Adjusting the wind generator parameters

The main dialogue of the wind generator enables the user to control the process of load generation. The meaning of individual parameters and control buttons is given in a brief table below.

$image\Wind_load_gener.gif$

The dialogue also displays the contour of the structure or its part (i.e. the planar section) that will be considered for the load generation. 1D members that will be subject to the generated load are drawn in thick line. The active 1D member is in red while the others are in green. The remaining 1D members of the structure, i.e. those that will not be subject to the generated wind load, are drawn in thin line.

If the wind load is to be generated to a specific code, it is possible that some of the loaded 1D members are divided into several intervals. The division is controlled by the regulations of the particular standard.

In addition, the user may decide to divide any of the existing intervals or 1D members into two parts. This division may be applied recursively, so any of the 1D members can be divided into as many intervals as necessary. And vice versa, any of the two adjacent intervals may be connected to create one interval and ultimately a single 1D member.

Hatches drawn at the thick-line, i.e. loaded, 1D members indicate the direction of the generated load. Hatches attached to a 1D member from outside of the structure contour mean that the load produces pressure. Hatches drawn on the inside of a 1D member indicate that the load produces suction.

Parameters

Direction	This parameter tells the generator the direction from which the wind is blowing. It can be blowing from the left or right side of the building section. The selected direction is also indicated by a hatched rectangle drawn at the left or right side of the structure.
Inside coefficients	These coefficients define the effect of the wind inside the building. None = there is none overpressure or underpressure inside the building Overpressure = there is overpressure inside the building Underpressure = there is underpressure inside the building See Note at the end of the chapter.
Preference	This parameter defines the preference, or priority, for places where the code allows for selection from multiple values: Pressure = greater values of shape coefficients will be preferred Suction = lower values of shape coefficients will be preferred
Frame distance	The distance between two adjacent frames defined before opening the dialogue may be reviewed and/or edited here.
Terrain level	Only the part of the structure that is ABOVE the terrain level is considered in the load generation. The terrain level parameter may be thus used to exclude some part of the structure from being subject to the generated wind load. The terrain level is always defined in global co-ordinate system.
Coefficients	This group defines shape coefficients. A set of control buttons (see below) accompanies the input boxes. Outside = adjusts the value of shape coefficient outside the building Inside = adjusts the value of shape coefficient inside the building

Control buttons

Set coefficients	The value of shape coefficients typed in the Outside and Inside input boxes, is assigned to the active interval or 1D member of the structure contour (i.e. to the 1D member drawn in red thick line).
Next	The focus is shifted to the next interval or 1D member. The next interval or 1D member becomes active.
Previous	The focus is shifted to the previous interval or 1D member. The previous interval or 1D member becomes active.
Divide	The active interval or 1D member is divided in the given point. The point of division is defined in a dialogue that opens after the action is started.
Connect	This function is applicable only if some 1D members have been already divided. The function does nothing, if undivided 1D members form the contour of the structure. Two intervals are joined together. The rule is that the active interval is preserved including the coefficients and the next interval is linked to it.
Regenerate	This button resets the program default values. It sets all the coefficients to their default values and deletes all possible intervals created by the user.
Print picture	The current picture can be printed on an installed printer.
Change (terrain level)	The level of terrain can be adjusted in these input boxes. It may be useful e.g. if the structure has not been defined in zero-level (measured in the global co-ordinate system) or if a part of the structure is protected by surrounding buildings. The wind load is always generated only on 1D members that are ABOVE the defined terrain level. The terrain may be inclined which can be defined by different values for terrain level on the left and right side of the structure.

Note: Czech standard (CSN) does not take the Inside coefficient into account, even though it may be defined.