Measurement plan targeting the accuracy of calibrated chloride ingress model for concrete structures in marine environment

IF 5.7 1区 工程技术 Q1 ENGINEERING, CIVIL
Ze Yuan, Quanwang Li, Kefei Li
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引用次数: 0

Abstract

Surface chloride concentration (CS) and chloride diffusion coefficient (DCl) are key parameters for durability assessment of concrete structures in marine environment; they are time-varying and highly dependent on the exposure condition. To reasonably model their behaviors at a specific location, durability measurement data are often needed to calibrate the apparent chloride ingress model based on Fick’s second law. In view of the significant variability of measurements and the bias of chloride ingress model, it remains unaddressed how to formulate a measurement plan to make the calibrated model achieve the required accuracy. This paper first establishes the probabilistic time-dependent models of CS and DCl with both sample variance and model bias considered, and then introduces the Bayesian method to update the two models using measurement data. By assuming realistic models of CS and DCl and comparing them with updated ones, the effectiveness of Bayesian updating method is demonstrated, and the key factors affecting the updated model accuracy are discussed, including prior estimate of parameters, model bias and measuring times. On this basis, a determination method of measurement plan targeting the calibrated model accuracy is proposed, which works for both Bayesian updating and linear fitting for model calibration. And finally numerical examples are presented to show the validity of the proposed method. The sample size obtained by the proposed method is exact for linear fitting and slightly more than required for Bayesian updating.

针对海洋环境下混凝土结构校正氯离子进入模型精度的测量方案
表面氯离子浓度(CS)和氯离子扩散系数(DCl)是海洋环境下混凝土结构耐久性评价的关键参数;它们是时变的,高度依赖于曝光条件。为了合理地模拟其在特定位置的行为,通常需要耐久性测量数据来校准基于菲克第二定律的表观氯化物进入模型。鉴于测量结果的显著可变性和氯化物进入模型的偏差,如何制定测量计划以使校准后的模型达到所需的精度仍然是一个未解决的问题。本文首先建立了考虑样本方差和模型偏差的CS和DCl的概率时间依赖模型,然后引入贝叶斯方法利用实测数据对这两个模型进行更新。通过假设CS和DCl的真实模型,并与更新后的模型进行比较,验证了贝叶斯更新方法的有效性,并讨论了影响更新后模型精度的关键因素,包括参数先验估计、模型偏差和测量时间。在此基础上,提出了一种以标定模型精度为目标的测量计划确定方法,该方法既适用于模型标定的贝叶斯更新,也适用于模型标定的线性拟合。最后给出了数值算例,验证了该方法的有效性。该方法得到的样本量对于线性拟合是精确的,而略大于贝叶斯更新所需的样本量。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Structural Safety
Structural Safety 工程技术-工程:土木
CiteScore
11.30
自引率
8.60%
发文量
67
审稿时长
53 days
期刊介绍: Structural Safety is an international journal devoted to integrated risk assessment for a wide range of constructed facilities such as buildings, bridges, earth structures, offshore facilities, dams, lifelines and nuclear structural systems. Its purpose is to foster communication about risk and reliability among technical disciplines involved in design and construction, and to enhance the use of risk management in the constructed environment
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