箱梁桥腹板斜裂缝与承载力研究

发布时间：2018-05-30 10:31

本文选题：箱梁桥 + 极限承载力　；参考：《湖南科技大学》2015年硕士论文

【摘要】：钢筋混凝土/预应力混凝土箱梁桥在施工及正常使用过程中易开裂,特别是易出现腹板斜裂缝,因此应对腹板主拉应力分布规律进行研究。腹板斜裂缝的出现对桥梁的整体刚度、承载能力以及正常使用性能将产生很大影响,同时桥梁刚度下降又会进一步促进腹板裂缝的发展。国内外关于箱梁腹板开裂对桥梁刚度、承载能力、使用性能的影响研究还不够明确,大多只进行了定性描述而没有形成一套量化的计算理论。对混凝土构件开裂情况的模拟还不够精确,特别是箱梁桥局部屈曲,非线性收敛等问题。本文以某预应力混凝土箱梁桥为背景,在全面总结箱梁桥开裂原因及裂缝分布规律的前提下,利用空间实体有限元模型研究了箱梁桥的腹板受力特性。并以软化桁架模型理论为基础,以小扭弯比的加载方式,建立了弯、剪、扭共同作用下的实体-桁架模型,在满足与实体模型刚度等效的前提下,研究了箱梁桥在自重荷载、车道荷载正载与偏载荷载情况下的箱梁受力特性。并利用该实体-桁架模型进行了非线性计算,得出了箱梁的开裂荷载与极限承载力。本文取得的成果有如下几个方面:1.在“软化桁架理论”的基础上提出了“实体-桁架”模型的数值分析与建模方法。2.建立了五种不同角度的实体-桁架模型,分析了箱梁挠度与腹板应力受桁架斜杆倾角的影响情况,并得出了桁架斜杆倾角的优选办法。3.推导了“实体箱梁”与“实体-桁架箱梁”的刚度等效计算公式。4.分别建立了“实体模型”和“实体-桁架模型”,分别做了不同荷载工况下的数值计算与受力特性分析,通过非线性数值计算得出了箱梁桥腹板的开裂荷载和极限承载力。最后,本文针对研究中发现的问题展开了探讨,并对实体-桁架模型理论的发展与实际应用做了总结。
[Abstract]:The reinforced concrete / prestressed concrete box girder bridge is prone to crack during construction and normal use, especially the inclined cracks of web plate, so it is necessary to study the distribution law of main tensile stress of web plate. The emergence of inclined web cracks will have a great impact on the overall stiffness, bearing capacity and normal service performance of the bridge, and the reduction of bridge stiffness will further promote the development of web cracks. At home and abroad, the influence of box girder web cracking on bridge stiffness, bearing capacity and service performance is not clear enough, most of them are only qualitatively described without a set of quantitative calculation theory. The simulation of concrete member cracking is not accurate enough, especially the local buckling and nonlinear convergence of box girder bridge. Taking a prestressed concrete box girder bridge as the background, this paper, on the premise of summing up the cracking reason and crack distribution law of the box girder bridge, makes use of the finite element model of space entity to study the stress characteristics of the web plate of the box girder bridge. Based on the theory of softened truss model and the loading mode of small torsional bending ratio, the solid-truss model under the joint action of bending, shear and torsion is established. On the premise that the stiffness of the box girder bridge is equivalent to that of the solid model, the deadweight load of the box girder bridge is studied. The load characteristics of box girder under positive load and eccentric load in driveway. The cracking load and ultimate bearing capacity of the box girder are obtained by nonlinear calculation using the solid-truss model. The achievements of this paper are as follows: 1. On the basis of "softening truss theory", a numerical analysis and modeling method of "solid truss" model is proposed. Five kinds of solid truss models with different angles are established, and the influence of box girder deflection and web stress on the inclined angle of truss bar is analyzed, and the optimum selection method of inclined truss bar angle is obtained. The equivalent stiffness calculation formula of "solid box girder" and "solid truss box girder" is derived. The "solid model" and "solid-truss model" are established respectively, and the numerical calculation and the analysis of the stress characteristics under different load conditions are done respectively. The cracking load and ultimate bearing capacity of the web plate of the box girder bridge are obtained by nonlinear numerical calculation. Finally, this paper discusses the problems found in the research, and summarizes the development and practical application of the solid-truss model theory.
【学位授予单位】：湖南科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441;U448.213

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