Construction method of energy-saving sloping roof disassembly-free cement fiber truss plate system

Abstract

The invention relates to the technical field of disassembly-free cement fiber truss plate construction, in particular to a construction method of an energy-saving sloping roof disassembly-free cement fiber truss plate system, which comprises the following steps: determining an initial support distance based on the daily average temperature difference between the roof slope angle of a sloping roof and the construction period; a formwork supporting system is installed, and truss plates are laid and fixed to serve as permanent formworks; a grading test load is applied to the permanent formwork, and whether the real-time safety margin of the formwork supporting system is qualified or not is determined based on the load ratio of the critical yield load to the designed wet concrete load, so that the initial equivalent stiffness is optimized; based on the distance deviation between the initial supporting distance and the actual supporting distance, the reinforcing mode of the formwork supporting system is determined; concrete is poured on the reinforced formwork supporting system and vibrated and compacted, and the preset ratio is optimized based on the compactness characterization value of the concrete layer after vibration is finished; curing of the concrete layer is completed, acceptance check is conducted, and construction of the truss plate system is completed. The construction safety risk is reduced.

Description

Technical Field

[0001] This invention relates to the field of construction technology for non-removable cement truss panels, and more particularly to a construction method for an energy-saving sloping roof non-removable cement fiber truss panel system. Background Technology

[0002] In the field of building construction, sloping roofs are widely used in various projects, including residential and public buildings, due to their excellent drainage performance and aesthetic appeal. Meanwhile, with the increasing popularity of green building concepts and rising energy efficiency requirements, the thermal insulation performance of sloping roofs has become a core consideration in engineering design and construction. Traditional sloping roof construction often uses wooden or steel formwork systems, which have many drawbacks. Firstly, the erection and dismantling of formwork is cumbersome, requiring significant manpower and resources, resulting in long construction cycles and low efficiency. Furthermore, the extensive use of wooden formwork leads to resource waste and does not meet energy conservation and environmental protection requirements. Secondly, traditional formwork systems need to be dismantled after the concrete has been poured and reached its design strength. This dismantling process can easily disturb the roof structure, and additional insulation and waterproofing layers need to be laid subsequently. The overlapping of these processes increases construction costs and may also lead to quality problems such as leakage and insulation failure due to weak bonding between layers. To address the aforementioned issues, non-removable truss panels have emerged as a new type of building material integrating formwork and load-bearing components. Among them, cement fiber truss panels, due to their advantages such as lightweight, high strength, fire resistance, and good durability, are gradually being applied to sloping roof construction. However, existing cement fiber truss panel systems mainly focus on structural load-bearing performance, with insufficient energy-saving and thermal insulation functions. Furthermore, considering the slope characteristics of sloping roofs, their support systems are prone to problems such as poor stability and insufficient anti-slip capacity. Frequent adjustments to support parameters are required during construction, further increasing construction difficulty and safety risks. Chinese Patent Application Publication No. CN112282165A discloses a multifunctional truss-supported floor slab and its construction method. Fiber cement board is used as the base plate, and triangular trusses are fixed to the fiber cement board as a framework. Reinforcing bars are installed on the fiber cement board between the triangular trusses to form a reinforcing mesh, which is fixed to the triangular trusses. Several phase change material packages are laid on the fiber cement board. This floor slab uses triangular trusses as the internal reinforcing structure, and the phase change material is filled into the floor slab. Water pipes are pre-embedded within it, allowing the floor slab to automatically regulate the indoor temperature, resulting in energy saving and consumption reduction. The floor slab also has good sound insulation, low installation and manufacturing costs, and reduces the amount of reinforcing steel used.

[0003] The existing technology also has the following problems: In the construction of the non-removable cement fiber truss panel system for sloping roofs, the support system is not adapted to the actual construction conditions, resulting in unreasonable support spacing design, which in turn leads to high construction safety risks and poor structural quality. Summary of the Invention

[0004] To address this issue, the present invention provides a construction method for an energy-saving, non-removable cement fiber truss panel system for sloping roofs, thereby overcoming the problem in the prior art where the support system is not adapted to the actual construction conditions, resulting in unreasonable support spacing design and consequently high construction safety risks.

[0005] To achieve the above objectives, the present invention provides a construction method for an energy-saving, non-removable cement fiber truss panel system for sloping roofs, comprising: The initial equivalent stiffness of the truss plate system is determined based on the roof slope angle of the sloping roof and the average daily temperature difference during the construction period. The initial support spacing of the template support system is then determined based on the initial equivalent stiffness and the maximum span of a single truss plate. Based on the initial support spacing, install the template support system, lay and fix the truss plate as a permanent template; Graded test loads are applied to the permanent template and the load-deflection curve of the truss plate is monitored in real time. Based on the comparison between the critical yield load of the load-deflection curve and the load ratio of the design wet concrete load and the preset ratio, it is determined whether the real-time safety margin of the template support system is qualified. Under the condition that the real-time safety margin of the template support system is not up to standard, the initial equivalent stiffness is optimized, and the initial support spacing is recalculated to obtain the actual support spacing. Based on the spacing deviation between the initial support spacing and the actual support spacing, the reinforcement method for the template support system is determined to be either to densify the vertical support or to add diagonal bracing. Concrete is poured and vibrated to compact the reinforced template support system. The compaction value of the concrete layer after vibration is obtained to determine whether the compaction quality of the concrete layer is qualified. The preset ratio is optimized under the condition that the compaction quality of the concrete layer is unqualified. After the concrete layer has passed the compaction quality test, the curing of the concrete layer is completed and the acceptance test is conducted, and the construction of the truss plate system is completed.

[0006] Furthermore, the process of determining the initial equivalent stiffness of the template support system based on the roof slope angle and the average daily temperature difference includes: Determine the benchmark equivalent stiffness; The roof slope angle is compared with the preset slope angle, and the average daily temperature difference is compared with the preset temperature difference. Based on the comparison results of the roof slope angle and the preset slope angle, the comparison results of the daily average temperature difference and the preset temperature difference are used to determine several stiffness adjustment coefficients, so as to correct the reference equivalent stiffness based on the several stiffness adjustment coefficients and obtain the initial equivalent stiffness.

[0007] Furthermore, the process of determining the critical yield load of the load-deflection variation curve includes: Determine the slope of each individual coordinate point sequentially along the horizontal axis, and calculate the absolute difference in slope between two adjacent coordinate points; The absolute difference in slope is compared with a preset difference in slope; The load corresponding to the coordinate point where the absolute difference in slope first appears to be greater than the preset slope difference is determined as the critical yield load.

[0008] Furthermore, the process of determining whether the real-time safety margin of the formwork support system is qualified based on the load ratio of the critical yield load to the design wet concrete load includes: Compare the load ratio with a preset ratio value; Based on the comparison result that the load ratio is less than the preset ratio, it is determined that the real-time safety margin of the template support system is unqualified.

[0009] Furthermore, under the condition that the real-time safety margin of the template support system is unqualified, the process of optimizing the initial equivalent stiffness includes: The difference between the preset ratio and the load ratio is used to obtain the relative load difference; Based on the comparison results between the relative difference of the load and the preset relative difference of the load, several stiffness correction coefficients are set to increase the initial equivalent stiffness.

[0010] Furthermore, the process of determining the reinforcement method of the formwork support system based on the spacing deviation between the initial support spacing and the actual support spacing includes: Compare the spacing deviation with the preset spacing deviation; Based on the comparison results of whether the spacing deviation is greater than or equal to the preset spacing deviation, the reinforcement method of the template support system is determined to be densified vertical support.

[0011] Furthermore, the process of determining the reinforcement method of the formwork support system based on the spacing deviation between the initial support spacing and the actual support spacing includes: Compare the spacing deviation with the preset spacing deviation; Based on the comparison results of the spacing deviation being less than the preset spacing deviation, the reinforcement method for the template support system is determined to be the addition of transverse bracing.

[0012] Furthermore, the process of determining the density characterization value of the concrete layer includes: After the concrete layer has set, the concrete layer is divided into several regions of equal area, and ultrasonic waves are emitted into any region to determine the wave velocity of the ultrasonic waves. The coefficients of variation of several wave velocities were determined as characterization values ​​for the density of the concrete layer.

[0013] Furthermore, the process of determining whether the compaction quality of the concrete layer is qualified based on the aforementioned compaction characterization value includes: The density characterization value is compared with a preset characterization value; Based on the comparison result that the density characterization value is greater than the preset characterization value, it is determined that the density quality of the concrete layer is unqualified.

[0014] Furthermore, under the condition that the compaction quality of the concrete layer is unqualified, the process of optimizing the preset ratio includes: The density characterization value is subtracted from the preset characterization value to obtain the density difference value; The density difference is compared with a preset density difference. Based on the comparison result between the density difference and the preset density difference, several ratio correction coefficients are set to increase the preset ratio.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: the slope angle of the sloping roof changes the transmission form of the vertical load, and the larger the slope angle, the higher the risk of slippage. The daily average temperature difference will generate temperature stress due to the difference in the thermal expansion coefficient of the components. The initial equivalent stiffness cannot adapt to the needs of different working conditions. By combining the slope angle of the sloping roof and the daily average temperature difference during the construction period to correct the initial equivalent stiffness, the initial equivalent stiffness can be accurately matched with the load transmission characteristics and deformation requirements caused by temperature difference under different slope angles. This avoids the insufficient anti-slip capacity of the support when the slope angle is large, which leads to the misalignment and warping of the truss plate, and the excessive stiffness when the slope angle is small, which leads to material waste. At the same time, it offsets the structural damage caused by temperature stress, ensures the coordinated stress stability of the truss plate and the support system, and thus reduces the construction safety risk.

[0016] Furthermore, this invention addresses the challenge of static design failing to match actual construction load fluctuations and support stiffness deviations. It also addresses the issue of different spacing deviations corresponding to different support defect types by setting up graded loading tests to obtain load-deflection curves and selecting reinforcement methods based on these deviations. Dynamic testing precisely captures the critical yield load of the support system, enabling scientific determination of real-time safety margins and avoiding errors from subjective experience. Simultaneously, targeted reinforcement methods such as denser vertical supports or additional diagonal bracing are employed to ensure precise matching of reinforcement measures with defect requirements. This effectively compensates for initial design deficiencies, enhances the load-bearing capacity and stability of the support system, and further reduces construction safety risks.

[0017] Furthermore, this invention addresses the issue that insufficient concrete density leads to deterioration of its mechanical properties, causing load transfer to the support system. The original safety margin cannot cover this additional risk, and different density defects have varying degrees of impact on structural safety. By monitoring concrete density and optimizing a preset ratio, and accurately characterizing the density quality using the wave velocity variation coefficient of ultrasound, corresponding repair measures are taken for different defect types. At the same time, by optimizing the preset ratio, the safety reserve of the support system is actively improved, offsetting the load-bearing risk caused by concrete deterioration, ensuring the structural collaborative stress performance, and avoiding support overload instability or subsequent structural cracking caused by concrete defects, thereby further reducing construction safety risks. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to an embodiment of the present invention; Figure 2 A flowchart for determining whether the real-time safety margin of the template support system is qualified in an embodiment of the present invention; Figure 3 A flowchart illustrating the reinforcement method for the template support system in an embodiment of the present invention; Figure 4 This is a flowchart illustrating how to determine whether the compaction quality of a concrete layer meets the requirements in an embodiment of the present invention. Figure 5 This is a schematic diagram of the structure of the cement fiber truss plate according to an embodiment of the present invention; In the diagram: 1. Top chord reinforcement, 2. Bottom chord reinforcement, 3. Bottom formwork, 4. Crest, 5. Trough, 6. Web reinforcement, 7. Truss connector. Detailed Implementation

[0019] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0020] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0021] Please see Figures 1-5 As shown, Figure 1 This is a flowchart illustrating the construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to an embodiment of the present invention; Figure 2 A flowchart for determining whether the real-time safety margin of the template support system is qualified in an embodiment of the present invention; Figure 3 A flowchart illustrating the reinforcement method for the template support system in an embodiment of the present invention; Figure 4This is a flowchart for determining whether the compaction quality of a concrete layer is up to standard in an embodiment of the present invention.

[0022] The construction method of the energy-saving, non-removable cement fiber truss panel system for sloping roofs according to embodiments of the present invention includes: Step S1: Determine the initial equivalent stiffness of the formwork support system based on the roof slope angle of the sloping roof and the average daily temperature difference during the construction period, and determine the initial support spacing of the formwork support system based on the initial equivalent stiffness and the maximum span of a single truss plate. Step S2: Install the template support system based on the initial support spacing, and lay and fix the truss plate to obtain a permanent template; Step S3: Apply graded test loads to the permanent template and monitor the load deflection curve of the truss plate in real time. Based on the comparison of the ratio of the critical yield load of the load deflection curve to the load ratio of the design wet concrete load with the preset ratio, determine whether the real-time safety margin of the template support system is qualified. Step S4: Optimize the initial equivalent stiffness under the condition that the real-time safety margin of the template support system is not up to standard, and recalculate the initial support spacing to obtain the actual support spacing. Based on the spacing deviation between the initial support spacing and the actual support spacing, determine the reinforcement method for the template support system as either densifying the vertical support or adding diagonal bracing. Step S5: Pour concrete on the reinforced template support system and vibrate it to make it dense. Obtain the density characterization value of the concrete layer after vibration to determine whether the density quality of the concrete layer is qualified. Optimize the preset ratio if the density quality of the concrete layer is unqualified. Step S6: Under the condition that the concrete layer is dense and of acceptable quality, complete the curing of the concrete layer and conduct acceptance inspection to complete the construction of the truss plate system.

[0023] In practice, the non-removable cement fiber truss panel used in the embodiments of the present invention is a prefabricated composite panel in the factory. The bottom formwork material is a 12mm thick fiber cement board. The fiber cement board is mechanically connected to the steel truss through special connectors and self-tapping screws to form a combined floor panel in which the steel truss and the fiber cement board are integrated. It is a new type of material for prefabricated building systems.

[0024] Specifically, the initial equivalent stiffness is obtained by correcting the benchmark equivalent stiffness based on the roof slope angle and the average daily temperature difference. The benchmark equivalent stiffness is determined according to the support type and keel material, and can be referenced in the "Code for Construction of Concrete Structures" GB50666-2011. Commonly used values ​​in engineering are shown in Table 1. Alternatively, it can be determined on-site through load-displacement tests, which is existing technology and will not be elaborated further.

[0025] Table 1: Commonly Used Values ​​for Benchmark Equivalent Stiffness ; Taking the support structure combination in combination 1 as an example of the template support system, the benchmark equivalent stiffness was obtained by field measurement as 212kN / mm.

[0026] Specifically, the process of determining the initial equivalent stiffness of the formwork support system based on the roof slope angle and the average daily temperature difference includes: Determine the benchmark equivalent stiffness; The roof slope angle is compared with the preset slope angle, and the average daily temperature difference is compared with the preset temperature difference. Based on the comparison results of the roof slope angle and the preset slope angle, the comparison results of the daily average temperature difference and the preset temperature difference are used to determine several stiffness adjustment coefficients, so as to correct the reference equivalent stiffness based on the several stiffness adjustment coefficients and obtain the initial equivalent stiffness.

[0027] Specifically, a first stiffness adjustment coefficient of 1.02 is determined based on the comparison result that the roof slope angle is less than the first preset slope angle; The second stiffness adjustment coefficient of 1.1 is determined based on the comparison result that the roof slope angle is greater than or equal to the first preset slope angle and less than or equal to the second preset slope angle; Based on the comparison result that the roof slope angle is greater than the second preset slope angle, a third stiffness adjustment coefficient of 1.15 is determined; The fourth stiffness adjustment coefficient 1 is determined based on the comparison result that the average daily temperature difference is less than or equal to the first preset temperature difference; Based on the comparison result that the average daily temperature difference is greater than the first preset temperature difference and less than or equal to the second preset temperature difference, the fifth stiffness adjustment coefficient is determined to be 1.04. Based on the comparison result that the average daily temperature difference is greater than the second preset temperature difference, the sixth stiffness adjustment coefficient is determined to be 1.08.

[0028] Specifically, the first preset slope angle is 15°, the second preset slope angle is 30°, the first preset temperature difference is 10℃, and the second preset temperature difference is 20℃. However, the above values ​​are not limited to these, and those skilled in the art can select values ​​according to actual needs.

[0029] Specifically, the corresponding stiffness adjustment coefficients are determined based on the comparison results of the roof slope angle and the average daily temperature difference. The product of the two stiffness adjustment coefficients and the product of the reference equivalent stiffness are used as the initial equivalent stiffness. For example, in implementation, if the roof slope is 20°, corresponding to the second stiffness adjustment coefficient of 1.1, and the average daily temperature difference is 15℃, corresponding to the fifth stiffness adjustment coefficient of 1.04, then the initial equivalent stiffness = 1.1 × 1.04 × 212 = 242.528 kN / mm, rounded to 243 kN / mm.

[0030] Specifically, the average daily temperature difference during the construction period refers to the difference between the average daily maximum temperature and the average daily minimum temperature over seven consecutive days during the construction phase; the roof slope angle is obtained using a total station.

[0031] Specifically, the slope angle of a sloping roof decomposes the vertical load into a normal component perpendicular to the roof surface and a tangential component along the roof slope direction. The larger the slope angle, the greater the risk of slippage. If the initial equivalent stiffness is not adjusted according to the slope angle, a large slope angle will result in insufficient stiffness, leading to weak anti-slip capability of the support system. The truss plates are prone to misalignment and warping along the slope direction. A small slope angle will result in excessive stiffness, causing material waste and construction redundancy. By adjusting the initial equivalent stiffness according to the slope angle, the load transfer characteristics under different slope angles can be accurately matched to ensure the stability and load transfer efficiency of the support system. The daily average temperature difference can cause temperature stress. The coefficients of thermal expansion of cement fiber truss panels, concrete and supporting structures are different. The daily average temperature difference will cause different amounts of thermal expansion and contraction of each component, which will generate temperature stress. Temperature stress will cause irregular deformation of the truss panel, and may even cause the support points to be unbalanced, leading to cracks in the panel or leakage of grout at the joints. Adjusting the initial equivalent stiffness can offset the deformation driving force caused by temperature stress by optimizing the distribution of support stiffness, avoiding irreversible damage to the structure due to thermal expansion and contraction, and ensuring the integrity of the truss panel and the concrete layer.

[0032] Specifically, the initial support spacing of the formwork support system is calculated using a formula based on the initial equivalent stiffness and maximum span. In this embodiment of the invention, the formwork support system adopts a bidirectional equidistant arrangement, as shown in the following formula: ; Where S represents the initial support spacing in meters (m); K represents the initial equivalent stiffness in kN / mm; 2.5L represents the allowable deflection in mm; and F represents the total load per unit area in kN / mm². 2 .

[0033] Specifically, the process of laying and fixing truss panels to obtain permanent formwork includes: First, mark the axis and edge positioning control lines of the truss plate on the support system, and then initially place the truss plate according to the lines; Adjust the position of each truss panel so that the edge of the panel is aligned with the control line, and control the gap between panels to 5mm-10mm; Along the long side of the truss plate parallel to the span direction, at the crest of each steel truss, use special connectors for truss plates to fasten the upper chord of the steel truss of the two plates together, and then fix them with three-dimensional self-tapping screws with a diameter ≥5mm and a length ≥25mm, with a screw spacing ≤300mm. Along the short side of the truss plate perpendicular to the span direction, at the steel truss node at the end of the plate, the cement fiber bottom mold of the two plates is directly connected with self-tapping screws, with a screw spacing of ≤200mm. Fill the gaps between the boards with sealant or micro-expansion mortar; At the trough position of the bottom formwork of the truss plate corresponding to the supporting keel, the bottom formwork is temporarily fixed to the keel with self-tapping screws, with a screw spacing of ≤1.5m, to obtain a permanent formwork.

[0034] Specifically, the crest and trough positions of a steel truss are defined by the geometric shape of the truss (areas formed by the inclined and intersecting arrangement of the web reinforcement, corresponding to the highest and lowest points in the vertical direction of the truss). A steel truss is a grid-like skeleton composed of top chord (top horizontal reinforcement), bottom chord (bottom horizontal reinforcement), and web reinforcement (diagonal / vertical reinforcement connecting the top and bottom chords). The web reinforcement typically alternates between V-shaped, W-shaped, or serrated inclinations, connecting the top and bottom chords, giving the truss an overall wavy shape with periodic convex and concave sections. The crest position refers to the highest point in the vertical direction of the steel truss, corresponding to the convex peak where the web reinforcement converges diagonally upwards from the bottom chord and connects to the top chord. This is typically used to secure adjacent truss panels using specialized connectors. The trough position refers to the lowest point in the vertical direction of the steel truss, corresponding to the concave low point where the web reinforcement disperses diagonally downwards from the top chord and connects to the bottom chord. This typically corresponds to the joists of the support system. The supporting force is transferred to the truss through the troughs, preventing damage to the top chord reinforcement.

[0035] Specifically, the process of establishing the load-deflection variation curve of the truss plate is as follows: Select the truss plate with the largest span, and arrange one observation point at each of the two end troughs and the middle trough of a single truss plate. Fix an electronic displacement gauge with an accuracy of 0.01mm at each observation point; use the total load per unit area during the construction period as the benchmark, and set the total load per unit area at 10kN / mm². 2 For example, based on 20% of the total load per unit area, i.e., 2kN / mm² 2 The load is increased uniformly in a single-level load increment; the total counterweight corresponding to each load level is calculated, and the total counterweight = load level × truss plate area; the sandbags of the total counterweight are evenly spread on the surface of the truss plate, requiring that they cover more than 90% of the plate area; after each loading level is completed, the plate is left to stand for 10-15 minutes; the average value of 3 observation points is taken as the deflection under that load level, as shown in Table 2. The load-deflection variation curve is established by fitting the load as the horizontal axis and the deflection as the vertical axis using the least squares method.

[0036] Table 2: Graded Load-Deflection ; Specifically, the process of determining the critical yield load of the load-deflection variation curve includes: Determine the slope of each individual coordinate point sequentially along the horizontal axis, and calculate the absolute difference in slope between two adjacent coordinate points; The absolute difference in slope is compared with a preset difference in slope; The load corresponding to the coordinate point where the absolute difference in slope first appears to be greater than the preset slope difference is determined as the critical yield load.

[0037] Specifically, the preset slope difference value is set to a range of [0.03, 0.07], and preferably 0.05 in this embodiment of the invention.

[0038] Specifically, the process of determining whether the real-time safety margin of the formwork support system is qualified based on the load ratio of the critical yield load to the design wet concrete load includes: Compare the load ratio with a preset ratio value; The real-time safety margin of the template support system is determined to be qualified based on the comparison result that the load ratio is greater than or equal to the preset ratio. Based on the comparison result that the load ratio is less than the preset ratio, it is determined that the real-time safety margin of the template support system is unqualified.

[0039] Specifically, the preset ratio is set to a range of [1.2, 1.5], and in this embodiment of the invention, 1.4 is preferred.

[0040] Specifically, the design wet concrete load refers to the most unfavorable load combination that the formwork support system must withstand during the construction phase of the truss slab as permanent formwork, i.e., before the initial setting of the concrete. This load consists of the wet concrete's self-weight, the truss slab's self-weight, and construction live loads. The design wet concrete load is a theoretical calculation value, but in actual construction, situations such as excessively thick pouring and concentrated material stacking may occur. The actual stiffness / bearing capacity of the support system may be lower than the design value due to erection errors, such as excessive support spacing, loose top supports, and material losses, such as rusted steel pipes and rotten timber. Real-time safety margin determination is a dynamic matching between the actual bearing capacity and the actual load requirements, avoiding the disconnect between static design and dynamic construction. The formwork support system is a temporary structure, but it bears the maximum load during the construction period. Failure can cause mass casualties. An unqualified safety margin means that the ultimate bearing capacity of the support system is close to or lower than the actual load. Subsequent loading will directly trigger abrupt changes in stiffness and uncontrolled deflection, ultimately leading to collapse. The critical yield load is the nonlinear abrupt change point of the load-deflection curve, corresponding to the starting point of failure of the support system and the truss plate's collaborative load-bearing system. Once the load exceeds the critical yield load, the support system enters a stiffness decay stage, with a sharp increase in deflection. Subsequent small increases in load may lead to instability. Therefore, the critical yield load is the dividing line between safety and danger for the support system and a core indicator for measuring its load-bearing capacity. During the construction period, the wet concrete load accounts for the largest proportion of the loads borne by the support system. It is an instantaneously applied and continuously acting load. The design wet concrete load already includes the most unfavorable combination of the wet concrete self-weight, the truss plate self-weight, and the construction live load. It represents the minimum load requirement that the support system must meet. Comparing the critical yield load with this load is a direct comparison between the ultimate bearing capacity and the maximum load requirement, avoiding subjective errors in judging the stability of the support based on experience.

[0041] Specifically, when the real-time safety margin of the template support system is not up to standard, the process of optimizing the initial equivalent stiffness includes: The difference between the preset ratio and the load ratio is used to obtain the relative load difference; Based on the comparison results between the relative difference of the load and the preset relative difference of the load, several stiffness correction coefficients are set to increase the initial equivalent stiffness.

[0042] Specifically, based on the comparison result that the relative load difference is greater than or equal to the preset relative load difference, the initial equivalent stiffness is increased by a first stiffness correction coefficient. Based on the comparison result that the relative load difference is less than the preset relative load difference, the initial equivalent stiffness is increased by a second stiffness correction coefficient.

[0043] Specifically, the preset load relative difference is set to a range of [10%, 30%], and preferably 20% in this embodiment of the invention. The first stiffness correction coefficient is set to a range of [1.08, 1.12], and preferably 1.1 in this embodiment of the invention. The second stiffness correction coefficient is set to a range of [1.03, 1.07], and preferably 1.05 in this embodiment of the invention.

[0044] Specifically, the relative load difference refers to the percentage of the difference between the preset ratio and the load ratio relative to the preset ratio.

[0045] Specifically, the process of determining the reinforcement method of the formwork support system based on the spacing deviation between the initial support spacing and the actual support spacing includes: Compare the spacing deviation with the preset spacing deviation; Based on the comparison result that the spacing deviation is greater than or equal to the preset spacing deviation, the reinforcement method of the template support system is determined to be densified vertical support; Based on the comparison results of the spacing deviation being less than the preset spacing deviation, the reinforcement method for the template support system is determined to be the addition of transverse bracing.

[0046] Specifically, the spacing deviation refers to the absolute difference between the actual support spacing and the initial support spacing. The preset spacing deviation range is set to [0.2m, 0.4m], and 0.3m is preferred in this embodiment of the invention.

[0047] Specifically, by increasing the number of vertical uprights and reducing the support spacing, the vertical stiffness, load-bearing capacity, and overall stability of the support system are directly improved, compensating for the safety margin defects caused by insufficient initial stiffness. The vertical uprights are made of φ48×3.0mm Q235B welded steel pipes; steel top supports with a load-bearing capacity ≥30kN, adjustable stroke ≥150mm, and support plate dimensions ≥150×150×8mm are used; steel bases with dimensions ≥150×150×8mm are used; and horizontal tie rods made of φ48×3.0mm steel pipes, matching the uprights, are used to connect the uprights to form the overall frame. Based on the recalculated actual support spacing, upright positioning lines are marked below the truss plate bottom formwork, corresponding to the keel positions, so that the uprights are placed at the troughs of the truss plate web members, with the spacing between adjacent uprights less than or equal to 50mm, and the verticality deviation of the uprights less than or equal to 1°. By incorporating diagonal tie members, the lateral stiffness, anti-slip capacity, and overall coordinated load-bearing performance of the support system are enhanced, making it suitable for conditions with small spacing deviations. φ48×3.0mm steel pipes are preferred. Diagonal ties are installed at the horizontal tie rod nodes and the top nodes of the uprights in the existing support system. One diagonal tie is installed every 3-4 uprights horizontally, and one diagonal tie is installed every 2-3 layers of horizontal tie rods vertically. The angle between the diagonal tie and the horizontal direction is 60°-75°, and must not be less than 45° or greater than 80°. The specific implementation processes for densifying the vertical supports and adding diagonal ties are existing technologies and will not be elaborated further.

[0048] Specifically, the process of determining the density characterization value of the concrete layer includes: After the concrete layer has set, the concrete layer is divided into several regions of equal area, and ultrasonic waves are emitted into any region to determine the wave velocity of the ultrasonic waves. The coefficients of variation of several wave velocities were determined as characterization values ​​for the density of the concrete layer.

[0049] Specifically, 48 hours after the concrete pouring and vibration are completed, the concrete layer is divided into several areas of 2.5m × 2.5m. On the surface of each concrete layer, along the direction perpendicular to the truss reinforcement and avoiding the position of the steel truss, several ultrasonic transmitting sensors and ultrasonic receiving sensors are installed to transmit low-frequency ultrasonic waves of 50-200kHz and receive ultrasonic waves.

[0050] Specifically, the process of determining whether the compaction quality of the concrete layer is qualified based on the compaction characterization value includes: The density characterization value is compared with a preset characterization value; The compaction quality of the concrete layer is determined to be qualified based on the comparison result that the compaction characterization value is less than or equal to the preset characterization value. Based on the comparison result that the density characterization value is greater than the preset characterization value, it is determined that the density quality of the concrete layer is unqualified.

[0051] Specifically, the preset value range is set to [8%, 20%], and in this embodiment of the invention, 12% is preferred.

[0052] Specifically, when the compaction quality of the concrete layer is substandard, the process of optimizing the preset ratio includes: The density characterization value is subtracted from the preset characterization value to obtain the density difference value; The density difference is compared with a preset density difference. Based on the comparison result between the density difference and the preset density difference, several ratio correction coefficients are set to increase the preset ratio.

[0053] Specifically, based on the comparison result that the density difference is greater than or equal to the preset density difference, it is determined to increase the preset ratio by a first ratio correction coefficient; Based on the comparison result that the density difference is less than the preset density difference, the preset ratio is increased by a second ratio correction coefficient.

[0054] Specifically, the preset density difference value is set to a range of [3%, 7%], and preferably 4% in this embodiment of the invention. The first ratio correction coefficient is set to a range of [1.09, 1.15], and preferably 1.12 in this embodiment of the invention. The second ratio correction coefficient is set to a range of [1.05, 1.08], and preferably 1.07 in this embodiment of the invention.

[0055] Specifically, insufficient concrete density significantly degrades its mechanical properties, having a fatal impact on the overall structure. For every 5% decrease in density, the concrete's compressive strength may drop by 10%-15%, with a simultaneous decrease in the elastic modulus. This indicates that the concrete cannot bear the compressive stress as designed, and the load originally borne by the concrete will be transferred to the formwork support system and truss plates, causing the actual stress on the support system to far exceed the design value. Porous and porous areas within the concrete layer become weak points, leading to stress concentration under load, potentially causing localized cracking of the concrete, which can then extend to the truss plates, disrupting the coordinated stress distribution between the support system and the structure. Insufficient density also allows moisture and harmful substances to easily penetrate, accelerating the corrosion of the steel truss and concrete carbonation, ultimately reducing the structure's service life. However, the most direct risk during construction is insufficient load-bearing capacity leading to overload and instability of the support system. Inadequate concrete density is equivalent to a defect in the structure's own load-bearing framework. In this case, the support system must bear more load than originally borne by the concrete, and the original safety margin corresponding to the preset ratio is insufficient to cover this additional risk; therefore, the preset ratio needs to be increased.

[0056] In practice, when the compaction quality of the concrete layer is substandard, it is necessary to increase the preset ratio, i.e., to reinforce the support system, and then determine the defect type based on the ultrasonic wave velocity to correct the defect. For example, taking C30 concrete with a pouring thickness of 100-150mm as an example, when the compaction quality is qualified, the ultrasonic wave velocity is between 3.8km / s and 4.2km / s. For cases where the ultrasonic wave velocity is between 3.5km / s and 3.8km / s, the defect type is a small number of pores on the surface or in the shallow layer of the concrete layer, indicating slight looseness. The concrete layer needs to be surface-sealed by evenly applying polymer cement slurry or epoxy sealing primer to the surface, penetrating to the shallow pores to form a sealing layer, and curing for 7 days. For cases where the ultrasonic wave velocity is between 3.2km / s and 3.5km / s, the defect type is localized deep looseness and small-scale but not penetrating voids. Radar detection is needed to accurately mark the range and depth of looseness / voids, avoiding the truss. For the location of the reinforcing bars, drill holes at 500mm×500mm intervals in the defect area, with a hole diameter of 10mm-15mm and a drilling depth of 20mm below the bottom of the defect. Use cement grout or epoxy grout with a water-cement ratio of 0.4-0.5 to grout each hole. After grouting, cure for 14 days. For cases where the ultrasonic velocity is less than 3.2km / s, and the defect type is large-area looseness, through voids, or structural cracks, the defect area needs to be excavated. Apply an interface agent to the concrete interface in the excavated area to enhance the bond between the new and old concrete. Select shrinkage-compensating concrete with a strength one grade higher than the original design strength, such as C35 instead of C30. Use a small vibrator to compact the concrete during pouring, and pour the concrete to the same height as the original concrete surface. Cure for 28 days.

[0057] Please see Figure 5 As shown, it is a structural schematic diagram of the cement fiber truss plate of an embodiment of the present invention.

[0058] The cement fiber truss panel of this embodiment is formed by several trusses composed of upper chord 1, lower chord 2 and web 6, which are arranged at equal intervals and fixed to the bottom mold 3 by truss connectors 7, wherein the bottom mold 3 is made of cement fiber board.

[0059] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A construction method for an energy-saving, non-removable cement fiber truss panel system for sloping roofs, characterized in that, include: The initial equivalent stiffness of the truss plate system is determined based on the roof slope angle of the sloping roof and the average daily temperature difference during the construction period. The initial support spacing of the template support system is then determined based on the initial equivalent stiffness and the maximum span of a single truss plate. Based on the initial support spacing, install the template support system, lay and fix the truss plate as a permanent template; Graded test loads are applied to the permanent template and the load-deflection curve of the truss plate is monitored in real time. Based on the comparison between the critical yield load of the load-deflection curve and the load ratio of the design wet concrete load and the preset ratio, it is determined whether the real-time safety margin of the template support system is qualified. Under the condition that the real-time safety margin of the template support system is not up to standard, the initial equivalent stiffness is optimized, and the initial support spacing is recalculated to obtain the actual support spacing. Based on the spacing deviation between the initial support spacing and the actual support spacing, the reinforcement method for the template support system is determined to be either to densify the vertical support or to add diagonal bracing. Concrete is poured and vibrated to compact the reinforced template support system. The compaction value of the concrete layer after vibration is obtained to determine whether the compaction quality of the concrete layer is qualified. The preset ratio is optimized under the condition that the compaction quality of the concrete layer is unqualified. After the concrete layer has passed the compaction quality test, the curing of the concrete layer is completed and the acceptance test is conducted, and the construction of the truss plate system is completed.

2. The construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to claim 1, characterized in that, The process of determining the initial equivalent stiffness of the formwork support system based on the roof slope angle and the average daily temperature difference includes: Determine the benchmark equivalent stiffness; The roof slope angle is compared with the preset slope angle, and the average daily temperature difference is compared with the preset temperature difference. Based on the comparison results of the roof slope angle and the preset slope angle, the comparison results of the daily average temperature difference and the preset temperature difference are used to determine several stiffness adjustment coefficients, so as to correct the reference equivalent stiffness based on the several stiffness adjustment coefficients and obtain the initial equivalent stiffness.

3. The construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to claim 2, characterized in that, The process of determining the critical yield load of the load-deflection variation curve includes: Determine the slope of each individual coordinate point sequentially along the horizontal axis, and calculate the absolute difference in slope between two adjacent coordinate points; The absolute difference in slope is compared with a preset difference in slope; The load corresponding to the coordinate point where the absolute difference in slope first appears to be greater than the preset slope difference is determined as the critical yield load.

4. The construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to claim 3, characterized in that, The process of determining whether the real-time safety margin of the formwork support system is qualified based on the load ratio of the critical yield load to the design wet concrete load includes: Compare the load ratio with a preset ratio value; Based on the comparison result that the load ratio is less than the preset ratio, it is determined that the real-time safety margin of the template support system is unqualified.

5. The construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to claim 4, characterized in that, When the real-time safety margin of the template support system is not up to standard, the process of optimizing the initial equivalent stiffness includes: The difference between the preset ratio and the load ratio is used to obtain the relative load difference; Based on the comparison results between the relative difference of the load and the preset relative difference of the load, several stiffness correction coefficients are set to increase the initial equivalent stiffness.

6. The construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to claim 5, characterized in that, The process of determining the reinforcement method of the formwork support system based on the spacing deviation between the initial support spacing and the actual support spacing includes: Compare the spacing deviation with the preset spacing deviation; Based on the comparison results of whether the spacing deviation is greater than or equal to the preset spacing deviation, the reinforcement method of the template support system is determined to be densified vertical support.

7. The construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to claim 5, characterized in that, The process of determining the reinforcement method of the formwork support system based on the spacing deviation between the initial support spacing and the actual support spacing includes: Compare the spacing deviation with the preset spacing deviation; Based on the comparison results of the spacing deviation being less than the preset spacing deviation, the reinforcement method for the template support system is determined to be the addition of transverse bracing.

8. The construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to claim 6 or 7, characterized in that, The process of determining the density characterization value of a concrete layer includes: After the concrete layer has set, the concrete layer is divided into several regions of equal area, and ultrasonic waves are emitted into any region to determine the wave velocity of the ultrasonic waves. The coefficients of variation of several wave velocities were determined as characterization values ​​for the density of the concrete layer.

9. The construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to claim 8, characterized in that, The process of determining whether the compaction quality of a concrete layer is up to standard based on the aforementioned compaction characterization value includes: The density characterization value is compared with a preset characterization value; Based on the comparison result that the density characterization value is greater than the preset characterization value, it is determined that the density quality of the concrete layer is unqualified.

10. The construction method of the energy-saving sloping roof non-removable cement fiber truss panel system according to claim 9, characterized in that, The process of optimizing the preset ratio when the compaction quality of the concrete layer is substandard includes: The density characterization value is subtracted from the preset characterization value to obtain the density difference value; The density difference is compared with a preset density difference. Based on the comparison result between the density difference and the preset density difference, several ratio correction coefficients are set to increase the preset ratio.

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