Determination of optimum snow loads of roofs in the Eastern Black Sea region

SUMMARY Determination of Optimum Snow Loads of Roofs in the Eastern Blacksea Region In Turkey especially in the Eastern Blacksea region, it has been frequently met with roof damages and collapses due to snow loads. Most important reason of this is that the design snow loads have not being determined correctly. Optimum design roof snow load is determined by multiplying ground snow load with conversion coefficients that can be obtained according to the factors effect the accumulation of the snow on the roof. The aim of this study is to constitute a ground snow load map for the Eastern Blacksea region in order to evaluate roof snow loads correctly, to lead the future studies to constitute ground snow load maps for the other regions in Turkey, to compare the conversion coefficients from American ANSI/ASCE 7-98 with those from Turkish codes, and to suggest some revisions of Turkish codes if necessary. In this study, 50-year mean recurrence interval (MRI) ground snow loads for 32 DMI (State Meteorological Service) stations located in the Eastern Blacksea region and neighboring cities were determined with snow data collected from the stations using the latest developed statistical analysis methods. Ground snow load map of the Eastern Blacksea region was constituted using GIS (Geographically Information System) techniques in order to obtain a representation of the variation of the ground snow load in the region using 50-year snow loads determined for each station. Roof snow loads for various types of roofs were derived using the conversion coefficients from ANSI/ASCE 7/98, TS 498 and TS 7046. According to the ground snow load map constituted and the results obtained in the study, it can be concluded that ground snow loads suggested by TS 498 for Eastern Blacksea region are completely unsafe, and TS 7046 that suggest statistical analysis only to evaluate ground snow loads is not economic for each case. It is also observed that conversion coefficients suggested by the available codes to determine roof snow loads from ground snow loads do not give optimum result for every kind of roofs since the conversion coefficients reflect geometric characteristic of the roofs only. Key Words: Ground Snow Load, Roof Snow Load, Statistical Analysis, GIS, TS 498, TS 7046, ANSI/ASCE 7-98 VII