A method for measuring snow load of large-span cylindrical latticed shell structure in situ

Abstract

This invention discloses a method for on-site measurement of snow load on a large-span cylindrical reticulated shell structure, relating to the field of structural health monitoring technology in building engineering. The method includes the following steps: Step 1: Dividing the surface of the cylindrical reticulated shell structure with θ < 60° into regions. Horizontally, it is divided into 9 segments with proportions of 0.1, 0.1, 0.1, 0.1, 0.2, 0.1, 0.1, 0.1; vertically, it is divided into 7 segments with proportions of 0.1, 0.2, 0.1, 0.2, 0.1, 0.2, 0.1. The region division uses the smallest unit of the structural surface, namely the grid composed of the upper chord members, as the basic dividing unit, forming a total of 59 monitoring regions. Step 2: Placing pressure sensors in each of the 59 regions to collect snow load data in real time. This invention is adapted to the quantitative proportional zoning system of large-span cylindrical reticulated shell structures, forming a standardized roof zoning standard, significantly improving the accuracy and standardization of snow load measurement.

Description

Technical Field

[0001] This invention relates to the field of structural health monitoring technology in building engineering, specifically a method for on-site measurement of snow load on large-span cylindrical reticulated shell structures. Background Technology

[0002] Large-span industrial structures (such as coal sheds, material sheds, stadiums, and airport terminals) are extremely sensitive to snow loads due to their large spans, lightweight roofs, and complex shapes. After snowfall in winter, phenomena such as separation, reattachment, and drift of snow on the roof surface can lead to severe snow accumulation in localized areas, creating non-uniform snow loads that can easily cause structural overload or even collapse. According to incomplete statistics, many major snow disasters in northern my country have been closely related to uneven snow distribution on roofs.

[0003] Currently, research on snow loads on building roofs, both domestically and internationally, mainly focuses on theoretical analysis, numerical simulation, and scaled-down model tests, with limited on-site full-scale measurement studies. Existing measurement methods largely rely on empirical zoning (e.g., 13 x 6 = 78 zones laterally, 3 x 5 = 15 zones laterally), but the zoning criteria are highly subjective and fail to consider key factors such as wind direction, slope, and curvature, resulting in insufficient representativeness of the measured data and poor comparability between regions.

[0004] Furthermore, under the combined effects of wind and snow, snow distribution dynamically changes with the wind direction angle, while existing methods mostly provide static zoning, which is insufficient to reflect real-world conditions. Therefore, we propose a field measurement method for snow load on large-span cylindrical reticulated shell structures. Summary of the Invention

[0005] The purpose of this invention is to provide a method for on-site measurement of snow load on large-span cylindrical reticulated shell structures, in order to solve the problem that existing methods proposed in the prior art are mostly static partitions and cannot reflect the real working conditions.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for on-site measurement of snow load on a large-span cylindrical reticulated shell structure, comprising the following steps:

[0007] Step 1: Divide the surface of the cylindrical reticulated shell structure with θ < 60° into regions. Laterally, divide it into 9 segments with proportions of 0.1, 0.1, 0.1, 0.1, 0.2, 0.1, 0.1, 0.1, and 0.1 respectively; vertically divide it into 7 segments with proportions of 0.1, 0.2, 0.1, 0.2, 0.1, 0.2, and 0.1 respectively. The region division uses the smallest unit of the structural surface, namely the grid composed of the upper chord members, as the basic dividing unit, forming a total of 59 monitoring areas.

[0008] Step 2: Pressure sensors are installed in the 59 areas to collect snow load data in real time.

[0009] Step 3: Compile and analyze the monitoring data from various pressure sensors to determine the distribution characteristics and action patterns of snow load on the surface of the cylindrical reticulated shell structure, providing a basis for structural safety assessment and design verification.

[0010] As a preferred technical solution, θ is the angle between the normal to a point on the surface of the cylindrical reticulated shell and the vertical direction. When θ ≥ 60°, the area is not included in the snow load measurement and is regarded as a snowless accumulation area.

[0011] As a preferred technical solution, the horizontal and vertical division ratio is a relative length ratio, which is normalized based on the structural span or vertical length to ensure that the area of ​​each region matches the actual geometric shape of the structure.

[0012] As a preferred technical solution, the pressure sensors are arranged at the center point or representative nodes of each area, and the sensor type is preferably a piezoresistive or capacitive pressure sensor with a sampling frequency of not less than 1Hz.

[0013] As a preferred technical solution, in step three, the snow load data needs to be corrected by combining environmental parameters such as temperature, wind speed, and wind direction to improve the accuracy and comparability of the measured data.

[0014] As a preferred technical solution, in step two, the pressure sensor is installed in close contact with the outer surface of the mesh roof, and the sensor placement position avoids the nodes of the upper chord members and the obstructing area to ensure the accuracy of the snow pressure data collection.

[0015] As a preferred technical solution, in step three, the monitoring data includes dynamic snow load parameters under different snowfall periods and different wind force and direction conditions, which can provide real-time feedback on local snow accumulation and uneven overload on the roof.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] This invention provides a quantitative proportional zoning system adapted to large-span cylindrical reticulated shell structures, forming a standardized roof zoning standard, which significantly improves the accuracy and standardization of snow load measurement.

[0018] It enables precise measurement of snow load under all wind directions for full-size, large-span cylindrical reticulated shell structures. It can accurately capture the dynamic characteristics of snow drift, local accumulation, and uneven overload on the roof under the coupling effect of wind and snow. The measured data truly reflects the actual working conditions of the project. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process structure of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To enable those skilled in the art to clearly and completely understand the technical solution of the present invention and to complete on-site engineering operations based on this solution, the following detailed explanation of the complete implementation process, equipment selection, operation details, data processing, and effect verification of the actual measurement method of the present invention is provided in conjunction with specific engineering embodiments without changing the core technical principle of the present invention.

[0022] The first step is standardized and precise zoning of the roof. In the initial stage of the actual measurement, a three-dimensional survey and tilt angle verification of the structural roof are completed. A high-precision tilt angle detector is used to detect the tilt angle of the entire cylindrical reticulated roof area by area, eliminating areas with theoretically θ≥60° where there is no snow accumulation, and locking in all effective snow accumulation monitoring areas. Then, grid division is carried out strictly according to the quantitative zoning standard of this invention: the roof is horizontally divided into 9 segments along the span direction according to a fixed ratio of 0.1, 0.1, 0.1, 0.1, 0.2, 0.1, 0.1, 0.1, 0.1; the roof is vertically divided into 7 segments along the length direction according to a fixed ratio of 0.1, 0.2, 0.1, 0.2, 0.1, 0.2, 0.1. Through the cross-coupling of horizontal and vertical segments, the entire roof is divided into 59 well-defined, regular... Standardized monitoring areas that are independent, non-overlapping, and without blind spots; in this embodiment, the smallest unit of all zones is uniformly defined as a standard grid unit enclosed by the upper chord members of the shell. At the same time, combined with the finite element preprocessing method, the roof snow distribution coefficient value of each grid unit is extracted. Adjacent grid units with similar roof positions and snow distribution coefficient differences within the allowable error range of the project are adaptively merged and optimized. This abandons the traditional manual subjective zoning and experience-based zoning methods, forming a quantitative, standardized, and replicable roof zoning system, eliminating zoning errors from the source, and ensuring the uniformity and rationality of subsequent measurement point layout. After zoning is completed, each monitoring area is numbered and archived to establish a roof zoning coordinate ledger, laying the foundation for accurate sensor deployment and corresponding data collection for each zoning.

[0023] The second step is the standardized deployment and debugging of snow pressure sensors. This embodiment uses a high-precision, low-temperature snow pressure sensor, suitable for complex working conditions such as low temperatures, snow, and outdoor humidity in winter. The sensor's measurement accuracy error is ≤0.5%, and it can accurately collect the static snow pressure on the roof and the dynamic snow pressure coupled with wind and snow. Based on the 59 standardized monitoring areas numbered in the previous stage, a full-coverage deployment principle of "one monitoring point per area" is implemented, with one snow pressure sensor placed at the center of each independent monitoring area. During the deployment process, strict avoidance is exercised over nodes of the upper chord members of the rebar shell, connectors, reinforcing ribs, and roof protrusions that obstruct the view, to prevent structural obstruction. This leads to abnormal snow accumulation and distorted pressure data acquisition. The sensors are installed using a fitted, fixed method to ensure that the sensor sensing surface is flush with the curved surface of the roof, making full contact with the snow without any gaps, protrusions, or depressions, thus maximizing the reproduction of the actual stress state of the snow. After all sensors are deployed, they are uniformly connected to the on-site data acquisition terminal to complete line debugging, signal calibration, zero-point calibration, and data transmission testing. Issues such as signal delay, data disconnection, and numerical drift are investigated to ensure that all measuring point equipment operates stably and data acquisition is synchronized, meeting the requirements for continuous monitoring around the clock.

[0024] To clearly and quantitatively demonstrate the standardized zoning ratio parameters of this invention, and to facilitate replication by those skilled in the art, the horizontal and vertical zoning ratios of the columnar reticulated roof are summarized in the table below:

[0025]

[0026] The third step involves the synchronous acquisition and refined analysis of data across all operating conditions. During the entire winter snowfall cycle, an all-weather automated monitoring mode is activated. Data acquisition terminals synchronously collect real-time snow pressure data from 59 zone monitoring points at a fixed sampling frequency of once per minute, achieving continuous dynamic data recording throughout the entire snowfall process. Simultaneously, a miniature meteorological monitoring device is equipped to synchronously record on-site environmental parameters in real time, including key parameters such as real-time wind speed, wind direction, ambient temperature, air humidity, snowfall duration, snowfall amount, and freeze-thaw cycle status, achieving a one-to-one correspondence between snow load data and meteorological operating condition data. The monitoring cycle covers the entire process of a single snowfall event, including the initial snow accumulation stage, the mid-snowfall snow stabilization stage, the snow drift and redistribution stage during strong winds, and the late-snowfall stage involving freeze-thaw melting under sunlight, comprehensively covering various complex operating conditions in the actual project. After monitoring is completed, the collected raw data is preprocessed to remove equipment interference. Invalid anomaly data caused by instantaneous extreme values ​​and signal fluctuations were used to calibrate numerical deviations caused by temperature and wind force. Subsequently, all valid zone monitoring data were summarized, and data analysis software was used to draw a cloud map of the roof's overall snow load distribution, snow accumulation time history curves, and zone load comparison curves. This visually presented the overall snow distribution pattern of the cylindrical reticulated shell roof, the peak areas of local snow accumulation, and the characteristics of snow drift and redistribution under wind and snow action, accurately identifying dangerous areas of local overload and uneven snow concentration on the roof. Finally, combined with the measured snow load values ​​of each zone, the total total snow load of the structure and the standard values ​​of local snow loads in each area were calculated to obtain the actual stress parameters of the structure. This completed the accurate on-site measurement of snow load on the large-span cylindrical reticulated shell structure, providing reliable measured data support for subsequent structural bearing capacity verification, safety risk assessment, structural health monitoring data calibration, and operation and maintenance reinforcement optimization.

[0027] The fourth step is to verify the effectiveness and analyze the advantages. After completing the snow load monitoring through the standardized measurement process described above, this embodiment compares the measured results of the present invention with those of traditional manual zoning measurement methods and standardized theoretical calculations. The results show that the present invention, through quantitative and standardized zoning, completely avoids the problems of high randomness, inconsistent standards, and uneven density of measurement points in manual zoning. The measured data highly matches the actual snow stress state of the structure, and the data error is significantly lower than that of traditional measurement schemes. Furthermore, this scheme only monitors the effective snow-covered area, eliminating the need for redundant measurement points. While ensuring full monitoring coverage and high accuracy, it effectively reduces the cost of on-site monitoring equipment and the workload of data processing, balancing engineering practicality and computational economy. In addition, this scheme can accurately capture local snow drift and localized overload phenomena on curved roofs that are difficult to identify using traditional measurement methods. It can realistically reproduce the dynamic distribution law of snow load under wind-snow coupling conditions in all wind directions, fully meeting the engineering measurement needs for health monitoring, load verification, and wind and snow disaster prevention of large-span cylindrical reticulated shell structures, and possesses extremely strong engineering application value.

[0028] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for measuring snow load on site of a long-span cylindrical latticed shell structure, characterized in that: Includes the following steps: Step 1: Divide the surface of the cylindrical reticulated shell structure with θ < 60° into regions. Laterally, divide it into 9 segments with proportions of 0.1, 0.1, 0.1, 0.1, 0.2, 0.1, 0.1, 0.1, and 0.1 respectively; vertically divide it into 7 segments with proportions of 0.1, 0.2, 0.1, 0.2, 0.1, 0.2, and 0.1 respectively. The region division uses the smallest unit of the structural surface, namely the grid composed of the upper chord members, as the basic dividing unit, forming a total of 59 monitoring areas. Step 2: Pressure sensors are installed in the 59 areas to collect snow load data in real time. Step 3: Compile and analyze the monitoring data from various pressure sensors to determine the distribution characteristics and action patterns of snow load on the surface of the cylindrical reticulated shell structure, providing a basis for structural safety assessment and design verification.

2. The method according to claim 1, wherein the method is characterized in that: θ is the angle between the normal to a point on the surface of the cylindrical reticulated shell and the vertical direction. When θ ≥ 60°, this area is not included in the snow load measurement and is regarded as a snowless accumulation area.

3. The method according to claim 2, wherein the method is characterized in that: The horizontal and vertical division ratios are relative length ratios, which are normalized based on the structural span or longitudinal length to ensure that the area of ​​each region matches the actual geometric shape of the structure.

4. The method according to claim 3, wherein the method is characterized in that: The pressure sensors are arranged at the center point or representative nodes of each area. The preferred sensor type is a piezoresistive or capacitive pressure sensor, and the sampling frequency is not less than 1Hz.

5. The method for on-site measurement of snow load on a large-span cylindrical reticulated shell structure according to claim 3, characterized in that: In step three, the snow load data needs to be corrected by combining environmental parameters such as temperature, wind speed, and wind direction to improve the accuracy and comparability of the measured data.

6. The method for on-site measurement of snow load on a large-span cylindrical reticulated shell structure according to claim 5, characterized in that: In step two, the pressure sensor is installed in close contact with the outer surface of the mesh roof. The sensor placement avoids the nodes of the upper chord members and obstructed areas to ensure the accuracy of the snow pressure data.

7. The method for on-site measurement of snow load on a large-span cylindrical reticulated shell structure according to claim 1, characterized in that: In step three, the monitoring data includes dynamic snow load parameters under different snowfall periods and wind force and direction conditions, which can provide real-time feedback on local snow accumulation and uneven overload on the roof.

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