Appeal 33747

Section 13.4 of ASCE 7-16

NONSTRUCTURAL COMPONENT ANCHORAGE
Nonstructural components and their supports shall be attached (or anchored) to the structure in accordance with the requirements of this section, and the attachment shall satisfy the requirements for the parent material as set forth elsewhere in this standard. Except where permitted in Section 13.6.12, component attachments shall be bolted, welded, or otherwise positively fastened without consideration of frictional resistance produced by the effects of gravity. A continuous load path of sufficient strength and stiffness between the component and the supporting structure shall be provided. Local elements of the structure, including connections, shall be designed and constructed for the component forces where they control the design of the elements or their connections. The component forces shall be those determined in Section 13.3.1. The design documents shall include sufficient information relating to the attachments to verify compliance with the requirements of this section.

Work proposed for Airport Way Police Training Facility is primarily for replacing the roof assembly on the existing building - but the City of Portland (owner) also wanted to improve maintenance staff safety on the roof with the addition of OSHA compliant railings - both mechanically fastened where cost effective and ballasted railings at very limited locations.
The proposed counterweighted (ballasted) railings provide added protection to personnel for maintaining rooftop equipment, skylights and clearing debris within 10’ of the edge of the roof. The roof is accessed by maintenance staff only. Linear feet of ballasted = approx. 902 lf vs. mechanically fastened = approx. 640 lf.

The existing concrete tilt-up walls were designed with a mix of low to medium height parapet walls at the flat roof. In the proposed roof replacement work some parapet walls need to be raised in height to capture the new (thicker) roof assembly that includes additional layers of insulation. At these locations (as noted on the plan) the built-up parapet wall is proposed to be 15” min to capture the new roof assembly and coping. The ballasted railings are proposed to provide OSHA-required fall protection at 42” high at these low parapet wall locations only. Mechanically-attached OSHA railings are proposed where existing parapet walls are 20” tall. Equivalent protection is provided by the ballasted railing system that is tested to meet the requirements for personal safety per OSSC 1607.9.1 per attached report. The counterweighted railing system is to be publicly bid with the complete scope therefore the product test results are provided for reference and will be procured with this manufacturer or an approved equal.

The existing concrete tilt-up exterior walls would require complicated structural upgrades in order to provide 42” tall parapet walls or to mechanically-attach OSHA railings in all locations. We have limited the ballasted railings to only the areas that would require more complicated modifications to the existing building.
Personnel accessing the roof are restricted to maintenance staff with OSHA safety training. At the front facade the existing marquee construction would require complete re-design to accommodate new mechanically attached OSHA railings and would alter the building elevation.