Lightning strike probability and current simulation for simple structures and floating roof tank

Abstract

Air terminations must be strategically positioned at high-risk points to prevent lightning bypass. The likelihood of a direct lightning strike to points on a building can be evaluated using the dynamic electro-geometrical model (DEGM), which considers the geometric proximity of lightning orientation points in spaces around the structure to meshed points on the structure. This study evaluates the probability of a direct strike to simple structures and the maximum lightning currents that may strike the structure. The DEGM concept is applied within a defined lightning collection volume which saves computation time. Patterns that can lead to alternatives to DEGM are identified within the percentage strike probability for different heights of two cuboid structures. Three floating roof tanks of radii 20 m, 30 m, and 40 m are analysed. Four classes of lightning protection are applied for a simple building in compliance with the International Electrotechnical Commission guidelines using different heights of air termination rods for a gable roof structure. For class I, the lightning strike interception probability of the two rods is 99.96%, 99.90% for class II, 99.72% for class III, and 99.48% for class IV. Magnitude colour-coded 3D diagrams are presented to highlight strike probability and current variations.

Keywords

• Data pattern recognition
• Dynamic electro-geometrical model
• Lightning protection system
• Lightning strike probability
• Lightning current distribution
• Interception efficiency