本文選題：C型冷彎鋼構(gòu)件 + 落錘實驗��； 參考：《寧波大學(xué)》2017年碩士論文

【摘要】：冷彎薄壁鋼構(gòu)件由于重量輕、強度高、便于加工,能批量化生產(chǎn),已經(jīng)越來越廣泛地用于各種高層建筑作為承重結(jié)構(gòu)中,當(dāng)然也會被用于高地震、大風(fēng)壓或可能遭受沖擊載荷的軍事工程。然而,國內(nèi)外對于常見的開口薄壁冷彎鋼構(gòu)件(C型、Z型等)在動態(tài)沖擊載荷作用下的失穩(wěn)和失效研究卻非常缺乏,這一點也影響該類結(jié)構(gòu)在設(shè)計、施工尤其是災(zāi)后安全使用的評估工作。目前國、內(nèi)外冷彎鋼結(jié)構(gòu)設(shè)計規(guī)范等都沒有對承受沖擊載荷工況下該類結(jié)構(gòu)的設(shè)計做出過明確的條款說明,故而研究開口薄壁冷彎鋼構(gòu)件在承受沖擊載荷下的失穩(wěn)和受損傷后試樣的剩余承載能力有很大的實際工程意義。首先,本文對選取的冷彎薄壁C型鋼構(gòu)件進(jìn)行了系列在不同沖擊速度下的動態(tài)落錘軸向沖擊試驗,并結(jié)合高速攝影儀和Vic-2D軟件分析沖擊過程中試樣的屈曲發(fā)展過程、軸向位移曲線和殘余破壞形態(tài)。其次,采用商業(yè)有限元軟件Abaqus建立了能夠反映沖擊過程的有限元模型,考慮了應(yīng)變率強化效應(yīng)和幾何非線性,同時,基于廣義梁理論對有限元屈曲模態(tài)進(jìn)行分析識別的基礎(chǔ)上在后續(xù)非線性屈曲分析中引入了合適的模態(tài)組合作為初始缺陷。最后通過構(gòu)件腹板頂部的軸向位移時程曲線,錘頭速度時程曲線以及試樣屈曲殘余變形進(jìn)行了驗證,并得到了以下結(jié)論:冷彎薄壁槽鋼在受到?jīng)_擊載荷時,構(gòu)件自身對初始缺陷異常敏感且在較高的沖擊能量加載的過程中,卷邊將率先屈曲從而失去對翼緣的加勁作用,卷邊破壞嚴(yán)重,隨后引起翼緣、腹板承載能力下降,致使構(gòu)件整體發(fā)生屈曲,因此,在可能受到?jīng)_擊載荷的實際工程中,若使用的槽鋼構(gòu)件尤其在卷邊處存在初始缺陷,將是一個嚴(yán)重的隱患;該尺寸槽鋼試樣在受到10m/s及以上沖擊速度的情況下,呈現(xiàn)向高階非對稱畸變屈曲模態(tài)躍遷的跡象;隨著沖擊速度的提升,構(gòu)件的動態(tài)屈曲臨界載荷也會相應(yīng)提升;應(yīng)力波的傳播在C型鋼構(gòu)件在沖擊載荷作用下的動態(tài)失穩(wěn)中起到主要的作用。最后,利用WAW-2000型微機控制電液伺服萬能試驗機對受過沖擊載荷的槽鋼試樣和完整試樣進(jìn)行軸壓破壞實驗并進(jìn)行對比,分析了槽鋼構(gòu)件的殘余變形形態(tài),荷載位移曲線,并得到了沖擊能量與構(gòu)件剩余承載能力的關(guān)系。
[Abstract]:Because of its light weight, high strength, easy processing and mass production, cold-formed thin-walled steel members have been more and more widely used in various high-rise buildings as load-bearing structures, of course, they will also be used in high earthquakes.Military engineering with high wind pressure or potential impact load.However, the research on the instability and failure of common thin-walled cold-formed steel members, such as C type and Z type, under dynamic impact load, is very scarce, which also affects the design of this kind of structure.Safety assessment of construction, especially after disaster.At present, the code for design of cold-formed steel structures inside and outside of China has not made a clear provision on the design of this kind of structures under impact load.Therefore, it is of great practical significance to study the instability of thin-walled cold-formed steel members under impact load and the residual load-bearing capacity of specimens after damage.First of all, a series of dynamic drop weight axial impact tests are carried out on the cold-formed thin-walled C-shaped steel members under different impact velocities, and the buckling development process of the specimens during the impact process is analyzed by using high-speed photography and Vic-2D software.Axial displacement curves and residual failure patterns.Secondly, the commercial finite element software Abaqus is used to establish a finite element model which can reflect the impact process. The strain rate strengthening effect and geometric nonlinearity are considered.Based on the generalized beam theory, the finite element buckling modal analysis is identified, and the suitable modal combination is introduced as the initial defect in the subsequent nonlinear buckling analysis.Finally, the axial displacement time history curve at the top of the member web, the velocity time history curve of the hammer head and the residual deformation of the specimen buckling are verified, and the following conclusions are obtained: the cold-formed thin-walled channel steel is subjected to impact load.The member itself is very sensitive to the initial defect and in the process of high impact energy loading, the crimping will buckle first and lose the stiffening effect on the flange. The edge of the flange is damaged seriously, and then the flange is damaged, and the load carrying capacity of the web plate decreases.As a result of the overall buckling of the member, it is a serious hidden trouble if the channel steel member used in the actual project may be subjected to impact load, especially at the edge of the crimping.Under the impact velocity of 10m/s and above, the specimens of this size show signs of transition to higher-order asymmetric distortion buckling mode, and the critical load of dynamic buckling of the member will be raised accordingly with the increase of impact velocity.The propagation of stress wave plays an important role in the dynamic instability of C section steel member under impact load.Finally, WAW-2000 microcomputer controlled electro-hydraulic servo universal testing machine is used to test the axial compression failure of channel steel specimen and intact specimen under impact load, and the residual deformation pattern and load displacement curve of channel steel member are analyzed.The relationship between the impact energy and the residual bearing capacity is obtained.
【學(xué)位授予單位】：寧波大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TU392.1

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