Uncertain programming of building cooling heating and power (BCHP) system based on Monte-Carlo method

Uncertainty of building energy demands has large influence on accuracy of building cooling heating and power (BCHP) programming model. Uncertain programming model is proposed to optimize BCHP system with consideration of uncertainty of energy demands. Monte-Carlo method (MCM) and mixed-integer nonlinear programming (MINLP) are integrated in the model (M-M model for short). MCM can be used to simulate the uncertainty of energy demands avoiding dimension disaster and complex calculation. Correlation between different energy demands can also be considered in the model. And facility scheme and operation strategy can be optimized simultaneously in MINLP model. A numerical example is calculated with the M-M model. Convergence rate of expected values of the variables optimized in the model is high. Influence of energy demand uncertainty is studied with investigation of expected values, standard deviations of evaluation indicators and facility capacities. Sensitivity of the parameters to energy demand uncertainty is much different. It is unnecessary to consider uncertainty of energy demands when evaluating system feasibility with indicators of annual cost saving rate and annual natural gas saving rate, for they are influenced only a little by uncertainty of energy demands. While uncertainty of energy demands must be considered when studying parameters related to assistant facilities, which are very sensitive to the uncertainty. The result is valuable for designing strategy of facility scheme.     

负荷不确定性对三联供系统配置和经济性的影响

利用围绕代表日负荷的概率分布来描述所有负荷的不确定性,以年总费用期望值为目标函数,建立了三联供系统的优化模型.根据一实例,系统地研究了负荷不确定性对三联供系统配置和经济性的影响.结果表明,负荷不确定性对三联供系统核心设备的配置影响不大,对辅助设备影响较大;随不确定性的增大,三联供系统初投资和运行费用都有所增加,系统经济优势有所下降.     

Variability of seismic demands according to different sets of earthquake ground motions

It is a challenging task to predict seismic demands for earthquake resistant design, particularly for tall buildings. In current seismic design provisions, seismic demands are expressed as a design base shear of which the key components are linear elastic design response spectra, force reduction factor (‘R factor’), and building weight. For tall buildings, response spectrum analysis or response history analysis is recommended in current design provisions. In recent years, new methods for predicting seismic demands have been developed, such as the capacity spectrum method (CSM) and displacement coefficient method. This study investigates the effect of different earthquake ground motion (EQGM) sets on seismic demands. Key components of the base shear and performance points in the CSM are considered as the seismic demands to be tested. For this purpose three EQGM sets are collected independently at rock sites. This study found that seismic demands can vary significantly according to different EQGM sets even though those sets were obtained at sites with similar soil conditions. This study also attempts to provide a criterion for reducing the variability in seismic demands according to different EQGM sets. Copyright © 2007 John Wiley & Sons, Ltd.     

A modified response spectrum analysis procedure to determine nonlinear seismic demands of high‐rise buildings with shear walls

The standard response spectrum analysis (RSA) procedure prescribed in various design codes is commonly used by practicing engineers to determine the seismic demands for structural design purpose. In this procedure, the elastic force demands of all significant vibration modes are first combined and then reduced by a response modification factor (R) to get the inelastic design demands. Recent studies, however, have shown that the response of higher vibration modes may experience much lower level of nonlinearity, and therefore, it may not be appropriate to reduce their demand contributions by the same factor. In this study, a modified RSA procedure based on equivalent linearization concept is presented. The underlying assumptions are that the nonlinear seismic demands can be approximately obtained by summing up the individual modal responses and that the responses of each vibration mode can be approximately represented by those of an equivalent linear SDF system. Using 3 high‐rise buildings with reinforced concrete shear walls (20‐, 33‐, and 44‐story high), the accuracy of this procedure is examined. The inelastic demands computed by the nonlinear response history analysis procedure are used as benchmark. The modified RSA procedure is found to provide reasonably accurate demand estimations for all case study buildings.     

Influence of energy demands ratio on the optimal facility scheme and feasibility of BCHP system

Building cooling heating & power (BCHP) system has advantages of energy saving and environment protection. Accurate feasibility evaluation and rational match between energy supply and energy demands are necessary for the realization of advantages of BCHP system. The influence of energy demands on the optimal facility scheme and feasibility of BCHP system needs especially to be studied. Mixed-integer nonlinear programming model is established with integrated optimization of facility scheme and operation strategy of BCHP system. A series of energy demands with different heat-electricity ratio and cooling-electricity ratio are achieved based on the energy demands of a hotel. Sensitivity analysis about energy demands ratios is carried out in this paper to study their influence on optimal capacity of facilities and feasibility indices. And the reason of the results is analyzed. Indices of feasibility evaluation include annual cost, annual cost saving rate and annual natural gas saving rate. It is shown in result that energy demands of different type have different weight in optimal capacities. Optimal capacities of facilities should be designed with consideration of all three kinds of energy demands. Different feasibility evaluation are achieved with different indices. The BCHP system is preferable for buildings with high heat demand.     

Adaptation and validation of an existing bottom-up model for simulating temporal and inter-dwelling variations of residential appliance and lighting demands

The design and analysis of community-scale energy systems and incentives is a non-trivial task. The challenge of such undertakings is the well-documented uncertainty of building occupant behaviours. This is especially true in the residential sector, where occupants are given more freedom of activity compared to work environments. Further complicating matters is the dearth of available measured data. Building performance simulation tools are one approach to community energy analysis, however such tools often lack realistic models for occupant-driven demands, such as appliance and lighting (AL) loads. For community-scale analysis, such AL models must also be able to capture the temporal and inter-dwelling variation to achieve realistic estimates of aggregate electrical demand. This work adapts the existing Centre for Renewable Energy Systems Technology (CREST) residential energy model to simulate Canadian residential AL demands. The focus of the analysis is to determine if the daily, seasonal, and inter-dwelling variation of AL demands estimated by the CREST model is realistic. An in-sample validation is conducted on the model using 22 high-resolution measured AL demand profiles from dwellings located in Ottawa, Canada. The adapted CREST model is shown to broadly capture the variation of AL demand variations observed in the measured data, however seasonal variation in daily AL demand behaviour was found to be under-estimated by the model. The average and variance of daily load factors was found to be similar between measured and modelled. The model was found to under-predict the daily coincidence factors of aggregated demands, although the variance of coincident factors was shown to be similar between measured and modelled. A stochastic baseload input developed for this work was found to improve estimates of the magnitude and variation of both baseload and peak demands.     

Work–life fit: identification of demand and resource typologies within a systems framework*

Work–life fit occurs when people have the resources required to meet demands such that role performance (both at work and in non-work life domains) is effective. Interviews were conducted with 59 construction workers based in Melbourne, Australia to explore how demands and resources were experienced. Using a systems framework, data were analysed using thematic analysis. Results identified two demand typologies associated with demand-to-demand interaction. Demands operating as ‘influencers’ have a major impact on the conditions of the interdependent demand, while demands operating as ‘creators’ generate a new demand and shape the conditions of that demand. One resource typology related to resource–demand interaction was identified. ‘Enabling resources’ enable an individual to manage multiple demands across multiple domains, and may also enable an individual to manage multiple demands within a single domain. A new conceptual contribution is made to an area in which theory is under-developed, by adopting a systems approach to understanding the dynamic interactions between demands and resources. A lack of fit is damaging for the individual; therefore, it is useful to know that demands and resources are interdependent and these interdependencies will vary according to individuals. Using a systems approach to understanding demands and resources will be helpful to organizations seeking to support workers to achieve optimal work–life fit.     

Optimal reduction of inelastic seismic demands in high‐rise reinforced concrete core wall buildings using energy‐dissipating devices

Recently, the issue of large inelastic seismic force demands at severe ground shakings such as maximum considered earthquake level has been highlighted in the conventionally designed high‐rise reinforced concrete core wall buildings. Uncoupled modal response history analysis was used in this study to identify the modes responsible for the large inelastic seismic force demands. The identification of dominant modes and mean elastic design spectra of seven representative ground motions for different damping ratios has led to the identification of three control measures: plastic hinges (PHs), buckling‐restrained braces (BRBs) and fluid viscous dampers (FVDs). The identified control measures were designed to suppress the dominant modes responsible for the large inelastic seismic force demands. A case‐study building was examined in detail. Comparison of the modal as well as the total responses of the case‐study building with and without the control measures shows that all the control measures were effective and able to reduce the inelastic seismic demands. A reduction of 33%, 22% and 27% in the inelastic shear demand at the base and a reduction of 60%, 22% and 26% in the inelastic moment demand at mid‐height were achieved using the PHs, BRBs and FVDs, respectively. Furthermore, a reduction of about 30–40% in the inelastic seismic deformation demands was achieved for the case of the BRBs and FVDs. The study enables us to gain insight to the complex inelastic behavior of high‐rise wall buildings with and without the control measures. Copyright © 2011 John Wiley & Sons, Ltd.     

On‐Line Vehicle Routing Problems for Carbon Emissions Reduction

This paper proposes formulations and a hybrid meta‐heuristic algorithm to solve the on‐line vehicle routing problem (VRP) for minimizing costs related to economics and emissions. The on‐line VRP considers real‐time demands. Vehicle emissions are affected by travel speed and vehicle load. A hybrid meta‐heuristic algorithm GA‐Tabu is designed to solve the on‐line VRP and a solution framework using DynaTAIWAN simulation is implemented. The numerical results show CO₂ can be reduced by combining the emission factors into the objective function. Also, the route updates for on‐line demands are analyzed and the performance measures of the on‐line VRP are investigated by using various on‐line demands.     

对房屋抗震评估中采用的非线性静力分析方法的评估

基于设计的性能分析方法的一个关键部分是,对地震需求谱参数的准确采用。非线性静力方法(NSPs)现在广泛应用在工程实践上,主要用于预测房屋建筑的抗震能力。利用NSPs,地震需求谱可以从特定地点的危险性谱中直接计算出来,而非线性时程分析需要全部地面运动和针对地震记录可变性的相关性评估。除此之外,基于恒载模式(ATC-40和FEMA-356中所推荐的)NSP简化版本有条文说明其无法考虑由结构弹塑性而导致的更高模态效应以及模态变化。因此,研究者纷纷提出解决了以上缺点的改进Pushover法。通过对典型的钢结构和钢筋混凝土结构的突出反应特征与一套全面的NTH分析中得到的基准反应的比较,研究了多种非线性静力分析方法(NSPs)的有效性。更重要的是,考虑到多种地面运动特征,还采用了一组从普通的远断层记录到近断层地面运动的时间序列。这项分析研究的结果显示,较之该项研究中的其他非线性分析方法,适应性组合模型方法可以更为准确地预测如层间位移、塑性角等的极值。     

Assessment of current nonlinear static procedures for seismic evaluation of BRBF buildings

Nonlinear static procedures (NSPs) are now standard in engineering practice to estimate seismic demands in the design and evaluation of buildings. This paper aims to investigate comparatively the bias and accuracy of modal, improved modal pushover analysis (MPA, IMPA) and mass proportional pushover (MPP) procedures when they are applied to buckling-restrained braced frame (BRBF) buildings which have become a favorable lateral-force resisting system for earthquake resistant buildings. Three-, 6-, 10-, and 14-storey concentrically BRBF buildings were analyzed due to two sets of strong ground motions having 2% and 10% probability of being exceeded in 50 years. The assessment is based on comparing seismic displacement demands such as target roof displacements, peak floor/roof displacements and inter-storey drifts. The NSP estimates are compared to results from nonlinear response history analysis (NL-RHA). The response statistics presented show that the MPP procedure tends to inaccurately estimate seismic demands of lower stories of tall buildings considered in this study while MPA and IMPA procedures provide reasonably accurate results in estimating maximum inter-storey drift over all stories of studied BRBF systems.     

Improved probabilistic quantification of drift demands for seismic evaluation

This study deals with the evaluation and formulation of methods to improve the probabilistic quantification of maximum story drift demands for structural systems exposed to severe ground motions. The focus is on flexible structures that are prone to dynamic instability. The quantification of drift demands is based on the probability distribution of the maximum story drift over the height, for a given ground motion hazard level, which in this study is represented by the spectral acceleration at the first mode period of the building. Improvements in the probabilistic estimation of maximum story drift demands are illustrated with a nine-story, moment-resisting frame building exposed to a set of 40 ground motions. It is concluded that (1) the three-parameter LN distribution more rationally describes maximum story drifts at higher values of spectral acceleration; (2) statistically adding values to replace truncated data points provides better goodness-of-fit in maximum drift demand prediction when the structure is close to the onset of dynamic instability, and (3) the least-squares fitting of the LN distribution yields parameters that provide an improved fit compared to that from maximum likelihood estimation and the method of moments.     

Computer‐based evaluation of design methods used for a steel plate shear wall system

Vertical boundary elements (VBEs) play a key role in seismic performance of steel plate shear wall (SPSW) system and consume major part of the steel material in a structure. The different methods allowed by design standards for computing the force demands exerted on the VBEs yield in widely varied results and are evaluated in this study through a computer‐based approach. After elaborating these methods, development of a versatile and user‐friendly program is presented that implements various SPSW design algorithms. The program relies on component object model technology and interactively communicates with a component object model supporting program, etabs , as the analysis core. It also benefits from an object‐oriented structure. At the next phase, the developed program is utilized to design SPSWs with different heights and extract VBE demands using different methods. Nonlinear time history analyses of the structures, performed in opensees software using a bin of seven ground motion records, have been ultimately used for assessing the precision of different demand estimation methods. The AISC 341‐10 capacity‐based design method was shown to provide overestimations that reached 90% and 1888%, respectively, for axial and flexural VBE demands of 17‐story building. Lower overestimation ratios were found for shorter structures. Copyright © 2016 John Wiley & Sons, Ltd.     

Seismic response of base isolating systems with U-shaped hysteretic dampers

This paper proposes a base isolating system to reduce the seismic demands of low- or medium-rise structures and experimentally investigates its seismic response using shake-table tests. The base isolating system considered in this study consists of laminated-rubber bearings and U-shaped hysteretic (UH) dampers which are made of high toughness steel (HTS) and are machined with slotted holes to increase their deformation capacities. A base isolated 2-story specimen for shake-table tests was first designed and cyclic tests of laminated-rubber bearings and UH dampers implemented in the base isolating systems were then carried out. The component test for the laminated-rubber bearings shows typically low lateral stiffness with enough vertical stiffness to carry gravity loads. The test results for the UH dampers demonstrate that the use of HTS material and the introduction of the slotted holes details increase deformation capacities by inducing uniform stress distribution along a UH damper. Finally, shake-table tests were performed using specimens shaken with increasing ground acceleration records. The shake-table tests show that the proposed base isolating system with UH dampers limits the seismic demands of a base isolated structure by lengthening its structural period, concentrating displacement demands on the base isolating floor and adding seismic energy dissipation from the UH dampers.     

Dynamics of water use in Scotland

This paper uses a variety of data sources and methodologies to construct business as usual (BAU) water‐use scenarios for the Water Framework Directive (WFD) characterisation report, a key preliminary benchmarking requirement for member states. The paper addresses the most significant water‐use sectors in Scotland over the period 2001–2015. In terms of volumetric use, our figures are dominated by the demands of electricity generation. The next highest demands come from fish farming/aquaculture, which is mostly direct abstraction. Various industrial uses are estimated to be associated with significant volumetric uses (specifically electrical and engineering, fibres and food and drink). Because of structural changes in farm support, agriculture is the only sector showing a decline. Household demand is also a highly significant use and we are able to specify the public/private breakdown of demand.     

热电冷三联供系统中热水网参数的选择

结合北京第一热电厂、北京第二热电所所属供热系统,分析在夏季具有冷负荷和生活热水负荷时,热网参数,即供／回水温度,对热电冷联供系统一次能耗的影响。     

Estimating inelastic drift demands for wood portal frame systems considering accumulated damages

As one key to the implementation of the performance‐based design methodologies for wood structures, the performance objectives and their corresponding limit state criteria are usually correlated with the peak (maximum) interstory drift demands. This paper evaluates the inelastic drift demands including the peak drift and the residual drift for the prototype timber portal frame structural elements. Analytical 2D‐framed model representative of the study‐case were subjected to a suite of 50 pulse‐type earthquake ground motions. In addition, an accumulated damage index is added to the inputs of the nonlinear analyses to account for the damage caused by the previous ground excitations. Larger accumulated damages lead to larger inelastic drifts. Strong correlation is revealed among the drift demands, the peak ground accelerations, and the variables characterizing the nonlinear system behavior. Finally, estimation formulas for the peak and residual drift demands are proposed and validated with the simulated results from nonlinear time‐history analyses. Based on the presented formulas, the resilience ratio and the effective elastic drift are further derived to comprehend the nonlinear behavior of such timber made structures.     

ANALYSIS OF WATER SUPPLY NETWORKS CONSIDERING CONSUMPTION ALONG LINKS

Even though consumers are situated along links of water supply networks and thus water is withdrawn at different points along links, the usual network analysis procedures assume node-concentrated demands. An analysis methodology that considers consumption along links and thus link-distributed demands is developed. Necessary equations are formulated and their solution through the commonly used methods is described. An illlustrative example that compares the analysis results considering link-distributed demands with that considering node-concentrated demands is provided. As illustrated, the available nodal heads are generally lower for link-distributed demands than those for node-concentrated demands. Thus, a network that may be satisfactory considering node-concentrated demands may become unsatisfactory when link-distributed demands are considered.     

Superpave技术在嘉金高速公路(二期)中的应用

Superpave(Superior Performance Asphalt Pavement)技术是1个体系。它包括沥青胶结料规范、沥青混合料设计方法以及混合料分析体系。从原材料要求、混合料技术要求、施工质量控制和路面检测指标等4个方面,介绍了Superpave技术在嘉金高速公路(G15)二期项目中的应用及质量控制。     

大连老虎滩海洋极地馆空调及维生系统介绍

海洋极地馆是极地动物展示和表演的场所。为满足各种海洋动物对海水温度及环境的不同要求，满足游人观赏、工作人员办公的温湿度要求，该工程除采用常规空调系统外，还设置了极地海洋动物维生空调系统和维生水系统。冷热源为直燃式溴化锂机组，可同时供冷、供热，在不能满足要求的地方设置直接蒸发式风冷机组。该工程已正常运行两年，满足使用要求。