Relationship between wind incidents and wind-induced damage to construction in West Java, Indonesia

Abstract

In recent decades, the wind has been a major contributor to severe damages to residential constructions in Indonesia. The province of West Java has the highest recorded wind-related damages in the country. Even more, the wind is consistently the second or third source of residential damage, which shows that there is a need to understand the nature of wind as a hazard. However, despite the many cases of destruction due to wind, the data of the destruction is not supported by the wind speed data of the area in question, which makes it difficult to understand how severe the wind condition at the time truly was. Under the classification of the Indonesian National Board for Disaster Management, all cases are classified under severe wind speed or windstorm, even when the wind data is non-existent. This paper explores incidents of wind damages in West Java and matches this data with estimated wind speed conditions obtained from numerical weather model ERA 5. This paper aims to investigate the relationship between wind incidents and wind-induced damage by estimating the wind speed at which wind incidents occur to clarify whether the occurrence is in accordance to the design wind speed, or the strong wind speed definition given by the law. The research was done using field data from the Indonesian National Board for Disaster Management and the West Java Regional Board for Disaster Management. The maximum gust wind speed was estimated from ERA5 reanalysis hourly data. From the analysis of 121 cases between 2011-2018, no gust wind speed that resulted in the damages is above the designated wind speed of 32.1 m/s. Even then, only 2% of the wind speed is above the strong wind definition by the National Board of Disasters at 12.5 m/s. The resulting fragility curve shows that even with a wind speed of 5 m/s and 8 m/s, there is a 50% and 90% possibility of wind-induced damages respectively.