Search

The selection of seismic motions is one of the most important issues for the time-history analysis of buildings. This paper discusses four different methods for obtaining spectrum-compatible acceleration time histories (i.e., accelerograms) of seismic motions. Based on these methods, four sets of accelerograms compatible with the design spectrum for Vancouver were selected for this study. These included ( i) scaled real accelerograms, ( ii) modified real accelerograms, ( iii) simulated accelerograms, and ( iv) artificial accelerograms. The selected sets were used as excitation motions in the nonlinear analysis of three reinforced concrete frame buildings designed for Vancouver. The buildings included a 4-storey, a 10-storey, and a 16-storey building, which can be considered representative of low-rise, medium-rise, and high-rise buildings, respectively. The storey shears, interstorey drifts, and curvature ductilities for beams and columns obtained from the analysis were used for the evaluation of the effects of the selected sets on the responses of the buildings. Based on the results from the analysis, scaled real accelerograms are recommended for use in time-history analysis of reinforced concrete frame buildings. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract: In formation of building external envelope, as two important criteria, climatic data and wall types must be taken into consideration. In the selection of wall type, the thickness of thermal insulation layer (di ) must be calculated. As a new approach, this study proposes determining the thermal insulation layer by using artificial neural network (ANN) technique. In this technique five different wall types in four different climatic regions in Turkey have been selected. The ANN was trained and tested by using MATLAB toolbox on a personal computer. As ANN input parameters, Uw , Te ,Met , Te,TSE , Rwt , and qTSE were used, while di was the output parameter. It was found that the maximum mean absolute percentage error (MRE, %) is less than 7.658%. R 2 (%) for the training data were found ranging about from 99.68 to 99.98 and R 2 for the testing data varied between 97.55 and 99.96. These results show that ANN model can be used as a reliable modeling method of di studies. [ABSTRACT FROM AUTHOR]

Abstract: A transient model of airflow and heat transfer in an indoor ice rink and a quasi-steady model of its refrigeration system have been coupled and used to simulate their response to the time dependent ambient conditions and operating schedule for a typical meteorological year. The results for two different cases show that it is possible to reduce significantly the time of operation of the compressors and the energy consumption of the refrigeration system by simultaneously reducing the ceiling emissivity and increasing the secondary coolant temperature without affecting the quality of the ice. [ABSTRACT FROM AUTHOR]

Abstract: This article presents an experimental analysis of cooling buildings using night-time cold accumulation in a phase change material (PCM), otherwise known as the “free-cooling principle”. Studies of the ceiling and floor free-cooling principle, as well as passive cooling, are presented. The free-cooling principle is explained and some of the types of PCMs suitable for summer cooling are listed. An experiment was conducted using paraffin with a melting point of 22 °C as the PCM to store cold during the night-time and to cool hot air during the daytime in summer. Air temperatures, heat fluxes and heat as a function of time are presented for different air velocities and inlet temperatures. [ABSTRACT FROM AUTHOR]

Abstract: This article presents the results of an investigation into the free cooling efficiency in a heavyweight and lightweight low energy building using a mechanical ventilation system with two latent heat thermal energy storages (LHTESs), one for cooling the fresh supply air and the other for cooling the re-circulated indoor air. Both LHTESs contain sphere encapsulated PCM (paraffin RT20). Using a developed and experimentally verified numerical model of the LHTES, the temperature response functions, based on the heat storage size, the air flow rates and the PCM''s thermal properties, are established in the form of a Fourier series and empirical equations and used in the TRNSYS building thermal response model. Several mechanical ventilation, night cooling and free cooling operation modes were analysed and compared. It was found that the free cooling technique enables a reduction in the size of the mechanical ventilation system, provides more favourable temperatures and therefore enables better thermal comfort conditions, and in our studied case also fresh air for the occupants. [Copyright &y& Elsevier]