Comparison on dominance of wind loading versus seismic loading in building structural design by static method in different conditions of the country

 According to sixth issue of the National Building Regulations in Iran, the calculation of building structures against lateral forces of wind and earthquake is done separately. Maximum effect of these two lateral forces is used to calculating criterion of each element of the structure. In any case, it is mandatory to observe the special rules of seismic design according to the structural system in all members. Since most parts of the country are located on the plateau of Iran, which is at a high level in terms of seismicity, many engineers pay special attention to the seimic loads, versus wind loads.

In this study, while reviewing the wind phenomenon, within the framework of the methods approved by the regulations and applicable standards of the country, all possible situations and design criteria in the lateral wind force calculating in different buildings of the country have been analyzed by comparing the earthquake lateral force. Among the studied areas, the results of provincial centers are presented in this article. The impact of all types of soil, structural systems, seismic hazard zone, the importance of buildings according to the building function and existing standards of the country is considered in this study. More over, according to the different building function and structural system, the necessary gravitational loads have been applied in the calculation process.

The elevation level of dominance of static wind load versus equivalent static earthquake load is obtained in studied areas and considering the allowable height of the structural systems. According to the rules; the lateral wind load from this level upwards should be the main criterion for the design of building structures. The results in the form of different tables indicate the height levels that the design needs to be considered more seriously against lateral wind force.

The results of the analysis indicate that by increasing the values ​​of the behavior factor of buildings, the height level of the structure when the lateral force of the wind overcomes the lateral force of the earthquake decreases. Ardabil, Zahedan and Kerman are among the critical areas against wind due to the regional wind speed of 130 km per hour, which requires more attention of structural engineers. Alborz, Ilam, Kohkiluyeh and Boyer-Ahmad provinces have less sensitivity in terms of wind lateral load because they have an average wind speed of less than 80 km per hour in all seasons. The wind lateral force in the initial levels of altitude is dominant over the seismic lateral force for all types of structural systems with different importance in most sites with soil type I. Therefore, it needs special attention.