【摘要】 进行了碳化环境下预应力混凝土试件弯曲受拉和直接受压的耐久性试验研究,阐述了碳化作用对预应力混凝土结构的损伤机理。引进拉、压应力状态影响函数χσ,以反映碳化深度和应力状态及应力水平的关系。分别假定Fick第Ⅰ定律中的碳化时间指数α为0.50或为变量,由此建立了多因素影响下的预应力混凝土结构碳化深度预测模型,且采用一次可靠性方法(FORM)对碳化深度预测模型进行了分析。研究结果表明,拉、压应力分别可加快和减缓混凝土结构的碳化速度,χσ反映了碳化速率的变化趋势。最优的碳化时间指数α=0.48,若近似取α=0.50,计算结果也是足够准确的,由此印证了Fick第Ⅰ定律的正确性,而且采用FORM计算预应力混凝土结构碳化深度的离散程度是可靠的。更多还原

【Abstract】 The durability experiment of prestressed concrete specimens in the bending tensile status or in the directly compressive status in carbonation environment has been carried out.The degradation mechanism of prestressed concrete structure under the coaction of stress and carbonation corrosion is discussed.Assuming the index of carbonation time in Theory of Steady Diffusion is constant(i.e.α=0.50) or variable,the multi-factor model predicting the carbonation depth of prestressed concrete structure has been constructed,with introducing the stress status function χ-σ which describes the relationship between carbonation depth and stress status.In addition,the prediction model of carbonation depth is analyzed with the first order reliability method(FORM).The results indicate that the tensile or compressive stress are able to accelerate or slow down the concrete carbonation,respectively,and χ-σ reflects the effects of the stresses very well,and the optimum index of carbonation time α=0.48.If let α=0.50,the calculation results are also adequately accurate,which coincide with Theory of Steady Diffusion.Moreover,the deviation degree of carbonation depth of prestressed concrete structures,which is calculated with FORM,is very reliable.更多还原