Structural performance evaluation under extreme wind conditions has been a crucial issue for structural designs, especially for those with asymmetrical shapes. Prominent torsional moments of irregular shape buildings in these conditions could be a major cause of the twisting motions of the building, of which the structural members at the corners can experience much larger deformations than those of the others. A combination of the three load components is of significance to calculate the resultant top drifts that serves as the performance criteria for structural design.

Supposing that the probability density function of three load components follows the multivariate normal distribution at each incident wind direction, the statistical threshold of correlated wind-induced loads based on...[ Read more ]

Structural performance evaluation under extreme wind conditions has been a crucial issue for structural designs, especially for those with asymmetrical shapes. Prominent torsional moments of irregular shape buildings in these conditions could be a major cause of the twisting motions of the building, of which the structural members at the corners can experience much larger deformations than those of the others. A combination of the three load components is of significance to calculate the resultant top drifts that serves as the performance criteria for structural design.

Supposing that the probability density function of three load components follows the multivariate normal distribution at each incident wind direction, the statistical threshold of correlated wind-induced loads based on wind-tunnel-measured time history samples forms an ellipsoid in 3-dimensional (3D) space. A polyhedron enclosing all collective ellipsoids corresponding to a number of incident wind directions serving as the design envelope is depicted where each vertex point represents one load combination case. A drift-oriented evolutionary refining load combination approach is employed where load cases are densified in the vicinity area of the vertex with maximum top deflection.

For a torsional sensitive structure, it is desirable to deal with the layout of the structure and strengthen the torsional resistance in the first place. Additionally, a rigorously derived optimality criteria (OC) method is employed to search for the optimal distribution of structural element sizes, meanwhile minimizing the total cost of the structure as well as satisfying certain performance constraints. Once the structural system is improved, a substantial reduction of wind loads can be anticipated and the wind-induced structural loads need to be updated in order to avoid any overestimation or underestimation. A 40-story L-shape building and a crescent shape tall building were tested in the wind tunnel using high frequency base balance (HFBB) method to derive wind loads and the integrated optimization framework is applied. The examples results will demonstrate that a remarkable improvement of the structure layout can significantly reduce the twisting moments acting on the building, which verifies the impact of structural properties on wind-induced structural loadings, and the integrated design approach is not only able to accurately acquire critical load cases but also capable of producing a cost-effective structure form.