钢管混凝土构件热脱粘问题研究

发布时间：2018-03-07 13:36

本文选题：钢管混凝土　切入点：热脱粘　出处：《福州大学》2014年硕士论文　论文类型：学位论文

【摘要】：钢管混凝土构件在工程结构中得到广泛应用,得益于在钢管与混凝土的结构性协同。只有粘结良好的钢管混凝土构件才能使其优越性得到充分发挥,然而脱粘,尤其是温度变化导致的热脱粘,破坏钢-混界面的粘合状态,给现有结构带来不利影响。为研究脱粘及脱粘带来的影响,有必要知道钢-混界面的粘结强度,而相关文献对粘结强度看法不一,也没有考虑养护条件对其的影响。为此,本研究对钢管混凝土构件热脱粘相关问题进行了进一步试验研究和有限元分析；同时,考虑到钢管混凝土中混凝土所处密闭条件与自然环境有所不同,试验中增加了养护条件这一影响因素。本研究采用两种试验方法,开展了钢与混界面法向粘结强度的试验。试验结果表明法向粘结强度值受混凝土强度与养护条件的影响。根据试验结果的统计分析,建立了不同养护条件下法向粘结强度与混凝土强度关系的公式。根据前面得到的粘结强度,结合干海子大桥所在地实测的大气温度和太阳辐射强度值,研究采用ANSYS软件分析了实际自然环境下钢管混凝土界面的拉应力。分析表明在强烈太阳辐射作用下的夏季中午时刻,钢管混凝土构件界面将因拉应力大于法向粘结强度而发生热脱粘。研究还进一步分析了处在火灾环境下钢管混凝土构件界面的拉应力,结论是在火灾环境下钢管混凝土构件必定发生热脱粘。本研究基于ANSYS建立了钢-混界面有限元模型,用于分析部分脱粘的构件温度场。有限元模拟结果与构件实测结果的对比分析表明,该模型可较准确地模拟发生脱粘构件截面温度场。参数分析表明在自然环境下,随着脱粘厚度的增大,构件截面温差增大,增大的幅度不大且增大的幅度随着脱粘厚度的增大呈现减小的趋势；火灾高温环境下,脱粘厚度对钢管表面温度的影响在火灾作用时间为30-60min时最为明显,钢管表面所达到的最高温度值受脱粘厚度的影响不大,而构件内填混凝土温度值随着脱粘厚度的增大而大为减小,温度降低的趋势随着脱粘厚度的增大而减小。在桥梁工程中,多数钢管混凝土拱选择在夜间低温时段合拢从而导致构件的基准温度较小,参数分析表明在这种情况下,热脱粘更容易发生。另外,从分析结果可知选用吸收系数低的钢管表面涂层材料和颜色可有效地避免热脱粘；选择径厚比大的钢管混凝土构件也有助于降低界面拉应力从而缓解热脱粘。
[Abstract]:Concrete filled steel tube (CFST) members are widely used in engineering structures, which benefit from the structural cooperation between steel tube and concrete. Only the CFST members with good bond can make the full use of the advantages of CFST members, however, the advantages of CFST members can be brought into full play by debonding. In particular, the thermal debonding caused by the change of temperature destroys the bonding state of the steel-mixed interface and adversely affects the existing structure. In order to study the effect of debonding and debonding, it is necessary to know the bond strength of the steel-mixed interface. However, there are different views on the bond strength in the relevant literature, and the influence of curing conditions on the bond strength is not taken into account. Therefore, further experimental research and finite element analysis are carried out on the thermal debonding of concrete-filled steel tubular (CFST) members. Considering that the confined condition of concrete in concrete-filled steel tube is different from that of natural environment, the influence factor of curing condition is added in the experiment. Two kinds of test methods are used in this study. Tests on normal bond strength between steel and mixing interface have been carried out. The results show that the normal bond strength is affected by the strength and curing conditions of concrete. A formula for the relationship between normal bond strength and concrete strength under different curing conditions is established. According to the bond strength obtained before, combined with the measured values of atmospheric temperature and solar radiation intensity at the site of the Qianhaizi Bridge, The tensile stress of concrete-filled steel tube (CFST) interface in natural environment is analyzed by ANSYS software. The results show that the stress of concrete filled steel tube interface is at noon in summer under strong solar radiation. Thermal debonding occurs at the interface of CFST members because the tensile stress is greater than the normal bond strength. The conclusion is that thermal debonding will occur in concrete filled steel tube members under fire environment. A finite element model of steel-concrete interface is established based on ANSYS. The comparison between the finite element simulation results and the measured results shows that the model can simulate the cross-section temperature field of debonding members more accurately. The parameter analysis shows that in the natural environment, the temperature field of the debonding member can be simulated accurately. With the increase of debonding thickness, the cross-section temperature difference increases, the amplitude of increase is small and the increasing amplitude decreases with the increase of debonding thickness. The effect of debonding thickness on the surface temperature of steel tube is most obvious when the fire time is 30-60 min, and the maximum temperature of steel tube surface is not affected by the thickness of debonding. However, the temperature value of filled concrete decreases with the increase of debonding thickness, and the decreasing trend of temperature decreases with the increase of debonding thickness. Most concrete-filled steel tube arches are closed at low temperature at night, which results in smaller reference temperature. Parameter analysis shows that thermal debonding occurs more easily in this case. From the analysis results, it can be concluded that selecting the coating material and color on the surface of steel tube with low absorption coefficient can effectively avoid thermal debonding, and selecting the steel tube concrete members with large diameter to thickness ratio can also help to reduce the interface tensile stress and thus to ease the thermal debonding.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU398.9

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