历史荷载与环境因素联合作用下高强混凝土损伤性能研究

发布时间：2018-05-17 11:37

本文选题：高强混凝土 + 荷载历史　；参考：《烟台大学》2017年硕士论文

【摘要】：高强混凝土在长期的使用过程中因施工不当、自然灾害、混凝土意外受荷载等原因会使混凝土遭受不同程度的损伤,而混凝土结构也难免会处在化学介质、大气中的CO2等侵蚀条件下工作,结构的耐久性及力学性能均会发生劣化。因而研究在历史荷载与环境因素联合作用下对高强混凝土的损伤作用有重要意义。本文的主要工作如下:(1)对尺寸为100mm?100mm?300 mm经历不同程度轴压荷载历史的高强混凝土试件进行硫酸盐长期浸泡和干湿循环试验,并在侵蚀180d后对其进行单轴压缩试验。分析历史荷载水平、硫酸盐浓度、侵蚀方式对混凝土质量、峰值应力、峰值应变、弹性模量、应力-应变全曲线等的影响。结果表明:高强混凝土随着硫酸盐溶液浓度的增加,长期浸泡下,峰值应变先减小后增加,干湿循环条件下则持续增加;其峰值应力、弹性模量在长期浸泡条件下,有先增加后降低的趋势,而干湿循环条件下则为持续下降。两种侵蚀方式下,随着历史荷载的增加,峰值应力降低、峰值应变增加、弹性模量减小,但变化的幅度较小。(2)对尺寸为100mm?100mm?300 mm的高强混凝土试块在疲劳历史荷载与碳化侵蚀联合作用后进行试验研究,研究不同疲劳历史荷载水平、碳化龄期对高强混凝土的碳化深度、峰值应力、峰值应变、弹性模量、应力-应变全曲线等的影响,结果表明:随着碳化时间的增加,碳化深度逐渐增加,弹性模量增加,峰值应力逐渐增加,峰值应变降低,且疲劳历史荷载越大,峰值应力随碳化时间增长的速度越大,但峰值应变变化不明显。单一疲劳历史荷载作用下,随着疲劳历史荷载的增加,高强混凝土的峰值应力变小,峰值应变增大,但随着碳化时间的增加,后期的这种趋势在逐渐的缩小。(3)研究了历史荷载与环境因素联合作用后的损伤特性,通过提出联合因子K与延性损伤因子△D,表明荷载历史损伤与硫酸盐侵蚀、碳化侵蚀等环境因素联合作用下对混凝土损伤是促进作用,且各因素水平越高,这种联合作用后加速损伤作用一般越是明显。
[Abstract]:During the long-term use of high strength concrete, due to improper construction, natural disasters and unexpected loads on concrete, the concrete will suffer different degrees of damage, and the concrete structure will inevitably be in the chemical medium. The durability and mechanical properties of the structure will deteriorate under the condition of CO2 erosion in the atmosphere. Therefore, it is of great significance to study the damage of high strength concrete under the combination of historical load and environmental factors. The main work of this paper is as follows: (1) High strength concrete specimens whose size is 100mm?100mm?300 mm have been subjected to long term soaking and wet and dry cycling tests with different axial compression loads, and uniaxial compression tests have been carried out after 180 days of erosion. The effects of historical load level, sulfate concentration and erosion mode on concrete quality, peak stress, peak strain, elastic modulus, stress-strain curve and so on are analyzed. The results show that with the increase of sulfate concentration, the peak strain decreases first and then increases, and the peak stress and modulus of elasticity increase under the condition of long-term immersion. There was a tendency to increase at first and then to decrease, while under dry and wet cycle conditions, it continued to decrease. With the increase of historical load, the peak stress decreases, the peak strain increases and the elastic modulus decreases. However, the range of variation is small. (2) after the combined action of fatigue history load and carbonation erosion, the carbonation depth of high strength concrete with different fatigue historical load level and carbonation age is studied. The effects of peak stress, peak strain, elastic modulus, stress-strain curve and so on. The results show that with the increase of carbonation time, the carbonation depth increases gradually, the elastic modulus increases, the peak stress increases, and the peak strain decreases. The higher the fatigue history load, the faster the peak stress increases with the carbonization time, but the change of peak strain is not obvious. Under the action of single fatigue history load, with the increase of fatigue history load, the peak stress of high strength concrete becomes smaller, the peak strain increases, but with the increase of carbonization time, In the later period, the damage characteristics of historical load combined with environmental factors were studied. By proposing the combined factor K and ductile damage factor D, it was shown that historical load damage and sulfate erosion. Under the combined action of environmental factors such as carbonization erosion, the damage of concrete is promoted, and the higher the level of each factor is, the more obvious the accelerated damage is after the combined action.
【学位授予单位】：烟台大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528.31

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