Design Live Loads for Office Gathering Spaces

Abstract

Since the 1800s, there have been live load surveys and analyses carried out, particularly of area-dependent loads in office buildings. While some occupancies have received careful examination, there has been no systematic review and consideration of reliability-based scenarios for office gathering space live loads. The results of the research reported here indicates (supports) a more consistent, reliable, and economic design load for office gathering spaces in buildings. These results provide the theoretical and practical basis for design live loads for gathering spaces within offices, a step toward possible enactment in the current standard, and subsequently by adoption into the International Building Code and materials standards. Following a review of historical load surveys and theoretical models, the paper presents models and observations of crowding, serving as a basis for a different approach for such areas, including a Delphi among leading design firms in the United States. The paper concludes with recommendations for a new live load use category for gathering spaces for offices. Modern office usage often contains work spaces for meeting, gathering, and collaboration. The current standard for minimum design loads and associated criteria for buildings and other structures does not directly address this situation. Interpretation has led to conflicting requirements for the design loads of such spaces, including the possibility of assigning them as assembly areas. This can lead to overdesign and uneconomical structures. This research reviews historical office surveys with an emphasis on assembly spaces, presents the results of a Delphi of design firms throughout the United States, and contains a stochastic maximum load analysis. These various assessments lead to a consistent evaluation of plausible loads for such spaces, and a recommendation for a new subcategory in the standard live load table. The study recommends treating these spaces similar to general offices, with a basic live load of 2.39 kN/m2 (50 psf), and permissible live load reduction as is currently in the standard for offices. Exception is made for such work spaces that are directly accessible from outside and intended for use by the general public.