体育馆建筑被动式节能技术实测与分析——以广东药学院体育馆为例

体育馆建筑照明和空调能耗巨大,如何充分利用自然采光和自然通风是体育馆建筑节能的关键问题。广东药学院多功能体育馆在设计中考虑了多种被动式节能措施,如东、西向立面设置带有垂直遮阳的条形采光窗,南、北向立面设置可开启的外窗,附馆屋顶采用种植屋面等。该体育馆的实测结果表明上述被动式设计方法可以增加比赛场地自然光照度,防止眩光;提高观众区自然通风风速,改善舒适度;降低附馆屋顶内表面温度,减少热辐射。     

地聚物砂浆高温后抗拉和粘结性能及退化机理

为考察地聚物砂浆在有耐高温要求的混凝土结构加固领域的应用可行性,开展了常温下和高温后地聚物砂浆的抗拉强度试验以及地聚物砂浆与普通水泥砂浆及普通混凝土基体的粘结性能试验,并与普通水泥砂浆的抗拉及粘结性能进行试验比较;通过热重分析-差示扫描量热分析(TG-DSC),探究了地聚物砂浆的高温强度退化机理.试验结果表明:地聚物砂浆与水泥砂浆及混凝土之间的常温粘结强度分别达2.15 MPa及1.7 MPa,经300℃高温后残余粘结强度仍有1.5 MPa左右,远高于普通水泥砂浆的粘结强度;超过300℃以后地聚物砂浆的强度急剧退化,这主要是因地聚物砂浆高温脱水、微观结构遭受破坏引起.基于上述试验结果,可将地聚物砂浆用于300℃以下高温环境的混凝土结构修补加固.     

Effect of magnesium sulfate on the durability of limestone mortars based on quaternary blended cements

Currently, the use of blended cements incorporating various supplementary cementing materials, preserved in aggressive environments has become common. This paper describes the investigation results conducted on the evaluation of the resistance to magnesium sulfate solution (MgSO₄) of limestone mortars containing simultaneously; limestone filler, blast furnace slag and natural pozzolan. In this study, the deterioration of limestone mortars due to sulfate attack was evaluated by measuring changes in weight, length and compressive strength at the ages of 30, 60, 90, 120 and 180 days of immersion in exposure environments. The X-ray diffraction was also used in order to determine the different mineral phases. It is noteworthy that, the pH variation of the conservation solutions has been monitored during tests. The exposure solution was renewed monthly until the end of tests. The results showed that, the resistance to sulfate attack of mortars made with quaternary binders was better than that of mortars based on ordinary Portland cement.     

平面声场中四传声器阵列理论精度的对比分析

主要探讨了两种四传声器阵列的理论精度,针对相应的传声器布置形式进行数值计算,比较了正四面体和直角四面体传声器探头在不同工况下的幅值误差和方向误差。结果表明,在平面波作用下,1~4 k Hz范围内正四面体传声器的幅值误差小于直角四传声器,且两者均小于1 d B,外接球心位置的幅值精度在高频段优势明显;当频率小于5 k Hz时,方向误差均控制在2°以内,因此可以满足相关的建筑声学测试要求。     

Electrical conductivity of self-monitoring CFRC

The present work is concerned with the analysis of the electrical conductivity in carbon fiber reinforced cement composites and of the main parameters influencing the phenomenon: fiber volume fraction, fiber length, hydration time and sand–cement ratio. AC measurements were carried out on CFRC (carbon fiber reinforced cement) and the experimental results were analyzed using the percolation theory. The present study could be useful for the adoption of CFRC as a smart material.     

HDR图像测量天空亮度及在动态采光模拟中应用

为解决在通用天空模型下进行建筑采光模拟所得到的结果准确程度不高的问题,尝试使用实测的天空亮度分布HDR图像作为光源进行建筑采光/动态采光模拟并对该方法进行了验证.首先,说明了通过高动态范围(HDR)图像测量天空亮度分布的方法;进而,介绍并验证了基于图像的采光/动态采光模拟(IBL):既使用HDR图像作为光源输入数值进行采光模拟的方法.验证实验于2017年7月4日至7月10日及2017年8月3日至8月12日进行,通过实测与模拟结果的比较分析验证了HDR图像测量天空亮度分布以及基于图像的采光模拟的准确程度.最后,文中讨论了基于天空数学模型的采光模拟以及基于图像的采光模拟的优缺点.结果表明:通过HDR图像可以准确地测量天空亮度分布;基于图像的采光模拟准确度良好,同一时刻模拟值与实测值之误差集中分布在-15%~47%范围之内;基于图像的动态采光模拟所求取的100 lxUDI3 000 lx指标值最大误差限制于±25%以内.     

External CFRP tendon members: Secondary reactions and moment redistribution

The response of prestress secondary reactions in the post-elastic range has been a topic of much controversy. Due to the brittleness of FRP (fiber reinforced polymer) composites, external FRP tendon members may have different moment redistribution characteristics compared to conventional concrete members. This paper presents a numerical investigation into the secondary reactions and moment redistribution in prestressed concrete continuous members with external CFRP tendons. The investigation parameters include the initial prestress level and the pattern of loading. The secondary reactions are computed using a newly developed method based on the linear transformation concept combined with a nonlinear finite element analysis. The results indicate that the secondary reactions increase quicker after concrete cracking and nonprestressed steel yielding. As a consequence, the secondary moment should be included in the design moment. The moment redistribution behavior for symmetrical loading is shown to be quite different from that for unsymmetrical loading. The study also shows that the effect of initial prestress on the moment redistribution is rather important.     

Measuring overall thermal comfort to balance energy use in sports facilities

A study for the development of a monitoring methodology that includes thermal comfort in a smart metering system for sports facilities is presented. The scope of this system is to obtain meaningful information on how energy is used in relation to the level of comfort perceived, so as to allow fully informed management operations. The main problem to be addressed is the accurate quantitative measurement of the thermal comfort inside indoor sports areas (e.g. swimming pools, fitness rooms, etc.), which in this work is estimated through the PMV (Predicted Mean Vote) index. The paper describes what needs to be dynamically measured, which parameters are required, which critical uncertainty factors may arise and how to estimate the indicators. A sensitivity and uncertainty analysis for the PMV measurement in this specific application is performed to develop a simplified approach. The results obtained from the measurement campaigns made in two different sports areas are presented to validate the approach. Finally, a simulation of swimming pool data is used to preliminarily demonstrate the feasibility and effectiveness of the global monitoring system proposed.     

预应力混凝土空心板耐火极限的试验研究

底面受火预应力混凝土空心板耐火极限由空心板跨中挠度、跨中挠度变化率和试件断裂破坏综合确定。通过5块预应力混凝土空心板底面受火耐火极限的对比试验,研究了不同持荷水平底面受火空心板的耐火极限。研究结果表明,分别持荷25%和50%极限荷载的空心板BP25和BP50的耐火极限分别为47 min和30 min,即随着持荷水平增加,底面受火空心板耐火极限明显降低。     

Thermal comfort of people in the hot and humid area of China—impacts of season,climate, and thermal history

We conducted a climate chamber study on the thermal comfort of people in the hot and humid area of China. Sixty subjects from naturally ventilated buildings and buildings with split air conditioners participated in the study, and identical experiments were conducted in a climate chamber in both summer and winter. Psychological and physiological responses were observed over a wide range of conditions, and the impacts of season, climate, and thermal history on human thermal comfort were analyzed. Seasonal and climatic heat acclimatization was confirmed, but they were found to have no significant impacts on human thermal sensation and comfort. The outdoor thermal history was much less important than the indoor thermal history in regard to human thermal sensation, and the indoor thermal history in all seasons of a year played a key role in shaping the subjects' sensations in a wide range of thermal conditions. A warmer indoor thermal history in warm seasons produced a higher neutral temperature, a lower thermal sensitivity, and lower thermal sensations in warm conditions. The comfort and acceptable conditions were identified for people in the hot and humid area of China.