Development of Test Method for Determining Plasterboard Bracing Performance

Abstract

The Australian Residential Timber-Framed Construction standard (AS1684:1999) has recently been revised to explicitly define the bracing contribution of nominally fixed plasterboard clad walls as 0.45 kN/m for cladding on one side and 0.75 kN/m for cladding on two sides. These values clarify the allowance, which designers may rely upon for the presence of plasterboard and their inclusion in the standard infers a necessity for plasterboard products to at least meet these requirements. A review of the relevant Australian, ISO, and ASTM standards, as well as plasterboard manufacturers’ in-house quality control tests has established that these tests mainly focus on serviceability aspect of plasterboard (e.g., storage, transportation, and installation) rather than that of structural bracing performance. It has also been determined that there are no direct correlations between serviceability conditions and structural bracing performance of plasterboard. In fact, a limited set of data provided by the plasterboard manufacturers shows that almost no correlation exists between the current quality control tests and the most commonly measured parameter, the density of plasterboard. It has been concluded that current tests are inadequate to serve as control measures for bracing performance of plasterboard. Nonetheless, it must be noted that density is not the only parameter that may influence the bracing performance of plasterboard; other parameters such as linerboard strength and bonding between gypsum and linerboard may also affect the bracing capacity. This paper details a new test, termed fastener bearing test, which provides a method to evaluate the bracing capacity of plasterboard. The results of this test show a very high correlation with shear connection tests. The proposed test is practical and simple to perform as part of the manufacturing process, in addition to the current tests, without severe cost and time penalty to the plasterboard manufacturers.