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平頭塔式起重機風荷載設計系數(shù)研究

發(fā)布時間:2018-05-22 19:53

  本文選題:平頭塔式起重機 + 風荷載 ; 參考:《華南理工大學》2015年碩士論文


【摘要】:塔式起重機是目前建筑工地使用的最為廣泛的施工起重機械,隨著現(xiàn)代建筑技術的不斷發(fā)展,塔式起重機的發(fā)展也朝著工作高度更高、臂架長度更長的方向發(fā)展。對于高聳結構的塔式起重機而言,風載荷對其結構的影響也是不容忽視。目前塔式起重機的設計還是遵循著國家標準GB/T13752-1992《塔式起重機設計規(guī)范》進行的,該標準中對于風載荷對塔機的影響僅從風力系數(shù)、擋風折減系數(shù)、風壓、迎風面積、截面充實率等幾個變量進行描述,其中主要對于風載荷誤差影響最大結構風荷載系數(shù)C已經(jīng)遠遠不能滿足現(xiàn)代塔機結構形式不斷更新的要求,《塔式起重機設計規(guī)范》在塔機技術發(fā)展迅速的今天明顯有著滯后性。本文針對QTP125平頭塔式起重機為研究實例,通過分析其主要結構特點,整理出平頭塔機常用的桿件類型,利用計算流體力學原理及有限元法,借助ANSYS CFX軟件,主要研究塔機桿件結構在風環(huán)境下的穩(wěn)態(tài)響應,穩(wěn)態(tài)模擬通過標準的雷諾應力模型(SST)進行,計算塔機各部件在不同的結構形式、工況下,風荷載與結構風荷載系數(shù)C。本文首先對平頭塔式起重機常用桿件進行分類整理,整理出圓管、圓角方管、槽鋼三種主要型材類型及對應截面規(guī)格共20種,并對各截面規(guī)格的桿件的在不同長細比(長徑比)下的風阻力特性、風荷載系數(shù)值進行模擬計算研究。并根據(jù)實際環(huán)境狀態(tài)將風速分為極限工作風速和極限非工作風速進行模擬分析。分析結果顯示,圓管的風荷載系數(shù)在所研究的范圍內(nèi)隨著直徑的增加而減小,圓角方管則基本不變,同時發(fā)現(xiàn)在規(guī)范中沒有詳細列明的槽鋼則明顯比規(guī)范參考值大幅增加,其主因是當槽鋼正面受風時,正面區(qū)域形成較大的低風速區(qū)并對結構形成較大的風壓。上述研究結果為后續(xù)的研究提供共重要的參考,也為現(xiàn)行的設計規(guī)范提供了很好的補充。最后,通過利用本文獲得的風荷載系數(shù)值對QTP125平頭塔式起重機進行結構抗風性能校核,通過計算結果與原設計進行對比發(fā)現(xiàn),回轉阻力矩值較原設計提高14.7%,整機結構風荷載值較原設計提高64%,并發(fā)現(xiàn)原設計塔身標準節(jié)L68B1結構存在明顯的抗風性能缺陷,并進行結構優(yōu)化設計。
[Abstract]:Tower crane is the most widely used construction crane on construction site. With the development of modern building technology, tower crane is developing towards higher working height and longer arm length. For towering tower crane, the influence of wind load on its structure can not be ignored. At present, the design of tower crane is carried out in accordance with the national standard GB/T13752-1992 "Design Code for Tower Crane". In this standard, the influence of wind load on tower crane is only from wind coefficient, windshield reduction coefficient, wind pressure, upwind area. Several variables, such as cross-section fullness ratio, are described. The maximum wind load coefficient C, which mainly affects the wind load error, is far from being able to meet the requirement of updating the structure form of modern tower crane. The Design Code for Tower Crane is obviously lagging behind with the rapid development of tower crane technology today. In this paper, by analyzing the main structural characteristics of QTP125 flat tower crane, the commonly used rod types of flat head tower crane are sorted out, and the principle of computational fluid mechanics and finite element method are used, with the help of ANSYS CFX software. The steady-state response of tower crane rod structure under wind environment is studied. The steady state simulation is carried out through the standard Reynolds stress model (SST). The wind load and wind load coefficient C of the tower crane are calculated under different structural forms and working conditions. In this paper, the common members of flat head tower crane are sorted out, and 20 kinds of circular pipe, round corner square tube and channel steel are arranged. The wind resistance characteristics and wind load coefficient of different aspect ratio (aspect / diameter ratio) of the members with different cross-section specifications are simulated and calculated. According to the actual environment condition, the wind speed is divided into the limit working wind speed and the limit non-working wind speed to carry on the simulation analysis. The analysis results show that the wind load coefficient of circular pipe decreases with the increase of diameter in the studied range, while the circular square tube is basically unchanged. At the same time, it is found that the channel steel which is not specified in detail in the code increases significantly compared with the reference value of the code. The main reason is that when the channel face is exposed to wind, the front area forms a large low wind speed zone and a large wind pressure on the structure. These results provide important reference for further research, and also provide a good supplement to the current design specifications. Finally, by using the wind load coefficient obtained in this paper to check the structural wind resistance of QTP125 flat head tower crane, the results are compared with the original design. Compared with the original design, the torque value of rotary resistance is increased by 14.7 and the wind load value of the whole machine structure is increased by 64. It is found that the original L68B1 structure of the tower body standard section has obvious anti-wind performance defects, and the structural optimization design is carried out.
【學位授予單位】:華南理工大學
【學位級別】:碩士
【學位授予年份】:2015
【分類號】:TH213.3

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