No abstract

In the risk assessment of buildings against severe wind loading, the vulnerability component of risk is highly affected by the geometry of the structure. Parameters such as the height, width, length, aspect ratio, eaves length, and roof slope, affect the pressure distribution around the structure, which in turn affects the response of galvanized iron (GI) roof covers to wind loadings. In developing countries, there is a large variation in the building geometric parameters which poses a challenge in determining the archetypes that would best represent the building population for risk assessment. This paper aims to develop and propose a method in determining the building archetypes based on its geometry. The hierarchy for grouping of geometries started with the roof type. These were gable type roofs, mono-slope type roofs and hip type roofs. The building datasets per roofing type were then clustered using a two-stage approach involving Hierarchical and K-means clustering which were based on the aforementioned geometric parameters. These algorithms will aggregate buildings having similar sets of geometric parameters but the number of clusters must be specified. In order to determine the optimal number of clusters, this study employs various validation tools or measures namely – dendrograms, variation of the variance ratio criterion (VRC) across number of clusters, validity indices such as, Davies Bouldin, Silhouette and Calinski Harabasz, and the elbow method. Although guided by these validation methods, the final selection of the number of clusters were determined considering computational time and resources. To define an archetype, the mean values of each parameter per cluster were selected. Resulting to 5, 3, and 3, archetypes for gable, hip, and mono-slope roof buildings, respectively. The selection of the archetype was further evaluated by investigating its effects on the vulnerability of GI roof covers in order to see how distinct each archetype would behave. A Kruskal Wallis test on the vulnerability curves of the different building archetypes showed that there is a significant difference between vulnerability curves under a roof shape category, which reinforces the distinction between the selected building archetypes.

For the Philippines, a country exposed to multiple natural hazards like severe wind, sustainable development includes resiliency. Severe wind hazard is brought by tropical cyclones in the Western Pacific, known as typhoons, that frequent the Philippines. Therefore, adequately evaluating the wind hazard and its impact is crucial for sustainable building design. Acknowledging the impacts of climate change on said hazards would require adaptation to its consequences which necessitate a deeper understanding on the changing behavior of typhoons in recent years. For this study, detailed wind information from the Japan Meteorological Agency from 1977-2021, the Holland-B parameter, and the radius of maximum wind speed for each typhoon, are determined for simulation of the regional cyclonic wind field. The analysis of the Holland-B parameters, which represent the steepness of the pressure gradient and tropical cyclone convection, suggest that the Holland-B parameters have been increasing since 2011. The regional wind fields caused by the typhoons also suggest an increasing trend in severe wind hazard. Seasonality for the location of severe wind hazard is also observed, with the Southern Philippines experiencing an increase (decrease) during the Northeast (Southwest) Monsoon season, and the Northern Philippines experiencing an increase (decrease) during the Southwest (Northeast) Monsoon season.

The Northwestern Pacific Ocean Basin is home to the strongest tropical cyclones in the world, called typhoons. The Philippines is situated as the gateway for the typhoons developing in the Northwestern Pacific Basin. As a result, the country is being exposed to the risk brought by significantly strong typhoons that occur more than once annually. Lightweight buildings, particularly wooden buildings, and their structural components are the most vulnerable to severe winds. This study aims to perform vulnerability analysis on wooden buildings, by developing vulnerability curves that relate the magnitude of severe winds to the variation of damages and by establishing the probabilities of identified damage states of the buildings at certain wind speeds - which are called fragility curves. This study employs an improved framework from a heuristic-empirical-computational methodology previously used in determining GMMA-RAP vulnerability curves. This enhanced framework uses a component-based Monte Carlo vulnerability analysis to determine the improved vulnerability curve to account for the statistical variations of documented building damage from severe winds. A maximum, average, and minimum vulnerability curve were developed by fitting a cumulative lognormal distribution function wherein the mean parameters are 250.92, 425.89, 148.80, and the variance parameters are 0.579, 0.257, 0.433, respectively—the functions used an offset of 72 kph for all the developed curves. The developed curves were then compared to empirical field survey data, wherein 71.43% of the empirical data was within the developed envelope.

For the Philippines, a country exposed to multiple natural hazards, such as severe winds, sustainable development includes resiliency. A severe wind hazard is raised by tropical cyclones in the Western Pacific, known as typhoons, which frequent the Philippines. Therefore, adequately evaluating wind hazards and their impact is crucial for sustainable building design. Acknowledging the effects of climate change on said hazards requires adaptation to their consequences, which necessitates a deeper understanding of the changing behavior of typhoons in recent years. For this study, detailed wind information from the Japanese Meteorological Agency from 1977 to 2021, the Holland-B parameter, and the radius of maximum wind speed for each typhoon, are determined for simulation of the regional cyclonic wind field. The analysis of the Holland-B parameters, which represent the steepness of the pressure gradient and tropical cyclone convection, suggests that the Holland-B parameters have been increasing since 2011. The evaluation of the maximum regional wind fields and the return period wind fields caused by typhoons also indicate an increasing trend in severe wind hazards. Seasonality for the location of severe wind hazards is also observed, with Visayas and Mindanao experiencing an increase (decrease) during the Northeast (Southwest) Monsoon season and Luzon experiencing an increase (decrease) during the Southwest (Northeast) Monsoon season.