Design of Steel Wall Studs with Service Holes

Installing plumbing and electrical services into residential buildings requires holes to be located in wall studs. Holes can be pre punched during production or cut on site. Generally 2 or 3 holes up to around 30 mm in diameter are required in each stud. It is often convenient for these holes to be relatively close together. Currently the Cold formed steel structures standard AS/NZS 4600:2005 (Standards Australia, 2005) gives design formulae for holes in channels up to 0.7 times the web depth, provided that the clear distance between holes is greater than or equal to 450 mm. Members containing holes that fall outside of these limits are required to be designed using testing or appropriate rational engineering analyses. A minimum hole spacing of 450 mm is not always suitable for the placement of service holes in wall studs, however since service holes are usually much smaller than 0.7 times the web depth a closer spacing may not structurally compromise the wall stud. This paper compares the structural performance of wall studs containing a range of hole sizes and spacings. Wall studs have been analysed and tested using a realistic combination of axial and bending loads. Suggested minimum spacing for holes up to 0.5 times the stud depth are presented.