Impact of Table Size on the Performance of Thermo-Plastic Roo ng Systems Under Wind Uplift Pressures


Department of Civil Engineering,University of Tehran


Roo ng systems have always been vulnerable to strong wind uplift pressures. Wind forces have
dynamic e ects on structures, as they change in time and space. Therefore, a dynamic means of
evaluating roo ng systems is necessary in order to identify the component of the system having
the least resistance to wind uplift forces. Although researchers worldwide have conducted tests
on roo ng structures, they have all used various table sizes, as there is still no standard chamber
size for experimental purposes. This paper aims to study the impact of table size on roo ng
system performance. To achieve this objective, extensive analytical work has been conducted
to investigate the performance of roo ng systems subjected to wind pressure. Analytical results
compared well with those obtained from experimental work, validating the numerical modeling.
This paper presents some of these result comparisons. It was found that an increase in table
width beyond a certain level, about 3 m for cases considered here, did not signi cantly change
the results, while the rate of fastener load change might be high for a smaller table width. This
speci c limit depends on the roo ng system con guration. Furthermore, a larger membrane
width (fastener row spacing) would increase the width of the ideal table. Ideal table sizes were
also suggested for various con gurations having a TPO (Thermo-Plastic Ole ns) membrane and
correction factors were eventually developed for di erent table sizes.