Rapid Assessment of Snow Drifting Conditions Using Physical Model Simulations

Methods for evaluating snow loads on roofs are described within building standards and codes such as American Society of Civil Engineers 7 and the National Building Code of Canada. These recommendations are often simplified and generic in order to be applicable to most structures and, as a result, do not account for the unique aerodynamics that can occur around a structure. In addition, these codes and standards do not address serviceability concerns, such as accessibility to building entrances, nor identify where mechanical air intakes may be prone to snow ingestion as is common to buildings located in cold regions. Scale model testing within an open channel water flume allows for the rapid assessment of the building aerodynamics and snow drifting conditions for the purposes of design. This paper presents snow accumulation patterns representing a snowfall event from a single direction for a building with commonly seen geometries including roof steps, arched roofs, and a projecting tower with mechanical penthouse. Multiple test directions are presented to illustrate the influence of wind directionality and resulting building aerodynamics on snow accumulations at grade level, on roof areas, and where mechanical intake equipment is often sited.Parapets, canopies, and recommendations for mechanical air intakes for reducing problematic snow accumulations are presented and discussed.