Fatigue performance assessment and service life prediction of high-speed ship structures based on probabilistic lifetime sea loads

This article focuses on estimating probabilistic lifetime sea loads for high-speed ship structures with the aim of assessing fatigue performance and predicting service life from available data. Performance assessment and service life prediction for naval ship structures are extremely important issues. In particular, understanding the effect of sea loading on naval high-speed vessels is still a challenge. Potential lifetime load effects including low frequency wave-induced and high frequency slam-induced whipping loadings are investigated in this article by using a probabilistic approach. Clearly, integration of probabilistic sea loads into structural reliability assessment and service life prediction will provide a more reliable estimation of the long-term structural performance. Accordingly, this article presents an approach for fatigue reliability evaluation of ship structures based on the estimated lifetime sea loads. Loading information associated with sea states, ship speeds and relative wave headings is obtained from a joint high-speed sealift ship monohull structural seakeeping trials, while the S–N curves are established based on the British Standards.     

基于RBF的钢筋混凝土结构剩余使用寿命预测

分析了一般混凝土结构剩余使用寿命预测方法，在吸取等维灰色递补GM（1，1）模型的优点之后，提出了利用RBF网络对既有钢筋混凝土结构的剩余使用寿命进行预测的方法，通过理论分析及应用，证明了其可行性。     

Reliability-based service life assessment for deteriorating reinforced concrete buildings considering the effect of cumulative damage

Most engineering systems used in maintenance strategies must consider deterioration and seismic structural damage. To identify the effects of deterioration and earthquakes simultaneously on structural performance, this study applies an integral simulation method. Compared with that of previous studies, the feature of the proposed method is its analysis of the time-dependent structural capacity of a deteriorating reinforced concrete (RC) building and the simulation of life-cycle earthquake events within a specified service period, while considering cumulative damage induced by deterioration and earthquakes. In addition, the proposed assessment method is applied to derive the reliability-based service life of a deteriorating RC building located in a region with high seismic hazard. Briefly, for deteriorating RC buildings, the proposed reliability-based service life assessment method provides useful information related to maintenance based on both serviceability and safety.     

冻融循环作用对混凝土路面使用寿命的影响

在研究了冻融循环作用下混凝土强度衰减规律的基础上,分析了冻融循环作用对混凝土路面使用寿命的影响及其影响机理,得出了冻融循环作用对混凝土路面使用寿命影响明显的结论,从而为完善我国寒冷地区水泥混凝土路面结构设计奠定基础。     

影响沥青路面使用寿命的因素及处置对策探讨

针对沥青路面早期破坏和使用寿命低等非常严重的现象,指出影响沥青路面使用寿命的因素比较复杂,涉及设计、施工、维护等多个方面,从设计、施工与维护三个方面进行了探讨,并进一步分析了应采取的处置对策.     

Integrating reliability and structural health monitoring in the fatigue assessment of concrete bridge decks

The overall objective of this article is to demonstrate how the concepts of reliability and structural health monitoring (SHM) can be integrated to create bridge assessment and decision systems. The steel-free concrete bridge deck system was chosen as a specific case study providing tangible focus for the research. The bridge assessment model therefore focused on fatigue cracking issues associated with wheel loads due to heavy truck traffic. The bridge assessment model required five components: a vehicle load model, a fatigue damage accumulation model, a residual strength model, a reliability model and an SHM decision model. Each of these components is discussed within the article with specific reference to previous research on steel-free bridge deck systems. The proposed model is used to develop a decision threshold for monitoring the oldest steel-free bridge deck in service.     

基于使用年限的高性能混凝土配合比设计与试验研究

工程实践证明,现今通常使用的普通混凝土的耐久性具有局限性,就算能够满足抵抗各种环境因素的耐久性要求,其安全性运行年限也较短。因此,研究的目的旨在将现行的混凝土耐久性试验检测的指标引入时间的因素,以此来推知混凝土的耐久性使用年限。通过试验研究发现:采用高性能混凝土配制技术,使用P.O 42.5和I级粉煤灰,当水胶比在0.33以下时,配制出的混凝土具有良好的抗冻性、抗侵蚀性及抗渗性,同时,配制出的混凝土具有较长的使用年限,可至少使用50年。     

Uncertainty assessment of field weld connections and the related effects on service life of steel buildings

Abstract

Delay in construction schedules has raised concerns regarding the quality of field weld connections. To address this issue, the effects of field weld quality are evaluated using test data and literature review. The evaluation provides evidence supporting the assumption that for the marginal workmanship quality, the strength of steel connections can reduce by approximately 5%. The effects are then used to predict the service life of 9-story and 20-story steel buildings with pre-Northridge connections. The prediction adopts a seismic risk-based framework, and considers the uncertainties of steel material and workmanship quality. The example buildings are highly vulnerable to earthquake damage owing to their lack of connection ductility. That also amplifies the effects of poor field weld quality. The result indicates that in the case of marginal quality workmanship, the service life can be reduced by 20?years, with taller buildings more significantly affected.     

Survival of the House Dust Mite,Dermatophagoides farinae,at High Temperatures (40–80°C)

Abstract Experiments were conducted to evaluate the survival time of randomly selected female D. farinae exposed to temperatures from 40 to 80°C and relative humidities (RHs) between 10 and 90%. Significant temperature effects were found on the length of time mites can survive under those conditions. The time needed to induce 100% mortality for female D. farinae held at 40°C varied between 39 and 84 h. At 70 and 80°C, all mites died within 5 minutes. At 50°C and above, RH had little influence and temperature alone was the determining factor for mite survival. The length of survival time decreased precipitously between 40 and 50°C, suggesting that a loss of physiological integrity of female D. farinae probably occurred in this range. The results of this study indicated that the technique of raising temperatures to above 40°C for a short duration can be used to reduce living house dust mite populations in homes significantly.     

基于生活圈理论的收缩型村镇公共服务设施配置研究 ——以黑龙江省肇源县为例

乡村人口收缩是城镇化进程持续推进 的必然,为满足村镇居民不断提升的需求并避 免人口收缩造成的资源浪费,亟待对村镇公共 服务设施配置体系进行优化与重构。以黑龙江 省肇源县为例,引入生活圈理论探讨收缩型村 镇公共服务设施配置优化方法。首先基于对村 镇收缩类型与强度的分类,结合居民出行意愿 的时距转换调查,将肇源县村镇划分为“县域— 扩展—基本—基础”四级动态半径生活圈。然 后通过筛选与生活圈等级对应的公共服务中心, 并依据相关规范及居民实际需求,确定各级公 共服务中心配置的项目内容和优化建议。     

Performance‐based evaluation and strengthening of tall buildings in the Los Angeles region by using Bayesian structural reliability

This paper presents the motivation and the mathematics required for the introduction of Bayesian structural reliability theory into the process of evaluating and strengthening any tall building located in the Los Angeles region. Copyright © 2013 John Wiley & Sons, Ltd.