Tall building is one of the phenomenons of 21th century in building and urban which now has been continued in most of the cities in the world. From economists view or urban geographer this phenomenon is natural result of urban processes. Lack of land in central area of cities, increasing demand for work and living in centre of cities is caused that the land prices would be increased so the height of building would be taller.
Improvement building technology, power-show, competition among cities with each other, increasing morality and urban culture all are as reason for this phenomenon.
However this process should be use and approve by planners and urban authorities but as general they are beaten of this process and accept.
Because of these events, critical management is not considered in decision –making in this field.
Usually when the critical management would be use in urban development that is not time to do work and it would not be suitable.
Zaravng Holding in designing and implementing tall- building always despite of social & economical aspects has considered to environmental and technical dimensions , risk analyze and their damages to urban spaces . Depended to type and amount of risk in an area, tall –building could be right or worst. For example, in areas which have high risk because of natural disaster, such as earthquake and its consequence, tall –building has special conditions with other lands.
Also most of the risks are special for denser areas or in there they would be rise by high speed.
But by ignoring to type and amount of the risks, usually rising density of activities and living because of population growth and welfare causes increase vulnerability.
So small events even in these areas would be caused many damages or wastes in them.