| 日光温室荷载组合方法及应用 |
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| 引用本文： | 齐飞,闫冬梅,胡林,黄大同.日光温室荷载组合方法及应用[J].农业工程学报,2022,38(7):264-271. |
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| 作者姓名： | 齐飞 闫冬梅 胡林 黄大同 |
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| 作者单位： | 1. 农业农村部规划设计研究院,北京 100125; 2. 农业农村部农业设施结构设计与智能建造重点实验室,北京 100125;;3. 中国船舶重工集团国际工程有限公司,北京 100021; |
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| 基金项目： | 农业农村部规划设计研究院自主研发项目（SP202101） |
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| 摘 要： | 荷载组合是日光温室结构设计的前提和依据,为了使工程设计人员科学认识和正确使用荷载组合,需要对日光温室的荷载特点、组合效应进行分析和构建。该研究分析了日光温室荷载的特征,通过分析国家规范体系中对结构设计荷载组合的要求,并以北京地区日光温室为例,分析了12个荷载工况下温室骨架的最大应力比,表明多种可变荷载成为主导荷载的可能性;研究提出了基于精确分析所有可能荷载组合的逻辑、方法,并在此基础上研发了日光温室全荷载组合自动生成软件;继续以北京地区日光温室为例,分析了该日光温室在1 216种荷载组合下的最大应力比,与当前普遍采用的预估等简化设计方式进行了比较。分析表明,采用部分荷载组合的日光温室简化设计方法没有涵盖算例中所出现的最不利荷载组合方式,存在组合上的漏洞,而采用"全荷载组合"进行结构分析是必要的、科学的,可以作为新国家规范要求下荷载组合取值的具体方法。应用表明,在电算化条件下,运算时间不到1 s,在工程设计中是高效的。研究结果具有较强的现实意义,可在满足现行国家标准的前提下,直接应用于日光温室工程设计、专业软件开发、既有软件改造升级之中。
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| 关 键 词： | 日光温室 荷载 结构设计 荷载组合 规范 |
| 收稿时间： | 2021/10/15 0:00:00 |
| 修稿时间： | 2022/3/21 0:00:00 |
Method and application of load combination in solar greenhouses |
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| Qi Fei,Yan Dongmei,Hu Lin,Huang Datong.Method and application of load combination in solar greenhouses[J].Transactions of the Chinese Society of Agricultural Engineering,2022,38(7):264-271. |
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| Authors: | Qi Fei Yan Dongmei Hu Lin Huang Datong |
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| Institution: | 1. Academy of Agricultural Planning and Engineering, MARA, Beijing 100125, China; 2. Key Laboratory of Farm Building in Structure and Construction, MARA, Beijing 100125, China;;3. CSIC International Engineering Co., Ltd, Beijing 100021, China; |
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| Abstract: | Load combination is the premise of the structural design of a solar greenhouse under a variety of external forces. A Chinese-style solar greenhouse has been one of the most commonly used types for the season extension in specialty crop production. The load combination of Chinese solar greenhouse can be also required in the National Standard "Code for the design load of horticultural greenhouse structures" (GB/T 51183-2016). However, no example has been found to combine the external loads in the design and practice, according to the National Standard in China. The less implementation of National Standard has brought the potential threat to the sustainable and safe development of greenhouse structures. Furthermore, some damage and collapses of the solar greenhouse have often occurred under the strong wind or snow in some areas in recent years. It is a high demand to analyze the features of the load combination in the National Standards of Chinese solar greenhouses. Taking a solar greenhouse in Beijing, China as an example, a systematic investigation was made to evaluate the load combination under various loads. The stress ratios were also calculated under 12 types of loads, including the wind, snow, crop, hanging, and uniform living loads on the roof, as well as the weight of insulation of the solar greenhouse. Several boundary conditions were then considered, including the wind, snow, and hanging loads. The sample greenhouse was a typical style for the design service life of 10 years, particularly in the structural size with a span of 8 m, the opening of 1m, the height of ridge of 4.15 m, and the height of the back wall of 2.55 m. Because the ellipse section was widely chosen for the greenhouse, the ellipse steel tube was selected as the beam with a section size of 90 mm?30 mm?2 mm. The tube material was the plain low carbon steel Q235. The 3D3S software developed by Tongji University was used to analyze the spatial steel structure of the sample greenhouse. The Euler-Bernoulli beam elements were used in the 3D3S software, and the arch beams were replaced by the straight beams in the simulation model. The support abutments of the beams connected to the walls were assumed to the fixed ones during calculation. The results showed that there were some possibilities of variable loads to be the dominant ones in the structure analysis of the Chinese solar greenhouse. All the load combinations were suitable for the structural design, according to the National Standard code. A subroutine written in the C++ program on the software platform was also developed to automatically create all the load combinations. As such, the mutual exclusive load conditions were avoided in the software, for example, the uniform living load on the roof should not be combined with the snow load. The proper formats of files were then generated by the popular commercial design software. More importantly, the software copyright (2022SR0081153) was granted in January 2022 by National Copyright Administration. In the case of the example, the load combinations analysis was performed on the software to determine the maximum stress under all the 1 216 load combinations. It was found that the simplified approaches were often used to estimate the load combinations of the Chinese solar greenhouses. The most unfavorable load combination was significantly varied with the external conditions, compared with the simplified calculation with the partial load combinations. Therefore, it is very necessary to consider the structure of the solar greenhouse with the "compressive load combination". Anyway, the feasible approach can fully meet the requirement of National Standards, thus greatly contributing to the first National Standard of greenhouse structure to be released in the future. The running time was less than 1 s in the computerized design. Hence, these findings can provide practical support to develop the new or updated software for the design of the solar greenhouse. |
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| Keywords: | solar greenhouse load structural design load combination code |
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