Mexico Wind Code Options - CAESAR II - Help

Specifies the options available for the Mexico wind code.

Design Wind Speed

According to Paragraph 4.6.2, Isotach Maps. Regional Velocity (VR), the velocity of the wind, VR, is the maximum mean velocity likely to occur within a certain recurrence period in a determined zone or region of the country.

The Isotach maps that are included in this clause with the different periods of return, such velocities refer to homogenous conditions that correspond to a height of 10 meters over the surface of the floor in the flat terrain (Category 2 per Table I.1). It does not consider the local terrain roughness characteristics or the specific topography of the site. Therefore, the velocity is associated with three-second wind gusts and condiders the possibility that there might be hurricane winds present in the coastal zones.

The software determines the regional velocity, VR,by considering the geographic location of the site of the building's uproot and its destination.

In Figures I.1 through I.4, the Isotach regional maps are shown, corresponding to the periods of recurrence for 200, 50, and 10 years.

The importance of the structures (Paragraph 4.3) dictates the periods of recurrence which should be considered for the wind design. From this, the groups A, B and C associate themselves with the periods of return of 200, 50 and 10 years, respectively. The uproot site is in the map with the recurrence period which corresponds to the group to which the building belongs to, in order to obtain the regional velocity. In the Tomo III from Ayudas de Dise O a table is shown with the main cities in the country and their corresponding regional velocities for the different periods of return.

Structural Classification

Specifies the structural classification.

Terrain Category

Defined in Table I.1, based on the type of soil and roughness.

Topographic Factor (Ft) (Paragraph 4.5.4)

This factor considers the local topographic effect from the place in which the structure uproots. For example, if the building is found on the hillsides, on top of hills, or on mountains at important heights with respect to the general level of the terrain of its outskirts, it is probable that wind generates accelerations and the regional velocity should be increased.

Damping Factor (Zeta)

Typically, this value is 0.01.

Strouhal Number (St)

The Strouhal number is unitless; 0.2 for circular sections and 0.14 for rectangular sections.

Barometric Height (Omega)

Typical units (depending on your unit system):

• ft

• m

• mm

Indicates the barometric pressure in mm Hg, as shown in the following table:

Ambient Temperature

Indicates the ambient temperature in degrees Celsius.

Frequency

Specifies the fundamental frequency time interval, in Hz.