發(fā)布時間：2018-04-28 11:05

  本文選題：FAST反射面支承索網(wǎng) + 串聯(lián)拉索　； 參考：《東南大學》2015年碩士論文

【摘要】：我國利用中國貴州喀斯特洼地,建造500m口徑具有主動反射面的大型射電望遠鏡FAST (Five-hundred-meter Aperture Spherical Telescope)。其中,FAST主動反射面的支承結構屬于巨型空間結構。主索網(wǎng)固定在周圈環(huán)梁上,下拉索下端與地面促動器相連以控制整個索網(wǎng)變形。主索網(wǎng)水平投影直徑達到500m,最高點到最低點的落差達到134.0m。FAST主動反射面主體支承結構由主索網(wǎng)、下拉索、格構式圈梁和格構式鋼柱以及格構柱基礎組成。主索網(wǎng)為短程線型三角形網(wǎng)格,除邊界節(jié)點外每個主索網(wǎng)節(jié)點連接6根主索和1根下拉索,共2225個主索節(jié)點,合計約400t,6670根主索和2225根下拉索,約1170噸,主索長度為11.0m左右,下拉索長度在4.0m至60.0m之間不等,索體采用OVM.ST型高應力幅拉索體系。建設場地為喀斯特洼地,洼地呈“鍋狀”,但其形狀與理想球面相距甚遠,僅在洼地底部有較為平坦的場地,拉索無法在地面展開進行組裝,不能進行整體提升,搭設滿堂支撐塔架平臺安裝的方法也不可行。因為周圈鋼圈梁施工完成后再進行索網(wǎng)施工,所以可以考慮借助周圈鋼圈梁進行空間牽引安裝。根據(jù)索網(wǎng)結構的對稱性,索網(wǎng)結構劃分為5+1個區(qū)域施工,其中1個區(qū)域為支撐塔架安裝區(qū),5個對稱區(qū)域由沿導索牽引安裝區(qū)和擴展部分安裝區(qū)組成。其中支撐塔架安裝區(qū)先施工安裝完畢,接著安裝對稱軸位置的拉索,然后對稱向兩側(cè)擴展施工。主索和下拉索安裝完成后,促動器預緊張拉下拉索。本文根據(jù)索網(wǎng)結構特點,提出了串聯(lián)拉索沿導索空中累積滑移安裝方法,即將串聯(lián)的結構索通過吊桿或倒鏈葫蘆掛在導索下,利用牽引索將拉索由下至上沿導索累積牽引就位。串聯(lián)拉索沿導索空中累積滑移安裝施工方法主要運用于對稱區(qū)域索網(wǎng)徑向索的安裝。該方法充分發(fā)揮了導索既導向又承重的作用,構成簡單,施工措施費用低。牽引過程中存在包括松垂拉索、滑移的機構大位移,結構索、導索和牽引索的索力和位形相互影響大,應進行牽引過程分析,掌握過程中各索力和整體位形的變化規(guī)律,確定合理的施工參數(shù),包括：導索和牽引索的最大拉力、導索安裝無應力長度(簡稱原長)等。其過程分析方法,是基于NDFEM法找形,根據(jù)導索單元組總原長不變的原則,采用調(diào)整導索各單元原長的方法來模擬滑輪在導索上的移動,并提出和對比了四種策略,通過算例分析,指出“逐單元遞推倍增”策略具有更高分析效率。分別設定導索原長為主索原長、端點距離和中間值,采用“逐單元遞推倍增”策略分析對比三種原長下的分析模型。指出了關鍵施工參數(shù)的變化規(guī)律,得出：(1)導索線形在起始工況是最不利的,導索原長不宜過長且不應超過主索原長；(2)導索和牽引索的索力變化受導索原長影響大,且較為敏感；(3)合理的導索原長應介于主索原長和兩端距離之間。對對稱軸處沿導索牽引安裝區(qū)索網(wǎng)的施工過程分析時,取出一根導索進行施工方法及施工過程分析方法的研究。采用“逐單元遞推倍增”策略進行對比分析,得出了與算例基本相符的結果,同時根據(jù)計算結果,得出了實際施工時所需要的施工參數(shù),包括：導索無應力長度和拉力、牽引索拉力等。本文根據(jù)沿導索牽引安裝區(qū)的導索和擴展部分安裝區(qū)的貓道下端錨固位置,并結合施工現(xiàn)場情況確定了獨立塔架的布置位置。通過對沿導索牽引安裝區(qū)和擴展部分安裝區(qū)進行施工過程分析,得到導索和貓道索對下錨固點的作用力。根據(jù)作用力大小及方向,確定了通過單層平面桁架連接獨立塔架增加結構整體性,通過設置背索減小塔架負擔的塔架總體設計方案。根據(jù)施工過程設定多組荷載組合,對塔架進行了施工過程分析,確定了一套切實可行的施工方案。作為高精度的天文望遠鏡,FAST索網(wǎng)支承結構的制作和安裝精度要求都非常高,所以精度控制就異常重要。本文對索網(wǎng)結構進行誤差敏感性分析,確定誤差因素及其敏感性程度,并結合實際施工可達到的精度,確定施工精度控制指標,為索網(wǎng)施工的精度控制提供依據(jù)。
[Abstract]:China uses the Karst depression in Guizhou, Guizhou, China to build a large radio telescope FAST (Five-hundred-meter Aperture Spherical Telescope) with an active reflector. Among them, the supporting structure of the FAST active reflector is a giant space structure. The main cable net is fixed on the circumferential ring beam and the lower end of the lower cable is connected with the ground actuators. Control the whole cable net deformation. The horizontal projection diameter of the main cable network reaches 500m, the maximum point to the lowest drop reaches the main support structure of the 134.0m.FAST active reflector, which consists of the main cable net, the lower cable, the lattice beam and the lattice steel column and the lattice column foundation. The net node connects 6 main cables and 1 lower cables, with a total of 2225 main cable nodes, with a total of about 400t, 6670 main cables and 2225 lower cables, about 1170 tons, the length of the main cable is about 11.0m, the length of the cable is between 4.0m and 60.0m, and the cable body uses the OVM.ST type high stress cable system. The construction site is the Karst depression, the low-lying land is "pot like" in the low-lying land. The shape is far away from the ideal sphere, and there is a relatively flat site at the bottom of the depression. The cable can not be assembled on the ground and can not be promoted as a whole. It is not feasible to set up the installation method of the full support tower platform. Because the steel ring beam of the circle ring is completed after the construction is completed, it can be considered by the circumferential steel ring beam. According to the symmetry of the cable network structure, the cable net structure is divided into 5+1 area construction, of which 1 areas are the support tower installation area, the 5 symmetrical areas are composed of the lead cable traction and installation area and the extended part installation area. After the installation of the main cable and the lower cable is completed, the actuators are pretense to pull down the cables after the installation of the main cables and the lower cables. In this paper, according to the characteristics of the cable net structure, a method of accumulative slip installation in the air of a series cable is put forward, and the connecting cable is hung under the guide cable through the hanger or the chain hoist, and the cable is made of the cable from the bottom to the top. The construction method of the cumulative sliding of the cable in the air is mainly applied to the installation of the radial cable of the cable net in the symmetrical area. This method fully exerts the effect of guiding and bearing of the guide cable. The construction is simple and the cost of the construction measures is low. The cable, cable and traction cable have great influence on the cable force and the shape of the cable. We should carry out the analysis of the traction process, grasp the change law of the cable force and the overall position in the process, and determine the reasonable construction parameters, including the maximum pulling force of the guide cable and traction cable, the installation of the guide cable without stress length (simply called the original length) and so on. The process analysis method is based on the NDFEM method. According to the principle of the invariability of the total length of the unit group, the method of adjusting the original length of the guide cable is used to simulate the movement of the pulley on the guide cable. Four kinds of strategies are proposed and compared. Through an example analysis, it is pointed out that the strategy of "unit by unit recurrence multiplication" has higher analysis efficiency. And the intermediate value, using the "unit by unit recurrence multiplication" strategy analysis and comparison of the three original analysis models. The change law of key construction parameters is pointed out. (1) the line shape of guide cable is the most unfavorable in the starting condition, the original length should not be too long and should not exceed the original length of the main cable; (2) the change of cable force of guide cable and traction cable is subject to the original length of guide cable. The influence is large and sensitive; (3) the original length of the guide cable should be between the original length of the main cable and the distance between the two ends. According to the calculation results, according to the calculation results, the construction parameters needed in the actual construction are obtained, including the non stress length and tension of the guide cable, pulling force and so on. This paper is based on the anchorage position of the lower end of the cat track in the guide cable and the extended part of the mounting area along the guide cable, and it is true that the construction site is true. The arrangement position of the independent tower is fixed. Through the analysis of the construction process of the traction and installation area and the expansion part of the guide cable, the force of the anchor and the cable to the anchorage point is obtained. According to the size and direction of the force, the structure of the independent tower is connected by a single plane truss to increase the structure integrity, and the small tower is set by the back cable. According to the construction process, the multi group load combination is set, the construction process of the tower is analyzed and a set of practical construction scheme is determined. As a high-precision astronomical telescope, the fabrication and installation accuracy of the FAST cable net support structure are very high, so the precision control is very important. The error sensitivity analysis is carried out on the cable net structure, the error factor and the degree of sensitivity are determined, and the precision of the construction is combined with the actual construction. The control index of the construction precision is determined, which provides the basis for the precision control of the cable network construction.

【學位授予單位】：東南大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU758.11

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本文編號：1815006