复杂环境下混凝土结构内湿度微环境的特征及响应规律

钢筋混凝土结构在服役过程中,容易受到环境作用,特别是滨海盐雾区,环境因素复杂,对混凝土结构的微环境有较大的影响。分析了环境作用下混凝土内部湿度微环境的特征及响应规律,结果表明:混凝土在干燥与湿润过程中,距离暴露面越近,内部对外界湿度的响应越快;响应存在着明显的滞后效应,距离暴露面越远,滞后效应越明显;在干燥与湿润过程中,混凝土内部与外界环境湿度差越大,湿度变化速率越大;混凝土内外的相对湿度存在着湿度梯度,且随着湿度响应过程发展,湿度梯度减小,造成早期湿度变化速率较大,后期逐渐减小。     

混凝土中钢筋腐蚀过程的温湿度综合效应

环境的温度和相对湿度是影响混凝土中钢筋锈蚀速度的重要因素,这2个因素对混凝土中钢筋的腐蚀电流强度的影响并不是孤立的,而是互相交织在一起彼此产生影响的。通过试验研究了温湿度共同作用下混凝土中钢筋腐蚀速度的变化规律。研究表明,温度愈高,钢筋的腐蚀电流强度达到最大峰值时所对应的相对湿度愈大;相对湿度不同,温度升高对钢筋的腐蚀电流强度提高的幅度也不同。     

气候条件对碳化混凝土内钢筋腐蚀速度的影响

环境气候条件是影响混凝土内钢筋腐蚀速度的重要因素，本文利用人工气候环境条件对碳化试件混凝土内钢筋的腐蚀速度规律进行了试验研究。研究结果表明：环境的温度、相对湿度对碳化混凝土内钢筋的腐蚀速度具有重要的影响，而且存在一临界环境相对湿度RH0。当环境相对湿度超过RH0时。混凝土内钢筋的腐蚀速度随着环境相对湿度、环境温度的升高而增大；当环境相对湿度低于RH0时。混凝土内钢筋的腐蚀速度很低。环境温度的变化对其不产生明显影响。     

A technique for the prediction of the conditions leading to mould growth in buildings

Epidemiological evidence suggests that the presence of mould growth in buildings can have a detrimental effect on the well-being of occupants. Based on an extensive literature review, growth limits for six generic mould categories have been formulated in terms of the minimum combination of temperature and relative humidity for which growth will occur on building materials. These limits were incorporated within the ESP-r system for building energy and environmental simulation in order to provide a design tool which can predict the likelihood and extent of mould infestation. The systems new predictive capability has been tested against monitored data and mycological samples taken from a mould infested house.     

Information-theoretic environment features selection for occupancy detection in open office spaces

Knowing the presence or the actual number of occupants in a space at any given time is essential for the effective management of various building operation functions such as security and environmental control (e.g., lighting, HVAC). As occupants “interact” with the indoor environment, they will affect environmental conditions through the emission of CO₂, heat and sound, and relatively little effort has been reported in the literature on utilizing this environmental sensing data for occupancy detection. This paper presents the findings of a study to address this question by exploring the most effective environmental features for occupancy level detection. A sensor network with robust, non-intrusive sensors such as CO₂, temperature, relative humidity, and acoustics is deployed in an open-plan office space. Using information theory, the physical correlation between the number of occupants and various combination of features extracted from sensor data has been studied. The results show significant correlation between features extracted from humidity, acoustics, and CO₂, while little correlation with temperature data. Using features from multiple sensors increases correlation further, and nearly 90% information gain is acquired when nine of the most informative features are combined.     

温湿度耦合效应下早龄期混凝土的相对湿度场

早龄期混凝土温度和相对湿度的时间空间变化规律是揭示混凝土早期开裂的关键。为此,建立了早龄期混凝土温度湿度耦合作用分析模型,采用无条件稳定向后差分格式,考虑水化作用、自干燥作用、温湿度扩散作用以及温湿度耦合机制,分析早期混凝土相对湿度的时间空间变化规律,定量揭示相对湿度的空间不均匀性,分析了水灰比、环境相对湿度以及表面水分交换系数等对相对湿度及其空间变化规律的影响。与实验结果的对比验证了模型的合理性,结果表明:温湿度扩散作用对相对湿度的影响随距扩散表面距离的增加而减小,水灰比对相对湿度的影响与位置无关,而环境相对湿度和表面水分交换系数主要影响混凝土扩散表面附近的相对湿度场。     

Increasing the indoor humidity levels in buildings with ventilation systems: Simulation aided design in case of passive houses

In modern societies, people spend about 90 percent of their time inside buildings. The challenge of building physics is to ensure that buildings are planned, constructed and built to provide a comfortable and healthy working and living environment. As construction style has changed during recent years, the planning phase has to be much more precise and the need of simulation programs that respond to every little change arises. An increasing problem in Austria is the indoor humidity. In the field of renovated buildings with airtight new building envelopes, mould growth due to high indoor relative humidity (RH) is a persistent problem. On the other hand, in recently realized Austrian passive houses with an air treatment system, the low humidity level of the indoor air is a problem with which scientists have been struggling for some time. It has been observed in numerous measurements and it is also easily computationally detectable that in winter period the indoor relative humidity level often drops below 30% RH. Low and high relative humidity levels have negative effects on the comfort feeling and health of the occupants of the dwelling and should therefore be avoided. However, it is expensive to increase or decrease the humidity in houses mechanically. Therefore, the existing room moisture should be used sensibly in buildings with a ventilation system. In buildings with a high indoor humidity it is necessary to adjust the ventilation depended on moisture production. This paper focuses on low indoor humidity and presents some different methods by which the indoor relative humidity can be regulated. The effects of adapting parameters such as ventilation rate and buffering material in the dwelling were clearly reflected in the measured temperature and relative humidity. “BuildOpt_VIE” software developed at the Vienna University of Technology was used for the dynamic building simulation in this study.     

混凝土结构空间多尺度相对湿度值

针对环境作用具有空间分布特性,借鉴空间多尺度环境作用模型框架(包括全局环境、地区环境、工程环境、构件表面环境、内部环境)及其数学模型,对相对湿度进行了空间多尺度研究：在分析空间各尺度上相对湿度的不同影响因素的基础上,由全局环境尺度开始,通过地区环境尺度、工程环境尺度以及构件表面环境尺度上环境因素的逐步调整,最终计算得到混凝土内部的相对湿度值。研究结果表明,采用“常规统计模型+空间残差”的方法,可有效建立地区环境尺度上的相对湿度值与工程环境尺度上相对湿度值的定量关系;混凝土结构构件的表面相对湿度与表面温度有关;实际工程结构应考虑构件表面相对湿度与内部相对湿度之间的不同。     

温湿度异常引起混凝土收缩测试误差的修正

研究了混凝土收缩测试过程中环境温度和湿度异常波动引起的收缩测试误差。结果表明热胀冷缩是温度影响收缩测试的主要原因,引起的误差超过混凝土的收缩值,对收缩测试结果影响很大。热胀冷缩变形是可逆的,可通过在总变形中减去热膨胀变形对收缩测试结果进行修正,消除温度误差。环境相对湿度异常引起混凝土内部相对湿度变化,进而导致毛细孔压力改变,引起收缩测试误差。湿度异常对收缩的影响与相对湿度差值和持续时间成正比,与试件最小截面尺寸成反比,可据此对测试误差进行修正。     

Plasters and renders for salt laden substrates

The EU project COMPASS, Compatibility of Plasters and renders with Salt loaded Substrates in historic buildings, aimed at improving the maintenance of monuments by means of a better understanding of the working principles of the plasters and the damage mechanisms induced by salt crystallisation. Salt damage was effectively studied modelling the moisture and salt transport and degradation (irreversible dilation) and a fast and efficacious salt crystallisation test developed. Practical results were the assessment of the requirements for plasters to be used on salt loaded substrates and guidelines for selecting plasters suitable for different situations. The dissemination of the results was also entrusted to the expert system MDDS.     

Hysteresis of the water retention curves of geosynthetic clay liners in the high suction range

This paper examines two needle-punched geosynthetic clay liners' water retention behaviour at high suction ranges using the vapour equilibrium technique where super-saturated salt solutions controlled the relative humidity. This study shows that the bentonite form and its mineralogy affect the absorption/desorption of GCLs and their corresponding water retention curves. In particular, a granular bentonite-based GCL was found to absorb more and release less water than a powdered bentonite-based GCL due to its higher montmorillonite content and larger pores. The water retention curves of both GCLs exhibited very little hysteretic behaviour at high suction. Repeated wetting-drying cycles shifted the WRCs of both GCLs slightly downward with minimal impact on their degree of hysteresis.     

Improved HVAC operation to preserve a church organ

The common operation of heating systems installed in churches in the Netherlands has led to typical building physics problems directly related with heating. One of the main problems is the drying related shrinkage and damage to (monumental) wooden organs under cold winter conditions. The paper presents an integrated heat, air and moisture model including modelling components for: the indoor climate of the church, the heating systems and operation, and the moisture distribution in wood. The modelling components are validated with measurements. Two types of control strategies are discussed. The first type is a limited indoor air temperature changing rate. The second type is a limited indoor air relative humidity changing rate. This preliminary study shows that a limitation of indoor air temperature changing rate of 2 K/h can reduce the peak drying rates by a factor of 20 and a limitation of the relative humidity changing rate of 2% per hour can reduce the peak drying rates by a factor of 50. The second strategy has the disadvantage that the heating time is not constant and therefore more difficult to implement in relation with early start-up.     

Two-phase Euler-Lagrange CFD simulation of evaporative cooling in a Wind Tower

A new design of Wind Tower is investigated numerically under different structural parameters and environmental conditions. The new design is some wetted columns, consisting of wetted curtains hung in the tower column, which are modeled as surfaces that inject droplets of water with very low speed. The CFD open source package - Open FOAM - is used. The current three-dimensional CFD simulation has adopted both the Eulerian approach for the air phase and the Lagrangian approach for the water phase. The effects of water droplet diameter and water droplet temperature on the thermal performance of the Wind Tower are investigated at specific inlet air velocity and relative humidity and height of wetted columns. Also, the effects of wind velocity, temperature, and relative humidity inlet to Wind Tower are studied. Changing the height of the wetted columns and its effect on the evaporative cooling in other specific parameters is studied. The results obtained from the present CFD study are compared with the analytical data taken from the literature and a good agreement is observed. As a result, the height of 10 m of wetted columns decreases 12 K of the ambient air temperature and increases 22% of its relative humidity.     

Low relative humidity and aircraft cabin air quality

Mucosal irritation remains a common complaint among travelers and flight attendants in aircraft cabins. Despite the fact that very low humidity is routinely encountered, few studies of its effects have been conducted in the cabin environment. The authors reviewed chamber and field studies in the experimental literature to explore whether there is an association and, if so, at what level it was likely to be present. Subjects who participated in prior research were not always able to perceive low humidity or changes in the humidity level and, at times, this inability has been confused in the literature with the lack of a humidity effect. The studies with more powerful experimental designs have demonstrated the effects of low humidity, such as drying of the skin and mucus membranes, and that a modest increase in relative humidity seems to alleviate a great number of symptoms. The exposure duration below during which the effects of low humidity are not noticeable is in the order of 3 to 4 h. It is conceivable that some symptoms experienced by flight attendants and passengers, especially on flights lasting 3 h or longer, may stem from low humidity.     

A new method of determination of indoor temperature and relative humidity with consideration of human thermal comfort

A new method is described in this article for selecting indoor temperature and indoor relative humidity to achieve minimum energy consumption for a required indoor thermal comfort level which is evaluated with indoor effective temperature. This method is derived from a central air-conditioning system and is based on our investigation that under a same indoor effective temperature, the system cooling load and the system energy consumption increase with an increase of indoor temperature. As such, energy consumption cannot be reduced with increasing indoor temperature for a given human thermal comfort level. In order to reduce energy consumption while keeping a same indoor thermal comfort level, indoor temperature and relative humidity may be determined with the proposed method described in this article. With the proposed method, a parameter variation study has also been conducted, which suggests that for a given indoor effective temperature, a combination of high indoor relative humidity and low indoor temperature be generally taken. The proposed method is based on the central air-conditioning system; yet it can be easily extended to other systems.     

冻融循环过程中混凝土内部温度-相对湿度关系

研究了不同配合比混凝土试件在经历不同冻融循环次数时的内部温度-相对湿度关系,并将这一关系划分为4个阶段,即降温增湿段、降温降湿段、增温增湿段和增温降湿段.在降温增湿段,混凝土内部相对湿度随温度降低而增大,当相对湿度出现转折表现为降低趋势时,表明混凝土内部开始结冰,温度-相对湿度关系进入降温降湿段;在增温增湿段,混凝土内部相对湿度随温度升高而增大,当相对湿度出现转折表现为降低趋势时,表明混凝土内部的冰晶开始融化,温度-相对湿度关系进入增温降湿段.当混凝土水灰比相同时,试件内部相对湿度随着深度增大而增大;当深度相同时,试件内部相对湿度随着水灰比的减小而降低,且结冰温度和融化温度呈现减小的趋势.低水灰比混凝土内部较低的相对湿度可能会导致更大的自收缩和较小的冻胀作用力.     

Setpoint control for air heating in a church to minimize moisture related mechanical stress in wooden interior parts

The paper presents the setpoint control for air heating in a church to minimize moisture related mechanical stress in wooden interior parts, with the focus on the preservation of a monumental organ. The setpoint operation of the heating, ventilation, and air conditioning (HVAC) system is evaluated by simulation using MatLab, COMSOL and Simulink models. The main model components are presented and combined in a single integrated Simulink model: (1) a HAMBase Simulink building model for simulating the indoor temperature and relative humidity, (2) a COMSOL partial differential equation model for simulating detailed dynamic moisture transport and related mechanical stresses in the monumental wood (organ) and (3) a Simulink controller model. The main advantage of the integrated model is that it directly simulates the impact of HVAC control setpoint strategies on the indoor climate and the related mechanical stresses in wooden objects, like a monumental organ. As control strategy the limited indoor air temperature changing rate is discussed. Recommendations from international literature suggest that a limitation of the relative humidity changing rate of 2 to 5RH%/h will preserve the interior of churches. This study shows that a limitation of indoor air relative humidity changing rate of 2RH%/h can reduce mechanical stresses by a factor of 2.5, compared to maximum capacity heating.     

自然气候条件下混凝土内部温湿度响应规律研究

采用在混凝土上钻孔并埋入温湿度探头的方法测定了混凝土内部的温湿度,由此得到混凝土内部微环境下的气候条件随室外自然气候条件昼夜变化的响应曲线,并对混凝土内部微环境的温度,相对湿度滞后响应规律进行了分析.结果表明,自然气候条件下混凝士内部的温湿度响应主要表现为滞后效应,特别是混凝土内部相对湿度,不仅存在滞后效应,而且变化规律同自然气候相对湿度变化呈相反趋势.     

移植和本土化——中西文化共同作用下的宁波江北天主教堂

江北天主教堂属于较为典型的哥特式建筑,是西方建筑文化在宁波的移植和渗透。受本土文化的影响,江北天主教堂建筑也融合了本土传统建筑的许多成份,成为一种西式建筑形式与本土建筑技术结合而成的新的建筑体系,对宁波近代传统建筑的转型有着促进作用。本文以江北天主教堂创建的时代背景为出发点,从教堂的平面形式、内部空间、外部造型及结构技术等方面论述宁波江北天主教堂的建筑特色及其所具有的价值。     

Ecumenical Patriarch Bartholomew: insights into an Orthodox Christian worldview

No other church leader has been so recognized for his leadership and initiatives in confronting the theological, ethical and practical imperative of environmental issues in our time as the Ecumenical Patriarch Bartholomew of Constantinople. He has long placed the environment at the head of his church’s agenda, earning him numerous awards and the title ‘Green Patriarch’. This paper describes the work of Patriarch Bartholomew for the protection of the natural environment, and especially for significant water bodies of the planet. This work has been done first in his own church, and subsequently in the wider society through international, inter‐religious, and interdisciplinary gatherings that have gained the attention of policymakers and the mass media. The paper contains various insights into the Orthodox Christian worldview that direct the vision and activities of the Patriarch.