by Dave Leister Design Tech at RedBuilt™
When RedBuilt sold a large dormitory project, we thought it would be like any other project. However, when it came time to prepare the layout drawings and calculations for the project, something caught my eye: one of the details showed Simpson ITS joist hangers attached directly to a light gauge steel joist track. I hadn’t seen this application in my 12 year career. So, I consulted my Simpson catalog and discovered that there are no published values for this application.
To find a solution to the problem, I called Thom Murphy with Simpson. Thom confirmed that they did not have values for this particular application. The initial simple solution was to replace the steel joist track with tube steel, a standard application for the ITS hanger. However, given the scale of the project, the change proved to be very costly. So, we went back to the drawing board, and asked Simpson if they would be willing to test the hangers for the application. Thanks to our long history of working together and mutual benefit we would gain, Simpson agreed to perform the test.
Getting the testing in a timely fashion was critical to maintaining the project schedule. Dustin Muhn (Simpson –Pleasanton,CA) coordinated an effort to test the ITS to get usable data to continue the floor design. Processes such as these touch many people before getting the final answer; from concept, to test design, building the test specimens, performing the tests, and finally compiling the test results. Simpson is fortunate to have a wide area of expertise that included cold formed steel, engineered wood products, and the knowledge and facility to run an appropriate test. In the meanwhile, RedBuilt continued to work with the EOR transforming a complex set of structural plans into a set of shop drawings.
The testing demonstrated that ITS hanger capacity on the light gauge steel track has a capacity limited by the required connection (4 – #10×3/4”self-tapping screws). Although the capacity in this application is approximately 65% of the published capacity with nails on a wood plate, it was sufficient for most of the applications in this project. The early identification of the potential issue and the rapid response by all parties not only kept the project on track while simultaneously keeping costs in check, but more importantly, prevented the use of hangers in some locations where they would have been over capacity. In the end, the customer got just what they needed; an economical hanger and information in time to keep the project moving forward.