arranged at the upper end and the lower end of the elongated slot, a left supporting shaft rod 7 is fixed to the front end and the rear end of the left holder 4 respectively, a semicircular axial groove is formed in the right side of the left holder fixing seat 5, the cylindrical portion of the left holder 4 is coaxially arranged with the axial groove and the left supporting shaft rod 7, the two left supporting shaft rods 7 are rotatably mounted at the front end and the rear end of the left holder fixing seat 5 respectively, a plurality of left rollers 6 are arranged between the cylindrical portion of the left holder 4 and the semicircular axial groove of the left holder fixing seat, and the left rollers 6 are uniformly distributed along the circumferential direction of the axial groove to achieve the purpose that the left holder 4 is rotatably connected to the left holder fixing seat 5.
Preferably, the middle of the base 1 is upwardly convex, the left and right sides are downwardly concave, the middle convex part is used as a bearing platform, the loading mechanism comprises upright columns 18, frame beams 19, an electric lifting platform 20 and a hydraulic jack 21, the two sides of the base 1 are respectively fixed with the lower ends of the two upright columns 18 to form a self-reaction structure, the four upright columns are arranged along the vertical direction, the upper end of each upright column 18 is respectively fixed with a vertex of the frame beam 19, the frame beam 19 is in a rectangular structure, the central axes of a machine body 22 of the hydraulic jack 21 and a bearing plate 23 of the hydraulic jack 21 pass through the spherical center of a movable spherical hinge 24, the machine body 22 of the hydraulic jack 21 and the bearing plate 23 form a spherical hinge connection through the movable spherical hinge 24, the hydraulic jack 21 is fixed on the lower surface of the electric lifting platform 20, and the fixing position on the electric lifting platform 20 can be adjusted along the front-back and left-right directions, the electric lifting platform 20 is of a rectangular structure, four corners of the electric lifting platform are respectively connected with one upright in a sliding manner, and lifting height adjustment can be carried out along the four uprights 18.
Preferably, pedestal 3 on be provided with a plurality of horizontal chutes 12 that set up along the fore-and-aft direction equipartition, horizontal chute 12 begins to end to the right part from the 3 left parts of pedestal, horizontal chute 12 sets up along left right direction level, horizontal slider 10 of a left side slidable mounting of every horizontal chute 12, the lower extreme of the vertical spring 8 of a set of left of fixed on every horizontal slider 10 of a left side, the quantity of the vertical spring 8 of a set of left is two, two vertical springs 8 set up side by side along left right direction for realize that the vertical spring 8 of the vertical spring of a left side provides vertical stiffness in the loading process of test piece 2.
Preferably, the right side surface of the left restraint plate 14 is provided with a plurality of left vertical rails 13 uniformly distributed along the front-back direction, the left vertical rails 13 are arranged along the vertical direction, a left vertical slider 11 is slidably mounted in each left vertical rail 13, and the left end of a group of left horizontal springs 9 is fixed on the right side of each left vertical slider 11. The quantity of a set of left horizontal spring 9 is two, and two left horizontal springs 9 set up side by side along vertical direction for realize that test piece 2 loading in-process left horizontal spring 9 provides horizontal rigidity.
Preferably, the structure that the left restraining plate 14 and the base 3 are slidably connected in the left-right direction is: pedestal 3's left side be provided with a plurality of left track grooves 17 along the fore-and-aft direction equipartition, left track groove 17 sets up along the left-and-right direction level, 14 lower extremes of left side about board rotate a plurality of left gyro wheels 15 of installation, a plurality of left gyro wheels 15 set up along the fore-and-aft direction equipartition, a left gyro wheel 15 rolls in a corresponding left track groove 17.
Preferably, pedestal 3 left end be provided with ascending bellying, the bellying of pedestal 3 left end is through dismantling mode with a plurality of hydraulic ram 16, a plurality of left hydraulic ram 16 along the equipartition setting of fore-and-aft direction, the hydraulic stem of left hydraulic ram 16 stretches out the end and presses on the left end face of left restraint board 14.
The use method of the self-reaction force loading device for the concrete slab bending test comprises the following steps:
step one) anchoring the test piece 2: cutting the test piece 2, punching the left and right clamping edges of the test piece 2, punching the left edge of the test piece 2 corresponding to the left anchor bolt 26 at the left clamping plate 27, punching the right edge of the test piece 2 corresponding to the right anchor bolt at the right clamping plate of the right supporting mechanism, measuring the left and right dimension of the test piece 2, namely the dimension of the short side, controlling the expansion amount of the left hydraulic ejector rod 16 and the expansion amount of the right hydraulic ejector rod of the right supporting mechanism, pushing the left restraint plate 14 to advance or retreat by virtue of the left roller 15, pushing the right restraint plate of the right supporting mechanism to advance or retreat by virtue of the right roller, moving the left anchor bolt 26 of the left clamp holder 4 to the left punching position of the test piece 2, moving the right anchor bolt of the right clamp holder of the right supporting mechanism to the punching position at the right side of the test piece 2, placing the test piece 2 in the axial long groove arranged at the right side of the left clamp holder 4, the test piece 2 is anchored by the left anchoring bolt 26, and simultaneously the test piece 2 is placed in the axial elongated slot arranged on the left side of the right holder of the right supporting mechanism, and the test piece 2 is anchored by the right anchoring bolt.
Step two) primary position calibration is carried out on the test piece 2: the position of the hydraulic jack 21 is adjusted, the central position of the upper end face of the test piece 2, namely the front and back direction of the loading point coincides with the axis of the hydraulic jack 21, the test piece 2 with different thicknesses is clamped and fixed by adopting cushion blocks placed in a left clamping plate 27 and a right clamping plate gap of a right supporting mechanism, the inclination angle sensor 25 is installed at the clamping edge of the test piece 2, and the front and back and left and right directions of the test piece 2 are adjusted to be horizontal according to the reading of the inclination angle sensor 25.
Step three), adjusting the boundary constraint rigidity: formula (1) is calculated from the stiffness of the compression spring:
wherein R is the spring rate, P is the load, and X is the compression or extension of the spring, i.e. the deformation.
The restraining stiffness of the left vertical spring 8 and the right vertical spring of the right supporting mechanism is adjusted, and in the embodiment, the left vertical spring 8 and the right vertical spring of the right side supporting mechanism are symmetrically arranged about the left-right symmetrical plane of the base 1, the left horizontal spring 9 and the right horizontal spring of the right side supporting mechanism are symmetrically arranged about the left-right symmetrical plane of the base 1, so that the restraining rigidity of the left vertical spring 8 and the restraining rigidity of the left horizontal spring 9 are adjusted, the restraining rigidities of the right vertical spring and the right horizontal spring are adjusted, the structural boundary is restrained into a bidirectional plate with fixed left and right ends when the test piece 2 is not cut, a unidirectional plate strip in the middle of the bidirectional plate strip is selected to be cut into the test piece 2, calculating the restraining bending moment M of the part of the test piece 2 at the boundary before cutting to the test piece 2 according to a structural mechanics formula, in order to enable the vertical spring to simulate the bending moment, the compression amount X of the left vertical spring is adjusted by combining the formula (3).1At the moment, the vertical force provided by the vertical spring on one side is P1，P1The size of (c) can be obtained by formula (2):
wherein D1For the distance of the central axis of the bearing shaft 7 from the axis of the left anchor bolt 26, obtained by measurement with a straight edge, P1Is the left vertical spring axial force, N1The number of all the left vertical springs 8.
Adjusting the restraining stiffness of the left horizontal spring 9: the horizontal restraint stiffness of the test piece 2 is the tensile stiffness EA of the plate, and the stiffness of the left horizontal spring 9 is determined by the amount X of tension or compression of the spring2Determine, so in the embodiment, the amount X of extension or compression of the left horizontal spring 92Is given by the formula (4) And calculating to obtain:
in this formula P2Is a force reading of the single left hydraulic ram 16, N2The number of the left hydraulic jacks 16, E the modulus of elasticity of the test piece 2, and a the cross-sectional area in the front-rear direction of the test piece 2, i.e., the cross-sectional area in the longitudinal direction. Compression amount X of left horizontal spring 92A left horizontal restraining stiffness is determined by taking and reading a left hydraulic ram 16 force reading from the extension of the left hydraulic ram 16.
Step four), carrying out secondary position calibration: and adjusting the position of the hydraulic jack 21 to ensure that the left and right directions of the loading point at the central position of the test piece 2 coincide with the axis of the hydraulic jack 21, and controlling the electric lifting platform 20 to be at a proper height to ensure that the bearing plate 23 of the hydraulic jack 21 is attached to the surface of the test piece 2.
And step five), firstly applying load by adopting a force control method, finding out and recording the cracking load of the test piece 2, then loading the test piece 2 in a grading manner until the test piece 2 yields, and loading the test piece 2 in a displacement control manner after yielding until the test piece 2 is damaged.
Compared with the prior art, the invention has the beneficial effects that: the combination of the horizontal sliding block and the vertical sliding block can ensure that the vertical spring always keeps vertical rigidity and the horizontal spring always keeps horizontal rigidity in the loading process of the test piece, the boundary constraint condition of a cutting part of the test piece in the loading stress process is simulated, namely the boundary is supported by the outer side and the upper side under the condition of no cutting, and the clamp holder and the clamp fixing seat are rotationally connected to ensure that the test piece freely rotates at the boundary bearing part to adapt to the stress deformation posture of the test piece in the loading process so as to simulate the boundary condition of the bridge deck under the stress condition in the actual use process.
The roller is arranged at the bottom of the restraint plate, the distance between the restraint plate and the clamping plate is changed by pushing or contracting the hydraulic ejector rod so as to adjust the rigidity of the spring, the operation is convenient, the loading device is integrally designed into a self-reaction structure, and the self-reaction loading device has good applicability to a laboratory without a built reaction foundation.
The vertical spring is adopted to support the boundary of the test piece, and due to the yielding property of the spring, the edge of the test piece is uniformly loaded and consistent with the actual stress condition of the cutting boundary of the test piece, so that the accuracy of experimental data is improved.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a general structure schematic diagram of a self-reaction force loading device for a concrete slab bending test;
FIG. 2 is a top view of the self-reaction loading device for the concrete slab bending test;
FIG. 3 is a front view of the self-reaction loading device for a concrete slab bending test;
FIG. 4 is a first structural schematic diagram of the connection of the left clamp and the left clamp fixing seat;
FIG. 5 is a second schematic structural view of the connection between the left clamp and the left clamp holder;
FIG. 6 is a schematic view of the left restraint panel mounted with the left roller;
FIG. 7 is a schematic view of the mounting structure of the left vertical spring and the left horizontal spring;
FIG. 8 is a schematic structural view of the left support mechanism;
fig. 9 is a schematic structural view of the hydraulic jack.
Description of reference numerals: 1. a base; 2. a test piece; 3. a pedestal; 4. a left gripper; 5. a left holder fixing seat; 6. a left roller; 7. a left support shaft; 8. a left vertical spring; 9. a left horizontal spring; 10. a left horizontal slider; 11. a left vertical slide block; 12. a horizontal chute; 13. a left vertical rail; 14. a left restraint panel; 15. a left roller; 16. a left hydraulic ejector rod; 17. a left track groove; 18. a column; 19. a frame beam; 20. an electric lifting table; 21. a hydraulic jack; 22. a body; 23. a pressure bearing plate; 24. a movable spherical hinge; 25. a tilt sensor; 26. a left anchor bolt; 27. and a left clamping plate.
Detailed Description
In order to make the objects, technical solutions and feasibility of the present invention clearer and more detailed, the present invention is described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific examples described below are only for illustrating the present invention and are not to be construed as limiting the present invention.
Referring to fig. 1 to 9, a self-reaction force loading device for a concrete slab bending test comprises a base 1, a test piece fixing mechanism and a loading mechanism. The upper, lower, left and right directions of this application are defined respectively with the upper, lower, left and right directions of figure 3 to describe this application, base 1 is bilateral symmetry's structure, loading mechanism, test piece fixed establishment all set up about the bilateral symmetry plane symmetry of base 1, test piece fixed establishment include pedestal 3, left supporting mechanism, right supporting mechanism, left supporting mechanism and right supporting mechanism set up about the bilateral symmetry plane symmetry of base 1, pedestal 3 sets up about the bilateral symmetry plane symmetry of base 1, the cross section of base 1 be wrong desk-top structure, the centre is upwards protruding, both sides are recessed, the protruding part in the centre is as the bearing platform, upper surface fixed pedestal 3 in the middle of base 1, loading mechanism include stand 18, frame roof beam 19, electronic elevating platform 20, hydraulic jack 21, activity ball hinge 24, inclination sensor 25, base 1 both sides fix the lower extreme of two stands 18 respectively, a self-reaction structure is formed, four upright columns are arranged along the vertical direction, the upper end of each upright column 18 is respectively fixed with one vertex of a frame beam 19, the frame beam 19 is of a rectangular structure, and the four upright columns 18, the frame beam 19 and the base 1 form a rigid truss. The central axes of the body 22 of the hydraulic jack 21 and the bearing plate 23 of the hydraulic jack 21 pass through the spherical center of the movable spherical hinge 24, the body 22 of the hydraulic jack 21 forms a spherical hinge connection with the bearing plate 23 through the movable spherical hinge 24, the bearing plate 23 flexibly rotates around the movable spherical hinge 24, the pressure bearing plate 23 can automatically adapt to the slight inclination of the test piece 2 in the height direction after contacting with the top surface of the test piece 2, so that the pressure bearing plate 23 is completely contacted with the top surface of the test piece 2 to ensure the uniform stress of the test piece 2, the hydraulic jack 21 is fixed on the lower surface of the electric lifting platform 20, and the fixing position on the electric lifting platform 20 can be adjusted along the front-back and left-right directions, the hydraulic jacks 21 are symmetrically arranged about the left-right symmetrical plane of the base 1, the electric lifting platform 20 is in a rectangular structure, the four corners of the frame are respectively connected with a stand column in a sliding way, and are lifted along the four stand columns 18 to adjust the height in the vertical direction.
The left supporting mechanism comprises a left clamp 4, a left clamp fixing seat 5, a left rolling shaft 6, a left supporting shaft lever 7, a left vertical spring 8, a left horizontal spring 9, a left horizontal slider 10, a left vertical slider 11, a left vertical rail 13, a left restraining plate 14, a left roller 15 and a left hydraulic ejector rod 16, the left clamp 4 is cylindrical, the left clamp 4 is horizontally arranged along the front-back direction, a long groove along the front-back direction is arranged on the right side of the left clamp 4, the upper end and the lower end of the long groove are respectively provided with a left clamping plate 27 extending rightwards, a plurality of left anchor bolts 26 are uniformly distributed on the two left clamping plates 27 along the front-back direction, the front end and the rear end of the left clamp 4 are respectively fixed with the left supporting shaft lever 7, the left clamp fixing seat 5 is horizontally arranged along the front-back direction, and the right side of the left clamp fixing seat 5 is provided with a semicircular axial groove, the cylindrical position and the axial recess of left holder 4 and the coaxial setting of left bearing axostylus axostyle 7, two left bearing axostylus axostyles 7 rotate respectively and install the front end at left holder fixing base 5, the rear end, left side holder 4 rotates with left holder fixing base 5 to be connected, be provided with a plurality of left roller bearings 6 between the semicircular axial recess of left holder fixing base 4's cylinder portion and left holder fixing base, left side roller bearing 6 sets up along axial recess circumferencial direction equipartition, it uses bearing axostylus axostyle 7 to realize that left holder 4 realizes the rotation function at certain angle range as the center in left holder fixing base 5 is inside, with the gesture of nimble adjustment test piece 2, the deformation rotation condition after the simulation test piece 2 atress.
Left about board 14 set up along the fore-and-aft direction level, the right flank of left about board 14 is provided with a plurality of left vertical tracks 13 along the fore-and-aft direction equipartition, left vertical track 13 sets up along vertical direction, vertical slider 11 of a left slidable mounting in every left vertical track 13, the left end of two left horizontal springs 9 is fixed on the right side of every left vertical slider 11, two left horizontal springs 9 set up side by side along vertical direction, the left end face of the fixed left holder fixing base 5 of right-hand member of whole left horizontal springs 9, for left horizontal spring 9 uses left vertical slider 11 as the direction, freely slide in order to adjust vertical position on left vertical track 13, left horizontal spring 9 remains the level all the time in order to provide test piece 2 horizontal stiffness.
3 left ends of pedestal be provided with ascending bellying, the bellying of 3 left ends of pedestal is through dismantling the mode with a plurality of hydraulic ram 16, a plurality of left hydraulic ram 16 along the fore-and-aft direction equipartition setting, the hydraulic stem of left hydraulic ram 16 stretches out the end and presses on the left end face of about board 14 on a left side for the position of about board 14 is fixed in the adjustment.
The distance between the left restraint plate 14 and the left clamp holder fixing seat 5 can be adjusted by controlling the elongation of the left hydraulic mandril 16, and then the compression amount of the left horizontal spring 9 is changed to adjust the rigidity of the left horizontal spring 9.
The hydraulic ejector rod 16 adopts a sensor with a display force value.
In the test process, a plurality of inclination sensors 25 are fixed on the inner side of the clamping edge of the test piece 2 and used for detecting the boundary rotation angle of the test piece 2 in the loading process.
The use method of the self-reaction force loading device for the concrete slab bending test comprises the following steps:
step one) anchoring the test piece 2: cutting the test piece 2, punching the left and right clamping edges of the test piece 2, punching the left edge of the test piece 2 corresponding to the left anchor bolt 26 at the left clamping plate 27, punching the right edge of the test piece 2 corresponding to the right anchor bolt at the right clamping plate of the right supporting mechanism, measuring the left and right dimension of the test piece 2, namely the dimension of the short side, controlling the expansion amount of the left hydraulic ejector rod 16 and the expansion amount of the right hydraulic ejector rod of the right supporting mechanism, pushing the left restraint plate 14 to advance or retreat by virtue of the left roller 15, pushing the right restraint plate of the right supporting mechanism to advance or retreat by virtue of the right roller, moving the left anchor bolt 26 of the left clamp holder 4 to the left punching position of the test piece 2, moving the right anchor bolt of the right clamp holder of the right supporting mechanism to the punching position at the right side of the test piece 2, placing the test piece 2 in the axial long groove arranged at the right side of the left clamp holder 4, the test piece 2 is anchored by the left anchoring bolt 26, and simultaneously the test piece 2 is placed in the axial elongated slot arranged on the left side of the right holder of the right supporting mechanism, and the test piece 2 is anchored by the right anchoring bolt.
Step two) primary position calibration is carried out on the test piece 2: the position of the hydraulic jack 21 is adjusted to enable the central position of the upper end face of the test piece 2, namely the front and back direction of the loading point to coincide with the axis of the hydraulic jack 21, for test pieces 2 with different thicknesses, cushion blocks are placed in a left clamping plate 27 and a right clamping plate gap of a right supporting mechanism to clamp and fix the test piece 2, an inclination angle sensor 25 is installed on the clamping edge of the test piece 2, and the front and back directions and the left and right directions of the test piece 2 are adjusted to be horizontal according to the reading of the inclination angle sensor 25.
Step three), adjusting the boundary constraint rigidity: formula (1) is calculated from the stiffness of the compression spring:
wherein R is the spring rate, P is the load, and X is the compression or extension of the spring, i.e. the deformation.
The restraining stiffness of the left vertical spring 8 and the right vertical spring of the right supporting mechanism is adjusted, in the embodiment, the left vertical spring 8 and the right vertical spring of the right supporting mechanism are symmetrically arranged about the bilateral symmetry plane of the base 1, and the left horizontal spring9 and a right horizontal spring of the right side supporting mechanism are symmetrically arranged about a bilateral symmetry plane of the base 1, so that the constraint rigidity of the left vertical spring 8 and the constraint rigidity of the left horizontal spring 9 are adjusted, the constraint rigidities of the right vertical spring and the right horizontal spring are adjusted at the same time, when the test piece 2 is not cut, the structural boundary is constrained into a two-way plate with fixed left and right ends, a one-way plate belt in the middle part is selected to be cut into the test piece 2, the deformation of the left vertical spring 8 in the technical scheme of the application is slightly influenced by the weight, the constraint bending moment M for the left side edge of the test piece 2 before cutting is calculated according to a structural mechanics formula, and in order to enable the vertical spring to simulate the bending moment, the compression X of the left side vertical spring is adjusted according to the formula (3)1At this time, the vertical force provided by the vertical spring at one side is P1，P1The size of (c) can be obtained by formula (2):
where D1 is the distance from the central axis of the bearing shaft 7 to the axis of the left anchor bolt 26, obtained by measurement with a straight edge, P1Is the left vertical spring axial force, N1The number of all the left vertical springs 8.
Adjusting the restraining stiffness of the left horizontal spring 9: the horizontal restraint stiffness of the test piece 2 is the tensile stiffness EA of the plate, and the stiffness of the left horizontal spring 9 is determined by the amount X of tension or compression of the spring2Determine, so in the embodiment, the amount X of extension or compression of the left horizontal spring 92Calculated from equation (4):
in this formula P2Is a force reading of the single left hydraulic ram 16, N2Is a left hydraulic jackThe number of the rods 16, E is the modulus of elasticity of the test piece 2, and A is the cross-sectional area of the test piece 2 in the front-rear direction, i.e., the cross-sectional area in the longitudinal direction. Compression amount X of left horizontal spring 92A left horizontal restraining stiffness is determined by taking and reading a left hydraulic ram 16 force reading from the extension of the left hydraulic ram 16.
Step four), carrying out secondary position calibration: and adjusting the position of the hydraulic jack 21 to ensure that the left and right directions of the loading point at the central position of the test piece 2 coincide with the axis of the hydraulic jack 21, and controlling the electric lifting platform 20 to be at a proper height to ensure that the bearing plate 23 of the hydraulic jack 21 is attached to the surface of the test piece 2.
And step five), firstly applying load by adopting a force control method, finding out and recording the cracking load of the test piece 2, then loading the test piece 2 in a grading manner until the test piece 2 yields, and loading the test piece 2 in a displacement control manner after yielding until the test piece 2 is damaged.
Claims (8)
1. The utility model provides a concrete slab bending test self-reaction loading device which characterized in that: the device comprises a base (1), a test piece fixing mechanism and a loading mechanism, wherein the base (1) is of a bilaterally symmetrical structure, a pedestal (3) is fixed on the base (1), a left supporting mechanism comprises a left clamp holder (4) and a left clamp holder fixing seat (5), the left clamp holder (4) and the left clamp holder fixing seat (5) are horizontally arranged along the front and back direction, the left clamp holder (4) is rotatably installed on the left clamp holder fixing seat (5), two left clamping plates (27) extending rightwards are arranged on the right side of the left clamp holder (4), and a plurality of left anchoring bolts (26) are uniformly distributed on the two left clamping plates (27) along the front and back direction and used for anchoring the left edge of a test piece (2);
a plurality of groups of left vertical springs (8) are fixed on the lower side of the left holder fixing seat (5), a plurality of groups of left horizontal springs (9) are fixed on the left side of the left holder fixing seat (5), the plurality of groups of left vertical springs (8) and the plurality of groups of left horizontal springs (9) are uniformly distributed along the front and back directions of the left holder fixing seat (5), the lower ends of the plurality of groups of left vertical springs (8) are in sliding connection with the pedestal (3) along the left and right directions, the left ends of the plurality of groups of left horizontal springs (9) are in sliding connection with the left restraint plate (14) along the up and down directions, and the left restraint plate (14) is in sliding connection with the pedestal (3) along the left and right directions;
a plurality of left hydraulic push rods (16) are arranged between the left end of the pedestal (3) and the left side surface of the left restraint plate (14), and the left hydraulic push rods (16) are uniformly distributed along the front-back direction;
and a loading mechanism is arranged above the pedestal (3) and used for loading the test piece (2) in the vertical direction.
2. The self-reaction force loading device for the concrete slab bending test according to claim 1, characterized in that: the left holder (4) is cylindrical, an axial long groove is arranged on the right side of the left holder (4), a left holding plate (27) extending rightwards is arranged at the upper end and the lower end of the long groove, the front end and the rear end of the left holder (4) are respectively fixed with a left supporting shaft lever (7), the right side of the left holder fixing seat (5) is provided with a semicircular axial groove, the cylindrical part of the left holder (4) is coaxially arranged with the axial groove and the left supporting shaft lever (7), the two left supporting shaft levers (7) are respectively rotatably arranged at the front end and the rear end of the left holder fixing seat (5), a plurality of left rolling shafts (6) are arranged between the cylindrical part of the left holder (4) and the semicircular axial groove of the left holder fixing seat, the left rolling shafts (6) are uniformly distributed along the circumferential direction of the axial groove, the rotary connection of the left clamp holder (4) on the left clamp holder fixing seat (5) is realized.
3. The self-reaction loading device for the concrete slab bending test according to claim 2, characterized in that: the middle of the base (1) is upwards convex, the left side and the right side are concave, the middle convex part is taken as a bearing table, the loading mechanism comprises upright columns (18), frame beams (19), electric lifting tables (20) and hydraulic jacks (21), the two sides of the base (1) are respectively fixed with the lower ends of the two upright columns (18) to form a self-reaction structure, the four upright columns are arranged along the vertical direction, the upper end of each upright column (18) is respectively fixed with a top point of the frame beam (19), the frame beams (19) are in a rectangular structure, a machine body (22) of the hydraulic jack (21) and a bearing plate (23) of the hydraulic jack (21) are connected with each other through a spherical center of a movable spherical hinge (24) through the central axis, the machine body (22) of the hydraulic jack (21) is connected with the bearing plate (23) through the movable spherical hinge (24) in a spherical hinge manner, the hydraulic jack (21) is fixed on the lower surface of the electric lifting tables (20), the fixed position on the electric lifting platform (20) can be adjusted along the front-back direction and the left-right direction, the electric lifting platform (20) is of a rectangular structure, four corners of the electric lifting platform are respectively connected with one upright post in a sliding manner, and the lifting height can be adjusted along the four upright posts (18).
4. The self-reaction loading device for the concrete slab bending test according to claim 3, characterized in that: pedestal (3) on be provided with a plurality of horizontal sliding groove (12) that set up along the fore-and-aft direction equipartition, horizontal sliding groove (12) begin to the right part from pedestal (3) left part and end, horizontal sliding groove (12) set up along left right direction level, horizontal slider (10) in a left side of every horizontal sliding groove (12) left side slidable mounting, the lower extreme of fixed a set of left vertical spring (8) is gone up in every left horizontal slider (10), the quantity of a set of left vertical spring (8) is two, two vertical spring (8) set up side by side along left right direction, be used for realizing that test piece (2) loading in-process left vertical spring (8) provide vertical rigidity.
5. The self-reaction force loading device for the concrete slab bending test according to claim 4, characterized in that: the right flank of left restrain board (14) be provided with a plurality of left vertical tracks (13) along the fore-and-aft direction equipartition, left vertical track (13) set up along vertical direction, vertical slider (11) in the sliding mounting left of every left vertical track (13), the left end of the fixed a set of left horizontal spring (9) in right side of every left vertical slider (11), the quantity of a set of left horizontal spring (9) is two, two left horizontal springs (9) set up side by side along vertical direction, be used for realizing that test piece (2) loading in-process left horizontal spring (9) provide horizontal rigidity.
6. The self-reaction loading device for the concrete slab bending test according to claim 5, characterized in that: the structure that left restraint board (14) and pedestal (3) along left and right direction sliding connection do: the left side of pedestal (3) be provided with a plurality of left track grooves (17) along the fore-and-aft direction equipartition, left track groove (17) set up along left right direction level, left about board (14) lower extreme rotate a plurality of left gyro wheels (15) of installation, a plurality of left gyro wheels (15) set up along the fore-and-aft direction equipartition, a left gyro wheel (15) rolls in a corresponding left track groove (17).
7. The self-reaction loading device for the concrete slab bending test according to claim 6, characterized in that: pedestal (3) left end be provided with ascending bellying, the bellying of pedestal (3) left end is through dismantling mode with a plurality of hydraulic ram (16), a plurality of left hydraulic ram (16) set up along the fore-and-aft direction equipartition, the hydraulic stem of left hydraulic ram (16) stretches out the end and presses on the left end face of left restraint board (14).
8. The use method of the self-reaction force loading device for the concrete slab bending test according to claim 7 is characterized in that: the method comprises the following steps:
step one), anchoring a test piece (2): cutting a test piece (2), punching the clamping edges of the left side and the right side of the clamping of the test piece (2), wherein the punching position of the left edge of the test piece (2) corresponds to the position of a left anchoring bolt (26) at a left clamping plate (27), the punching position of the right edge of the test piece (2) corresponds to the position of a right anchoring bolt at a right clamping plate of a right supporting mechanism, the left and right direction size of the test piece (2), namely the size of a short side, is measured, the expansion amount of a left hydraulic ejector rod (16) and the expansion amount of a right hydraulic ejector rod of the right supporting mechanism are controlled, a left restraint plate (14) is pushed to advance or retreat by virtue of a left roller (15), a right restraint plate of the right supporting mechanism is pushed to advance or retreat by virtue of a right roller, the left anchoring bolt (26) of a left clamping device (4) is moved to the punching position of the left side of the test piece (2), and the right anchoring bolt of the right clamping device of the right supporting mechanism is moved to the punching position of the right side of the test piece (2), placing the test piece (2) into an axial elongated slot arranged on the right side of the left holder (4), anchoring the test piece (2) by using a left anchoring bolt (26), simultaneously placing the test piece (2) into an axial elongated slot arranged on the left side of a right holder of the right supporting mechanism, and anchoring the test piece (2) by using a right anchoring bolt;
step two), primary position calibration is carried out on the test piece (2): adjusting the position of a hydraulic jack (21), enabling the central position of the upper end face of a test piece (2), namely the front and back directions of a loading point to coincide with the axis of the hydraulic jack (21), adopting cushion blocks to be placed in gaps between a left clamping plate (27) and a right clamping plate of a right supporting mechanism for the test pieces (2) with different thicknesses to clamp and fix the test piece (2), installing an inclination angle sensor (25) on the clamping edge of the test piece (2), and adjusting the front and back directions and the left and right directions of the test piece (2) to be horizontal according to the reading of the inclination angle sensor (25);
step three), adjusting the boundary constraint rigidity: formula (1) is calculated from the stiffness of the compression spring:
wherein R is the spring stiffness, P is the load, X is the compression amount or the extension amount of the spring, namely the deformation amount;
regulating the restraining stiffness of the right vertical spring (8) and the right vertical spring of the right supporting mechanism, in the embodiment, the left vertical spring (8) and the right vertical spring of the right supporting mechanism are symmetrically arranged about the bilateral symmetry plane of the base (1), the left horizontal spring (9) and the right horizontal spring of the right supporting mechanism are symmetrically arranged about the bilateral symmetry plane of the base (1), so that the restraining stiffness of the left vertical spring (8) and the restraining stiffness of the left horizontal spring (9) are regulated, the restraining stiffness of the right vertical spring and the right horizontal spring is regulated at the same time, when the test piece (2) is not cut, the structural boundary is restrained as a two-way plate with the left end and the right end fixed, a one-way plate strip in the middle part is selected to be cut into the test piece (2), the restraining bending moment M of the left edge of the test piece (2) by the part of the boundary of the test piece (2) before cutting is calculated according to a structural mechanics formula, in order to enable the vertical spring to simulate the bending moment, the compression amount X of the left vertical spring is adjusted by combining the formula (3)1At the moment, the vertical force provided by the vertical spring on one side is P1，P1The size of (c) can be obtained by equation (2):
wherein D1For supporting the distance from the central axis of the shaft (7) to the axis of the left anchor bolt (26), obtained by measurement with a straight edge, P1Is the left vertical spring axial force, N1The number of all the left vertical springs (8) is equal;
adjusting the restraining stiffness of the left horizontal spring (9): the horizontal constraint rigidity of the test piece (2) is the tensile rigidity EA of the plate, and the rigidity of the left horizontal spring (9) is determined by the tensile or compression amount X of the spring2Determining, so in the embodiment, the amount X of extension or compression of the left horizontal spring (9)2Calculated from equation (4):
in this formula P2Is a force reading of a single left hydraulic ram (16), N2The number of the left hydraulic ejector rods (16), the elastic modulus of the test piece (2), the front-back section area of the test piece (2), namely the section area of the long side direction, and the compression amount X of the left horizontal spring (9)2Taking and reading force readings of the left hydraulic ram (16) through the elongation of the left hydraulic ram (16) to determine left horizontal constraint stiffness;
step four), carrying out secondary position calibration: adjusting the position of a hydraulic jack (21), enabling the left and right directions of a loading point at the central position of the test piece (2) to coincide with the axis of the hydraulic jack (21), controlling an electric lifting platform (20) to be at a proper height, and enabling a bearing plate (23) of the hydraulic jack (21) to be attached to the surface of the test piece (2);
and step five), firstly applying load by adopting a force control method, finding out and recording the cracking load of the test piece (2), then loading the test piece (2) in a grading manner until the test piece (2) yields, and loading the test piece (2) in a displacement control manner after yielding until the test piece (2) is damaged.
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| CN202210357862.4A CN114720290A (en) | 2022-04-06 | 2022-04-06 | Self-reaction force loading device for concrete slab bending test and using method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115266389A (en) * | 2022-09-29 | 2022-11-01 | 苏州普尚信息技术有限公司 | Building material strength detection machine |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115266389A (en) * | 2022-09-29 | 2022-11-01 | 苏州普尚信息技术有限公司 | Building material strength detection machine |
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Application publication date: 20220708 |