Probabilistic transition of condition: render facades

The service life of cement-rendered facades is closely related to the environmental conditions to which they are exposed. The probability distribution is determined for the degradation condition of render facades considering different environmental exposures. A sample of 100 render facades was subjected to meticulous fieldwork to determine their condition. The analysis focuses on the environmental factors that most influence the overall degradation of the facades, evaluated through the condition level. Probabilistic models based on Markov chains are developed to predict the evolution of facade deterioration according to exposure to outdoor environmental conditions. The proposed model provides data on the synergy between the degradation agents and the degradation condition of render facades, the average time of permanence in each degradation level, and indications of the effect of degradation on the durability of render that may be applied in the implementation and fine-tuning of maintenance procedures. A better understanding of the durability of render facades allows a more rational management of their maintenance, contributing to a reduction of their life cycle costs. The proposed stochastic model provides information that can be applied in the context of insurance policies, allowing an evaluation of the risk of failure of coatings.     

垂直绿化在建筑外立面中的应用

本文重点阐述了垂直绿化在城市环境中的重要作用,重点研究了垂直绿化的在实施过程中的各种类型和植物选择的原则。为建筑师和景观师在设计时提供必要支持,让更多人了解垂直绿化,推广垂直绿化,从而改善城市的人居环境。     

基于现场耐久性检测的承台海工混凝土寿命预测

金塘大桥受恶劣的海洋气候环境和海水腐蚀影响严重,其结构设计基准期为100年.根据现场对大桥已建部分承台混凝土检测的保护层厚度、表面氯离子浓度和氯离子扩散系数等耐久性参数,以Fick第二定律为基础的理论模型对混凝土结构抵抗氯离子侵蚀耐久寿命进行预测.此研究成果可为氯盐侵蚀环境下混凝土结构耐久性设计与评估提供参考.     

Automated cleaning of windows on standard facades

The aim of this applied research project is a cleaning robot which automatically cleans the outside of windows on a facade with vertical jambs and horizontal bars. The facade has to possess certain constructive properties. This “interface” enables the cleaning robot — which is detachable from the building and portable — to operate on any respectively designed facade on several buildings. A special cleaning-head keeps the water used for cleaning in a constant cycle. It is wielded through a filter and reused. The cleaning robot in operation is quicker, safer and cheaper than manual cleaning. Its use is environment-friendly and considerate with regard to resources.     

Serviceability of facade claddings

In the present world economic situation, the resources directed to the maintenance of buildings are very limited. Therefore, an increasing concern arises for the planning and prioritization of necessary maintenance works during buildings’ life cycle. The planning of maintenance action is achieved by predicting the moment when construction elements reach degradation levels that exceed acceptable standards. To be able to make such forecasts, crucial developments must be made regarding the methods to predict the serviceability of building materials and components. In this study, 444 facades located in the cities of Lisbon and Almada and the Algarve region (Portugal) are analysed based on in situ visual inspections. The approach proposed can be employed in various scopes of service life prediction and maintenance of constructions. This paper develops a priority hierarchy of maintenance actions for the claddings under analysis. The expertise acquired in buildings’ serviceability is very useful to support decision-making in the development of proactive maintenance strategies. The results reveal accurate outcomes in the correlation with the functionality and degradation parameters of facade claddings. The serviceability of the most common types of facades claddings (render, ceramic and paints) applied in Portugal is analysed.     

混凝土使用寿命预测的研究进展

讨论了混凝土使用寿命的定义和混凝土使用寿命预测的基本方法,系统地总结与评价了几种混凝土使用寿命预测模型,并指出了该领域今后可能的发展方向。     

多因素作用下混凝土碳化模型及寿命预测

本文在回顾国内外混凝土碳化模型的基础上，考虑了包括荷载、温度、湿度及碳化速率系数时间依赖性等因素。结合试验结果初步建立了包括荷载在内的多因素作用下的混凝土碳化模型，并结合具体工程进行了寿命预测。     

有机防火堵料使用寿命研究

以在工业消防领域使用中的有机防火堵料为研究对象,对其理化性能和耐火性能进行分析测试,研究有机防火堵料的性能与环境、使用年限的关系.得到良好使用环境、一般使用环境、恶劣使用环境下防火堵料使用后的耐火性能变化情况,探索有机防火堵料的使用寿命.     

Re-characterization of architectural style of reinforced concrete building facades by exterior seismic strengthening

Recent earthquakes in Turkey have shown the poor seismic performance of reinforced concrete residential buildings. This led to widespread utilization of several strengthening methods, each of which is convenient in different aspects. However, what is required to apply any of these methods is to evacuate the building in question, since the interruptions are mostly within the building and to the structural members. In this article, a method is introduced for external strengthening of typical reinforced concrete buildings that represent the majority of the built environment in Turkey. The method suggests addition of shear walls, which are connected to each other by means of reinforced concrete diaphragms on two separate floor levels and to the existing external columns and floor system at corners of the building. The advantage of shear walls in seismic performance is already known; however, this article discusses the feasibility of the proposed method in terms of architectural viewpoint, since the method unavoidably covers great modifications on the architectural form of the building. As a whole, this external strengthening method provides a typical facade resemblance by means of additional structural members without emptying the building.     

混凝土结构耐久性设计与耐久性寿命预测

当前工程结构设计方法正在由强度设计向耐久性设计转变,混凝土结构耐久性设计包括耐久性设计和耐久性寿命预测两部分,作者扼要介绍了仅考虑钢筋锈蚀的寿命预测模型,并提出了耐久性设计今后的发展方向。     

Service life prediction of exterior cladding components under standard conditions

An empirical method was developed for the prediction of the service life of building components, based on an evaluation of their actual performance and on the identification of failure mechanisms affecting their durability. The service life of exterior components subjected to normal service conditions is predicted. Four types of exterior claddings are exemplified: cementitious mortar, synthetic rendering, ceramic mosaic, and wet‐fixing stone cladding. The proposed prediction models yield high degrees of fit to the data (R ² in the range of 0.86 to 0.93 at a 0.0001 level of significance). Life cycle costs (LCC) analysis – following service‐life prediction results – leads to the conclusion that maintenance and replacements costs account for 10–80% of initial capital costs. Synthetic rendering exhibited the highest LCC effectiveness, reflecting durability and low capital costs. The method can be used for planning preventive maintenance, evaluating economic implications of failures, and planning service life.     

混凝土结构碳化寿命预测模型分析

混凝土碳化是影响结构耐久性的重要因素.根据碳化寿命准则,对现有混凝土结构碳化寿命预测模型进行分析比较,并用试验值或实测值验证.还对混凝土结构碳化寿命预测模型的影响因素进行了分析,对混凝土结构耐久性设计以及施工和维护期间应控制的影响因素提出了建议.     

住宅建筑有关期限问题的探讨

对"短命建筑"产生的原因作了简要分析,介绍了住宅建筑的设计使用年限、合理使用年限、合理使用寿命、设计基准期的来源与定义,并对设计使用年限与其他三者的关系进行了探讨,指出可以在规范标准中采用设计使用年限代替合理使用年限、合理使用寿命。     

建筑密封胶的耐久性及使用寿命分析

通过对建筑密封胶耐久性及使用寿命的分析,指出建筑物有效密封能够获得的能量远远超过生产密封胶的生产链能耗,但密封胶耐久性不佳会对建筑的长期能效产生影响;具有出色弹性回复能力和较高位移能力的中模量硅酮密封胶是建筑物保持长期耐久性的较优选择。     

胶州湾海底隧道衬砌混凝土服役寿命预测

胶州湾海底隧道是中国自行建造的第2条海底隧道,其设计服役寿命为100 a。分析了海底隧道衬砌混凝土的服役环境,建立了综合考虑氯离子扩散、碳化和弯曲荷载影响的服役寿命预测模型。调查了海底隧道现行施工里程的混凝土耐久性关键参数,建立了海底隧道混凝土氯离子扩散系数与回弹强度间的函数关系,通过预测模型计算了混凝土中氯离子随时间的演化规律及衬砌混凝土服役寿命。结果表明:隧道衬砌混凝土的保护层厚度波动值-4(-6)~+15 mm,标准养护衬砌混凝土氯离子扩散系数均值为2.1(2.7)×10-12 m2/s,混凝土中初始氯离子浓度小于0.35 kg/m3。隧道衬砌混凝土氯离子扩散系数与回弹强度呈线性函数关系,施工里程内氯离子扩散系数波动为1.5~3.5×10-12 m2/s。基于模型计算,胶州湾海底隧道左右线衬砌混凝土的服役寿命均超过100 a。     

基于计算机视觉的建筑外墙剥落和裂缝两阶段检测方法

地震灾害中,对建筑物外墙立面损伤状况进行快速检测有利于灾情评估与灾后重建。为实现建筑外墙立面剥落和裂缝的自动化非接触式检测,提出了一种结合深度学习与图像处理的外墙损伤定位与量化评估的两阶段检测方法。通过建立并标定北川老县城地震破坏房屋数据集,采用基于损失函数模型Focal Loss的目标检测网络定位破损区域目标框,并克服小尺度区域的正负样本不均衡问题。根据提取的目标破损区域单幅图像,提出图像滤波、阈值分割和形态学操作的组合处理流程,进行贴面砖墙面下剥落和裂缝的像素级别分割与提取。进一步结合像素尺度与物理尺度的映射关系,完成剥落面积、裂缝宽度等关键破损信息的计算与识别。结果表明,该方法可较好地对震后建筑物外墙立面的墙面剥落和裂缝进行定位和提取,对墙面损伤可实现像素级分割并准确地识别损伤关键物理参数,能实现对建筑物震后损伤的准确和快速检测。     

基于区间分析的锈蚀钢筋混凝土结构使用寿命预测

钢筋锈蚀程度具有很大的不确定性,为体现锈蚀不确定性对结构寿命预测结果的影响,将区间分析方法引入锈蚀钢筋混凝土结构的使用寿命预测。首先,对区间分析的基础知识及区间参数问题的求解方法作简单介绍,针对区间运算法则导致运算结果区间扩张的缺陷,优化方法是求解区间参数问题的有效方法;其次,基于钢筋锈蚀过程的确定性预测模型,采用区间数描述结构参数及环境参数,提出结构锈蚀损伤的区间预测方法;再根据选取的使用寿命终结标准,提出结构使用寿命的区间预测方法。工程实例分析表明,该方法分析过程简单,不需要建立不确定参数的概率模型,分析结果以区间形式给出,预测结果较概率方法更直观,易于接受。     

影响起重钢丝绳使用寿命的因素分析及对策

通过对钢丝绳的制造、选型及相关部件设计、维护使用等方面可能影响钢丝绳使用寿命的因素分析,指出针对不同的情况,应采取不同的措施来避免钢丝绳的损坏,以期尽可能地延长钢丝绳的使用寿命。