Monitoring method for construction process of supporting beam and pulling column

Abstract

The invention provides a monitoring method for a beam supporting and column pulling construction process, and relates to the technical field of civil engineering, and the method comprises the steps: arranging at least one first observation point in the height direction of a supporting steel frame, and installing a steel bar strain gauge at each first observation point; second observation points are arranged at the two ends and the midspan of each underpinned beam respectively, and the total number of the second observation points is three; simultaneously arranging a steel bar stress meter and a concrete strain meter as third observation points on the target beam with the increased cross section according to the monitored cross section; determining an initial corresponding edge value by using a steel bar strain gauge; determining a strain variation according to the initial stress edge value; observing the deflection of the beam by using a level gauge; determining the section by using a steel bar stress meter and a concrete strain meter to increase the stress of the concrete beam; and setting corresponding thresholds for the strain variation, the deflection of the beam and the stress of the concrete beam with the increased cross section so as to judge the state of each node. The problem that potential safety hazards exist due to the fact that node data are measured and read manually in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of civil engineering, and in particular to a monitoring method for a beam-supporting and column-pulling construction process. Background Art

[0002] The technology of supporting beams and removing columns has been applied in engineering projects in scenarios such as adding floors to the bottom of existing buildings, functional transformation, and foundation reinforcement. Common methods of support and replacement reinforcement include increasing the cross-section reinforcement, prestressed reinforcement, inclined support reinforcement, and combined reinforcement. Engineering practice shows that during the column truncation and unloading stage, the upper load is redistributed, and the stability of the support system, the deflection of the reinforced beam, and the internal stress-strain of the increased cross-section beam become the focus of safety control. Current projects generally use discrete manual measurement and monitoring methods, which can provide basic displacement, deflection, and strain data; however, manual measurement only at key nodes cannot capture the rapid changes before the instantaneous unloading of the column or the instability of the support, posing a great safety hazard. Summary of the Invention

[0003] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a monitoring method for the construction process of supporting beams and removing columns. The present invention solves the problem of potential safety hazards in the prior art caused by manual measurement and reading of node data.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A monitoring method for a beam support and column removal construction process, comprising:

[0006] At least one first observation point is arranged along the height direction of the supporting steel frame, and a steel bar strain gauge is installed at each first observation point;

[0007] The second observation points are arranged at both ends and the middle of each beam to be replaced, for a total of three points;

[0008] On the target beam with increased cross-section, steel bar stress gauges and concrete strain gauges are arranged simultaneously according to the monitoring cross-section as the third observation point;

[0009] Setting a first data monitoring period, and determining an initial strain value using a steel bar strain gauge according to the first observation point;

[0010] Determining the strain variation according to the initial strain value;

[0011] Setting a second data monitoring period, and observing the deflection of the beam using a level at the second observation point;

[0012] Determining the stress of the reinforced concrete beam in cross section using a steel bar stress gauge and a concrete strain gauge according to the third observation point;

[0013] Corresponding thresholds are set for the strain variation, the beam deflection, and the cross-section increase stress of the concrete beam to determine the state of each node.

[0014] Preferably, the first data monitoring period is one month.

[0015] Preferably, the calculation formula for the strain change is:

[0016] ;

[0017] in, Measure the strain value for the current instrument, is the initial strain value, Test temperature for the current sensor, is the initial temperature, is the linear expansion coefficient of the steel chord, is the linear expansion coefficient of the steel pipe.

[0018] Preferably, the second data monitoring period is 1 month.

[0019] Preferably, the calculation formula for the deflection of the beam is:

[0020] ;

[0021] Where L is the length of the beam, 、 and They are the left elevation, right elevation and middle elevation of the beam respectively.

[0022] The present invention discloses the following technical effects:

[0023] The present invention provides a monitoring method for a construction process of beam support and column removal, comprising:

[0024] At least one first observation point is arranged along the height direction of the supporting steel frame, and a steel bar strain gauge is installed at each first observation point; second observation points are arranged at both ends and the mid-span of each supported replacement beam, for a total of three points; on the target beam with increased cross-section, steel bar strain gauges and concrete strain gauges are arranged simultaneously as third observation points according to the monitoring cross-section; a first data monitoring period is set, and the initial strain value is determined based on the first observation point using the steel bar strain gauge; the strain change is determined based on the initial strain value; a second data monitoring period is set, and the deflection of the beam is observed based on the second observation point using a level; the stress of the concrete beam with increased cross-section is determined based on the third observation point using the steel bar strain gauge and the concrete strain gauge; corresponding thresholds are set for the strain change, the deflection of the beam, and the stress of the concrete beam with increased cross-section to judge the status of each node. By synchronously and continuously collecting data and determining graded thresholds for the strain of the support system, the deflection of the replaced beams, and the stress-strain of the increased cross-section beams, an automated monitoring chain with a unified time base was established. This allows for real-time detection of hidden dangers such as support system buckling, excessive beam deflection, or coordinated cross-section failure. Compared with existing discrete manual measurement or single-parameter monitoring methods, this solution significantly improves monitoring integrity and early warning timeliness, avoids construction safety risks caused by information lags, and generates traceable data records for the entire process, providing a quantitative basis for subsequent structural analysis and quality acceptance. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 A flow chart of a method for monitoring the construction process of beam support and column removal provided by an embodiment of the present invention;

[0027] Figure 2 A first observation point arrangement diagram provided in an embodiment of the present invention;

[0028] Figure 3 Schematic diagram of arranging strain gauges at the upper ends and the middle bottom of two beams according to an embodiment of the present invention;

[0029] Figure 4 Schematic diagram of arranging strain gauges at the upper ends and the middle bottom of both sides of the beam according to an embodiment of the present invention;

[0030] Figure 5 Schematic diagram of arranging strain gauges at the middle bottom position provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] like Figure 1 As shown, the present invention provides a monitoring method for the construction process of beam support and column removal, comprising:

[0034] Step 100: Arrange at least one first observation point along the height direction of the supporting steel frame, and install a steel bar strain gauge at each first observation point;

[0035] Step 200: Arrange second observation points at both ends and the mid-span of each entrusted replacement beam, for a total of three points;

[0036] Step 300: On the target beam with an increased cross-section, a steel bar stress gauge and a concrete strain gauge are simultaneously arranged according to the monitoring cross-section as a third observation point;

[0037] Step 400: setting a first data monitoring period, and determining an initial strain value using a steel bar strain gauge according to the first observation point;

[0038] Step 500: determining the strain variation according to the initial strain value;

[0039] Step 600: Setting a second data monitoring period, and observing the deflection of the beam using a level according to the second observation point;

[0040] Step 700: Determine the stress of the reinforced concrete beam in cross section using a steel bar strain gauge and a concrete strain gauge according to the third observation point;

[0041] Step 800: setting corresponding thresholds for the strain variation, the beam deflection, and the cross-section increase stress of the concrete beam to determine the status of each node.

[0042] Furthermore, the first data monitoring period is one month.

[0043] Specifically, support system monitoring process:

[0044] The purpose of monitoring the stability of the steel frame is to ensure that the steel frame does not overturn or buckle during construction, and to ensure the safety of the underpinning process.

[0045] like Figure 2As shown, the first observation point is arranged:

[0046] The monitoring points are arranged along the height of the support system, and one steel bar strain gauge is arranged on each support system.

[0047] Strain gauges are used to monitor the strain of the support system using an integrated automated monitoring system. Strain monitoring utilizes integrated modal surface strain gauges, collecting data in real time over a one-month period. The stress of the support system can be calculated based on the elastic modulus of the support system. After the strain gauge is installed and stabilized, the initial value is read. Subsequently, when a force is applied to the support system, the measured value is read again. The difference between the initial value and the measured value represents the strain of the support system.

[0048] The instrument can automatically measure the frequency of the steel string. The calculation formula of strain and frequency is:

[0049] ;

[0050] A is the strain value in µε, f is the vibration frequency of the wire, K=0.0031559;

[0051] When the linear expansion coefficient of the support system is inconsistent with the steel string in the strain gauge, temperature changes can also cause strain changes, and its influence must be eliminated during testing. The calculation formula is as follows: The actual strain change of the support system ;

[0052] The strain value measured by the current instrument, in µε, is the initial strain value, Test temperature for the current sensor, is the initial temperature, =12.2—The linear expansion coefficient of the steel string is 12.2µε / ℃, =11.7—Under normal circumstances, the linear expansion coefficient of the steel pipe is µε / ℃;

[0053] According to calculation results, the yield strain of Q355 steel is approximately 1720µε. Once this value is exceeded, the material enters the plastic deformation stage, at which point an additional support system is required to ensure construction safety.

[0054] Furthermore, the second data monitoring period is 1 month.

[0055] Specifically, beam deformation monitoring is as follows:

[0056] The original structural beam monitoring is to ensure timely understanding of the deformation of the beam after the column is removed during the construction process, to prevent problems with the support system during the column removal process, which may damage the beam and affect the structural safety.

[0057] Arrangement of the second observation point:

[0058] Beam monitoring points are arranged at both ends and the middle of the span of the reinforced beam (the measuring points need to remain fixed). Three measuring points are set up on each beam, and a level is used to observe the deflection of the beam.

[0059] Before disconnecting the frame column, use an electronic level and a tower ruler to measure the deflection of the original beam and calculate the original deflection data. The elevation of both sides of the beam is measured. 、 and the middle elevation , deflection L is the length of the beam. After disconnecting the frame columns, continuously monitor beam deflection twice daily for a period of one month. Deflection limits should not exceed the relevant regulations in the "Code for Design of Concrete Structures," as shown in the table below. If deflection exceeds the limit, inspect the support system and re-roof the reinforced beams and surrounding beam-slabs to ensure structural safety. Continue with the next step after strengthening and adjusting the support system.

[0060] After the reinforced beams are cast and before the formwork is removed, the formwork support system must be monitored using the same monitoring methods as described above. If the deflection difference exceeds the specified limit, the formwork support system must be reinforced, increasing the spacing between the vertical and horizontal bars of the supporting scaffolding to ensure structural safety.

[0061] During the demolition process, personnel are arranged to conduct monitoring three times a day. After the concrete beam reinforcement is completed (the formwork is removed), monitoring will be carried out for another week, with the monitoring frequency being once a day.

[0062] Furthermore, the deflection limits of flexural members are as shown in Table 1:

[0063] Table 1

[0064]

[0065] Furthermore, the stress and strain monitoring of the concrete beam with increased cross-section is as follows:

[0066] Stress monitoring of enlarged-section concrete beams involves measuring the stresses and strains generated by concrete structures under load and other factors, and their changes, using monitoring instruments and equipment embedded within the beams. The goal is to understand the stresses and strains within the reinforced concrete during normal operation. Under normal conditions, reinforcement stress is less than 360 MPa and concrete strain is less than 2000 µε. This allows analysis of the beam's operational status, assessment of its safety, and a scientific basis for the safe implementation of the proposed solution.

[0067] Arrangement of the third observation point:

[0068] Considering that the added concrete in the increased cross-section of the beam after reinforcement works in synergy with the original concrete, and monitoring the stress and strain of the concrete beam after demolition, steel and concrete strain gauges were embedded in the newly poured concrete in the increased cross-section to monitor the stress and strain of the concrete beam. Three typical scenarios were selected for stress and strain monitoring in the columns to be demolished, with one steel and one concrete strain gauge deployed at each point.

[0069] Case 1: After the column is removed, the cross-section of the beams in both directions needs to be increased. Strain gauges are arranged at the upper ends and the middle bottom of the two beams (see the arrangement for details). Figure 3 ); Case 2: After the column is removed, the cross section of the beams in one direction needs to be increased, and strain gauges are arranged at the upper ends and the middle bottom of both sides of the beams (see arrangement for details). Figure 4 Case 3: After the column is removed, one beam in one direction needs to have its cross section increased, while the other does not. Strain gauges are placed at the upper end of the beam away from the column removal position and at the middle bottom of the beam close to the column removal position (see the arrangement). Figure 5 ).

[0070] According to the requirements of concrete strain and steel stress value, the concrete strain should not be greater than 0.002 during the monitoring process, and the steel stress value should not exceed the steel design strength value.

[0071] Strain gauges are used to monitor the stress-strain inside the concrete beams. An integrated automatic monitoring system is used. Strain monitoring uses integrated vibration-type surface strain gauges to collect data in real time. The data collection cycle is 1 month.

[0072] A level is used to observe the deformation of the beam after the columns are pulled out and the supports are removed. The observation period is 7 days.

[0073] Furthermore, Table 2 is a table of observation equipment:

[0074] Table 2

[0075]

[0076] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0077] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A monitoring method for the construction process of beam support and column removal, characterized in that: include: At least one first observation point is arranged along the height direction of the supporting steel frame, and a steel bar strain gauge is installed at each first observation point; The second observation points are arranged at both ends and the middle of each beam to be replaced, for a total of three points; On the target beam with increased cross-section, steel bar stress gauges and concrete strain gauges are arranged simultaneously according to the monitoring cross-section as the third observation point; Setting a first data monitoring period, and determining an initial strain value using a steel bar strain gauge according to the first observation point; Determining the strain variation according to the initial strain value; Setting a second data monitoring period, and observing the deflection of the beam using a level at the second observation point; Determining the stress of the reinforced concrete beam in cross section using a steel bar stress gauge and a concrete strain gauge according to the third observation point; Corresponding thresholds are set for the strain variation, the beam deflection, and the cross-section increase stress of the concrete beam to determine the state of each node.

2. A method for monitoring the construction process of beam support and column removal according to claim 1, characterized in that: The first data monitoring period is one month.

3. The method for monitoring the construction process of beam support and column removal according to claim 1, characterized in that: The calculation formula of the strain change is: ； in, Measure the strain value for the current instrument, is the initial strain value, Test temperature for the current sensor, is the initial temperature, is the linear expansion coefficient of the steel chord, is the linear expansion coefficient of the steel pipe.

4. The method for monitoring the construction process of beam support and column removal according to claim 1, characterized in that: The second data monitoring period is 1 month.

5. The method for monitoring the construction process of beam support and column removal according to claim 1, characterized in that: The calculation formula for the deflection of the beam is: ； Where L is the length of the beam, 、 and They are the left elevation, right elevation and middle elevation of the beam respectively.

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