Continuous beam closure section demolition internal force measuring device and testing method

Abstract

The invention belongs to the technical field of bridge construction, and particularly relates to a continuous beam closure section demolition internal force measuring device and a testing method. A continuous beam closure section dismantling internal force measuring device comprises two truss structures longitudinally arranged along a girder of a closure section, a plurality of bolts are arranged at two ends of each truss structure, each truss structure comprises a first chord member and a second chord member which are arranged in parallel, and a first web member, a central web member and a second web member are sequentially arranged between each first chord member and the corresponding second chord member. A first inclined strut is further arranged between the first web member and the central web member, a second inclined strut is further arranged between the central web member and the second web member, and strain measuring points are arranged on the first chord member, the first web member, the second web member, the first inclined strut, the second inclined strut and the second chord member. By means of the two truss structures, system conversion internal force during closure section dismantling is borne, internal force testing is facilitated, the real internal force state of a bridge is determined, reference is provided for follow-up dismantling construction of similar bridges, and construction safety is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of bridge construction, and in particular relates to a device and a method for measuring internal forces of a continuous beam joint section dismantling. Background Art

[0002] Due to the long-term operation of the old bridge, the attenuation of the structural bearing capacity is unknown, and the constant load internal force state is uncertain and the construction state is uncontrollable. Therefore, the demolition of the bridge beam section is dangerous. In particular, there may be forced matching measures and construction temperature differences when the old bridge is closed. The acquisition of its internal force state can effectively evaluate the impact of system conversion on bridge performance, help clarify the force characteristics of bridge demolition construction, and provide a reference for the subsequent demolition of similar bridges.

[0003] At present, the principle of concrete strain test is mostly used to test the system conversion internal force during the bridge demolition stage. The test accuracy is low, and due to factors such as the vibration of the beam during demolition, it is easy to cause damage to the measuring point and distortion of the data. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide an internal force measuring device and testing method for the dismantling of the joint section of a continuous beam. The device uses two truss structures to bear the system conversion internal force when the joint section is dismantled, which is convenient for internal force testing. It can effectively evaluate the impact of the system conversion on the performance of the bridge, clarify the actual internal force state of the bridge, provide a reference for the subsequent dismantling construction of similar bridges, and ensure construction safety.

[0005] The technical solution of the present invention is: a device for measuring internal forces of a continuous beam joint section removal, comprising two truss structures arranged longitudinally along the main beam of the beam section at the joint, a plurality of bolts are respectively arranged at both ends of the truss structure, the truss structure comprises a first chord and a second chord arranged in parallel, a first web member, a central web member and a second web member are sequentially arranged between the first chord and the second chord, a first diagonal brace is further arranged between the first web member and the central web member, and a second diagonal brace is further arranged between the central web member and the second web member, a first strain measuring point and a second strain measuring point are respectively arranged at both ends of the first chord, a third strain measuring point and a sixth strain measuring point are respectively arranged in the middle of the first web member and the second web member, a fourth strain measuring point and a fifth strain measuring point are respectively arranged in the middle of the first diagonal brace and the second diagonal brace, a seventh strain measuring point and an eighth strain measuring point are respectively arranged at both ends of the second chord, and strain gauges are attached to the first strain measuring point, the second strain measuring point, the third strain measuring point, the fourth strain measuring point, the fifth strain measuring point, the sixth strain measuring point, the seventh strain measuring point and the eighth strain measuring point.

[0006] The two truss structures are symmetrically distributed on the inner surface of the web of the main beam of the beam section at the joint, and are fastened to the web of the main beam by bolts.

[0007] The bolts are arranged in a matrix, and the number of the bolts is not less than 2×2.

[0008] A method for testing internal forces of a continuous beam joint section removal, using the above-mentioned continuous beam joint section removal internal force measuring device, comprises the following steps:

[0009] S1: Install the internal force measuring device for the joint section of the continuous beam. The specific process is: drill holes in the concrete of the main beam of the joint section, install bolts at both ends of the truss structure, and fix them to the inner surface of the web of the main beam of the joint section;

[0010] S2: Arrange strain measuring points; the specific process is: a first strain measuring point and a second strain measuring point are respectively arranged at both ends of the first chord, a third strain measuring point and a sixth strain measuring point are respectively arranged in the middle of the first web member and the second web member, a fourth strain measuring point and a fifth strain measuring point are respectively arranged in the middle of the first diagonal brace and the second diagonal brace, a seventh strain measuring point and an eighth strain measuring point are respectively arranged at both ends of the second chord, and strain gauges are attached to the first strain measuring point, the second strain measuring point, the third strain measuring point, the fourth strain measuring point, the fifth strain measuring point, the sixth strain measuring point, the seventh strain measuring point and the eighth strain measuring point;

[0011] S3: After the joint section is removed, monitor the strain of the truss structure and the displacement of the joint mouth beam section;

[0012] S4: dismantle the truss structure, release the internal force of the beam section at the joint, and monitor the final displacement of the beam section at the joint;

[0013] S5: Determine the actual internal force of the beam section at the original joint through the monitoring results of the truss structure strain and the displacement of the beam section at the joint.

[0014] In step S3, the strains monitored at the first strain measuring point, the second strain measuring point, the third strain measuring point, the fourth strain measuring point, the fifth strain measuring point, the sixth strain measuring point, the seventh strain measuring point and the eighth strain measuring point are recorded as ε 21 ~ε 28 , the displacement of the joint beam section is recorded as Δx1 and Δx2 respectively, and the internal force of each truss member can be obtained according to Hooke's law and recorded as N according to the position of the measuring point. 21 ~N 28 , the specific calculation formula is as follows:

[0015] N i =(ε i ·E)·A (1)

[0016] Where E is the elastic modulus of the rod material, and A is the cross-sectional area of ​​the rod.

[0017] In step S5, the actual internal force of the beam section at the original joint is determined by monitoring the strain of the truss structure and the displacement of the joint mouth beam section. The final displacement of the joint mouth beam section is recorded as x1 and x2 respectively. The internal force of the joint section is partially released by the truss and partially by deformation during dismantling. The moment conversion coefficient on both sides of the joint mouth is defined as Axial force conversion factor The shear force conversion coefficient is The actual internal force of the joint section is the sum of the internal forces of the two truss structures divided by the internal force conversion coefficient, that is:

[0018]

[0019]

[0020] Where M 1 , Q 1 、N 1 、M 2 , Q 2 、N 2 , are respectively the actual bending moment, shear force and axial force on both sides of the joint section; M1, Q1, N1, M2, Q2 and N2 are respectively the bending moment, shear force and axial force borne by a single truss structure;

[0021] By synthesizing the internal forces at the intersection points O1 and O2 of the truss structure height centerline and the closure cross-section line, the internal forces on both sides of the closure borne by the truss structure are:

[0022] M1=(F An +F Bn )·r1+(F Am -F Bm )·0.5h (4)

[0023] N1=-(F Am +F Bm ) (5)

[0024] Q1=-(F An +F Bn ) (6)

[0025] M2=-(F Cn +F Dn )·r1+(F Cm -F Dm )·0.5h (7)

[0026] N2=-(F Cm +F Dm ) (8)

[0027] Q2=-(F Cn +F Dn ) (9)

[0028] Among them, F An 、F Bn 、F Cn 、F Dn is the vertical reaction force of the truss; F Am 、F Bm 、F Cm 、F Dm is the horizontal reaction force of the truss; r1, r2, and h are the horizontal distance from the left fixed point of the truss to the resultant force application point O1, the horizontal distance from the right fixed point of the truss to the resultant force application point O2, and the height of the truss respectively; the resultant force application points O1 and O2 are the intersection points of the first diagonal brace and the second diagonal brace with the center line of the truss height; the reaction force of each constraint point can be determined according to the node force balance condition, and the results are as follows:

[0029] F Am =N 21 (10)

[0030] F An =-N 23 (11)

[0031] F Bm =N 27 +N 24 cosβ (12)

[0032] F Bn =-(N 23 +N 24 sinβ) (13)

[0033] F Cm =N 22 、F Cn =-N 26 (14)

[0034] F Dm =N 27 +N 25 cosβ (15)

[0035] F Dn =-(N 26 +N 25 sinβ) (16)

[0036] Where β is the horizontal angle of the truss brace.

[0037] The technical effects of the present invention are: 1. The truss structure of the present invention includes two chords, and a web member and a diagonal brace are arranged between the chords, which has high stability and can effectively bear most of the internal force conversion caused by the system conversion; 2. The present invention calculates the internal force conversion ratio of the truss by the displacement of the joint mouth, and determines the internal force distribution of the original joint section by strain monitoring the truss structure, and the data reliability is strong; 3. The present invention can realize the internal force measurement of the joint section through a small number of strain measuring points, which is convenient and concise. By obtaining the actual internal force distribution of the joint section, it can effectively evaluate the impact of the system conversion on the bridge performance, clarify the actual internal force state of the bridge, and provide a reference for the subsequent demolition construction of similar bridges.

[0038] The following is a further description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a schematic diagram of the installation of an internal force measuring device for dismantling a joint section of a continuous beam according to an embodiment of the present invention.

[0040] Figure 2 The present invention is a schematic structural diagram of a device for measuring internal forces during removal of a continuous beam joint section according to an embodiment of the present invention.

[0041] Figure 3 Schematic diagram of calculation parameters according to an embodiment of the present invention.

[0042] Figure 4 It is a schematic diagram of the deformation of the joint section removal according to an embodiment of the present invention.

[0043] Figure 5 This is a simplified calculation diagram of the truss according to an embodiment of the present invention.

[0044] Figure 6 It is a schematic diagram of force balance of a truss node according to an embodiment of the present invention.

[0045] Figure markings: 1-beam section at the joint, 2-truss structure, 3-bolt, 4-first chord, 5-first web member, 6-first diagonal brace, 7-second chord, 8-second diagonal brace, 9-second web member, 10-center web member, 21-first strain measuring point, 22-second strain measuring point, 23-third strain measuring point, 24-fourth strain measuring point, 25-fifth strain measuring point, 26-sixth strain measuring point, 27-seventh strain measuring point, 28-eighth strain measuring point. DETAILED DESCRIPTION

[0046] Example 1

[0047] like Figure 1 , Figure 2As shown, a device for measuring internal forces of a continuous beam joint section dismantling comprises two truss structures 2 arranged longitudinally along the main beam of the joint section 1, a plurality of bolts 3 are respectively arranged at both ends of the truss structure 2, the truss structure 2 comprises a first chord 4 and a second chord 7 arranged in parallel, a first web member 5, a center web member 10 and a second web member 9 are arranged between the first chord 4 and the second chord 7 in sequence, a first diagonal brace 6 is further arranged between the first web member 5 and the center web member 10, the center web member 10 and the second web member 9 are further provided with a second diagonal brace 8, and first strain measuring points 2 are respectively arranged at both ends of the first chord 4. 1 and a second strain measuring point 22, a third strain measuring point 23 and a sixth strain measuring point 26 are respectively provided in the middle of the first web member 5 and the second web member 9, a fourth strain measuring point 24 and a fifth strain measuring point 25 are respectively provided in the middle of the first diagonal brace 6 and the second diagonal brace 8, a seventh strain measuring point 27 and an eighth strain measuring point 28 are respectively provided at both ends of the second chord 7, and strain gauges are attached to the first strain measuring point 21, the second strain measuring point 22, the third strain measuring point 23, the fourth strain measuring point 24, the fifth strain measuring point 25, the sixth strain measuring point 26, the seventh strain measuring point 27 and the eighth strain measuring point 28.

[0048] The truss structure 2 of the present invention comprises two chords, namely a first chord 4 and a second chord 7, with a web member and a diagonal brace arranged between the chords. The truss structure 2 has high stability and can effectively bear most of the internal force conversion caused by the system conversion.

[0049] The two truss structures 2 are symmetrically distributed on the inner surface of the web of the main beam of the beam section 1 at the joint, and are fastened to the web of the main beam by bolts 3.

[0050] The bolts 3 are arranged in a matrix, and the number of the bolts 3 is not less than 2×2.

[0051] A method for testing internal forces of a continuous beam joint section removal, using the above-mentioned continuous beam joint section removal internal force measuring device, comprises the following steps:

[0052] S1: Install the internal force measuring device for the joint section of the continuous beam. The specific process is as follows: drill holes in the concrete of the main beam of the beam section 1 at the joint, install bolts 3 at both ends of the truss structure 2, and fix them to the inner surface of the web of the main beam of the beam section 1 at the joint;

[0053] S2: Arrange strain measuring points; the specific process is: a first strain measuring point 21 and a second strain measuring point 22 are respectively arranged at both ends of the first chord 4, a third strain measuring point 23 and a sixth strain measuring point 26 are respectively arranged in the middle of the first web member 5 and the second web member 9, a fourth strain measuring point 24 and a fifth strain measuring point 25 are respectively arranged in the middle of the first diagonal brace 6 and the second diagonal brace 8, a seventh strain measuring point 27 and an eighth strain measuring point 28 are respectively arranged at both ends of the second chord 7, and strain gauges are attached to the first strain measuring point 21, the second strain measuring point 22, the third strain measuring point 23, the fourth strain measuring point 24, the fifth strain measuring point 25, the sixth strain measuring point 26, the seventh strain measuring point 27 and the eighth strain measuring point 28;

[0054] S3: After the joint section is removed, monitor the strain of the truss structure 2 and the displacement of the joint mouth beam section;

[0055] S4: dismantle the truss structure 2, release the internal force of the beam segment 1 at the joint, and monitor the final displacement of the beam segment at the joint;

[0056] S5: Determine the actual internal force of beam segment 1 at the original joint through the monitoring results of the strain of truss structure 2 and the displacement of the beam segment at the joint.

[0057] like Figure 3 to Figure 6 As shown, in step S3, the strains monitored by the first strain measuring point 21, the second strain measuring point 22, the third strain measuring point 23, the fourth strain measuring point 24, the fifth strain measuring point 25, the sixth strain measuring point 26, the seventh strain measuring point 27 and the eighth strain measuring point 28 are recorded as ε 21 ~ε 28 , the displacement of the joint beam section is recorded as Δx1 and Δx2 respectively, and the internal force of each truss member can be obtained according to Hooke's law and recorded as N according to the position of the measuring point. 21 ~N 28 , the specific calculation formula is as follows:

[0058] N i =(ε i ·E)·A (1)

[0059] Where E is the elastic modulus of the rod material, and A is the cross-sectional area of ​​the rod.

[0060] 1. In step S5, the actual internal force of the beam segment 1 at the original joint is determined by monitoring the strain of the truss structure 2 and the displacement of the joint mouth beam segment. The final displacements of the joint mouth beam segment are recorded as x1 and x2 respectively. The internal force of the joint segment is partially released by the truss and partially by deformation during dismantling. The moment conversion coefficient on both sides of the joint mouth is defined as Axial force conversion factor The shear force conversion coefficient is The actual internal force of the joint section is the sum of the internal forces of the two truss structures (2) divided by the internal force conversion coefficient, that is:

[0061]

[0062]

[0063] Where M 1 , Q 1 、N 1 、M 2 , Q 2 、N 2 , are respectively the actual bending moment, shear force and axial force on both sides of the joint section; M1, Q1, N1, M2, Q2 and N2 are respectively the bending moment, shear force and axial force borne by a single truss structure (2);

[0064] By synthesizing the internal forces at the intersection points O1 and O2 of the height center line of the truss structure 2 and the cross-sectional line of the joint, the internal forces on both sides of the joint borne by the truss structure 2 are:

[0065] M1=(F An +F Bn )·r1+(F Am -F Bm )·0.5h (4)

[0066] N1=-(F Am +F Bm ) (5)

[0067] Q1=-(F An +F Bn ) (6)

[0068] M2=-(F Cn +F Dn )·r1+(F Cm -F Dm )·0.5h (7)

[0069] N2=-(F Cm +F Dm ) (8)

[0070] Q2=-(F Cn +F Dn ) (9)

[0071] Among them, F An 、F Bn 、F Cn 、F Dn is the vertical reaction force of the truss; F Am 、F Bm 、F Cm 、F Dmis the horizontal reaction force of the truss; r1, r2, and h are the horizontal distance from the left fixed point of the truss to the resultant force application point O1, the horizontal distance from the right fixed point of the truss to the resultant force application point O2, and the height of the truss respectively; the resultant force application points O1 and O2 are the intersection points of the first diagonal brace 6, the second diagonal brace 8 and the center line of the truss height; the reaction force of each constraint point can be determined according to the node force balance condition, and the results are as follows:

[0072] F Am =N 21 (10)

[0073] F An =-N 23 (11)

[0074] F Bm =N 27 +N 24 cosβ (12)

[0075] F Bn =-(N 23 +N 24 sinβ) (13)

[0076] F Cm =N 22 、F Cn =-N 26 (14)

[0077] F Dm =N 27 +N 25 cosβ (15)

[0078] F Dn =-(N 26 +N 25 sinβ) (16)

[0079] Where β is the horizontal angle of the truss brace.

[0080] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A device for measuring internal forces of a continuous beam joint section during dismantling, characterized in that: The invention comprises two truss structures (2) arranged longitudinally along the main beam of the beam section (1) at the joint, a plurality of bolts (3) are respectively provided at both ends of the truss structure (2), the truss structure (2) comprises a first chord (4) and a second chord (7) arranged in parallel, a first web member (5), a central web member (10) and a second web member (9) are sequentially provided between the first chord (4) and the second chord (7), a first diagonal brace (6) is further provided between the first web member (5) and the central web member (10), the central web member (10) and the second web member (9) are further provided with a second diagonal brace (8), a first strain measuring point (21) and a second strain measuring point (22) are respectively provided at both ends of the first chord (4), and a first strain measuring point (23) and a second strain measuring point (24) are respectively provided at both ends of the first chord (4). 2), a third strain measuring point (23) and a sixth strain measuring point (26) are respectively provided in the middle of the first web member (5) and the second web member (9), a fourth strain measuring point (24) and a fifth strain measuring point (25) are respectively provided in the middle of the first diagonal brace (6) and the second diagonal brace (8), a seventh strain measuring point (27) and an eighth strain measuring point (28) are respectively provided at both ends of the second chord member (7), and strain gauges are attached to the first strain measuring point (21), the second strain measuring point (22), the third strain measuring point (23), the fourth strain measuring point (24), the fifth strain measuring point (25), the sixth strain measuring point (26), the seventh strain measuring point (27) and the eighth strain measuring point (28).

2. According to claim 1, a device for measuring internal forces of a continuous beam joint section removal, characterized in that: The two truss structures (2) are symmetrically distributed on the inner surface of the main beam web of the beam section (1) at the joint, and are fastened to the main beam web by bolts (3).

3. The internal force measuring device for dismantling the joint section of a continuous beam according to claim 1, characterized in that: The bolts (3) are arranged in a matrix, and the number of the bolts (3) is not less than 2×2.

4. A method for testing the internal force of a continuous beam joint section removal, using a continuous beam joint section removal internal force measuring device as claimed in claims 1 to 3, characterized in that: The following steps are involved: S1: Installing the internal force measuring device for the joint section of the continuous beam, the specific process is: drilling holes in the main beam concrete of the joint section (1), installing bolts (3) at both ends of the truss structure (2), and fixing them to the inner surface of the web of the main beam of the joint section (1); S2: arranging strain measuring points; the specific process is as follows: a first strain measuring point (21) and a second strain measuring point (22) are respectively arranged at both ends of the first chord (4); a third strain measuring point (23) and a sixth strain measuring point (26) are respectively arranged in the middle of the first web member (5) and the second web member (9); a fourth strain measuring point (24) and a fifth strain measuring point (25) are respectively arranged in the middle of the first diagonal brace (6) and the second diagonal brace (8); a seventh strain measuring point (27) and an eighth strain measuring point (28) are respectively arranged at both ends of the second chord (7); strain gauges are attached to the first strain measuring point (21), the second strain measuring point (22), the third strain measuring point (23), the fourth strain measuring point (24), the fifth strain measuring point (25), the sixth strain measuring point (26), the seventh strain measuring point (27) and the eighth strain measuring point (28); S3: After the joint section is removed, monitor the strain of the truss structure (2) and the displacement of the joint mouth beam section; S4: dismantle the truss structure (2), release the internal force of the beam section at the joint (1), and monitor the final displacement of the beam section at the joint; S5: The actual internal force of the beam section (1) at the original joint is determined through the monitoring results of the strain of the truss structure (2) and the displacement of the beam section at the joint.

5. According to claim 4, a method for testing internal forces of a continuous beam joint section removal, characterized in that: In step S3, the strains monitored by the first strain measuring point (21), the second strain measuring point (22), the third strain measuring point (23), the fourth strain measuring point (24), the fifth strain measuring point (25), the sixth strain measuring point (26), the seventh strain measuring point (27) and the eighth strain measuring point (28) are recorded as ε 21 ~ε 28 , the displacement of the joint beam section is recorded as Δx1 and Δx2 respectively, and the internal force of each truss member can be obtained according to Hooke's law and recorded as N according to the position of the measuring point. 21 ~N 28 , the specific calculation formula is as follows: N i =(e i ·E)·A (1) Where E is the elastic modulus of the rod material, and A is the cross-sectional area of ​​the rod.

6. A method for testing internal forces of a continuous beam joint section dismantling according to claim 5, characterized in that: In step S5, the actual internal force of the beam section (1) at the original joint is determined by monitoring the strain of the truss structure (2) and the displacement of the joint-mouth beam section. The final displacements of the joint-mouth beam section are recorded as x1 and x2 respectively. The internal force of the joint section is released partly by the truss and partly by deformation during dismantling. The moment conversion coefficient on both sides of the joint is defined as Axial force conversion factor The shear force conversion coefficient is The actual internal force of the joint section is the sum of the internal forces of the two truss structures (2) divided by the internal force conversion coefficient, that is: Where M 1 , Q 1 、N 1 、M 2 , Q 2 、N 2 , are respectively the actual bending moment, shear force and axial force on both sides of the joint section; M1, Q1, N1, M2, Q2 and N2 are respectively the bending moment, shear force and axial force borne by a single truss structure (2); By synthesizing the internal forces at the intersection points O1 and O2 of the height center line of the truss structure (2) and the cross-sectional line of the joint, the internal forces on both sides of the joint borne by the truss structure (2) are: M1=(F An +F Bn )·r1+(F Am -F Bm )·0.5h (4) N1=-(F Am +F Bm ) (5) Q1=-(F An +F Bn ) (6) M2=-(F Cn +F Dn )·r1+(F Cm -F Dm )·0.5h (7) N2=-(F Cm +F Dm ) (8) Q2=-(F Cn +F Dn ) (9) Among them, F An 、F Bn 、F Cn 、F Dn is the vertical reaction force of the truss; F Am 、F Bm 、F Cm 、F Dm is the horizontal reaction force of the truss; r1, r2, and h are the horizontal distance from the left fixed point of the truss to the resultant force application point O1, the horizontal distance from the right fixed point of the truss to the resultant force application point O2, and the height of the truss respectively; the resultant force application points O1 and O2 are the intersection points of the first diagonal brace (6) and the second diagonal brace (8) with the center line of the truss height; the reaction force of each constraint point can be determined according to the node force balance condition, and the results are as follows: F Am =N 21 (10) F An =-N 23 (11) F Bm =N 27 +N 24 cosβ (12) F Bn =-(N 23 +N 24 sinβ) (13) F Cm =N 22 、F Cn =-N 26 (14) F Dm =N 27 +N 25 cosβ (15) F Dn =-(N 26 +N 25 sinβ) (16) Where β is the horizontal angle of the truss brace.

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