Stochastic Nature of Building Live Loads

by Ross B. Corotis, (M.ASCE), Assoc. Prof.; Dept. of Civ. Engrg., Northwestern Univ., Evanston, Ill.,
Victor Jaria, Formerly, Research Asst., Dept. of Civ. Engrg., Northwestern Univ., Evanston, Ill.,

Serial Information: Journal of the Structural Division, 1979, Vol. 105, Issue 3, Pg. 493-510

Document Type: Journal Paper


A general stochastic analysis of live loads includes areal and temporal effects. Spatial correlation of survey load is evaluated for office loads in the National Bureau of Standards Administration Building. No practical correlations are found for separations of 15 ft (4.6m) or more. The effect of additional correlation due to common use is investigated through a theoretical model, and it is found that for most building types the total correlation between two rooms of similar, but unspecified, occupancy is no greater than 0.4. The variation of the mean survey load with room size and the standard deviation of the survey load with area are both examined, and the latter is found to be well modeled by a log-linear model. The time varying behavior of live load is hypothesized with sustained plus extraordinary components. The sustained part consists of a nonstationary trend within each tenancy and stationary fluctuations. The extraordinary load must be physically derived, and is separated into a controllable part and an emergency part.

Subject Headings: Correlation | Geomatic surveys | Stochastic processes | Live loads | Load factors | Standards and codes | Mathematical models | Emergency management

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