Prefabricated Panels Research Articles

共用廊下増築を伴う既存壁式プレキャスト鉄筋コンクリート構造集合住宅建物の耐震性能評価

Significant number of wall-type precast reinforced concrete (WPC) residential buildings exist in Japan, constructed during the 1960-70s.They are assembled using prefabricated concrete panels for the slabs and walls and of high quality in terms of the structural conditions. In order to utilize them, seismic behavior of the existing buildings extended with new corridor and elevator structures were analytically evaluated. Static pushover analyses were conducted considering inelastic behavior of members and connections between the existing precast concrete wall panels. The ultimate lateral strength of the extended buildings were nearly equivalent to that of the existing buildings.

Experimental and numerical investigation of thermal bridging effects of jointed Vacuum Insulation Panels

Vacuum Insulation Panels (VIPs) are characterised by very low thermal conductivity, compared to traditional insulating materials. For this reason, they represent a promising solution to improve the thermal behaviour of buildings, especially in the case of energy retrofitting (where a higher performance and less thickness is desirable). VIPs are insulating components in which a core material is surrounded by an air tight envelope which allows a high degree of internal vacuum to be maintained. Such features, on the one hand, allow excellent thermal insulation properties to be achieved, but, on the other, require the manufacturing of prefabricated panels of fixed shape/size. This means that the use of these super insulating materials in the building envelope involves the problem of joining the panels to each other and of fixing them onto additional supporting elements.As a result, purposely studied supporting structures or systems are required. However, these structures and systems cause thermal bridging effects. The overall energy performance of the resulting insulation package can therefore be affected to a great extent by these additional elements, and can become significantly lower than that of the VIP panel alone.In order to verify the incidence of thermal bridges on the overall energy performance of an insulation system that makes use of VIP panels, an experimental campaign has been carried out using a heat flux metre apparatus and analysing different joint materials/typologies. First, a measurement method was proposed, tested and verified on the basis of data from the available literature. A series of measurements on different samples was then performed. The experimental results were then used to calibrate and verify a numerical model that allows the performance of various “VIP packages” to be predicted and the performance of the overall package to be optimised.

Reusing concrete panels from buildings for building: Potential in Finnish 1970s mass housing

A remarkable share of European mass housing was built with large-panel systems during the 1960s and 1970s. In many countries, this stock is already being demolished or demolition is discussed due to vacancies or social problems. This trend may result in the creation of an unforeseeable amount of concrete waste. Simultaneously, EU has issued the Waste Framework Directive aiming at reuse instead of recycling. Unlike in situ cast concrete, reclaimed prefabricated concrete panels from mass housing carry the potential for reuse. The purpose of this study is to review the reuse potential embedded in Finland’s mass housing stock from the perspective of the dimensions of the panels and spaces, i.e., their suitability for architectural (plan) design. The research material consists of architectural drawings of 276 blocks of flats that contain over 26000 prefabricated wall panels and nearly 14000 hollow-core slabs, the dimensions of which are compared to current norms and guidelines for dimensioning living spaces. The technical prerequisites for reuse are reviewed with the help of literature. The study results in identifying an inventory of panels typical to Finnish precast concrete construction, which, in principle, should not exist because the building plans were not standardized but were supposed to be unique. The panels are found to be still usable in architectural (plan) design of detached houses, which form one third of annual residential production in Finland.

Experiences when employing different alternatives for envelope upgrading

The challenges of achieving the 2020 goals in terms of energy savings and improving efficiency are guiding numerous research initiatives looking for more insulated envelopes, dealing with thermal performance of insulation materials and envelope systems. Nevertheless, the envelope integrates within the building and this improvement on the insulation performance has to be properly adopted, taking into account the interrelation of main elements composing the overall system (facade, frame, slabs, openings, partitions etc.), as well as side effects originated not only for new erected buildings, but specifically in renovation and retrofitting works. This paper describes real experiences when considering various options for upgrading the facade through the increase of the insulation capacity, starting from external overcladding prefabricated panels and ventilated facades, advancing to more sustainable low carbon systems and ending with even more highly insulated solutions employing aerogels. Lessons from these cases, where energy and hygrothermal assessments have being carried out, demonstrate the influence of the design and construction phases and the relevance of disregarded effects such as minor thermal bridges, uncontrolled craftsmanship on site, and moisture transfer for the different technologies considered. Finally, possible alternatives are provided to overcome some of the detected difficulties, such as combination with non-metallic structural components and building membranes, and being prepared for future challenges and new developments when these isolative elements are combined with other technologies, as for example, renewable energy harvesting devices.

Racking performance of timber studwork and hemp-lime walling

Hemp-lime is a natural, sustainable low carbon insulating material. It is formed from three main constituents: hemp shiv; lime based binder; and, water. Its use within the construction industry is a relatively recent development. In the UK hemp-lime is most widely used for solid wall insulation in conjunction with structural timber studwork, either cast in situ or more recently innovative prefabricated panels. Current design practice assumes that the hemp-lime does not contribute towards the structural capacity of the wall. Previous work by the authors has confirmed that hemp-lime significantly benefits vertical load bearing capacity of the timber studs. This paper presents research that has been undertaken to establish the enhancement hemp-lime provides to the in-plane racking strength of timber studwork framing. Laboratory testing was undertaken on a series of timber studwork frames both with and without hemp-lime. It was found that the hemp-lime significantly increases both the racking strength and stiffness.

Pre-fabricated sandwich panels using cold-formed steel and textile reinforced concrete

A novel prefabricated sandwich panel consisting of profiled steel sheet as a core material and textile reinforced concrete (TRC) as outer skins was developed. TRC consists of cementitious binder and an alkali resistant glass textile as reinforcement. The dimension of the TRC panel chosen for study was 1170mm×650mm×70mm. Experimental investigations were carried out to determine the response behavior of sandwich panel under flexural load. It is observed that the ultimate flexural stress of the panel is 28.12kN/m2 and is suitable for floor applications. Further, the panel showed ductile behavior even after the 25% reduction in ultimate load. Further, numerical modeling of two types of TRC sandwich panels was done using finite element software ABAQUS. TYPE-I sandwich panel considers perfect bond between profiled steel sheet and TRC. In TYPE II sandwich panel, self tapping screws were provided to connect profiled steel sheet and TRC skin. This panel is modeled with screws for attaching sheet and face skins. For material modeling, TRC, profiled steel sheet and self tapping screws were modeled as elastic–plastic. A displacement controlled analysis was performed for the TRC sandwich panels under two point loading condition. It was observed that the ultimate loads predicted by numerical models are in good agreement with experimental results.

Thermal, Moisture and Energy Performance of a Hempcrete Test Structure in the Northern Prairie Climate of Manitoba, Canada

The processing of industrial hemp, cannabis sativa, results in three basic constituents seed, fibre, and hurd. Within Manitoba the main focus is with seed and oil products. When considering the entire plant approximately 60-70% is the predominantly cellulose woody core called the hurd. A combination of hemp hurd, a binder and water in various proportions is used in the construction of buildings referred to as hempcrete. Hempcrete is used as an environmental barrier providing resistance to heat transfer and to manage moisture of the building envelope. Engineering and architectural designers practicing in the field of non-conventional material applications have clearly indicated a need for design data. This paper presents a portion of research data collected over the past 18 months from a 23.8 m2 (256 ft2) test building on the campus of the University of Manitoba at the Alternative Village. The design temperatures for this location range from-35°C to +32°C. The structure was built using 300 mm thick pre-fabricated hempcrete panels. In addition to indoor and exterior ambient conditions, the temperature is monitored at 40 locations within the envelope - at the interior, middle and exterior providing a profile through the wall system. Similarly, the relative humidity is monitored within the wall and used in conjunction with a sorption isotherm to estimate the moisture content within the assembly. The building is kept at a constant temperature during the heating season with the energy consumption monitored continuously. This building is one of several on the test site that are all identical in terms of size and configuration. This paper will provide a comparison between the thermal, moisture and energy performance of the hempcrete structure and a conventional wood frame, batt-insulated building that represents the vernacular construction in Manitoba.

Evaluation of Energy Efficiency in Retrofitting Residential Buildings with Large-Panel Structures

Modular blocks of flats built with large prefabricated panels have become widespread in most of central and East-European countries particularly in the 80es, populating large-scale neighbourhoods. In Romania are representing about 37% of the total fund of apartment blocks, being present in most of the cities. The high percentage of thermal bridges and reduced design thermal resistance of the envelope make these buildings a priority in thermal retrofitting. Using up-to-date calculation methods, the paper presents a thorough analysis of the energy performance of large-panel residential buildings (apartment blocks) before and after renovation. The conclusions are focused on the practical measures to be undertaken for bringing the energy efficiency after retrofitting at the highest possible degree, thus meeting the requirements of the EU legislation and the targets set in the field of energy performance and reduction of CO2 emissions.

Application of Prefabricated Panels for the Energy Retrofit of Portuguese Residential Buildings Facades: A Case Study

Abstract This article aims to evaluate the potential application of prefabricated panels in energy retrofit of facades in the Portuguese building stock. The fundamentals of this study were part of Annex 50, which was an international ECBCS IEA project, with the purpose of developing an innovative concept of building renovation for the most representative buildings based on prefabricated systems. To analyze the potential application of energy retrofit using prefabricated panels, was important to know the reality of the existing building stock and its morphology. To know the reality of the building stock, an analysis was done based on the existing statistical data and to find the most representative residential buildings, target of the study, three criteria were defined: buildings built before 1990, with 2 to 6 floors and with renovation needs in the exterior envelope.In the absence of statistical information about buildings morphology, a research work was done in the field. During the collection of data a methodology was developed in which each opening was classified according to a code with three parameters. In the end of the classification, 29 final codes were achieved and was verified that three types of panels have a higher probability of being applied.

A New Building System Made of Glass Fiber Reinforced Mineral Matrix Composites

The glass fiber reinforced mineral matrix composite (GFRMMC) solutions allow designing modular structural elements made of prefabricated panels. Important research works on calcium sulphate in the beta anhydride III’ form, led in finding a mixture with increased workability capable to be cast on glass fiber reinforcement and obtaining composite elements. This paper presents the results of designing concept for a new structural system for building houses made of GFRMMC. Prototypes for elements and building system made after the design processes are summarized. Observations of structures regarding the structural behavior, thermal efficiency or indoor air quality are presented in the conclusions. The technology and the structural systems analyzed have many advantages to be considered as an alternative for traditionally building systems.

Increase in buildings sustainability by using renewable materials and energy

Sustainable development could be seen as indispensable condition for survival of civilization. Construction sector is a field with immediate need for reducing environmental impacts. Sustainability measures applied for buildings could produce very efficient results to the people. The paper provides the methods of construction sustainability increase by researching, developing, and applying the technologies which use renewable materials and energy. The paper analyzes the cases of both a solar eco house which was built of original prefabricated straw-bale panels and was designed to use direct solar energy; and an educational project promoting straw-bale construction and seeking to mitigate climate change. The project results have shown the need of spreading information on sustainable building methods to be accepted by wider society and to be applied to the construction industry. Monitoring of solar ecohouse has proved that direct solar energy gains are significant in reducing heating degree-days in 55°N latitude and in allowing to save half the energy needed for heating.

Improvement in the tracking of special loads by using a three-level RFID system

Manufacturers usually control the quality of their products from raw materials reception till the delivery of final goods. Products should also be controlled along the distribution and transportation phases, although this is not always feasible. In this work, the goods whose features need to be preserved while going through the previously mentioned phases are considered as special loads. Non-homogeneous loads, which are the combination of different products, will be also considered. The errors made when using the actual product tracking systems involve additional costs and inconveniences. An auto managed three-level based RFID system is proposed in this paper in order to provide an efficient solution for the real-time monitoring (RTMS) of special loads. It has been implemented by means of RFID passive and active tags, plus wireless readers inside the items, pallets and containers, which allow a three level division of the supply chain. At the highest level, a wireless network connecting all the readers using ZigBee technology has been implemented to provide real-time localization of products (RTLS) all over the world as it is also connected to a GPRS system. Finally, the proposed system is applied to two different industrial scenarios: a bottling company for perishable beverages and high-quality wines, and the manufacturing and delivery of pre-fabricated concrete panels.

Off-Site Construction in Saudi Arabia: The Way Forward

Off-site construction, which gained prominence in the last quarter of the previous century, is the form of construction in which the intent is to move some of the effort that goes into construction from the construction site into the controlled environment of a manufacturing facility (Arif and Egbu 2010). Gibb (2001) traced the history of off-site construction as far back as 1851; however, Arif (2009) actually goes one step further and argues that the use of big boulders instead of smaller bricks in pyramids is no different from using prefabricated wall panels. Humanity has always looked for better ways of building faster, and the use of precut rocks and boulders leveraged the opportunity to fill large volumes of pyramid structures more quickly (Arif and Egbu 2010). The benefits of off-site construction have been well-documented in the literature. Gibb and Isack (2003) classified the benefits into five major categories: time, quality, cost, productivity, and people. Arif and Egbu (2010) identified off-site as a construction paradigm that can address the housing shortage in the future. However, there are some major challenges associated with the implementation of off-site construction. Pan et al. (2007) documented the barriers to the implementation of off-site construction. The most important five barriers identified by Pan et al. (2007) are higher capital cost, difficulties in achieving economies of scale, complexity of interfacing between systems, inability to freeze the design early on, and the nature of the planning system. Saudi Arabia, the world’s largest oil producer, has seen an economic boom in the previous five years, owing to high oil prices. Oil and gas exports have increased from 70.7 billion USD in 2001 to 205 billion USD in 2007 (Tabata 2009). This economic growth has resulted in significant economic activities being undertaken in the kingdom. However, the construction projects being performed are fraught with delays and inefficiencies (Alkharashi and Skitmore 2009). One documented benefit of off-site construction is productivity, leading to a higher speed of construction. To assess the issues with the implementation of off-site construction in Saudi Arabia, a workshop was organized in Jeddah in November 2010. There were 20 attendees in the workshop; all were project managers, either in government organizations or private construction companies. The objectives of the workshop were 1. To introduce the benefits and challenges associated with offsite construction to the audience. 2. To document the perceptions associated with off-site construction in the construction industry in Saudi Arabia. 3. To identify the major barriers to the implementation of off-site construction in Saudi Arabia. 4. To propose a way forward in implementing off-site construction in Saudi Arabia. Workshop Execution

Structural Behavior of Waffle Bridge Deck Panels and Connections of Precast Ultra-High-Performance Concrete

The AASHTO strategic plan in 2005 identified extending the service life of bridges and accelerating bridge construction as two of the grand challenges in bridge engineering. Previous studies have shown that using a prefabricated full-depth precast concrete deck system not only accelerated the bridge deck rehabilitation process but also extended its service life with reduced user delays and lower life-cycle costs. The recent use of ultra-high-performance concrete (UHPC) in the United States for bridge applications has proved efficient and economical because of its superior structural and durability characteristics. On the basis of the advantages of UHPC and precast systems, a design for a full-depth UHPC waffle deck panel system was developed. A full-scale, single-span, 60-ft long by 33-ft wide prototype bridge with full-depth prefabricated UHPC waffle deck panels has been planned as a replacement bridge in Wapello County, Iowa. In support of this project, structural performance and constructability of the UHPC waffle deck system and its critical connections were studied through an experimental program at Iowa State University. Two prefabricated, full-depth, UHPC waffle deck panels were connected to two 24-ft long precast prestressed girders, and the system was tested under service, fatigue, and ultimate loads. On the basis of the test observations and results and the experience gained from fabrication of deck panels and casting of UHPC infill joints (transverse and longitudinal), the prefabricated UHPC waffle deck system concept was found to be a viable option to achieve the goals of the AASHTO strategic plan.

Component sizing approach for the sandwich plate system

The sandwich plate system (SPS) is a bridge deck system consisting of steel face plates bonded to a rigid polyurethane core. SPS bridges are typically constructed as a series of pre-fabricated SPS deck panels compositely connected with traditional steel girders. The decks are thin, lightweight and modular, and can be tailored to numerous applications including both new bridge and rehabilitated bridges. With new system, there exist hurdles in the implementation; for SPS, the primary challenge is the lack of an established design method for the panel cross-sections. Presented herein is a method for sizing SPS panel sections for bridge applications. This method is limited to the selection of steel plate and core dimensions, subjected to American Association of State Highway and Transportation Officials (AASHTO) limit states of serviceability, strength and fatigue and does not consider connections or bond aspects of the system. The sizing approach considers the deck panels as plates with variable boundary conditions subjected to the loading conditions of the AASHTO Load Resistance Factored Design (LRFD) bridge design specification. Results from this study indicate that the component sizing for SPS deck panels is controlled by stiffness and that plates selected to satisfy the AASHTO limiting deflection criterion will also be adequate for the remaining serviceability, strength and fatigue limit states.

Guadua angustifolia frames' performance when stiffened with precast adobe panels

Studying the structural behaviour of adobe systems in Colombia became extremely relevant after the 1999 earthquake in Armenia due to these systems' good performance during seismic events. These studies were aimed at modernising adobe house construction (by increased use of technology) and providing minimum requirements for them having a suitable degree of seismic resistance, thereby avoiding their collapse. Besides, if it is taken into account that guadua (the main material used in these systems) represents a cheap and profitable material which is socially and culturally-accepted in most of the country, then one has an alternative, unconventional material available which may be suitably used in constructing cheap, functional and safe housing (its limitations and best use having been identified). The foregoing gave rise to the present investigation in which an experimental evaluation was made of a guadua frame system using two types of prefabricated panels in adobe, under horizontal load. Two fullscale frames were built with guadua at the Universidad Nacional de Colombia's School of Engineering in Bogota; the frames' ability to dissipate energy and support inbuilt rigidity (by stiffening them with precast adobe) was tested and strength-deformation curves were experimentally found. Extremely encouraging results were obtained as drift was reduced by roughly 50% and the system's resistance was increased by more than 40%. Mathematical models were also constructed for comparing experimental results with analytical ones.

Investigation of prefabricated bridge systems using reduced-scale models

In 2001, the Bridge Office of the Ministry of Transportation of Ontario, Canada, initiated a research project to investigate the use of prefabricated bridge technology as an innovative approach to bridge construction and rehabilitation. Two potential prefabricated systems were investigated: prefabricated composite slab-on-girder beam elements connected with cast-in-place concrete closure strips and full-depth prefabricated concrete deck-slab panels laid across new or existing girders and connected with cast-in-place concrete closure segments. The proposed systems are applicable to bridges that use steel or concrete girders and trusses as longitudinal loadcarrying members. This paper presents the findings of a series of laboratory tests that were performed on scale models to study the overall structural behavior of the bridge systems under service loads, the long-term load effect on the longitudinal cold joints, and the ultimate punching-load capacity of the concrete deck slab. The test specimens were subjected to a minimum of 7 million load cycles, after which ultimate-strength tests were conducted on the deck slabs. Overall, the test results demonstrated the excellent performance and integrity of the prefabricated bridge systems under the applied test loads.

Fire behaviour of cross-laminated solid timber panels

Cross-laminated solid timber panels represent an interesting technical and economical product for modern timber structures. The use of large prefabricated cross-laminated solid timber panels for load-bearing wall and floor assemblies has become increasingly popular in particular for residential timber buildings. The fire behaviour of cross-laminated solid timber panels has been experimentally and numerically studied during two different ongoing research projects carried out at the Institute of Structural Engineering of ETH Zurich, Switzerland and the Trees and Timber Institute CNR-IVALSA in Trento, Italy. The paper presents the main results of the experimental and numerical analyses. Particular attention is given to the comparison of the fire behaviour of cross-laminated solid timber panels with homogeneous timber panels. The results of the analysis have shown that the fire behaviour of cross-laminated solid timber panels depends on the behaviour of the single layers. If the charred layers fall off, an increased charring rate needs to be taken into account. The same effect is observed for initially protected timber members after the fire protection has fallen off. Thus the fire behaviour of cross-laminated solid timber panels can be strongly influenced by the thickness and the number of layers. Further vertical structural members (walls) may show a better fire behaviour in comparison to horizontal members (slabs).

Acoustical vibration characterics of prefabricated panels employed in industrialized construction

With the development of industrialized steel construction, new constructive elements have been brought not only to the market, but to the everyday construction site as well and, in this way professionals and users have questioned their efficiency. In respect to vibrations in floors, what can be detected is that floor structures are thinner and a decrease of the mass in the horizontal closing panels and the utilization of new materials and systems have led them to have lower natural frequencies, and so are nearer to the frequencies produced by walking. This decrease of mass of the closing panels also lead to a considerable weakness in terms of acoustical insulation, which can cause unfavorable conditions and discomfort. Thus, it becomes necessary to do detailed studies of the efficiency of the vibration and acoustical performance of the new systems to obtain the characterization and the qualification parameters in order to optimize their use. This study does a comparative evaluation of some kinds of horizontal and vertical closing systems in respect to the vibrational and acoustical insulation performance.

Perforation Resistance of High-Strength Concrete Panels

This paper presents the results of experimental investigations about the influence of concrete composition on the impact resistance of high-strength concrete prefabricated panels. Main test variables were the type of aggregate, the maximum aggregate diameter, the grading curve, and the binder content. The tests were accomplished using high-speed projectiles with a hard core. The impact resistance of the panels was evaluated by measuring the volumes of the craters caused by the projectile's impact and the remaining energy of the projectile. With regard to the aggregates, the use of quartzite and basalt gives a good ratio between costs of production and the resistance of the panels. The binder content and the grading curve of high-strength concrete mixtures were adjusted to each application. The maximum aggregate diameter were to be equal to or larger than the projectile's diameter to obtain a sufficient impact resistance.