沿海钢结构栈桥的腐蚀安全评定研究

发布时间：2018-03-31 05:36

本文选题：钢结构栈桥　切入点：承载力分析　出处：《哈尔滨工业大学》2016年硕士论文

【摘要】：钢结构栈桥施工方便,可重复性利用,是施工时重要的运输通道,提高施工的效率。由于沿海环境的特点,氯离子浓度较高,钢栈桥往往在正常使用时间内发生大面积的腐蚀,降低结构的承载力和稳定性。然而,现阶段鲜有钢结构栈桥腐蚀规律,以及安全评定。本文系统研究了钢结构栈桥的受力特点、蚀坑分布规律和腐蚀安全评定等内容,具体如下:以栈桥整体结构为研究对象,考虑不同的荷载工况、不同的桥梁跨数、不同的弹性刚度,建立多个栈桥模型,对比分析栈桥受力特点。针对已确立的栈桥四联模型,研究了无锈蚀栈桥的承载力和稳定性,探讨了在不同腐蚀程度下,栈桥结构承载力和稳定性的变化情况,建立腐蚀指标。分析结果说明在主要构件中,桩顶横梁对于腐蚀程度比较敏感,最先达到承载力极限。梁先发生承载力破坏,钢管桩则先发生稳定性破坏。另外,通过车辆荷载的动力分析,得到主要构件的位移,与静力分析中的位移相比较,误差在合理范围内。以栈桥关键构件为研究对象,通过除锈实验和超景深实验,得到了局部蚀点的分布规律,建立腐蚀点的二维模型,分析了不同构件中蚀坑的分布特点。在含蚀坑的三维模型中,施加相同的边界条件,分析不同腐蚀程度下,部分构件的最大应力,建立传递系数,修正腐蚀指标。对梁的三维模型模拟四点弯曲试验,得到梁的承载力。分析得到蚀坑分布在桥面上构件符合高斯分布规律,桥面板以下构件没有符合任何分布规律,但是蚀坑的大小和深度近似相等。梁的承载力随着腐蚀指标的增大而减少,不同的梁,承载力减少的规律不同。建立腐蚀安全评定体系,对腐蚀等级进行划分,在不同腐蚀等级下,对主要构件进行梁承载力和结构应力分析,明确各个腐蚀等级的腐蚀厚度和最不利受力位置,提出腐蚀安全评定流程。
[Abstract]:The construction of steel trestle bridge is convenient and repeatable. It is an important transportation passage during construction and improves the efficiency of construction.Due to the characteristics of coastal environment and the high concentration of chloride ions, the steel trestle is often corroded in a large area during the normal service time, which reduces the bearing capacity and stability of the structure.However, there are few corrosion rules and safety assessment of steel trestle at the present stage.In this paper, the stress characteristics, corrosion pit distribution and corrosion safety assessment of steel trestle bridge are systematically studied. The concrete contents are as follows: taking the whole structure of the trestle bridge as the research object, considering different load conditions, different bridge span number, etc.With different elastic stiffness, several trestle models are established, and the stress characteristics of trestle are compared and analyzed.The bearing capacity and stability of rust-free trestle are studied according to the established trestle model. The variation of bearing capacity and stability of trestle structure under different corrosion degree is discussed and the corrosion index is established.The results show that the pile top beam is sensitive to corrosion and the ultimate bearing capacity is first reached.The bearing capacity of the beam is destroyed first, and the stability of the steel pipe pile is destroyed first.In addition, the displacement of the main components is obtained by dynamic analysis of vehicle loads, and the error is within a reasonable range compared with the displacement in static analysis.Taking the key components of the trestle bridge as the research object, the distribution law of the local corrosion point is obtained through the rust removal experiment and the depth of field experiment. The two-dimensional model of the corrosion point is established, and the distribution characteristics of the corrosion pits in the different components are analyzed.In the three-dimensional model of the corrosion pit, the maximum stress of some components under different corrosion degree is analyzed, the transfer coefficient is established and the corrosion index is modified by applying the same boundary condition.The three-dimensional model of the beam is simulated by four-point bending test, and the bearing capacity of the beam is obtained.It is found that the distribution of the corrosion pits on the bridge surface conforms to Gao Si's distribution law, and that the components below the bridge deck do not conform to any distribution law, but the size and depth of the pits are approximately equal.The bearing capacity of beams decreases with the increase of corrosion index.The corrosion safety assessment system is established and the corrosion grade is divided. Under different corrosion grades, the bearing capacity and structural stress of the main members are analyzed, and the corrosion thickness and the most unfavorable position of each corrosion grade are determined.The corrosion safety assessment process is proposed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U445.73;U448.18

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