發(fā)布時(shí)間：2018-04-27 23:59

  本文選題：空間網(wǎng)格結(jié)構(gòu) + 風(fēng)荷載　； 參考：《東南大學(xué)》2015年碩士論文

【摘要】：大跨空間網(wǎng)格結(jié)構(gòu)在風(fēng)荷載等交變荷載的作用下,結(jié)構(gòu)部分構(gòu)件的應(yīng)力變化幅值會(huì)很大,可能形成結(jié)構(gòu)的疲勞損傷。同時(shí),工程結(jié)構(gòu)服役的環(huán)境往往具有一定程度的腐蝕性,結(jié)構(gòu)構(gòu)件腐蝕加速了結(jié)構(gòu)構(gòu)件的疲勞過(guò)程,帶來(lái)的后果往往是災(zāi)難性的。因此,對(duì)在役大跨空間網(wǎng)格結(jié)構(gòu)進(jìn)行風(fēng)荷載作用下的疲勞分析和冗余度評(píng)價(jià)具有重要的現(xiàn)實(shí)意義。風(fēng)荷載作用下,大跨空間網(wǎng)格結(jié)構(gòu)構(gòu)件易出現(xiàn)疲勞。本文依據(jù)課題組測(cè)壓風(fēng)洞模型試驗(yàn)數(shù)據(jù)確定結(jié)構(gòu)承受的風(fēng)壓時(shí)程；應(yīng)用ANSYS軟件,采用梁?jiǎn)卧w模型與殼單元節(jié)點(diǎn)模型即局部模型相結(jié)合的方式,實(shí)現(xiàn)了風(fēng)致振動(dòng)響應(yīng)時(shí)程分析,運(yùn)用雨流計(jì)數(shù)法統(tǒng)計(jì)焊接球節(jié)點(diǎn)焊趾處應(yīng)力循環(huán)歷程；根據(jù)挪威船級(jí)社規(guī)范提供的相應(yīng)S-N曲線,結(jié)合Miner線性累計(jì)損傷理論,計(jì)算出空間網(wǎng)格結(jié)構(gòu)構(gòu)件的疲勞損傷值。若干算例證明了該計(jì)算流程的正確性。計(jì)算結(jié)果表明,結(jié)構(gòu)中最先出現(xiàn)疲勞構(gòu)件的位置為平均正風(fēng)壓與脈動(dòng)風(fēng)壓均最大的球殼迎風(fēng)面；結(jié)構(gòu)中疲勞構(gòu)件的疲勞損傷值隨平均正風(fēng)壓、脈動(dòng)風(fēng)壓的增大而增大。結(jié)構(gòu)敏感度是用來(lái)描述結(jié)構(gòu)行為與設(shè)計(jì)參數(shù)之間關(guān)系的響應(yīng)函數(shù),冗余特性是影響結(jié)構(gòu)魯棒性的重要因素,體現(xiàn)了損傷情況下的結(jié)構(gòu)安全性。本文借鑒P. C. Pandey方法,認(rèn)為結(jié)構(gòu)的冗余度與其結(jié)構(gòu)單元的敏感度成反比,以單元的材料彈性模量作為結(jié)構(gòu)參數(shù),將結(jié)構(gòu)參數(shù)敏感度定義為荷載作用下的結(jié)構(gòu)響應(yīng)對(duì)材料彈性模量的導(dǎo)數(shù)；然后以結(jié)構(gòu)響應(yīng)敏感度為基礎(chǔ),對(duì)風(fēng)荷載作用下的單層球面網(wǎng)殼的冗余特性進(jìn)行分析,識(shí)別結(jié)構(gòu)的關(guān)鍵構(gòu)件；并通過(guò)與單層球面網(wǎng)殼風(fēng)荷載疲勞分析結(jié)果對(duì)比,驗(yàn)證本章分析方法的正確性和有效性。若干算例表明風(fēng)荷載作用下的低冗余度桿件既包含了疲勞損傷最大的桿件,也包含了應(yīng)力最大的桿件,低冗余度桿件是結(jié)構(gòu)在荷載作用下易發(fā)生破壞的薄弱桿件和關(guān)鍵桿件,結(jié)構(gòu)的冗余度特性能很好地體現(xiàn)結(jié)構(gòu)在荷載作用下的結(jié)構(gòu)薄弱部位。鋼結(jié)構(gòu)極易出現(xiàn)銹蝕現(xiàn)象。本文結(jié)合文獻(xiàn)試驗(yàn)數(shù)據(jù),以銹蝕率和最大點(diǎn)蝕深度為基礎(chǔ),對(duì)點(diǎn)蝕孔深度、直徑及分布情況作出適當(dāng)假定,提出點(diǎn)腐蝕構(gòu)件力學(xué)性能劣化分析方法,確定不同銹蝕率下點(diǎn)蝕構(gòu)件的等效彈性模量,并建立試驗(yàn)室和自然大氣條件下銹蝕構(gòu)件力學(xué)性能參數(shù)的轉(zhuǎn)換關(guān)系,提出自然環(huán)境下點(diǎn)蝕構(gòu)件力學(xué)性能分析的實(shí)用計(jì)算方法。最后,對(duì)在役空間網(wǎng)格結(jié)構(gòu)分別進(jìn)行疲勞分析和冗余度評(píng)價(jià)。結(jié)果表明,考慮大氣腐蝕作用的影響,結(jié)構(gòu)表面平均正風(fēng)壓與脈動(dòng)風(fēng)壓最大處易出現(xiàn)疲勞構(gòu)件；在相同風(fēng)荷載歷程作用下,隨著大氣腐蝕作用的加重,結(jié)構(gòu)中疲勞桿件數(shù)目增加,疲勞桿件疲勞損傷量增大,即大氣腐蝕作用對(duì)網(wǎng)格結(jié)構(gòu)構(gòu)件疲勞效應(yīng)具有促進(jìn)作用；隨著大氣腐蝕作用的加重,風(fēng)荷載下結(jié)構(gòu)構(gòu)件的冗余度越來(lái)越低,但低冗余度桿件和應(yīng)力及疲勞損傷較大構(gòu)件仍具有良好的對(duì)應(yīng)性。本文主要?jiǎng)?chuàng)新點(diǎn)：1.將熱點(diǎn)應(yīng)力法應(yīng)用于風(fēng)荷載作用下的空間網(wǎng)格結(jié)構(gòu)疲勞分析。2.提出基于點(diǎn)蝕孔深度、直徑及分布的腐蝕構(gòu)件力學(xué)性能劣化分析方法。3.實(shí)現(xiàn)在役空間網(wǎng)格結(jié)構(gòu)的疲勞分析和冗余度評(píng)價(jià),得到其在風(fēng)荷載下的破壞模式。
[Abstract]:Under the action of alternating load such as wind load, the large span space grid structure can cause a large amplitude of stress variation of structural components, and may form structural fatigue damage. At the same time, the environment of construction service often has a certain degree of corrosiveness, and the corrosion of structural members accelerates the fatigue process of structural members, and the consequences are often the result. Therefore, the fatigue analysis and redundancy evaluation of a large span space grid structure under wind load is of great practical significance. Under wind load, the structural members of large span space grid are prone to fatigue. In this paper, the wind pressure time history of the structure subjected to the wind tunnel test is determined according to the number of wind tunnel test. The application of ANS In YS software, the wind induced response time history analysis is realized by combining the integral model of beam element and the node model of the shell element, that is, the local model, and the stress cycle process of welding joints at welding joints is calculated by using the rain flow counting method. According to the corresponding S-N curve provided by the Norway classification society standard, combined with the theory of Miner linear cumulative damage, the calculation is combined with the theory of linear cumulative damage. The calculation results show that the first fatigue component in the structure is the spherical shell with the highest average positive pressure and fluctuating wind pressure, and the fatigue damage value of the fatigue component increases with the average positive pressure and the fluctuating wind pressure in the structure. Structural sensitivity is a response function used to describe the relationship between structural behavior and design parameters. Redundancy is an important factor affecting the robustness of the structure. It embodies the structural security in the case of damage. This paper uses the P. C. Pandey method as a reference for the structural redundancy inversely proportional to its structural unit sensitivity. The elastic modulus of the material is used as the structural parameter, and the structural parameter sensitivity is defined as the derivative of the elastic modulus of the material under the load action. Then, based on the response sensitivity of the structure, the redundancy characteristics of the single-layer spherical reticulated shell under the wind load are analyzed, and the key members of the structure are identified and through the single layer ball. Comparison of wind load fatigue analysis results of surface reticulated shells verify the correctness and effectiveness of the analysis method in this chapter. Some examples show that the low redundancy rod under wind load includes both the maximum fatigue damage rod and the maximum stress bar, and the low redundancy rod is a weak rod which is easily damaged by the load. The redundancy characteristics of the structure can well reflect the weak structural parts of the structure under the load of the structure. The steel structure is easily corroded. Based on the literature test data, the corrosion rate and the maximum pitting depth are taken as the basis to make the proper assumption on the depth, diameter and distribution of the pitting hole, and the mechanics of the point corrosion component are put forward. The method of performance degradation is used to determine the equivalent elastic modulus of pitting components under different corrosion rates, and to establish the relationship between the mechanical performance parameters of the corroded component under the test room and the natural atmosphere, and put forward a practical calculation method for the analysis of the mechanical properties of the pitting members under natural environment. The results show that, considering the effect of atmospheric corrosion, the average positive pressure of the structure surface and the maximum pressure of the fluctuating wind pressure are easy to appear. Under the action of the same wind load, the number of fatigue bars in the structure increases with the aggravation of the atmospheric corrosion, and the fatigue damage of the fatigue bar increases, that is, atmospheric corrosion. It can promote the fatigue effect of the structural members of the grid. With the aggravation of the atmospheric corrosion, the redundancy of structural members is getting lower and lower, but the low redundancy rod and the stress and fatigue damage component still have good correspondence. The main innovation of this paper is: 1. the hot stress method is applied to the wind load. The fatigue analysis of space grid structure.2. presents a method of deterioration analysis based on the depth, diameter and distribution of pitting holes,.3., to achieve the fatigue analysis and redundancy evaluation of the active space grid structure, and to get the failure mode under the wind load.

【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU312;TU39

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