外文資料翻譯--溫度和相對(duì)濕度對(duì)沿印度海岸的鋼筋混凝土構(gòu)件腐蝕起始時(shí)間的影響(文件)
【正文】 the surface chloride concentration (Cs), cover depth (X), chloride diffusion coefficient in concrete (D), chloride threshold level (Cth) and exposure age (t ? tref ). Surface chloride concentration depends on the severity of the environmental exposure, whereas variability of concrete cover depth depends on quality control, workmanship and location and size of structure. Chloride diffusion coefficient in concrete mainly depends on watercement ratio of concrete and varies with age (t), temperature (T ) and relative humidity (h) and hence requires to be modified (by applying correction) according to the exposure conditions for continued hydration and metrological data in a region. Literature survey has shown the value of chloride threshold can vary widely and is a probabilistic function rather than being fixed or constant. Corrosion has been observed (Glass and Buenfeld,8) to initiate at chloride concentrations from to % chloride (expressed as total chloride by mass of cement). Such a wide variation causes service life estimates to differ, depending upon input parameters of model. This variation or uncertainty affects the validity of the choice and project scheduling of maintenance, repair, and rehabilitation alternatives. The deterministic approach uses mean values of the parameters and provide a 50% probability of corrosion initiation but the probabilistic approach provides expected time of first corrosion for chosen risk of corrosion and also gives sensitivity of parameters to probability of corrosion. Sensitivity analysis is necessary to assess the impact of uncertainties from the input parameters on the uncertainty of the model output. By identifying the most relevant parameters affecting the corrosion initiation time measures can be taken at design stage, during construction (by quality control), and in service (by scheduling inspection and maintenance) to reduce the uncertainty in corrosion initiation time (ti). Hence, a plete evaluation method for effective calculation of time to corrosion for chosen risk is necessary. Corrosion initiation time is useful for owner, designer, or to an organization to take decision in time of priority of repairs, repair strategy, corrosion protection, sell, purchase, or demolish. In order to optimize maintenance planning and budgeting, planned maintenance at the optimum time is the safest and most cost effective approach. The approach needs up to date information when the structure will need mainte
畢業(yè)設(shè)計(jì)相關(guān)推薦
鄂ICP備17016276號(hào)-1