Research of Wind Load on the Surface of YingLi Building in Chongqing

Considering the complicated distribution of wind load on the surface of the tall building, the 1:300 scale model test of YingLi building is completed in the No.2 environment wind tunnel, which belongs to the State Key Lab of Environmental Engineering College, Beijing University. Based on the calculation and analysis of the test results, this paper discusses the coefficient of wind-induced vibration and shape coefficient of wind load , gives the maximum and minimum value of surface wind load, which can be used for the wind resistant design and insure the security of the building under 100 years return period wind load.     

Characteristics of Interference Effects on Local Pressure of Two Square Tall Buildings in Tandem Arrangement

Wind tunnel tests were carried out to study the wind pressure on principal square building adjacent to another one in tandem. The interference effects on local pressure of the principal building were analyzed with different positions and heights of interfering building. It is shown that as height ratio is fixed, mean pressures on windward face are suctions when spacing ratio is less than 3, otherwise they are positive. The magnitudes of mean suctions on the side and leeward faces and fluctuating pressures on each face all get their maximums when spacing ratio is 3. As height ratios change, the magnitudes of mean suction on windward face increase with height ratio, meanwhile, the magnitudes on other faces obtain their minimums as the height ratio is 1.0 and the spacing ratio is less than 3. The fluctuating pressures on the windward and side faces get their maximums and that on the leeward face reaches its minimum as the height ratio is 1.0. When the spacing ratio is greater than 3, mean pressures on each face decrease, while fluctuating pressures on the windward and side faces increase as the height ratio increases, and the fluctuating pressures on the leeward face get the minimum when the height ratio is 1.0.     

Analysis of wind load spectrum of super tall buildings with round section in hilly terrain wind field

In order to get wind load and wind induced response of super tall buildings in hilly terrain wind field, effect of changing of turbulent intensity on wind loads must be known. 4 kinds of turbulent wind field are simulated, and 3 super tall building models with round section of different aspect ratio are manufactured. Effects of turbulent intensity, aspect ratio and layer height on along-wind and across-wind load are discussed. Different models are used in fitting of wind load spectrum on each direction. Parameters of load spectrum models are secondary fitted based on turbulent intensity and aspect ratio. Mathematical models of wind load spectrum of super tall buildings with round section in hilly terrain are preliminarily established. At last, an example is provided. According to vertical profile of mean velocity, turbulent intensity and mathematical model of wind load spectrum, wind induced dynamic response of super tall buildings in hilly terrain and flat terrain are compared.     

THE CALCULATION OF ALONGWIND RESPONSE FOR TALL BUILDINGS

This paper investigates the dynamic response of tall buildings subject toalongwind loading.According to the assumptions of the fundamental parame-ters,the function of the first vibration mode and that of the mass model,thecomputer program AWCTS is compiled.The availability of the procedure in thispaper is verified through practical calculations and comparison of results.     

高超声速风洞进气道流量系数测量精度影响因素研究

进气道是飞行器动力装置的重要组成部分,准确测量进气道流量系数是进气道风洞试验的重要内容。对来流马赫数Ma=4.5,5.0和6.0状态下皮托管进气道开展流量系数测量研究,通过对比理论值和实测值,获取各状态流量系数修正系数。试验结果表明,随着来流马赫数增加,进气道流量系数与理论值偏差较明显,并逐渐增大。超声速风洞试验通常认为测量截面总温与来流总温相等,通过对测量截面总温与来流总温偏差以及测量截面流场畸变情况的分析,判断测量偏差主要是由测量截面总温等于来流总温的假设导致的。在高超声速风洞试验中,由于模型壁面热交换的存在,测量截面总温低于来流总温,进气道流量系数测量时需要进行总温修正,以提高流量测量精度。      

Integrated Control Strategy for Dual State Continuously Variable Transmission System

Continuously variable transmission (CVT) is the ideal transmission for automobile, it is also one of the most important research items of researchers and automobile companies all over the world. In order to research vehicle with torque converter as starter and metal pushing belt as high speed transmission equipment(dual state CVT system), based on the test data of engine and torque converter, the integrated control strategy for vehicle with dual state CVT system is proposed and integrated control simulation for car with dual state CVT system is finished at the condition of multi mode. The research results provide the theory method of analysing and designing for CVT vehicle.     

Effects of Heat Transfer Coefficient of External Window on Residential Buildings in Subtropical Areas

Using Designer's Simulation Toolkit DeST h developed by Tsinghua University, research was carried out on the energy consumption of a typical residential building in Ningbo, P. R. China, with a focus on the heat transfer coefficient of external windows facing every direction. Results show that variation of the heat transfer coefficient of external windows in all directions has a substantial effect on energy consumption for heating but little effect on energy consumption for cooling. It is difficult to decrease cooling energy consumption by decreasing the heat transfer coefficient of external windows in summer. The heat transfer coefficient of external windows facing south has a significant effect on building energy consumption, but the windows facing north have less effect, and those facing east and west have the least impact. Decreasing the heat transfer coefficient of external windows facing north and south from 4.7 to 3.2 produces the most favorable performance cost ratio for energy saving investments. Reasons for the decrease in the heat transfer coefficient of external windows leading to increased air conditioning energy consumption were discussed. The conclusions are useful for guiding energy efficient building design in other subtropical cities.     

Wind induced Response Analysis on a Connected Tall Building Structure with Viscous Damper

The control effects of a connected tall building structure with viscous damper in several respects were studied, such as internal force, deformation, acceleration and energy under dynamic wind load. Firstly, wind pressure time history data were obtained from the wind tunnel test of the structure model, and then a wind load processing program WINDHIST V2.0 based on wind tunnel test was developed, by which wind pressure data processed and inputted into Finite Element Method(FEM) program. Thus wind induced vibration time history could be analysed under various working conditions. It was shown that both the internal force and deformation of the connected structure with viscous damper can be decreased, while the effect of the former was more obvious than the latter. The acceleration at the top of the connected structure caused by dynamic response of fluctuating wind can be controlled effectively by viscous damper.     

Analysis on drag coefficients of bundled conductors under wind load

Drag coefficients of quad-bundled conductor under different wind speeds and attack angles are firstly determined by means of wind tunnel test. Meanwhile, the drag coefficients are obtained by numerical simulation method and the results are consistent with those by the wind tunnel test. Furthermore, cross flows around six-bundled and eight-bundled conductors are numerically investigated, and the drag coefficients are then determined. Compared with the determination method of wind load on conductor in current Chinese code and the IEC code for the design of transmission line, the drag coefficients defined in the Chinese code may be too large for bundled conductors, and may need to be adjusted based on further theoretical and wind tunnel test investigation.     

Wind Power Utilization Efficiency on Roof of Rectangular Buildings

Installing small wind turbines on the roof of buildings is a new way of wind power utilization in recently years. Based on the annual mean wind speed, the efficiency of wind power utilization on roofs of buildings was studied and the evaluation indexes for the utilization efficiency were proposed. With the help of CFD numerical analysis, the analysis on wind power utilization efficiency on flat roofs of rectangular buildings was carried out. The performance indexes of reference points under different windward angles were investigated. The best position and arrangement of wind turbines on the roof were also discussed. Furthermore, the utilization efficiency of four roofs with different shapes were analyzed and compared with that of flat roof.     

三边形桅杆风荷载谱模型试验研究

对三边形格构式桅杆进行了均匀流和两种紊流下的高频测力天平风洞试验,得到了顺风向、横风向和扭转向的气动力系数以及脉动风荷载谱。采用基于风速谱的数学模型对顺风向脉动风荷载谱进行拟合,验证了该经验公式在不同流场下的适用性。根据试验所得横风向和扭转向脉动风荷载功率谱曲线的特点,建立由紊流激励和旋涡脱落激励两部分组成的谱函数数学模型,最小二乘法拟合结果与风洞试验结果吻合良好。横风向脉动风荷载谱以紊流激励为主,紊流强度15%时旋涡脱落激励贡献仅占10%,扭转向脉动风荷载谱中旋涡脱落激励贡献明显增大,达到40%。     

Opening Flow Coefficient and its Effect on Fire Smoke Flow

The flow coefficient of the typical doors and windows in different states between opening and closing was tested in a high rise experimental fire tower. It can be used for the prediction calculation of the fire smoke flow and the calculation of the positive air supply as well as for the ventilation. Using the prediction software of the fire smoke flow properties in the building, the effect of the flow coefficient on the fire smoke flow was also studied.     

NaCl对高羊茅萌发的胁迫效应研究

通过室内模拟盐胁迫对高羊茅不同品种萌发的胁迫效应研究,揭示单盐对牧草、草坪草种子萌发活力的影响和萌发盐分临界值,以期为盐碱地改良和优良牧草的引选提供依据;用不同浓度NaCl作为高羊茅萌发培养液,通过测定相对发芽率并对其进行回归分析;结果表明,NaCl盐胁迫对高羊茅种子的萌发有抑制作用,且在0～0.6%的低盐浓度范围内抑制作用不明显,NaCl盐浓度高于0.6%时抑制作用显著;0.4%、0.6%、1.2%的NaCl浓度是高羊茅相对发芽率变化的几个"拐点"(即敏感点);高羊茅相对发芽率与盐浓度呈极显著负相关,Y=101.75-47.371 x,r=-0.98;14个品种中萌发期较耐盐的品种有佛浪、爆发力和翠碧A,火凤凰、交战2和火凰RT耐盐性较差;高羊茅萌发阶段进行耐盐性评价时,相对发芽率和耐盐半致死浓度是很好的萌发能力的鉴定指标,可以作为种子耐盐能力评价指标,但耐盐致死浓度不宜作鉴定指标.     

高羊茅杂交后代ISSR遗传变异研究

利用ISSR分子标记对高羊茅(Festuca arundinacea)杂交后代进行遗传多样性及亲缘关系分析.19个ISSR引物共扩增出255条重复性好、清晰的条带,其中200条是多态条带,多态条带比率(PPL)为78.4％,平均每个引物扩增多态条带数为10.5条,扩增片段大小范围为100～2 000 bp.结果表明,高羊茅杂交后代的多态性较高,遗传多样性较丰富.高羊茅杂交后代遗传相似性系数为0.647 1～0.851 0,聚类分析将高羊茅杂交后代划分为4个大类,有相同亲本的杂交后代先聚类.总之,ISSR标记可以有效地对高羊茅杂交后代进行“亲缘跟踪”和定向选择,为杂交育种提供分子依据.     

Luminance Calculation Model and Modified Coefficient of Building Nightscape

The illumination computational formula recommended by the International Commission on Illumination (CIE) does not adapt to the modern construction materials with mixed reflection characters. In order to find a new luminance computational method adapting to the modern construction materials and to save building energy and control urban nightscape luminance, 30 frequently-used construction materials with respect to various directions in photometric laboratory were measured. Then the luminance modified coefficient K(i,β) was figured out, and analysed the connection of reflection luminance and atmospheric attenuation in the process of divergence of light. The K(i,β) and viewing distance, light kinds, luminaire use, material cleanliness, maintenance condition of lighting system as modified coefficient was adopted to amend the computational formula of CIE, and then a new calculation model is derived. Through calculating and comparing, the luminance value of the new calculation model is one-third as much as that of the traditional one.     

Reducing the Heating and Cooling Energy Consumption of Buildings

Abstract:This research aims at proposing measures to enhance the energy efficiency of buildings in the city of Guiyang. A computer simulation study was conducted on the basis of a building model using the DeST software package. The indoor temperature and year round heating and cooling loads were simulated. From analysis of the simulation results and taking into account the climate of Guiyang, three measures for energy efficient buildings in Guiyang are proposed. 1) Heating is a greater priority than cooling in comfortable air conditioning system design; 2) Natural ventilation should be given priority in cooling design and adjustment during seasonal transition is important to reducing energy consumption in building cooling; 3) Insulating the building envelope and lowering the glazing ratio of walls are critical for reducing energy consumption in heating buildings. Our conclusions will be useful for guiding energy efficient building design not only in Guiyang but also in mild climatic areas of P. R. China.     

Assessment Method of Buildings Damage Induced by Underground Construction

With increased urban highway tunnel construction in P.R. China,there are more shallow cover tunnels passing under buildings.Finding a means to appraise buildings' degree of damage is one of the most important preconditions so that tunnels can safely pass under buildings.First,the instance of damage should be confirmed according to the buildings' actual settlement.Then, referring to the buildings damage evaluation criteria,the buildings' control damage rank and critical distortion value can be determined.The permissible distortion value can be drawn from the difference of buildings' critical distortion value and distortion value corresponding to its damage ranking.Finally,a three-stage appraisement is carried out to assess the degree of buildings' damage induced by tunnel construction.If every stage's calculated result of this appraisement exceeds buildings' permissible distortion value,the buildings should be reinforced to assure that the tunnels could pass through safely.At the same time, the calculation method has important reference value for the similar projects.     

Endophyte Infection May Affect the Competitive Ability of Tall Fescue Grown with Red Clover

Cool-season grasses infected with Neotyphodium endophytes may be more persistent and competitive than non-infected plants. In a greenhouse experiment, two tall fescue ( Festuca arundinacea Schreb.) cloned genotypes (DN2 and DN11) with different growth characteristics and endophyte status (E−, non-infected; E+, infected) were grown in monocultures and in full competition with red clover ( Trifolium pratense L.) cv. Reddy Red for 20 weeks. When grown in monoculture, endophyte infection reduced the root dry matter (DM) of DN2 (16 %) and DN11 (5 %) when compared to E− plants, while shoot DM was not affected. In full competition with red clover, root and shoot DM of tall fescue were not influenced by endophytes, but cumulative herbage DM yield was less in E+ than in E− plants. Root growth of red clover was significantly depressed (22 %) in competition with E+ plants of DN2 compared to E− plants, but was not affected when plants were grown in competition with DN11. The relative yield total (RYT) did not differ from 1.0 in red clover mixtures with E− plants of DN2 and DN11, and with E+ plants of DN11, indicating competition between the competitors for the same resources. In contrast, RYT was less than 1.0 in the red clover/DN2 E+ mixture, suggesting a negative interaction between the competitors. Endophyte infection increased the competitive ability of DN2 but reduced that of DN11 when compared to E− plants. Because the concentration of pyrrolizidine alkaloids in roots of E+ plants of DN2 was twice that found in roots of DN11 (1083 and 536 μg g⁻¹, respectively), we suggest that pyrrolizidine alkaloids might influence the competitive ability of some endophyte–tall fescue associations through a possible allelopathic effect on companion species.