發(fā)布時間：2018-03-05 22:02

  本文選題：單層球殼　切入點：多點輸入時程分析　出處：《東南大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：作為大跨度空間結(jié)構(gòu)的一個重要分支,網(wǎng)殼結(jié)構(gòu)是目前大跨度空間結(jié)構(gòu)中應(yīng)用最廣泛的結(jié)構(gòu)類型。鑒于我國地處地震災(zāi)害嚴重的區(qū)域,學(xué)者們對以網(wǎng)殼結(jié)構(gòu)為代表的大跨度空間結(jié)構(gòu)在地震作用下的倒塌失效機理進行了系統(tǒng)的研究工作。與理論相比,從試驗角度去驗證和探索網(wǎng)殼結(jié)構(gòu)強震失效機理的工作相對較少。因此,本課題通過對多點輸入下單層球殼振動臺倒塌試驗的研究,從試驗角度觀察了地震作用下單層球殼的動力響應(yīng),并運用有限元軟件模擬了結(jié)構(gòu)在強震作用下的倒塌破壞過程。本文的主要內(nèi)容和結(jié)論如下：(1)根據(jù)相似比理論及原型的拓撲關(guān)系嚴格設(shè)計2個單層球殼縮尺模型,不做任何簡化。兩個模型的跨度為23.4m,矢高為11.7m。模型1正常設(shè)計,除了底部一圈加強之外,其余部分剛度均勻；模型2在模型1設(shè)計的基礎(chǔ)上人為設(shè)置了兩個薄弱區(qū),期待其在相同的地震激勵下發(fā)生與模型1不同的動力響應(yīng)。通過逐級提高輸入地震波的加速度峰值,觀測每個工況下模型的反應(yīng)特征,完成單層球殼振動臺倒塌試驗。從試驗結(jié)果來看,由于特殊的邊界條件,兩個模型都發(fā)生突然的倒塌破壞。倒塌前,模型1塑性區(qū)域不斷發(fā)展,桿件截面塑性開展充分。而模型2由于人為設(shè)置了薄弱區(qū),該區(qū)域的桿件最先失效,倒塌時該區(qū)域破壞嚴重。因此,在實際中進行結(jié)構(gòu)設(shè)計時,應(yīng)避免出現(xiàn)剛度不均勻。(2)根據(jù)設(shè)定的目標自功率譜密度函數(shù)和互功率譜密度函數(shù)模擬生成四條相干地震波,并對生成的地震波進行頻譜分析,驗證其合理性,以用于后期的數(shù)值模擬分析以及振動臺試驗的加載輸入。在ANSYS中采用大質(zhì)量法實現(xiàn)模型多點輸入時程分析,獲得結(jié)構(gòu)的動力響應(yīng)。模擬時考慮了幾何非線性和材料非線性。模擬時發(fā)現(xiàn),大質(zhì)量取為結(jié)構(gòu)總質(zhì)量的104-108倍時,可保證結(jié)構(gòu)多點輸入地震分析的準確性。(3)在倒塌工況下,利用生死單元技術(shù)模擬結(jié)構(gòu)在加載過程中因桿件失效退出工作而造成的結(jié)構(gòu)形式和邊界條件的變化,展現(xiàn)了結(jié)構(gòu)從彈性進入塑性以及塑性開展直至結(jié)構(gòu)倒塌的全過程。最終將倒塌模式與試驗結(jié)果進行對比分析,驗證了試驗方案和數(shù)值計算模型的合理性。
[Abstract]:As an important branch of long-span spatial structure, latticed shell structure is the most widely used structural type in long-span spatial structure at present. Scholars have systematically studied the collapse failure mechanism of long-span space structures, represented by latticed shell structures under earthquake. There is relatively little work to verify and explore the failure mechanism of reticulated shell structures from the point of view of test. Therefore, in this paper, the collapse test of single-layer spherical shell vibration table with multi-point input is studied. The dynamic response of a single-layer spherical shell subjected to earthquake is observed from an experimental point of view. The collapse and failure process of the structure subjected to strong earthquakes is simulated by using finite element software. The main contents and conclusions of this paper are as follows: (1) according to the similarity ratio theory and the topological relation of the prototype, two single-layer spherical shell scale models are strictly designed. There is no simplification. The span of the two models is 23.4m and the vector height is 11.7m.Model 1 is normally designed, and the stiffness of the rest of the model is uniform except for the one ring at the bottom. Model 2 has two weak areas artificially set up on the basis of the design of model 1. By increasing the acceleration peak of the input seismic wave step by step, the response characteristics of the model under each working condition are observed, and the dynamic response of the model is expected to be different from that of model 1 under the same earthquake excitation. The collapse test of single layer spherical shell vibration table was completed. According to the test results, both models collapsed suddenly because of special boundary conditions. Before the collapse, the plastic region of model 1 developed continuously. The plasticity of the section of the member is fully developed. Model 2, because of the artificial weak zone, the member in the region is the first to fail, and the area is damaged seriously when it collapses. Therefore, when the structural design is carried out in practice, Four coherent seismic waves should be generated according to the target self-power spectral density function and cross-power spectral density function, and the frequency spectrum analysis of the generated seismic waves is carried out to verify its reasonableness. It is used for the later numerical simulation analysis and the loading input of the shaking table test. The large mass method is used to realize the model multi-point input time history analysis in ANSYS. The dynamic response of the structure is obtained. Geometric nonlinearity and material nonlinearity are taken into account in the simulation. It is found that when the mass is 104-108 times of the total mass of the structure, the accuracy of the multi-input seismic analysis of the structure can be ensured under the collapse condition. The life and death element technique is used to simulate the change of structure form and boundary conditions caused by the failure and exit of the member during the loading process. The whole process from elasticity to plasticity and plastic development to collapse of the structure is shown. Finally, the rationality of the test scheme and the numerical calculation model is verified by comparing the collapse mode with the experimental results.
【學(xué)位授予單位】：東南大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TU317;TU399

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