ANSYS软件中预应力筋的实现与试验对比

叙述了在ANSYS软件中，施加预应力的几种方法；选取其中的一种方法进行了预应力有限元模拟，并与试验挠度、应力结果进行了比较，指出在ANSYS软件中利用整体式降温法和独立建模耦合法模拟预应力筋是可行的。     

谈张弦梁结构非线性有限元分析及预应力损失

针对预应力的施加方法——等效降温法和初应变法中存在的预应力损失问题，其影响了计算精度，介绍了用生死单元法来解决这一问题，通过实例分析，证明了该方法在求解这类结构方面的可行性。     

张弦梁结构预应力张拉的有限元模拟研究

文章介绍了张弦梁结构中预应力张拉有限元模拟的常用方法,对力模拟法、等效降温法和初应变法进行了比较,分析了这3种方法的特点,通过算例说明,采用等效降温法最合适,并讨论了张弦梁结构中需进一步研究的问题.     

张弦梁结构预应力张拉有限元模拟方法比较

阐述了在用有限元方法分析张弦梁结构的预应力张拉过程时，常用的施加预应力的方法有力模拟法、等效降温法和初应变法，分析了这三种方法的优缺点，并讨论了三种方法的适用范围，以使三种有限元模拟方法均能较准确地模拟张弦梁施工的预应力张拉过程。     

钢-混凝土组合梁桥支座位移法施加预应力技术

结合常州市马公桥工程的建设,对采用支座位移法来施加预应力、避免桥面混凝土开裂的技术进行研究.通过对施工中的实测数据和仿真计算结果的比较,明确了该施加预应力方法的实际效果,并得出有关经验和建议.     

新型体内预应力钢屋架的张拉成型与受力性能分析

提出一种新型自平衡结构--体内预应力钢屋架.采用等效降温法借助通用软件ANSYS对体内预应力钢屋架进行张拉成型模拟,之后对结构进行静力分析,并与体外预应力钢屋架以及普通钢屋架进行了用钢量比较.通过分析可知,新型体内预应力钢屋架受力性能优越.     

预应力混凝土箱梁结构数值模拟与施工控制

应用大型有限元软件ANSYS对箱梁结构以及预应力钢绞线进行数值建模,采用温度荷载来模拟预应力的施加,并结合节点耦合的方法使模拟与现场施工效果更加接近,并得出了预应力的施加情况,通过三种不同的荷载施加方法,分析了箱梁的挠度与跨中应变等,得出了在荷载施加过程中,预应力钢绞线的受力情况;有限元软件ANSYS模拟的预应力钢绞线效果比较明显,在结果分析中,预应力的施加已经达到了施工中预期的效果。     

BSS结构体系形状确定分析

对预应力索-梁结构体系的形状确定问题进行了分析.采用对索段进行降温以实现索-梁结构预应力施加的降温法,通过大型通用有限元程序ANSYS提供的APDL语言进行结构建模,考虑结构的强几何非线性进行求解,可成功的求解预应力索-梁结构体系的零状态放样几何和初状态的预应力分布.由于未破坏结构的整体性,还可以在此基础上进行结构荷载态的分析.     

一种基坑钢支撑预应力施加数值模拟方法研究

在FLAC^3D中,采用梁单元模拟基坑钢支撑时,现有的预应力施加模拟方法是在梁单元设置以后,通过对梁单元两端的节点施加一对相反的作用力来代表要施加的预应力,导致支撑预应力变为围护体系的外力这一与实际不符的情况发生。为此,本文根据钢支撑与围护结构相互作用的机理,提出一种改进的钢支撑预应力施加模拟方法—虚拟位移法,即先固定梁单元一端节点,另一端节点施加节点虚拟位移,虚拟位移再施加于梁单元上,使梁单元压缩形成预应力。以深圳地铁5号线前海湾站基坑工程为背景,进行了常规方法和虚拟位移法的比较:在对支撑结构的影响上,常规方法引起各道支撑的轴力变化与实际存在明显的差别,而虚拟位移法则与实际一致。本文工作有实际意义。     

某预应力混凝土简支梁降温法的有限元分析

利用大型有限元分析软件ANSYS10.0,建立了一个工字型预应力混凝土简支梁模型,采用整体式降温法对此模型力筋进行预应力模拟,求出在徐变作用下梁体的应力和变形,从而促进预应力混凝土简支梁降温法的研究。     

A simplified correlation method accounting for heating and cooling loads in energy-efficient buildings

Simplified correlation methods are powerful tools to compare both the energy performance of buildings and the efficiency of different HVAC control systems. For buildings in which both heating and cooling loads contribute to the energy consumption, widely used methods, like the energy signature models, are not appropriate, since they cannot simultaneously handle both heating and cooling aspects. This paper proposes a new correlation method to overcome this difficulty. The ‘Eta method’ deals with internal gains, as well as solar gains, and can be used to calculate a utilization factor for free gains in the heating and cooling periods. Two examples to illustrate the method are given. The first one is a passive solar office room, on which different blind controllers were tested by simulation. The second example is a non-residential building in which two HVAC controllers were carefully monitored     

Analyse der Genauigkeit des Monatsbilanzverfahrens zur Ermittlung des Kühlbedarfs von Nichtwohngebäuden

Analysis of the monthly method for cooling energy demand calculation in office buildings. On 16^th December of 2002 the European Union passed the directive 2002/91/EU regarding the “Energy Performance of Buildings”. The individual member states had to implement this directive until 4^th January 2006. For new and for existing buildings energy certifications must be issued. To calculate energy ratios of buildings the monthly method is often used. The monthly method is analysed in this paper. Therefore the cooling demand for an office zone model was calculated by the monthly method and by a simulation. The comparison of the calculated value of the cooling demand by the monthly method and the simulation shows that the balanced value is sometimes smaller than the simulated value. To get realistic values for the cooling demand it is imperative to use correction‐factors for the balanced cooling demand. Coupled zones are accounted incorrect by calculation of cooling demand with the monthly method.     

Numerical simulation of radiant floor cooling system: The effects of thermal resistance of pipe and water velocity on the performance

Using the existing floor heating system, the radiant floor cooling system can be used as an alternative to the conventional all-air cooling systems. In this paper, a numerical model for the radiant floor cooling system is built using finite volume method. The objective of this study is to research the effects of the thermal resistance of pipe and water velocity on the performance of the radiant floor cooling system. In order to provide better heat transfer simulation in the pipe, composite grids are used in the model. The numerical floor surface temperature and the heat flux are in agreement with the measured results. The results illustrate that the pipe has effect on the performance of the radiant floor cooling system when the thermal conductivity of the pipe is low. However, the effect of the water velocity on the performance of the cooling system is not great. The model is helpful to calculate and design such kind of radiant floor cooling systems.     

顶板辐射供冷加置换通风系统广州地区适用性分析

顶板辐射供冷加置换通风系统以其独有的舒适性好、能耗低等特点逐步被国内用户接受,并在民用建筑项目中被采用.本文以等效辐射换热系数方法对盘管式辐射顶板单位面积的供冷量进行了数值模拟分析,并以广州地区为例,对该系统的适用性及影响因素进行了讨论:顶板辐射供冷加置换通风系统更适用于围护结构冷负荷指标低的节能建筑;当围护结构冷负荷指标低于20 W/m2时,采用较高供回水温度的冷水机组可满足室内设计要求且有明显的节能效果;顶板承担的冷负荷随人员密度的增大而减小,降低送风温度、采取大温差送风,可降低顶板承担的冷负荷.     

办公建筑中庭空调冷负荷简化计算

以北京地区某实际工程为例,在一定简化计算的前提下,基于工程中常用的冷负荷系数法,根据太阳能的入射能量分析热平衡,介绍了具有高大中庭的办公建筑的空调冷负荷计算简化方法。并与中庭实测温度梯度进行对比,得出可应用于工程中的高大中庭及周边办公环境的负荷计算方法。     

Reducing peak requirements for cooling by using thermally activated building systems

This paper presents general guidelines for the required cooling capacity of an entire office building using thermally activated building systems (TABS). By activating the thermal mass of the building using pipes embedded in the floor, peak loads can be reduced. On-site measurements were performed to obtain the required cooling power of an entire building as well as individual zones. Beside this, the internal climate conditions of rooms and surface temperatures of the TABS were measured. The measured data were used to analyze the predictive performance of a simulation model. In order to acquire general guidelines for the required cooling capacity of a standard office building, simulations of an entire building were used to determine the impact of variable internal heat gains and different sized windows. The required cooling capacity was compared to the cooling capacity of a system without energy buffering (e.g. chilled ceiling panels). It was found that reductions up to 50% of the cooling capacity for a chiller can be achieved using TABS. The presented results within this paper can be used as design guidelines in the first stage of a design process. The results focus on temperate climates and were derived using Dutch climate conditions.     

风机盘管集中空调系统的焓差法冷量计量方法

针对风机盘管集中空调系统，从风机盘管换热平衡的角度，提出采用风侧焓差法对风机盘管冷／热量进行计量的设想，同时对该方法进行了实验研究和误差分析，并且介绍了焓差法冷量计量装置的特点，得出的结论是采用风侧焓差法计量可以使计量误差降低到20％以下，从而满足工程中对冷量计量的需要。风侧焓差法冷量计量疗法的出现有助于促进国内冷量计量收费工作的推广开展。     

蒸发式冷凝器在人防工程中的应用

本文简单地介绍了冷却塔和蒸发式冷凝器在工程应用中的优缺点,一般情况都将这两种冷却设备放在地面通风良好的环境中。银川市南门广场人防地下商场,地面为12,000平方米的市民休闲绿地广场,南于冷却塔的噪声、飘水,因此在广场上不宜设置冷却塔。本工程空调冷却水的冷却采用蒸发式冷凝器,并且将蒸发式冷凝器从地上移置到地下室的机房内,与热泵机组配套使用,夏天作为冷凝器,冬天作为蒸发器在本工程中创造了比较满意的空调效果。但是使用蒸发式冷凝器的初投资比冷却塔高出5、6倍,而且所需冷却风量较大,因此设计时应做充分的综合比较。     

Indoor cooling/heating load analysis based on coupled simulation of convection,radiation and HVAC control

A computational fluid dynamics (CFD) simulation for analyzing indoor cooling/heating load is presented in this study. It is coupled with a radiative heat transfer simulation and heating, ventilating, and air-conditioning (HVAC) controlling system in a room. This new method feeds back the outputs of the HVAC system control to the input boundary conditions of the CFD, and this method includes a human model to evaluate the thermal environment. It would be used to analyze the heating/cooling loads of different HVAC systems under the condition of the same human thermal sensation (e.g. PMV, operative temperature, etc.) even though the temperature and air-velocity distribution in the room are different from each other.To examine the performance of the new method, a cooling load and a thermal environment within a semi-enclosed space, which opens into an atrium space, is analyzed under the steady-state conditions during the summer season. This method is able to analyze the indoor cooling load with changes of target thermal environments of a room and/or changing clothing conditions of occupants considering the temperature and air-velocity distribution in the room. In this paper, two types of HVAC system are compared; i.e. radiation-panel system and all-air cooling system. The radiation-panel cooling system is found to be more energy efficient for cooling the semi-enclosed space. Changes of the level of thermal environment reduce cooling load effectively in case of the all-air cooling system while the radiation-panel system does not reduce cooling load even though the targeted thermal condition is relaxed. Energy saving effect is expected by easing the clothing conditions of occupants. In this study, the reducing effect of cooling load is quantitatively evaluated with clothing conditions also.     

再循环蒸发冷却技术及其应用

基于直接蒸发冷却和间接蒸发冷却方法,提出了一种再循环蒸发冷却方法。设计了一套再循环蒸发冷却装置,并通过试验测试了它的冷却效果。对再循环蒸发冷却技术在空调行业的应用进行了具体分析,提出了相应的系统应用设计方法。最后指出这种技术为开发节能环保空调设备和空调系统提供了一个新的途径。