Glass fiber reinforced gypsum (GFRG) walls are prefabricated large gypsum panels with hollow cores. Developed in Australia in the early 1990s and subsequently adopted by other countries, including China and India, this material is used in residential, commercial, and industrial buildings. GFRG walls are used both architecturally and structurally as walls and slabs, with no columns and beams required. They have already found wide application, even without mature structural design codes, largely because of their environmental friendliness. In India, GFRG walls have been approved by the World Bank as being eligible for Carbon Credits under the Kyoto Protocol. GFRG panels are a composite material consisting of gypsum plaster and glass fibers. When the cavities are filled with reinforced concrete, the interaction between the concrete and the GFRG panels produces another composite. As a result, the structural behavior of GFRG walls and the associated building system are more complicated than that of conventional structural systems. This paper presents the results of extensive experimental and theoretical investigations into the structural behavior of GFRG walls, and offers a structural design methodology for GFRG walls and the associated building system.
Known as Rapidwall in the building industry, glass fiber reinforced gypsum (GFRG) walls were developed in Australia in the early 1990s. GFRG walls are hollow machined panels made of modified gypsum plaster and reinforced with cut glass fiber. A typical panel and GFRG building is shown in Fig. 1. During the manufacturing process, glass fibers of about 300–350 mm in length are randomly distributed inside the panel skins and in the ribs. The fiber volume in the panel is about 0.8 kg per square meter of wall surface area. The physical properties of standard GFRG panels are listed in Table 1.In building construction, standard large GFRG panels are tailor-cut in the factory into building components that may have window and door openings. These components are then transported to the construction site and erected in a similar way to the construction of precast concrete panels. The cavities (hollow cores) inside the panel can be filled with various materials, such as concrete or insulation materials, to serve different purposes, such as to increase the strength or improve the thermal and sound insulation of the walls. In a GFRG building, most or all the components are constructed with GFRG panels, which means that the walls serve as a combination of architectural partitions and structural walls. Research has shown that GFRG building assemblies have a smaller embodied energy (EE) coefficient and CO2 gas emission (from the manufacturing of panels to the completion of building construction) than other traditional building construction materials, such as bricks, reinforced concrete, and precast concrete panels [1]. GFRG paneling is thus considered to be a green product that helps to save energy and protect the environment.
GFRG buildings are a new type of construction to which conventional structural theories and design codes are not applicable. Therefore, extensive research work has been undertaken by the author, both in Australia and Hong Kong, to gain a better understanding of the structural behavior of GFRG walls and the associated building system with a view to developing design guidelines. A comprehensive investigation that included about 120 experimental tests and theoretical studies was completed at the University of Adelaide and the University of South Australia in 2002 [2], and structural design theories and guidelines were developed based on this investigation [3], [4], [5], [6] and [7].
Large-scale experimental tests, similar to those conducted in Australia, have also been undertaken in India at the Indian Institute of Technology Madras [8] and [9]. The Indian tests also included six full-scale shake table model tests simulating two-story houses [10]. In China, large-scale experimental tests similar to those in Australia and India have been completed at Tianjin University [11], [12], [13] and [14] and Shandong Construction University [15] and [16]. A full-scale five-story GFRG building was constructed for a destructive test at Shandong Construction University [17], and an in-situ, non-destructive dynamic test was conducted on a recently built six-story GFRG building in Tianjin [12]. These Chinese tests were part of a combined Australian-Chinese test program aiming to develop Chinese design guidelines for GFRG construction.
This paper reports experimental and theoretical studies on GFRG walls and associated structural system undertaken by the author in Australia and Hong Kong since 2002. It should be noted that the experimental results for the axial and shear testing of GFRG walls have been published separately, but for completeness the results of the two tests are briefly introduced in this paper.
This paper has introduced GFRG walls and the associated building system, with the structural characteristics of that system described. Experimental and theoretical investigations undertaken by the author since 2002 have been presented from the structural element and overall building performance points of view.
The accurate calculation of the in-plane flexural strength of GFRG walls is a difficult, if not impossible, task due to the relative slips between the infill concrete cores and the GFRG panel. An upper and a lower bound solution for the in-plane flexural strength have been presented, of which the lower bound solution is most suitable for design use. Based on the results of the experimental and theoretical investigations and on a rational analysis of the existing design frameworks, a methodology and associated procedure for the design of GFRG buildings has been offered.