C60混凝土抗压强度测量不确定度的评定

混凝土抗压强度试验是评定混凝土工程质量的重要手段,本文通过对C60混凝土抗压强度测量结果不确定度的评定,分析了载荷、试样截面尺寸、加荷速度、上下承压面的平行度与数据修约等影响测量结果不确定度的因素和来源,对各分量进行了计算,并给出了最终结果测量不确定度的表示.     

混凝土路面砖抗压强度测量不确定度评定

通过对混凝土路面砖抗压强度不确定度的评定,分析了影响测量结果不确定度的主要因素,为提高检测水平提供指导.     

金属材料压缩试验测量结果的不确定度评定

本文介绍了依据JJF1059—1999《测量不确定度评定与表示》的要求，按照GB／T7314—1989《金属压缩试验方法》中的办法，对金属材料抗压强度σbc进行测量，并对其测量结果的不确定度评定的方法。通过评定得出金属材料抗压强度σbc测量结果的扩展不确定度。     

普通混凝土立方体抗压强度试验测量结果的不确定度评定

本文按照GB/T50081—2002《普通混凝土力学性能试验方法标准》对普通混凝土立方体抗压强度试验测量结果的不确定度进行分析评定。     

金属材料压缩试验测量结果的不确定度评定

本文介绍了依据JJF10 5 9- 1999《测量不确定度评定与表示》的要求 ,按照GB/T7314 - 1989《金属压缩试验方法》中的办法 ,对金属材料抗压强度σbc进行测量 ,并对其测量结果的不确定度评定的方法。通过评定得出金属材料抗压强度σbc测量结果的扩展不确定度。     

回弹仪测量结果不确定度评定中的几个误区

回弹仪是用于检测混凝土、砂浆、砖抗压强度的仪器,是一种现场检测中使用较为广泛的无损检测仪器。本文分析了回弹仪测量结果不确定度评定中广泛存在的几个误区,提供了更为合理的解决方案。     

硬质合金压缩试验中抗压强度不确定度的评定

根据《硬质合金压缩试验方法》国家标准的基本要求,通过对WC-Co系YG8牌号硬质合金的抗压强度测量结果不确定度评定的分析与计算,介绍了评定不确定度的基本原理及其在硬质合金压缩试验试验中的实践应用。     

预应力混凝土用钢绞线应力松弛试验结果不确定度的评定和分析

采用GB／T10120—1996标准规定的方法对预应力混凝土用钢绞线进行了应力松弛试验,根据JJF1059-1999《测量不确定度评定与表示》对试验结果的不确定度进行了评定和分析,提供了评定同类试验结果不确定度的参考依据。     

车速试验台示值误差的测量不确定度分析

文章从分析车速试验台的工作原理入手，建立了车速示值误差测量的数学模型与不确定度式，然后分析影响车速试验台测量结果误差的各个因素，对车速试验台输入输出量的测量结果作不确定度评定，最后得到测量结果示值误差的合成标准不确定度和扩展不确定度。实验结果表明．该车速试验台的不确定度评定能满足三分之一的量值传递要求，评定结果可靠、有效。     

检定混凝土回弹仪示值误差的测量不确定度评定

文章依据《混凝土回弹仪检定规程》,将混凝土回弹仪置于回弹仪检定器上,测量混凝土回弹仪的率定值,给出率定值检定结果的测量不确定度评定方法和测量不确定度报告。     

Microprocessor application to concrete crack depth measurement

This work investigates the possibility of utilizing the µp-8085 and its application to concrete crack depth evaluation. For the purpose of the nondestructive testing, ultrasonic pulses are of importance in assessing the quality of concrete as well as flaw detection and measurement. This will be useful in repairing concrete columns.     

基于承载力评估的混凝土结构火灾损伤的无损检测与评估方法

建立了基于承载力评估的混凝土结构火灾损伤的无损检测与综合评估方法,主要包括红外热像无损检测分析、电化学无损检测分析、构件截面温度场数值分析等方面。利用该方法,可由表及里、由现场实测结合理论计算,全面获取混凝土结构的火灾损伤信息,使评估指标和判据更科学合理,使评估结果更准确可靠。     

金属夏比缺口(V型)室温冲击试验检测结果不确定度的评定

介绍了测量不确定度在金属夏比（V型缺口）室温冲击试验中的应用，并对影响冲击试验结果的测量不确定度做了详细评定，从试样的形状和尺寸、缺口底部的光洁度、冲击试验机、试验温度、检查试样尺寸量具的最小分度值五方面分析了不确定度的来源，对各分量进行了计算、合成并作出评定。     

Continuous expansion measurement in accelerated concrete prism testing for verifying ASR-expansion models

The susceptibility of concrete structures due to alkali–silica reaction (ASR) can be assessed by means of ASR concrete prism testing at 60 °C, according to RILEM AAR 4.1. There, expansion of concrete prisms indicates alkali-reactivity of the examined concrete mix. This work applies in situ expansion measurement to accelerated concrete prism testing. Automated measuring facilitates both storage without the usually necessary interruptions for manual measurement and acquisition of quasi-continuous expansion data. A comparative experimental programme showed that conventional testing resulted in stronger expansion and leaching of alkalis than automated testing. Experimental simulation of interruptions, typically associated with manual measurements in conventional testing, could prove the influence of these cooling–heating cycles. Two phenomenological approaches, frequently used for describing reaction kinetics of ASR by linking it to expansion results from ASR-testing, were validated with continuous expansion data of three types of aggregate. Experimental expansion depicted s-shaped curves similar to them of the modelling approaches. However, strong swelling recorded in the beginning of the test was not covered by the model curves. Auxiliary measurement of acoustic emissions and ultrasonic velocity helped characterising mechanisms such as hydration and cracking, which also influence prism expansion. The proposed modification of the measurement procedure provides an extended basis to analyse expansion mechanisms. Regarding data for validation of ASR-expansion models, continuous expansion results are preferable to conventional test results.     

Relative damage evaluation of concrete in a road bridge by AE rate-process analysis

It is widely reported and realized that durability of concrete decreases due to such effects, as salt and chemical attack, freezing and thawing, and carbonation and fatigue. In existing structures mechanical damage of concrete has been practically estimated from the strength by a compression test and a rebound hammer test. For effective maintenance of concrete structures, it is necessary to evaluate quantitatively not only the strength of concrete but also the degree of damage. Quantitative damage evaluation of structural concrete is proposed by applying acoustic emission (AE) technique and damage mechanics. Consequently, damage evaluation is conducted on concrete cores of an existing structure. Core-samples were collected from an arch fragment of a reinforced concrete road bridge that had been in service for 87 years. Compressive strengths and Young’s moduli were measured during the compression test along with AE measurement. Dynamic Young’s moduli were also calculated from the longitudinal wave velocity. Thus the relative damages are quantitatively evaluated from static and dynamic Young's moduli and compared with results of AE rate-process analysis.     

Progress in ultrasonic imaging of concrete

Among present non-destructive methods for concrete evaluation, ultrasonic testing uses relatively short wavelengths and therefore has particular potential for detailed assessment of concrete. Methods like SAFT (Synthetic Aperture Focusing Technique) and tomographic reconstruction are able to provide high-resolution images of concrete areas, which can be employed for tasks such as area imaging, duct localization, fault detection, and thickness measurement. This contribution is intended to give insight into some of the principles and possibilities of ultrasonic concrete imaging using SAFT and tomographic reconstruction. It thereby review progress that has been achieved at the author's institute during the last years. For SAFT reconstruction, the processing steps are explained that are necessary to obtain an image that is easy to interpret including the influence of transducers, their coupling, and image noise suppression. Quantitative evaluation of ultrasonic images enables the examination of tendon ducts for voids and the objective assessment of image quality. A field example demonstrates the possibilities of SAFT reconstruction. In a separate section, ultrasonic tomography is shown to have the capability to detect faults such as honeycombing in concrete pillars. Finally, the potential of ultrasonic imaging and remaining steps, necessary to open broad practical application are described.     

Validation of Model Order Assumption and Noise Reduction Method for the Impact Resonance Testing of Asphalt Concrete

The impact resonance test is a free vibration-based nondestructive test method that has been increasingly used in evaluation and characterization of asphalt concrete for the past two decades. The rheological modeling of the impact resonance test is conceptualized by a linear viscous damping mechanism having single degree of freedom whose equation of the motion is assumed to be second order. In this study, the second order equation of motion assumption in the modeling of the impact resonance test response was evaluated for asphalt concrete testing. A set of asphalt concrete specimens was tested with the impact resonance test, and the obtained signals at a range of temperatures were evaluated by means of the Hankel matrix method. The results showed that the assumption is violated for asphalt concrete testing especially at high temperatures, mainly due to the presence of noise in the obtained response. However, the Hankel method was employed to filter out the noise. It was seen that the assumption could be employed for asphalt concrete at a range of temperatures including high temperatures, provided that the filtering is performed on the obtained signal. The results also showed that the employed filtering procedure produced improvements for the impact resonance test material dependent responses, resonant frequency and especially damping ratio calculations.     

基于电场作用的混凝土渗透性评价方法研究进展与展望

渗透性是反映混凝土耐久性最为直接的指标,基于外加电场的作用可快速评价混凝土的渗透性。通过对比分析现有基于外加电场作用下的混凝土渗透性评价的测试手段,总结了不同方法的实验条件差异。认为应进一步研究外加电场的作用和混凝土的材料组成所引起的误差,加强评价方法的基础理论研究。提出了通过改变实验条件和引入混凝土电学性质变化率的定量评价方法的设想,以及重点开展在役混凝土结构评价方法研究的建议。     

白酒中总酸含量测量不确定度的评定

酸碱滴定法测量白酒中总酸含量不确定度的影响,对测量不确定度的各个因素的评定,得到白酒中总酸测定结果的合成不确定度为4.36×10-3(g/L)。     

基于分位数函数和Bootstrap分布的不确定度评定研究

最大信息熵方法是基于概率分布评定测量不确度的主要方法之一。其所依赖的高阶矩需要较大样本的测量数据,而校准/检测实验室的测量一般为小样本,故用最大熵方法评定小样本测量不确定度缺乏一定的可靠性。提出了基于分位数函数和概率权重矩作为约束条件的最大信息熵不确定度评定法,把矩的计算从高次降为一次,并结合遗传算法求解概率分布,用Bootstrap分布估计扩展不确定度和包含区间,解决了由分位数区间估计分布不对称所致的复杂计算问题。