钢绞线腐蚀后的部分预应力混凝土梁受力性能研究

发布时间：2018-02-23 23:21

本文关键词： 腐蚀预应力混凝土梁静力性能疲劳性能　出处：《大连理工大学》2013年博士论文　论文类型：学位论文

【摘要】：车辆超载和环境腐蚀是引起桥梁结构使用寿命降低的两个主要原因。车辆超载容易引起混凝土内部发生疲劳损伤,环境腐蚀会致使桥梁结构耐久性降低,从而进一步加重混凝土内部损伤程度。本文结合科技部“863”计划资助项目“基于疲劳和寿命的混凝土桥梁结构设计方法”(2007AA11Z133),对腐蚀钢绞线以及钢绞线腐蚀后的部分预应力混凝土梁开展了静力和疲劳试验研究与分析,主要研究内容和结果如下： 1、通过对同批钢绞线进行的静力拉伸试验和疲劳试验,研究了腐蚀钢绞线的静力性能和疲劳性能。静力拉伸试验结果表明,钢绞线的塑性变形能力、极限强度以及弹性模量随腐蚀率的增加而衰减。疲劳试验结果表明,钢绞线的疲劳寿命随腐蚀率的增长按指数规律衰减,腐蚀缺陷与疲劳荷载之间的耦合作用是导致疲劳寿命下降的主要原因,腐蚀对钢绞线疲劳性能的影响远比对钢绞线的静力性能影响大。通过试验数据的回归统计建立了腐蚀钢绞线在静载作用下的本构关系模型与疲劳荷载作用下的S-N方程。 2、通过对同批钢绞线腐蚀后的部分预应力混凝土梁进行四点弯曲的静载和疲劳试验,研究了腐蚀对试验梁静力和疲劳性能的影响。静载试验结果表明,在静载试验中,钢绞线的腐蚀不仅导致部分预应力混凝土梁的破坏形态由延性破坏转为脆性破坏,还影响了腐蚀梁的开裂荷载大小,腐蚀对延性的影响远比对极限承载力影响显著。疲劳试验结果表明,腐蚀梁的疲劳破坏是由腐蚀钢绞线的疲劳断裂引起的,试验梁的疲劳寿命与疲劳强度随着钢绞线腐蚀程度的增加而显著降低。根据试验结果回归建立了疲劳荷载下钢绞线腐蚀后的部分预应力混凝土梁跨中挠度和混凝土残余应变的计算公式。此外,鉴于超载对既有桥梁结构的影响,本章还对一种新型预应力混凝土梁开展了单调荷载与循环荷载下的受力性能研究,结果表明,该种类型梁在单调与循环荷载作用下均有良好的承载能力和延性,具有良好的应用前景。 3、基于内力平衡方程和平截面假定,推导了试验梁的跨中挠度与钢筋应变关于混凝土受压区边缘应变的表达式,并引入分级加应变法对静载作用下钢绞线腐蚀后的部分预应力混凝土梁的受力过程进行分析。确立了受压区混凝土以及受拉钢筋(包括钢绞线)疲劳本构关系及疲劳破坏准则,运用分段线性方法并结合静载的分级应变法,建立了钢绞线腐蚀后的部分预应力混凝土梁的疲劳损伤全过程分析方法。 4、运用ANSYS有限元软件对钢绞线腐蚀后的预应力混凝土梁在静力荷载下的受力行为进行了数值分析,分析了钢绞线腐蚀对预应力混凝土梁的静力性能影响,并与试验结果进行比较。根据Corten-Dolan累积损伤理论与ANSYS中的疲劳分析模块对三级变幅疲劳荷载下的试验梁进行了等效疲劳寿命预测。
[Abstract]:Vehicle overload and corrosion is caused by two main reasons for the reduction of the service life of the bridge structure. Overloading easily lead to fatigue damage of concrete, corrosion will cause the bridge structure durability is reduced, which further aggravate the damage degree of concrete. Combined with the Ministry of science and technology "863" project "the design method of concrete bridge structure and fatigue based on life" (2007AA11Z133), the corrosion of steel strand and partially prestressed concrete beams after corrosion of steel strand is carried out static and fatigue test research and analysis, the main research contents and results are as follows:
1, through the static tensile test and fatigue test on the same batch of steel strand, of steel strands corroded the static and fatigue performance. Static tensile test results show that the plastic deformation capacity of steel strand, increase the ultimate strength and modulus of elasticity with corrosion rate and attenuation. The fatigue test results show that the fatigue life of steel with the wire corrosion rate growth exponentially, the coupling effect between defects and fatigue corrosion is the main cause of the decrease of fatigue life, corrosion effect on fatigue performance of steel wire than the impact of static performance of steel strand. By the statistical test data established the corrosion of steel strands under static load the constitutive model and fatigue loads of the S-N equation.
2, through four point bending static and fatigue test of partially prestressed concrete with steel wires after corrosion of the beam, study the corrosion effects on static and fatigue test beams. The static load test results show that in the static load test, the corrosion of steel strand not only leads to the damage form of partially prestressed concrete beams the ductile fracture to brittle failure, but also affect the size of corrosion cracking load of beams. The influence of corrosion on ductility than the ultimate bearing capacity was significant. The fatigue test results show that the corrosion fatigue damage of beam is caused by fatigue fracture corrosion of steel strand, the fatigue life and the fatigue strength of test beams decreased significantly with increase the degree of corrosion of steel strand. According to the results of regression is built of partially prestressed concrete beams after corrosion of steel strand under fatigue load deflection and residual strain in concrete span calculation Formula. In addition, the overloading effects of existing bridge, this chapter makes a model of prestressed concrete beam is studied. The stress performance under monotonic load and cyclic load. The results show that this kind of beams under monotonic and cyclic loading effect has good bearing capacity and ductility, and has good application prospect.
3, assuming that the internal force balance equation is deduced based on the plane section, the test beam deflection and strain of steel bar on the edge strain of concrete in compression zone, and introduce the classification process with stress analysis under static load on Corrosion of steel wire after partially prestressed concrete beam is established. The reform of concrete compression zone and the tensile steel (including steel strand) fatigue constitutive model and fatigue failure criterion, using piecewise linear method and combining the classification of static strain, established the corrosion of steel strands of partially prestressed concrete beams after fatigue damage process analysis method.
4, using the numerical analysis of prestressed concrete beams after corrosion of steel strands in the static load behavior of ANSYS finite element software, analyzes the influence of corrosion of steel strands static performance of prestressed concrete beam, and compared with the experimental results. According to the test of Corten-Dolan cumulative fatigue damage theory and analysis module of ANSYS the three variable amplitude fatigue loading beam predicted equivalent fatigue life.

【学位授予单位】：大连理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU378.2

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