BOS 536-3:2014

Description

The scope of application of this part of BOS 536 falls within the general scope of application as given in BOS 536-1. Scope of BOS 536-3 1.2.1 This part of BOS 536 gives guidance on the determination of natural wind actions for the structural design of buildings and industrial structures including the entire structure, part of the structure, or elements attached to the structure. 1.2.2 This part of BOS 536 is intended to predict characteristic wind actions on land-based structures and includes the following: n buildings and structures with an overall height of up to 100 m; n elements of buildings and structures having a natural frequency greater than 5 Hz; and n chimneys with circular cross-sections, with heights of less than 60 m and a height to diameter ratio of less than 6.5. 1.2.3 This part of SANS BOS 536 does not cover the following structures: a) structures and buildings higher than 100 m; b) dynamic effects and design of dynamically sensitive structures (for example slender chimneys); c) off-shore structures;d) bridge structures;e) structures and buildings of unusual shapes; f) structures, or their components, which are not fixed permanently but are designed to accommodate movement (for example, revolving antennas, telescope dishes and movable roofs); g) high risk structures (for example those containing nuclear or biological material); or h) transmission lines. 1.2.4 This part of BOS 536 does not cover wind loads and wind effects due to high intensity winds, for example, tornadoes or micro-bursts.
NOTE The high intensity winds are particularly rare and localised events, therefore, having a very small probability of occurrence at specific geographical location. However, wind forces generated by short duration gusts can be significantly greater than those considered in the international standard design practice. This part of BOS 536 does not cover designs assisted by testing and measurements where wind tunnel tests or properly validated numerical methods (or both), are used to obtained the load and response information, based on appropriate models of the structure, topography and the boundary-layer wind conditions.
NOTE Design standards are not able to consider the infinite permutations and combinations of building forms used in the modern design. The degree of applicability of the generic information included in the loading code to specific cases of structures to be designed needs to be assessed. In cases in which the agreement between the loading code information and the structure to be designed is poor, it is advisable to seek expert advice or design by testing (or both). This part of BOS 536 does not cover designs where the wind parameters appropriate to the specific site (for example a site which is significantly influenced by topography), as well as load response data have to be obtained from appropriate full-scale measurements.
NOTE In these cases the designer could consult appropriate standards such as EN 1991-1-4, or specialist literature.