Raised Floor System Research Articles

Predicting the thermal comfort of occupants in an indoor auditorium space with different UFAD ventilation arrangements

An “Underfloor Air Distribution” (UFAD) system employs the open area underneath a raised floor system to drive conditioned air to the supply outlets situated in the floor. To understand a UFAD, think of it as an “upside-down version” of an overhead (OH) system. The idea behind it is to increase both energy efficiency as well as the quality of air in a home. In this paper, an auditorium model has been simulated for analysing the temperature distribution as well as thermal comfort of human occupants provided with 4 different cases of ventilation. The auditorium has two AC inlets ducts, each 2.50 m wide further branched into a number of small diffusers over the auditorium ceiling in order to distribute the inlet air evenly throughout the theatre space. The first case involves an upward ceiling outlet at the front of the theatre near the screen area while the second case has a downward outlet on the floor in the screen area. The third case is similar to the second one with human occupants designed as cuboids on every staircase while for the fourth case, the outlets have been provided under every seat on the staircase. It has been observed in the analysis that the downward outlets in case 2 provide better temperature distribution than the upward outlets of case 1. But the position of outlets below every seat, as in case 4, in the auditorium provides the best thermal comfort for the occupants than all the other cases. Hence, for the “maximum thermal comfort” of the human occupants, the outlets are advised to be installed downward on the floor under every seat.

Raised Floor Systems with Ceramic Tiles

The objective of this study is to evaluate the mechanical strength of raised floor systems with ceramic coatings. The raised floor prototypes are made of three types of ceramic tiles, two of which have a dimension of 60 × 60 cm and one has a dimension of 60 × 120 cm. Instrumentation is performed by attaching the strain gauges to the surface of the ceramic tiles. The raised floor prototypes are subjected to vertical compression loads until visible cracks appear on the surface of the ceramic tiles, and the resistance to system rupture is evaluated by analyzing their deformations. The results indicate that the load application position interferes with the resistive ability of the systems. Systems with plates having low water absorption and high thickness yield high breaking loads, which can be considered as the determining factors for outdoor applications of raised floor systems.

Real-time hybrid simulation of smart base-isolated raised floor systems for high-tech industry

Adopting sloped rolling-type isolation devices underneath a raised floor system has been proved as one of the most effective approaches to mitigate seismic responses of the protected equipment installed above. However, pounding against surrounding walls or other obstructions may occur if such a base-isolated raised floor system is subjected to long-period excitation, leading to adverse effects or even more severe damage. In this study, real-time hybrid simulation (RTHS) is adopted to assess the control performance of a smart base-isolated raised floor system as it is an efficient and cost-effective experimental method. It is composed of multiple sloped rolling-type isolation devices, a rigid steel platen, four magnetorheological (MR) dampers, and protected high-tech equipment. One of the MR dampers is physically tested in the laboratory while the remainders are numerically simulated. In order to consider the effect of input excitation characteristics on the isolation performance, the smart base-isolated raised floor system is assumed to be located at the roof of a building and the ground level. Four control algorithms are designed for the MR dampers including passive-on, switching, modified switching, and fuzzy logic control. Six artificial spectrum-compatible input excitations and three slope angles of the isolation devices are considered in the RTHS. Experimental results demonstrate that the incorporation of semi-active control into a base-isolated raised floor system is effective and feasible in practice for high-tech industry.

Sloped multi‐roller isolation devices for seismic protection of equipment and facilities

SUMMARYThe rolling motion of mutually orthogonal rollers respectively sandwiched between two bearing plates in which one or both have V‐shaped sloping surfaces makes the sloped rolling‐type isolation device have an excellent in‐plane seismic isolation performance. In this study, the sloped rolling type isolation device in which a single roller moves between two V‐shaped sloping surfaces along each principle horizontal direction is refined by incorporating multi‐roller, built‐in damping, and pounding prevention mechanisms. The associated dynamic behavior is further clarified, and a simplified twin‐flag hysteretic model, which can be easily applied in most commercial computational tools is then proposed. Seismic simulation tests on the refined isolation devices (i.e. the sloped multi‐roller isolation devices) with different design parameters such as sloping angles of bearing plates and built‐in damping capabilities, together with a raised floor system by employing the sloped multi‐roller isolation devices, were conducted. Not only is the efficiency of the sloped multi‐roller isolation devices in seismically protecting the important objects, but also the practicability and accuracy of the proposed simplified numerical model in predicting the seismic responses of the sloped multi‐roller isolation devices is experimentally verified. Copyright © 2014 John Wiley & Sons, Ltd.

Seismic performance of raised floor system by shake‐table excitations

SUMMARYDamage of expensive equipment installed in the raised floor system of high‐tech fabs was often observed during past earthquakes in Taiwan. This resulted in a huge loss of manufacturing functions and properties for the high‐tech industry. Therefore, there is an urgent need to understand the dynamic characteristics of the raised floor system for future seismic protection. This paper explores the seismic performance of a raised floor system under shake‐table excitations. The raised floor used was a pedestal–stringer frame structure supporting the simulated equipment. This raised floor system was the typical system frequently used in semi‐conductor fabs of Taiwan. The input motions for the shake‐table tests were the waffle‐slab floor accelerations of a typical semi‐conductor fab to simulated ground motions. The ground motions were simulated according to the phase spectrum and the maximum potential earthquake of the site located at Hsin‐Chu Science Park, Taiwan. The dynamic characteristics of the raised floor system were studied and discussed. This study also employed the finite element package to carry out numerical simulation on seismic responses of raised floor systems. Comparison with the experimental data showed that the proposed simulation model achieved excellent performance. Finally, the effectiveness of base isolation for reducing the acceleration of the system was also studied. Copyright © 2011 John Wiley & Sons, Ltd.

Study on the Performance and Application of Interior Moisture Buffering Materials for the Typical Housing in Taiwan

The humidity issue is one of the essential factors regarding the indoor environment quality. Researchers attempt to control the moisture in different methods, and the quantity of the researches keeps rising, which indicates the importance of the moisture buffering effect. The moisture buffering effect is a kind of passive design method, which is considered as more sustainable, compared to mechanical and chemical solutions. Taiwan locates in subtropics. However, the local researches concerning the moisture buffering effect in Taiwan are relatively fewer than those countries, which have lower temperature and humidity climate conditions than Taiwan. In addition, the general dehumidifying methods used in Taiwan are more concentrated in mechanical or chemical dehumidifying solutions. Moreover, typical town house in Taiwan usually represents as a north-south or east-west long axis living system without opening at the opposite axis, which leads the closed spaces with less openings for ventilations in the typical Taiwan town house, and those closed spaces are the main areas where the moisture accumulates. Therefore, this study follows the JIS A1470-1:2008 standard testing the MBV(Moisture Buffering Value) of 4 plate building and interior materials (Paulownia wood, Plywood, Pinewood, and Moisture Buffering Tile) and 3 Granular building and interior materials (Bamboo Charcoal, Activated Charcoal, and Silica Gel), and proposed design strategies along with moisture buffering materials (Double Wall System and Raised Floor System for existing building, and Counter-Beam System and Vertical Ventilation Duct for new construction) to provide local examples or references to Architects and interior designers in Taiwan.

Framework for Improving the Constructability of Raised Floor Systems in Australian Office Buildings

Despite the great benefits that it can potentially contribute to modern workplace environment, raised floor system (RFS) encountered many barriers in the process of its applications for the fitout of office buildings in the Australian construction industry. Through a set of comprehensive research activities, the significant influence factors (SIFs) and problems associated with the RFS fitout implementation are identified. Further discussion of these SIFs and problems unearths a range of project level critical factors (PLCFs) pertaining to the RFS fitout design, construction, operation and maintenance, which presents firsthand checklists for the project team to review in the project delivery process. These factors need to be accommodated appropriately in order to enhance the implementation of the RFS fitout in Australian office buildings. Following a constructability study, a framework was developed by integrating these SIFs and PLCFs into the delivery of the RFS fitout in an aim to enhance the project constructability and minimize problems in the RFS service performance.

Antimicrobial resistance ofEscherichia coliandEnterococcus faecalisin housed laying-hen flocks in Europe

The aim of this study was to determine the potential association between housing type and multiple drug resistance (MDR) in Escherichia coli and Enterococcus faecalis isolates recovered from 283 laying-hen flocks. In each flock, a cloacal swab from four hens was collected and produced 1102 E. coli and 792 E. faecalis isolates. Broth microdilution was used to test susceptibility to antimicrobials. Country and housing type interacted differently with the MDR levels of both species. In the E. coli model, housing in a raised-floor system was associated with an increased risk of MDR compared to the conventional battery system [odds ratio (OR) 2·12, 95% confidence interval (CI) 1·13-3·97)]. In the E. faecalis model the MDR levels were lower in free-range systems than in conventional battery cages (OR 0·51, 95% CI 0·27-0·94). In Belgium, ceftiofur-resistant E. coli isolates were more numerous than in the other countries.

Influence of raised floor on zone design cooling load in commercial buildings

The installation of a raised floor system can change the thermal behaviour of the building by reducing the interaction between the heat gains and the thermally massive concrete slab. In this study, the influence of the raised floor on the summer design day zone cooling load profile is evaluated with EnergyPlus for an office building located in San Francisco. The effects of structure type, window-to-wall ratio and the presence of carpet on the thermal behaviour of the raised floor are also investigated. The results show that the mere presence of the raised floor largely affects the zone cooling load profile and the peak cooling load over the range of −7 to +40%. The most significant parameters are the zone orientation, i.e. the exposure to direct solar radiation, and the presence of floor carpeting. If carpeting is present, commonly used in U.S. office buildings, the overall impact on zone peak cooling load is reduced, ranging from 0 to 5% greater for the raised floor than without it. Without carpet the peak cooling load is 4% greater with raised floor than without it in the north zone, 22% in the east and west zones, and 12% in the south zone.

Predicting acoustic performance in reconfigurable classrooms.

Both laboratory component tests and field system evaluations were conducted to screen architectural designs relative to sound quality performance within a classroom, and noise intrusion between classrooms. Recognized standards such as ANSI S12.60 for Acoustics in Schools and other rating systems such as LEED for Schools and CHPS provide guidance on performance/design needs for K‐12 schools. But what about postsecondary schools and especially those designed with reconfigurable architectural elements such as relocatable walls and raised floor system—can these be made to work? Initial results from this ongoing research will be discussed, including wall performance, ceiling/plenum effects, and sound system effects.

Impact sound insulating performance of access floors

Access floor are raised floor systems consisting of modular panels supported by posts at a certain height to create a gap below the floor surface. Electrical wires and pipes can be placed inside the gap in order to avoid exposed installations and to simplify operations involving the inspection, repair, changing, or adding of system elements. This paper presents the results of the measurement campaign carried out on seven different access floor configurations, obtained by changing different floor elements: panels, surface finishes, damping materials under the posts base. Impact sound insulating properties of access floors combined with false ceilings were also tested and are reported in the paper. The tests were executed in two overlapping reverberating rooms available at the Acoustics Laboratory of the University of Perugia using the procedures given by ISO 140‐6 Standard. The results are expressed in terms of normalized sound impact pressure level Ln and of the corresponding single number index Ln,W.

Factors influencing the implementation of the raised floor system in Australian office buildings

Raised floor systems (RFS) were initially developed for computer room applications. As an alternative for general office space fitout, they have not been widely accepted, particularly in Australia. Despite the potential exhibited, such as improved ventilation and air quality when used with underfloor sub‐systems, and the flexibility for office space reconfiguration, RFS implementation had encountered problems, ranging from the excessive costs perceived by owners and developers, to the lack of technical expertise among builders and contractors on the installation of RFS and specialized components. In the research work reported in this article, these problems were identified together with the highlighting of 44 Significant Influence Factors (SIFs). This was achieved through RFS product study, questionnaire survey, interviews and site observations. These SIFs and problems were then amplified in the research by industry focus groups and life cycle cost comparison between RFS and ceiling based fitout methods. The resulting 36 Project Level Critical Factors (PLCFs) pertaining to fitout design, construction, operation and maintenance were then considered in a constructability study, which established an integrated constructability framework for RFS fitout implementation, the most appropriate contracting strategy, and a process‐based model for RFS product selection under local conditions. A set of guidelines that recommend main activities and subsidiary tasks through five stages of RFS project implementation was also presented. These findings will contribute to improved awareness, adoption rate and implementation efficiency of RFS fitout in the Australian office building industry.

Seismic support of electronic and computer equipment on raised floors

The paper includes the description of the functional features of the often used raised floor systems and the factors affecting their seismic performance. After describing some practical methods to support their frameworks and cabinets, considerations for the design of earthquake-resistant raised floor systems are suggested. Attention is given to the concept and design of the isolation system for the entire raised floor. Practical and economically feasible methods to provide such an isolation are recommended. The concept of a new nested isolation system and some preliminary test results indicate the practical merits of such a system.