外包角钢加固钢筋混凝土柱环箍效应数值分析研究
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摘要
据统计,到2010年年底,我国城镇建筑相当多已进入中老年期,质量问题频频发生,其中约十几亿平方米需要维修加固才能消除安全隐患,毫无疑问,当前和未来加固改造费用的份额将越来越高,建筑物加固行业发展会十分迅速。钢筋混凝土柱是钢筋混凝土结构中最基本的受力构件之一,承载着整个结构的安全,因此,对钢筋混凝土柱加固后的受力性能的研究具有重要的工程意义。而外包角钢加固法相对于其它加固方法,其显著优点是基本不增加构件的重量,不改变原设计的结构体系,施工简单,现场工作量小,而且能显著提高承载能力,改善截面的刚度和延性,限制原构件挠度的过快增长。目前,外包钢加固技术已经取得了大量的研究成果,但对于由角钢与缀板形成的钢骨架对混凝土柱的约束,从而使核芯混凝土由原来的单向应力状态转化为处于三轴受压应力状态下引发的环箍效应的研究几乎没有。因此,本文利用数值分析方法研究环箍效应对外包钢加固柱性能的影响,并分析环箍效应的机理,初步确立考虑环箍效应影响的外包钢加固柱的受压承载力计算公式。
本文首先根据本课题试验数据,初步建立外包角钢加固钢筋混凝土柱的数值分析模型,并对比分析了试验和有限元模拟两种方法下数据的差异,通过模型调整使数值分析结果与试验数据接近,从而建立起合适的模型,为分析环箍效应影响因素奠定基础。通过数值分析研究,分析了环箍效应的产生机理,探讨了缀板间距、角钢厚度、缀板厚度和箍筋直径等几个因素对于加固柱受力性能的影响,分析了这些因素与环箍效应之间的联系,并且建立了环箍效应影响下外包钢加固柱的轴心受压承载力计算公式。
通过研究,得出如下结论：在外包钢加固柱的环箍效应影响下,加固后混凝土柱的极限承载力得到了明显的提高,混凝土应力分布更均匀,并且提高了加固柱延性和变形能力,大大改善了受压构件的力学性能；随着角钢的厚度增大,角钢截面面积增大,缀板间距的减小,钢骨架分担更多荷载,承载力得到了提高,并且提高了环箍效应对于核心混凝土的环向约束,混凝土和角钢的位移都产生了一定幅度的减小,但承载力提高幅度与角钢厚度增加、缀板间距减小之间并不是线性变化的。在本文研究的影响环箍效应的几个因素中,根据对于加固柱承载力提高的比较,缀板间距和角钢厚度为主要因素,箍筋直径可视为次要因素。在工程实践中,可根据本文提供的承载力公式计算。
According to the statistics, the considerable urban construction of China has entered the old period by the end of 2010, so quality problems have occurred frequently, of which about billions of square meters need repairing and reinforcing in order to eliminate safety concerns. Undoubtedly, as the share of cost on reinforcement and reconstruction in current and future will be higher and higher, the building reinforcement industry will develop more and more quickly. Reinforced concrete column is one of the most basic force components of reinforced concrete structure, which carries the whole structure security; therefore, the study on mechanical performance of reinforced concrete column has a profound engineering significance. Compared with other reinforcement methods, outsourcing angle steel reinforced method has some significant advantages, for example, do not increase the weight of components; do not change the original design of the structure; the simple construction; a small amount of work site; improving the bearing capacity significantly; bettering rigidity and ductility of section; and limiting the rapid increase of the original component deflection. At present, the technology of outsourcing steel reinforcement has made a lot of research results, however, the steel skeleton from angle steels and batten plates constrains the concrete columns, so that the study on ferrule effect caused by the situation that the core concrete from the uniaxial stress state into a triaxial compressive stress state. Therefore, this paper studies the influence of outsourcing angle steel reinforced column by ferrule effect in the method of numerical analysis, analyses the mechanism of ferrule effect, and initially establish the bearing strength formulas of.outsourcing angle steel reinforced column influenced by ferrule effect.
Firstly, according to the experimental data under this project, the numerical analysis model of outsourcing angle steel reinforced concrete column has been established initially in his paper. Through the comparative analysis of the data differences between experimental and finite element simulation methods, and the adjusting the numerical analysis of model results close to the experimental data, a suitable model can be established, which lays the foundation of the analysis of the factors of ferrule effect. Similarly, through numerical analysis, we can analyze the production mechanism of ferrule effect, the effect of reinforced columns' properties of ferrule effect, three factors of stirrup diameter, angle steel's thickness and spacing battens, the change of mechanical properties of reinforced columns, and the links between these factors and ferrule effect to establish the bearing strength formulas of outsourcing angle steel reinforced column influenced by ferrule effect.
There are some conclusions followed through research:influenced by ferrule effect of outsourcing angle steel reinforced columns, the ultimate bearing capacity of reinforced concrete columns has been improved significantly, concrete stress has been better-distributed, the ductility and deformation capacity of reinforced columns has been improved, and the mechanical properties of compression members has been improved greatly; the stress of the end concrete columns is much larger than that of the central, while the deformation near the middle of steel skeleton is the largest, so more attention should be paid during construction of pouring concrete columns'end and welding the central of the steel frame; with the increasing of the angle steel's thickness and cross-sectional area, the decreasing of batten spacing, the steel skeleton shares more load bearing capacity, which makes bearing capacity improved and the hoop constraint of core concrete increased, at the same time, the displacement of concrete and angle steel decreases with a certain level, the stress of the angle steel also decreases, but the rate of capacity's improvement is not changed in a linear to the increasing rate of thickness and the decreasing rate of batten spacing. In the three factors influenced by ferrule effect studied in the paper, the thickness of angle steel and the batten spacing are the main factors, stirrup diameter can be regarded as a secondary factor according to the comparison of reinforced columns' bearing capacity. In engineering practice, it can be calculated under this capacity formula provided in the paper.
本文首先根据本课题试验数据,初步建立外包角钢加固钢筋混凝土柱的数值分析模型,并对比分析了试验和有限元模拟两种方法下数据的差异,通过模型调整使数值分析结果与试验数据接近,从而建立起合适的模型,为分析环箍效应影响因素奠定基础。通过数值分析研究,分析了环箍效应的产生机理,探讨了缀板间距、角钢厚度、缀板厚度和箍筋直径等几个因素对于加固柱受力性能的影响,分析了这些因素与环箍效应之间的联系,并且建立了环箍效应影响下外包钢加固柱的轴心受压承载力计算公式。
通过研究,得出如下结论：在外包钢加固柱的环箍效应影响下,加固后混凝土柱的极限承载力得到了明显的提高,混凝土应力分布更均匀,并且提高了加固柱延性和变形能力,大大改善了受压构件的力学性能；随着角钢的厚度增大,角钢截面面积增大,缀板间距的减小,钢骨架分担更多荷载,承载力得到了提高,并且提高了环箍效应对于核心混凝土的环向约束,混凝土和角钢的位移都产生了一定幅度的减小,但承载力提高幅度与角钢厚度增加、缀板间距减小之间并不是线性变化的。在本文研究的影响环箍效应的几个因素中,根据对于加固柱承载力提高的比较,缀板间距和角钢厚度为主要因素,箍筋直径可视为次要因素。在工程实践中,可根据本文提供的承载力公式计算。
According to the statistics, the considerable urban construction of China has entered the old period by the end of 2010, so quality problems have occurred frequently, of which about billions of square meters need repairing and reinforcing in order to eliminate safety concerns. Undoubtedly, as the share of cost on reinforcement and reconstruction in current and future will be higher and higher, the building reinforcement industry will develop more and more quickly. Reinforced concrete column is one of the most basic force components of reinforced concrete structure, which carries the whole structure security; therefore, the study on mechanical performance of reinforced concrete column has a profound engineering significance. Compared with other reinforcement methods, outsourcing angle steel reinforced method has some significant advantages, for example, do not increase the weight of components; do not change the original design of the structure; the simple construction; a small amount of work site; improving the bearing capacity significantly; bettering rigidity and ductility of section; and limiting the rapid increase of the original component deflection. At present, the technology of outsourcing steel reinforcement has made a lot of research results, however, the steel skeleton from angle steels and batten plates constrains the concrete columns, so that the study on ferrule effect caused by the situation that the core concrete from the uniaxial stress state into a triaxial compressive stress state. Therefore, this paper studies the influence of outsourcing angle steel reinforced column by ferrule effect in the method of numerical analysis, analyses the mechanism of ferrule effect, and initially establish the bearing strength formulas of.outsourcing angle steel reinforced column influenced by ferrule effect.
Firstly, according to the experimental data under this project, the numerical analysis model of outsourcing angle steel reinforced concrete column has been established initially in his paper. Through the comparative analysis of the data differences between experimental and finite element simulation methods, and the adjusting the numerical analysis of model results close to the experimental data, a suitable model can be established, which lays the foundation of the analysis of the factors of ferrule effect. Similarly, through numerical analysis, we can analyze the production mechanism of ferrule effect, the effect of reinforced columns' properties of ferrule effect, three factors of stirrup diameter, angle steel's thickness and spacing battens, the change of mechanical properties of reinforced columns, and the links between these factors and ferrule effect to establish the bearing strength formulas of outsourcing angle steel reinforced column influenced by ferrule effect.
There are some conclusions followed through research:influenced by ferrule effect of outsourcing angle steel reinforced columns, the ultimate bearing capacity of reinforced concrete columns has been improved significantly, concrete stress has been better-distributed, the ductility and deformation capacity of reinforced columns has been improved, and the mechanical properties of compression members has been improved greatly; the stress of the end concrete columns is much larger than that of the central, while the deformation near the middle of steel skeleton is the largest, so more attention should be paid during construction of pouring concrete columns'end and welding the central of the steel frame; with the increasing of the angle steel's thickness and cross-sectional area, the decreasing of batten spacing, the steel skeleton shares more load bearing capacity, which makes bearing capacity improved and the hoop constraint of core concrete increased, at the same time, the displacement of concrete and angle steel decreases with a certain level, the stress of the angle steel also decreases, but the rate of capacity's improvement is not changed in a linear to the increasing rate of thickness and the decreasing rate of batten spacing. In the three factors influenced by ferrule effect studied in the paper, the thickness of angle steel and the batten spacing are the main factors, stirrup diameter can be regarded as a secondary factor according to the comparison of reinforced columns' bearing capacity. In engineering practice, it can be calculated under this capacity formula provided in the paper.
引文
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