Determining the empirical model for estimating the permanent deformation in flat roof panels under hail impact

Abstract

Hailstorms cause significant economic losses every year all over the world. Roofs and many other exposed installations can be affected by the impact of hailstones. However, steel resistance to hail impact has not been sufficiently investigated. Predicting the result of hailstone impact is difficult. This can result in significant permanent deformation of the roof. This study aims to develop plastic deformation prediction models for plate structures investigating the plausibility of an equation predicting the dent depth as a function of kinetic energy and yield strength while also addressing the shortcomings of its testing scheme. Causes, results, and solutions to be implemented in the future are also addressed in this work. The proposed equation aims to provide an approximate value for the ratio of dent diameter to dent depth as an input to simplify the solution for the dent depth. For this goal, a new method of making artificial hailstones has been successfully conducted based on the characteristics of natural hailstones. The outcomes of the empirical model were further validated using experimental observations in this study. It was found that within the range of steel sheets tested, the theory gave accurate estimates of the dent depth before the impact. The proposed equation provides insights into the effect of hail impacts on roofs and enables the use of new design methods for the hail resistance of steel sheeting.