本文選題：疲勞荷載 + 鹽霧區(qū)��； 參考：《哈爾濱工業(yè)大學》2015年碩士論文

【摘要】：預應力跨海鐵路橋的箱梁位于鹽霧區(qū),工作環(huán)境極其惡劣,常年遭受疲勞荷載與鹽霧侵蝕的雙重耦合作用。在這種雙重耦合作用下,預應力鋼筋的銹蝕速度、混凝土的開裂程度與箱梁的力學性能劣化程度均會大幅增加,這會直接對鐵路橋的安全構成極大的威脅。本文針對鹽霧區(qū)的預應力鐵路橋箱梁進行疲勞荷載與氯離子侵蝕耦合作用下的氯離子分布性研究,研究結果有助于提高預應力鐵路橋箱梁的耐久性、完善其耐久性設計理論體系。首先,以ANSYS自帶的熱-結構耦合模塊計算耦合作用下的氯離子分布情況。由于該模塊具有局限性,計算所得的氯離子分布結果并不準確,因此以體積應變與孔隙率作為中間變量,給出從靜荷載到體積應變、從體積應變到孔隙率,再從孔隙率到氯離子傳遞系數(shù)的耦合計算過程。對于疲勞荷載,則通過ANSYS中的疲勞分析模塊計算損傷度D,并以基于應變的疲勞損傷理論作為依據(jù),計算疲勞荷載作用下的殘余應變與總應變,然后給出從疲勞荷載到體積應變再到氯離子傳遞系數(shù)的計算過程。最后將利用上述方法計算得到的結果與已有試驗結果進行對比。其次,建立預應力混凝土箱梁的精細化有限元模型。對預應力箱梁模型分別施加規(guī)范規(guī)定的靜活載與統(tǒng)計得到的疲勞荷載,計算鹽霧區(qū)靜活載、疲勞荷載與氯離子侵蝕耦合時箱梁內部的氯離子分布規(guī)律。同時,對比靜活載耦合與疲勞荷載耦合下的氯離子分布結果,研究不同荷載形式對耦合結果的影響。最后,在分別考慮鹽霧——靜活載耦合與鹽霧——疲勞荷載耦合的同時,對箱梁內部的預應力水平做出改變,研究不同預應力水平對箱梁內部氯離子滲透性的影響,并對比不同預應力水平下靜活載耦合與疲勞荷載耦合的計算結果。另外,對箱梁模型施加不同應力水平的疲勞荷載,研究鹽霧-疲勞荷載耦合情況下不同應力水平對計算結果的影響。最后,基于ANSYS提出鹽霧與疲勞的多次耦合分析法,將單次耦合與多次耦合的計算結果進行對比并分析。
[Abstract]:The box girder of the prestressed cross-sea railway bridge is located in the salt fog area, and the working environment is extremely bad, and it is subjected to the coupling action of fatigue load and salt spray erosion all the year round. Under this kind of double coupling action, the corrosion speed of prestressed steel bar, the cracking degree of concrete and the deterioration degree of mechanical properties of box girder will increase greatly, which will pose a great threat to the safety of railway bridge directly. In this paper, the distribution of chloride ions in the box girder of prestressed railway bridge in salt fog region under the coupling of fatigue load and chloride ion erosion is studied. The results are helpful to improve the durability of the box girder of prestressed railway bridge. Perfect its durability design theory system. Firstly, the distribution of chloride ions under coupling action is calculated by using the thermo-structural coupling module of ANSYS. Because of the limitation of the module, the calculated results of chloride ion distribution are not accurate. Therefore, the volume strain and porosity are used as the intermediate variables, from static load to volume strain, from volume strain to porosity. Then the coupling calculation process from porosity to chloride ion transfer coefficient is presented. For the fatigue load, the damage degree D is calculated by the fatigue analysis module in ANSYS, and the residual strain and the total strain under the fatigue load are calculated according to the strain based fatigue damage theory. Then the calculation process from fatigue load to volume strain to chloride ion transfer coefficient is given. Finally, the calculated results obtained by the above method are compared with the experimental results. Secondly, the fine finite element model of prestressed concrete box girder is established. The prestressed box girder model is subjected to the static live load and the statistical fatigue load, respectively, and the distribution of chloride ions in the box girder is calculated when the fatigue load is coupled with the chloride ion erosion in the salt fog region. At the same time, the results of chloride ion distribution under the coupling of static and live load and fatigue load are compared, and the influence of different load forms on the coupling results is studied. Finally, considering the coupling of salt fog and static live load and salt fog fatigue load, the prestress level of box girder is changed, and the influence of different prestress levels on the chlorine ion permeability of box girder is studied. The calculation results of static and live load coupling and fatigue load coupling under different prestress levels are compared. In addition, fatigue loads with different stress levels are applied to the box girder model, and the influence of different stress levels on the calculation results is studied under the coupling of salt fog and fatigue load. Finally, based on ANSYS, the multiple coupling analysis method of salt fog and fatigue is proposed, and the results of single coupling and multiple coupling are compared and analyzed.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U441;U448.35

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