脱空对钢管混凝土拱肋面外稳定性的影响
发布时间：2019-02-26 16:19
【摘要】：随着社会的快速发展,钢管混凝土这种复合材料在拱桥的领域中发展迅速,由于钢管和混凝土之间的良好配合,使钢管混凝土具有抗压性能强,耐火性能好,塑性和韧性好等特点。钢管混凝土材料首次应用在19世纪80年代英国的赛文铁路桥的桥墩中,但是钢管混凝土在桥梁中的真正得到发展是在我国,迄今为止,我国已经建成和正在建的钢管混凝土拱桥就达到了300多座,并且朝着大跨度的方向进行发展,那么拱肋的稳定问题就随之出现,由于拱肋主要是受压的结构,尤其是拱肋的面外稳定问题,通过大量的试验和理论分析得出拱肋的的横向刚度要小于竖向刚度,也就是说拱肋很容易在面内失稳前发生面外失稳。同时钢管混凝土拱桥在运营期间暴露了一些问题,其中比较突出的问题之一就是钢管和混凝土之间的脱空问题,脱空问题的存在使钢管和混凝土之间的紧箍作用失效,不同程度的影响了钢管混凝土拱桥的承载力,现阶段对钢管混凝土拱肋脱空问题的防治对策和解决办法诸多,但是后期的混凝土的徐变收缩引起的脱空却是不可避免的。由于混凝土后期脱空是不可避免的,并且钢管混凝土拱肋在受力过程中更容易发生面外失稳,因此本文研究混凝土脱空对钢管混凝土拱肋的平面外稳定性的影响。通过大型通用软件ANSYS对钢管混凝土拱肋进行建模分析,以陈宝春的单圆管拱肋的试验作为研究对象来建立有限元的模型,使有限元的结果与试验的结果相对比,在验证所建立的有限元模型的正确性和可靠性之后,在脱空的情况下研究长细比、含钢率、矢跨比和套箍系数等参数对钢管混凝土拱肋的面外稳定承载力的影响,同时对脱空率的大小、脱空的位置、脱空的长度以及荷载的作用位置进行了研究。研究表明:拱肋长细比越大,其极限承载力就越小,相反,拱肋的极限承载力随着含钢率、钢材强度等级和混凝土的强度的增大而增大,拱肋的极限承载力随着矢跨比的增大呈现出先增大后减小的趋势,最佳矢跨比在0.25-0.3之间。在拱肋发生脱空时,脱空率和脱空长度的增大使拱肋的极限承载力大幅度下降,应引起足够的重视,脱空的位置以及荷载的加载方式对拱肋的极限承载力影响较大,在对称荷载的作用下拱肋的极限承载力要明显高于非对称荷载作用下的极限承载力。在研究拱肋各参数的基础上,对现阶段的GB50936-2014《钢管混凝土结构技术规范》中构件空间受力的计算公式为研究对象,考虑在脱空的情况下引入脱空折减系数Kn和Km,通过对各参数的影响数据进行汇总,拟合得到了脱空折减系数的简化计算公式,简化计算公式所计算的结果与有限元计算结果相比较,二者之间的误差在10%左右,说明该公式具有较好的精度,可供实际工程参考。
[Abstract]:With the rapid development of society, concrete filled steel tube (CFST) is developed rapidly in the field of arch bridge. Due to the good coordination between CFST and CFST, CFST has strong compressive performance and good fire resistance. Good plasticity and toughness. Concrete filled steel tube (CFST) is first used in the pier of Severn railway bridge in Britain in the 1880s. However, the concrete filled steel tube (CFST) has been developed in China, so far, the concrete filled steel tube (CFST) has been developed in China. More than 300 concrete-filled steel tube arch bridges have been built and are being built in China, and the arch ribs are developed in the direction of long span, then the stability problem of arch ribs will appear, because the arch ribs are mainly compressed structures. Especially for the out-of-plane stability of arch rib, the lateral stiffness of arch rib is smaller than that of vertical stiffness through a lot of tests and theoretical analysis, that is to say, the out-of-plane instability of arch rib is easy to occur before in-plane instability. At the same time, the concrete-filled steel tube arch bridge has exposed some problems during the operation, one of the more prominent problems is the void between the steel tube and concrete, the existence of the void problem makes the fastening between the steel tube and the concrete invalid, The bearing capacity of concrete-filled steel tube arch bridge is affected in different degrees. At present, there are many preventive measures and solutions to the void problem of concrete-filled steel tube arch rib. However, the void caused by creep shrinkage of concrete in the later stage is inevitable. In this paper, the influence of concrete void on the out-of-plane stability of concrete-filled steel tube arch rib is studied because it is inevitable that the concrete-filled steel tube arch rib is out-of-plane instability in the process of loading. The finite element model of concrete-filled steel tube arch rib is established by means of large-scale general software ANSYS. The finite element model is established by taking Chen Baochun's single circular pipe arch rib test as the research object, and the results of the finite element method are compared with the experimental results, and the results of the finite element method are compared with the experimental results. After verifying the correctness and reliability of the established finite element model, the influence of the parameters such as slenderness ratio, steel content ratio, rise-span ratio and hoop coefficient on the out-of-plane stability bearing capacity of concrete-filled steel tube arch rib is studied under the condition of void. At the same time, the size, the position, the length and the action position of the emptying rate are studied. The research shows that the greater the slenderness ratio of arch rib is, the smaller the ultimate bearing capacity is. On the contrary, the ultimate bearing capacity of arch rib increases with the increase of steel content, steel strength grade and concrete strength. The ultimate bearing capacity of arch ribs increases first and then decreases with the increase of the rise-span ratio, and the optimum rise-span ratio is between 0.25 and 0.3. When the arch rib is emptied, the ultimate bearing capacity of the arch rib decreases greatly with the increase of the void ratio and the length of the void, which should be paid enough attention. The location of the void and the loading mode of the arch rib have a great influence on the ultimate bearing capacity of the arch rib. Under the action of symmetric load, the ultimate bearing capacity of arch rib is obviously higher than that under asymmetric load. On the basis of studying the parameters of arch rib, the calculation formula of spatial force of members in GB50936-2014 (Technical Code for concrete filled Steel Tubular structures) at present is studied, and the void reduction factor Kn and Km, are taken into account in the case of emptying. By summarizing the influence data of each parameter, the simplified calculation formula of void reduction coefficient is obtained. Compared with the results calculated by finite element method, the error between the simplified calculation formula and the results of finite element calculation is about 10%, and the error between the simplified formula and the finite element method is about 10%. It is shown that the formula has good accuracy and can be used for reference in practical engineering.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441
[Abstract]:With the rapid development of society, concrete filled steel tube (CFST) is developed rapidly in the field of arch bridge. Due to the good coordination between CFST and CFST, CFST has strong compressive performance and good fire resistance. Good plasticity and toughness. Concrete filled steel tube (CFST) is first used in the pier of Severn railway bridge in Britain in the 1880s. However, the concrete filled steel tube (CFST) has been developed in China, so far, the concrete filled steel tube (CFST) has been developed in China. More than 300 concrete-filled steel tube arch bridges have been built and are being built in China, and the arch ribs are developed in the direction of long span, then the stability problem of arch ribs will appear, because the arch ribs are mainly compressed structures. Especially for the out-of-plane stability of arch rib, the lateral stiffness of arch rib is smaller than that of vertical stiffness through a lot of tests and theoretical analysis, that is to say, the out-of-plane instability of arch rib is easy to occur before in-plane instability. At the same time, the concrete-filled steel tube arch bridge has exposed some problems during the operation, one of the more prominent problems is the void between the steel tube and concrete, the existence of the void problem makes the fastening between the steel tube and the concrete invalid, The bearing capacity of concrete-filled steel tube arch bridge is affected in different degrees. At present, there are many preventive measures and solutions to the void problem of concrete-filled steel tube arch rib. However, the void caused by creep shrinkage of concrete in the later stage is inevitable. In this paper, the influence of concrete void on the out-of-plane stability of concrete-filled steel tube arch rib is studied because it is inevitable that the concrete-filled steel tube arch rib is out-of-plane instability in the process of loading. The finite element model of concrete-filled steel tube arch rib is established by means of large-scale general software ANSYS. The finite element model is established by taking Chen Baochun's single circular pipe arch rib test as the research object, and the results of the finite element method are compared with the experimental results, and the results of the finite element method are compared with the experimental results. After verifying the correctness and reliability of the established finite element model, the influence of the parameters such as slenderness ratio, steel content ratio, rise-span ratio and hoop coefficient on the out-of-plane stability bearing capacity of concrete-filled steel tube arch rib is studied under the condition of void. At the same time, the size, the position, the length and the action position of the emptying rate are studied. The research shows that the greater the slenderness ratio of arch rib is, the smaller the ultimate bearing capacity is. On the contrary, the ultimate bearing capacity of arch rib increases with the increase of steel content, steel strength grade and concrete strength. The ultimate bearing capacity of arch ribs increases first and then decreases with the increase of the rise-span ratio, and the optimum rise-span ratio is between 0.25 and 0.3. When the arch rib is emptied, the ultimate bearing capacity of the arch rib decreases greatly with the increase of the void ratio and the length of the void, which should be paid enough attention. The location of the void and the loading mode of the arch rib have a great influence on the ultimate bearing capacity of the arch rib. Under the action of symmetric load, the ultimate bearing capacity of arch rib is obviously higher than that under asymmetric load. On the basis of studying the parameters of arch rib, the calculation formula of spatial force of members in GB50936-2014 (Technical Code for concrete filled Steel Tubular structures) at present is studied, and the void reduction factor Kn and Km, are taken into account in the case of emptying. By summarizing the influence data of each parameter, the simplified calculation formula of void reduction coefficient is obtained. Compared with the results calculated by finite element method, the error between the simplified calculation formula and the results of finite element calculation is about 10%, and the error between the simplified formula and the finite element method is about 10%. It is shown that the formula has good accuracy and can be used for reference in practical engineering.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U441
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1 王卓琦,吴齐正;钢管混凝土拱肋施工技术[J];华东公路;2003年04期
2 颜全胜,王，
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