Mega-structures and skyscrapers have become a fundamental need of the modern world because of the unique advantages they offer in terms of minimized space consumption on the earth and increased vertical accommodation. However, these structures have been known to exhibit unexpectedly large sways, especially in the higher stories because of the wind forces and the earthquakes. “In extreme cases, vibration may cause damage to the structure as a result of the loosening of connections, brittle fracture of welds, etc”. (Taranath, 2005: 830). Owing to the growing trend of the dependency of a vast majority of population on the high rise buildings all over the world, the aim of much of the research and development made in the past few decades in the field of Civil Engineering has been to gain increased control and command over the dynamic behavior of a structure when it is subjected to any kind of load in general and when it encounters forces because of winds and earthquakes in particular. This paper offers an introduction to a structure’s response to natural forces such as earthquakes and wind forces. Moreover, in this paper, advancements made in the way of exercising increased command over the structures’ response to naturally unpredictable and large forces are unveiled and all foreseeable achievements made to date in this area of Civil Engineering are recognized.
Structures constructed in regions prone to large scale earthquakes and windstorms may experience loads equal to their ultimate load-bearing capacity and sometimes even beyond that. In other words, the loads a structure is subjected to in its lifetime may be either insignificant or unexpectedly large. The danger to the integrity of a structure is much pronounced in the latter than in the former intensity of load. Conventionally, the tendency of a structure to resist the earthquakes is enhanced by enlarging the size of the various .constituent structural members because of the fact that larger structural members are equipped with added stiffness in comparison to their shorter alternatives.