本文選題：預應力混凝土箱梁 + 裂縫特征統(tǒng)計參數(shù)��； 參考：《長安大學》2015年碩士論文

【摘要】：在現(xiàn)役橋梁類型中最常見的就是預應力混凝土箱梁橋,其隨著運營時間的增加,在外荷載的反復作用以及主梁鋼束預應力損失等因素的影響下,主梁便會出現(xiàn)不同程度上的裂縫以及變形等病害。所以定期對橋梁做外觀檢測也成為對其加固和養(yǎng)護的必要前提。對主梁裂縫特征參數(shù)進行統(tǒng)計也是其中的一項重要指標。怎樣通過橋梁的外觀檢查得出的裂縫特征參數(shù)統(tǒng)計值來評估該橋梁在運營階段的安全性能具有十分重要的現(xiàn)實意義,同時也是本文主要的研究方向。本文主要把縱向鋼束預應力損失當作主梁底板開裂的主要原因,并以受彎混凝土梁段開裂后截面受壓區(qū)高度的計算方法作為理論基礎,通過對開裂箱梁底板橫向裂縫特征參數(shù)的統(tǒng)計,推導出開裂的箱梁截面特征值的計算公式。再考慮鋼束和混凝土之間由于相互作用而產(chǎn)生的應變差,進而計算出開裂截面同一水平面上鋼束應力均值,并將其近似的作為這一層鋼束中每根鋼筋的有效預應力值。通過縱向鋼束預應力實際分布值預測方法,并對其中的預測方法加以簡化,將其應用在開裂后的箱梁橋中,并通過實例對比分析證明此方法的正確性。通過對運營中某實橋的外觀檢查,對檢查得出的裂縫特征參數(shù)進行了統(tǒng)計,運用上述的模擬預測方法,調(diào)整預應力鋼束的參數(shù)值來模擬和預測橋梁的運營狀況,通過對其不同運營時間里主梁應力和撓度值的分析對比情況來評估該橋的安全性能,并相應的提出一些加固和養(yǎng)護措施。
[Abstract]:The most common type of bridge in active service is prestressed concrete box girder bridge. With the increase of operation time, the repeated action of external load and the loss of prestressing force of main girder, etc.The main beam will appear in varying degrees of cracks and deformation and other diseases.Therefore, regular inspection of the bridge appearance has become a necessary prerequisite for its reinforcement and maintenance.Statistical analysis of crack characteristic parameters is also an important index.How to evaluate the safety performance of the bridge through the statistical value of crack characteristic parameters obtained from the exterior inspection of the bridge is of great practical significance and is also the main research direction of this paper.In this paper, the prestress loss of longitudinal steel bundle is regarded as the main reason for the cracking of the main beam bottom slab, and the calculation method of the height of the section compression zone after cracking of the flexural concrete beam is taken as the theoretical basis.Based on the statistics of transverse crack characteristic parameters of cracked box girder bottom plate, the formula for calculating the cross section characteristic value of cracked box girder is derived.Considering the strain difference between the steel beam and concrete due to the interaction, the stress mean value of the steel beam on the same horizontal plane of the cracking section is calculated, which is approximately regarded as the effective prestress value of each steel bar in this layer of steel bundle.The prediction method of the actual distribution value of longitudinal steel prestress is simplified and applied to the cracked box girder bridge, and the correctness of the method is proved by the comparison and analysis of an example.By checking the appearance of a real bridge in operation, the crack characteristic parameters obtained from the inspection are statistically analyzed, and the parameters of prestressed steel bundle are adjusted to simulate and predict the operation condition of the bridge by using the above-mentioned simulation and prediction method.The safety performance of the bridge is evaluated by analyzing and comparing the stress and deflection of the main girder in different operation time, and some reinforcement and maintenance measures are put forward accordingly.
【學位授予單位】：長安大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：U448.213;U447

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本文編號：1772409