Using HFPI to Determine Wind-Induced Dynamic Effects of Tall Buildings – Structural Loads and Accelerations
HFPI (High Frequency Pressure Integration) is a relatively new data analysis method which, for tall buildings, enables wind tunnel pressure measurements to be used to determine time-varying structural loads and building accelerations. From a wind engineering perspective, the importance of this method is that enables us to “junk” many assumptions and empirical expressions which – in the past – have had to be made. Better still, HFPI removes the need for the “load factors” that combine orthogonal forces and twisting moments.
From a Structural Engineer’s point of view, HFPI enables worst-case Static Equivalent Structural Loads (SESLs) to be determined. This means that SESLs (with appropriate factors of safety) can be input directly into FE models to check the structural integrity. In fact, the original motivation for this work was for a Structural Engineer to “optimise” a building’s structural design, having been given only one set of wind tunnel test results.
With the help of a Brazilian colleague (Sergio Stolovas), over the last couple of years BRE have been developing the HFPI technology, and using it to help design iconic tall buildings in Brazil. However, the volume of the input data required, and the sheer volume of the data output has meant that the practical application of HFPI is not straight forward. However, we believe now that the application of HFPI can be realised in a way that is statistically robust.
This presentation will include a brief dissertation about HFPI (i.e. what HPFI is, what data input is needed, what output is produced); an example of the input data, and the results obtained using HFPI will be given. The presentation will then consist of a discourse about the practical and theoretical difficulties that HPFI has thrown up, and how these problems have been overcome.
Wind loads on offshore vessels & platforms
The wind loading acting on the topside of offshore structures plays an important role during installation and operational conditions and, in regions affected by extreme wind events, it represents a highly influential factor in the design process. During the early design stages, some designers adopt semi-empirical methods in order to estimate wind loads. While these approaches can, in principle, lead to a reasonable first estimation, due to the growing size and complexity of the topside structures they are becoming less and less reliable and could result in an under-estimation of the wind loads. To date, wind tunnel tests are generally considered to provide the most accurate method for wind load predictions for offshore structures and ships.
The talk will present a general introduction to the wind loads on the offshore structures and also include the importance of the design and build process of the wind tunnel models and wind tunnel set-up (including the marine boundary layer and its modelling).
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