Peer-to-Peer Standards Exchange

I'm analyzing an existing long-span steel roof truss from which a Contractor has proposed to suspend a temporary scaffolding platform in order to perform utility work at the roof level. Using ASCE 37-14 to determine the loads and load combinations, I'm multiplying the ground snow load by 0.8 since the construction period is 5 years or less. However, ASCE 37 section 2.3.1 provides no guidance on ASD load combinations including snow load during construction combined with other loads. Specifically, I'm interested in guidance for combining scaffolding construction live load with roof snow load. In the absence of ASCE 37's guidance on this item, I'm using ASCE 7-16 load combinations and considering construction live load as L. Therefore, I'm using D + .75*L (construction live load) + .75*S (w/. 0.8 reduction of ground snow load). Does anyone have additional guidance or thoughts on this? Thanks.

Hi,

Make sure that everyone knows what the conditions are based on the results of your calculations.

In 5 years there is the possibility of many things happening.  For example, if they need to do work on the roof then the live load might exceed capacity if they don't stop work on the utilities being supported from below.

Make sure to check ice and ponding loads as well.  Are you sure that with this roof there are no wind loads in the direction of the gravity loads?  For  a project I worked on we had wind tunnel results and there were negative and positive pressures on the roof.

Make sure the owner has a plan to ensure that the conditions are not forgotten if there is a change in personnel during those 5 years.