Survival

Survival wind speed is a simple calculation without considering any additional environmental or safety factors. This calculation utilizes the maximum 3 second gust wind speed recorded or expected for a site. Survival literally means that the tower will survive the stated wind speed with no permanent deformation or failure of tower components. Exceeding this stated wind speed will result in tower failure and collapse. Survival wind speed may only be used where tower failure and loss of service are tolerable, where there is no foreseeable risk of injury to humans in the event of collapse and where zoning requirements do not dictate the use of a particular code or standard.

TIA/EIA-222-F

This American design standard considers wind speed defined as a fastest mile wind speed and calculates member capacities in accordance with the AISC-ASD standard. This allowable stress standard considers the 1/3 increase in allowable stress since wind is the primary load. This tower design standard is utilized in the USA where dictated by zoning or building requirements. The local building authority for the county where this standard is mandated and tower to be constructed can provide the appropriate fastest mile wind speed to use for design as well as the appropriate ice thickness to consider in the design.

ANSI/TIA-222-G

This American design standard considers wind speed defined as a 3 second gust wind speed per ASCE-07 and calculates member capacities in accordance with the AISC-LRFD standard, this is a limit states design standard. This tower design standard is utilized in the USA where dictated by zoning or building requirements. The local building authority for the county where this standard is mandated and tower to be constructed can provide the appropriate 3 second gust wind speed to use for design as well as the appropriate ice thickness and ice wind speed to consider in the design. Finally an importance factor is defined with the following meaning: Class I may be specified where loss service in the event of failure is not critical and where in the event of failure the use and location of the tower represent a low hazard to human life or damage to surrounding property. Class II is specified where normal reliability is required, typically associated with commercial structures. Class III is specified where structures are designated as post disaster installations such as EMS, fire brigade, hospitals ect.

ASCE-07

This design standard option considers wind speed defined as a 3 second gust wind speed per ASCE-07 and calculates member capacities in accordance with the AISC-ASD standard. This allowable stress standard considers the 1/3 increase in allowable stress since wind is the primary load. In a sense similar to the EIA/TIA-222-F standard but wind loading on the tower calculated per ASCE-07. This tower design standard is often utilized for tower structures in the developing countries of among others Africa, Middle-East, Central and Latin America. The local building authority for the country where this standard option is required can provide the appropriate 3 second gust wind speed (often referred to as the maximum wind speed) to use for design purposes.

CSA S37-01

This Canadian limit states design standard considers site specific wind pressures (given in Pascals) and ice thickness (given in millimeters) that can be obtained from either provincial building codes or from Environment Canada. Site specific wind pressures can be ordered for any location in Canada (for a fee) from Environment Canada by sending the request to the following address: Ontario.Climate.Centre@ec.gc.ca

This site specific wind pressure is based on an hourly average wind speed based on a 30 year return period. Local building authorities in Canada require that all tower structures must be designed to meet this standard.

Eurocode 3 Part 3-1

This limit states design standard is in use within the European Union and other jurisdictions where mandated by the tower specification. This standard considers wind speed defined as a 10 minute average wind speed and calculates member capacities in accordance with the Eurocode 3 standard. The local building authority for the country where this standard is mandated and tower to be constructed can provide the appropriate wind speed to use for design.