PK3 plate production method capable of dynamically regulating and controlling prestress and intelligently maintaining

Abstract

A PK3 plate production method for prestress dynamic regulation and intelligent maintenance relates to the technical field of building prefabricated part production, and comprises the following steps: pre-burying a stress sensor before concrete pouring, and monitoring the internal stress change of concrete in real time; based on feedback data of the stress sensor, the tensioning force of the prestressed reinforcement is dynamically adjusted; a segmented tensioning mode is adopted, and differential prestress tensioning force is applied to different areas of the truss; pouring the concrete doped with the composite reinforcing material; and a steam curing process with multi-stage gradient control is carried out on the formed PK3 plate. According to the method, the distribution of the pre-compressive stress in the concrete is actively regulated and controlled, and the tensile stress generated by the external load is counteracted by the pre-stress, so that the generation of cracks is inhibited, and the production quality and reliability of the PK3 plate are improved.

Description

Technical Field

[0001] The invention relates to the technical field of production of building prefabricated components, and in particular to a production method of a PK3 board with dynamic prestress control and intelligent maintenance. Background Art

[0002] With the rapid development of building industrialization, prefabricated buildings have become an important direction in the field of modern construction due to their advantages of high construction efficiency, controllable quality, energy saving and environmental protection. As the core prefabricated component in prefabricated buildings, the production quality of PK3 panels is directly related to the overall performance and durability of the building structure. At present, the industry generally adopts the process of one-time tensioning of prestressed steel bars on the tensioning pedestals at both ends and then pouring concrete to produce PK3 panels.

[0003] Although this process can achieve the basic application of prestress, in actual application, the traditional process uses fixed tensioning force and timing, which cannot dynamically match the shrinkage strain curve during the concrete hardening process. Due to factors such as curing conditions, environmental temperature and humidity fluctuations, concrete shrinkage and truss deformation are prone to stress differences, resulting in a significant increase in the risk of interface cracking. Studies have shown that the probability of PK3 plate cracking under conventional processes is as high as 35%, which seriously affects the safety of the structure. Not only that, ordinary fine stone concrete is prone to microcracks during the prestress transfer process due to its low tensile strength (usually ≤2.5MPa), and the cracks are prone to rapid expansion under load. Summary of the invention

[0004] The purpose of the present invention is to provide a PK3 board production method with prestressed dynamic regulation and intelligent maintenance, so as to improve the production quality and reliability of PK3 boards.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solution: a PK3 board production method with prestressed dynamic regulation and intelligent maintenance, comprising the following steps: S1. Pre-embed stress sensors before concrete pouring to monitor the stress changes inside the concrete in real time; S2. Dynamically adjusting the tensioning force of the prestressed steel bar based on the feedback data of the stress sensor; S3, adopt segmented tensioning method to apply differentiated prestressing force to different areas of the truss; S4, pouring concrete mixed with composite reinforcement materials; S5. Implement a multi-stage gradient-controlled steam curing process on the formed PK3 plate.

[0006] Preferably, in step S1, the stress sensors are optical fiber sensors, which are arranged at intervals along the length direction of the prestressed steel bars, with a spacing of ≤300 mm.

[0007] More preferably, in step S3, the prestressed tensioning force at both ends of the truss is 105%-115% of the design value, and the prestressed tensioning force in the mid-span area is 90%-100% of the design value.

[0008] More preferably, in step S4, the composite reinforcement material comprises steel fiber and nano-silicon dioxide, wherein the content of the steel fiber is 0.1%-0.3% of the total mass of the concrete, and the content of the nano-silicon dioxide is 2%-4% of the total mass of the concrete.

[0009] More preferably, in step S5, the steam curing process comprises: During the static stage, maintain at 15-25℃ for 3-5 hours; In the heating stage, the temperature is raised to 55-65°C at a rate of 5-15°C / h; Constant temperature stage: maintain 55-65℃ for 10-14 hours, and control humidity ≥90%; During the cooling stage, the temperature is lowered to room temperature at a rate of ≤10℃ / h.

[0010] In addition, the present invention also provides an intelligent maintenance system for implementing the above-mentioned production method, which includes: a dynamic tensioning control module connected to a stress sensor network; a steam curing cabin with integrated temperature and humidity sensors and an adaptive control device; and a multi-point hydraulic tensioning device for performing segmented tensioning.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. Pre-embedded stress sensors are used to monitor the stress changes inside the concrete in real time, and the prestressing force is adjusted dynamically to match the prestressing process with the concrete shrinkage strain in real time, effectively alleviating the interface cracking problem caused by the incoordination between shrinkage deformation and prestress distribution in traditional processes, and significantly reducing the risk of cracking.

[0012] 2. The segmented differentiated tensioning process is adopted to apply differentiated prestress according to the stress characteristics of different areas of the truss (such as the two ends and the middle of the span), optimize the overall stress distribution, avoid the uncontrolled structural deformation caused by local stress concentration, and improve the collaborative working performance of the truss and concrete.

[0013] 3. By pouring concrete mixed with composite reinforcing materials, the synergistic effect of multiple reinforcing materials can be used to effectively inhibit the initiation and expansion of concrete microcracks and improve tensile strength and durability without relying on the performance improvement of a single material.

[0014] 4. A multi-stage gradient-controlled steam curing process is adopted to reduce the internal temperature stress gradient of the concrete by regulating the heating, constant temperature and cooling rates in stages, avoid surface cracking caused by too rapid temperature drop, and ensure that the curing quality is stable and controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the position structure of concrete, trusses and prestressed steel bars in the embodiment; Figure 2 It is a schematic diagram of the process flow of the dynamic prestressing control system in the embodiment; Figure 3 Schematic diagram of the gradient curing temperature relationship in the embodiment; Figure 4 It is a schematic diagram of the layout of the PK3 production line in the embodiment.

[0016] In the figure: 1——Concrete 2——Prestressed steel bars 3——Truss DETAILED DESCRIPTION

[0017] In order to facilitate the understanding of those skilled in the art, the present invention is further described below in conjunction with embodiments and drawings. The contents mentioned in the implementation modes are not intended to limit the present invention.

[0018] like Figures 1 to 4 As shown, a PK3 board production method with prestressed dynamic regulation and intelligent maintenance includes the following steps: S1. Before pouring concrete, embed stress sensors to monitor the stress changes inside the concrete in real time. The stress sensors are optical fiber sensors, which are arranged at intervals along the length of the prestressed steel bars with a spacing of ≤200mm.

[0019] S2. Based on the feedback data of the stress sensor, the tensioning force of the prestressed tendons is dynamically adjusted. The neural network model of the artificial intelligence algorithm can be used to dynamically adjust the timing and amplitude of the application of the tensioning force according to the predicted value of the concrete shrinkage strain. Since the application of LSTM network in concrete shrinkage prediction has been disclosed in the prior art, and the servo hydraulic tensioning system accurately executes the preset tensioning curve, which belongs to the prior art, it will not be described in detail.

[0020] S3. Use segmented tensioning to apply differentiated prestressed tension to different areas of the truss; the prestressed tension at both ends of the truss is 110% of the design value, and the prestressed tension in the mid-span area is 95% of the design value. The tension offsets the tensile stress caused by the external load through the precompression stress. For example, when σpc reaches 1.92 MPa, the crack resistance of C40 concrete is increased to 1.8 times that of ordinary plates, and the steel tube truss enhances the overall stiffness (the moment of inertia increases by about 62%), reducing deformation and cracking. When super tension (1.03-1.05σcon) compensates for relaxation losses, the risk of instantaneous stress concentration can be reduced. In the specific tensioning process, the initial tensioning force is 80% of the design value, that is, a hydraulic jack is used to apply an initial tensioning force of 80% of the design value to both ends of the truss. The shrinkage strain is predicted by a model based on the LSTM neural network. After the initial setting of the concrete, the mid-span tensioning force is increased to 105% of the design value through a multi-point hydraulic tensioning device. When the concrete is finally set, the total tensioning force is released to 100% of the design value.

[0021] S4. Cast concrete mixed with composite reinforcement materials. The concrete mix ratio is: 0.2% steel fiber (diameter 0.2mm) and 3% nano-silicon dioxide are mixed into C50 fine stone concrete.

[0022] S5. Implement a multi-stage gradient controlled steam curing process on the formed PK3 plate, such as Figure 3 As shown, the specific steps are as follows: During the static stage, the curing chamber should be closed immediately after pouring, and the ambient temperature should be maintained at 20±2℃ and the humidity should be ≥95% for 4 hours to prevent the evaporation of water on the concrete surface; During the heating stage, the temperature is raised to 60°C at a rate of 10°C / h, and saturated steam is evenly sprayed through the annular steam pipe in the cabin.

[0023] Constant temperature stage: maintain at 60°C for 12 hours and control humidity ≥ 95%; During the cooling stage, the temperature is lowered to room temperature at a rate of ≤10℃ / h.

[0024] The experiment simulated the prestressing process in actual engineering by setting different tension control stresses (such as 0.4-0.8 times the material strength fptk / fpyk) to perform graded tensioning on prestressed concrete components. In each group of experiments, the prestressed tendons were subjected to set stresses by hydraulic tensioning equipment, the prestressing stress values ​​generated on the concrete surface were measured simultaneously, and the cracking loads of the components in subsequent loading tests were recorded to calculate the crack resistance ratio. The results are shown in Table 1 below.

[0025] Table 1 Tensile test data Tension control stress (acon) Precompression stress (C40 concrete) Crack resistance ratio (σpc+ftk) / ftk Improvement effect of qualified rate 0.7-0.8fptk (1395MPa) 2.70MPa 2.24 times Improved by 80%-90% 0.6fpyk(942MPa) 2.30MPa 2.08 times Increase by 60%-70% 0.5fpyk (785MPa) 1.92MPa 1.80 times Increase by 30%-50% 0.4fpyk(628MPa) 1.54MPa 1.64 times Increase by 10%-20% After the test was completed, by comparing the changes in prestress, crack resistance ratio and qualified rate of batch components under different prestressing stresses, it was verified that increasing the prestressing control stress can significantly enhance the crack resistance of concrete, providing data support for optimizing prestressing process parameters.

[0026] The present invention optimizes the tension control stress of the prestressed tendons (such as 0.4-0.8 times the material strength), actively regulates the prestress distribution inside the concrete, and uses the prestress to offset the tensile stress generated by the external load, thereby inhibiting the generation of cracks. The core is to match the tensile strength of concrete through graded tensioning process parameters, and maximize the strengthening effect of prestressed tendons while ensuring structural safety.

[0027] The PK3 board produced by the production method of the present invention can improve its crack resistance by up to 2.24 times compared with the baseline working condition, and the component qualification rate can be increased to nearly 90%. This method can improve the durability of concrete structures while reducing construction quality fluctuations by accurately controlling the level of prestressing, providing a cost-effective solution for engineering crack resistance design.

[0028] In order to make it easier for ordinary technicians in the field to understand the improvements of the present invention over the prior art, some drawings and descriptions of the present invention have been simplified, and the above-mentioned embodiments are preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the present technical solution is within the protection scope of the present invention.

Claims

1. A method for producing PK3 boards with dynamic prestress control and intelligent maintenance, characterized in that: The following steps are involved: S1. Pre-embed stress sensors before concrete pouring to monitor the stress changes inside the concrete in real time; S2. Dynamically adjusting the tensioning force of the prestressed steel bar based on the feedback data of the stress sensor; S3, adopt segmented tensioning method to apply differentiated prestressing force to different areas of the truss; S4, pouring concrete mixed with composite reinforcement materials; S5. Implement a multi-stage gradient-controlled steam curing process on the formed PK3 plate.

2. The method for producing PK3 boards with dynamic prestress control and intelligent maintenance according to claim 1 is characterized in that: In step S1, the stress sensors are optical fiber sensors, which are arranged at intervals along the length direction of the prestressed steel bars, with a spacing of ≤300 mm.

3. The method for producing PK3 boards with dynamic prestress control and intelligent maintenance according to claim 1 is characterized in that: In step S3, the prestressed tensioning force at both ends of the truss is 105%-115% of the design value, and the prestressed tensioning force in the mid-span area is 90%-100% of the design value.

4. The method for producing PK3 boards with dynamic prestress control and intelligent maintenance according to claim 1 is characterized in that: In step S4, the composite reinforcement material includes steel fiber and nano-silicon dioxide, wherein the content of the steel fiber is 0.1%-0.3% of the total mass of the concrete, and the content of the nano-silicon dioxide is 2%-4% of the total mass of the concrete.

5. The method for producing PK3 boards with dynamic prestress control and intelligent maintenance according to claim 1 is characterized in that: In step S5, the steam curing process includes: During the static stage, maintain at 15-25℃ for 3-5 hours; In the heating stage, the temperature is raised to 55-65°C at a rate of 5-15°C / h; Constant temperature stage: maintain 55-65℃ for 10-14 hours, and control humidity ≥90%; During the cooling stage, the temperature is lowered to room temperature at a rate of ≤10℃ / h.

6. An intelligent maintenance system for implementing any one of the production methods of claims 1 to 7, characterized in that: include: A dynamic tension control module connected to a stress sensor network; Steam curing cabin with integrated temperature and humidity sensors and adaptive control devices; Multi-point hydraulic tensioning device for performing segmented tensioning.

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