Optimum Layout of Mega Buckling-Restrained Braces to Optimize the Behavior of Tall Buildings Subjected to Blast Load

The use of buckling-restrained braces began in Japan at 1980s and was then followed by other countries all over the world. Many behavioral problems associated with the conventional steel braces might be neglected when this type of bracing system is used, due to the difference between their tension and compression strength capacity. In this paper, the effect of mega buckling-restrained braces on the response of tall structures subjected to the blast load is investigated. For this purpose, a 30-story structure is retrofitted by mega buckling-restrained braces in twelve different modes. Then, the best positioning of this control system is introduced based on the maximum response of the structure. In this regard, the structure is subjected to four states of blast loads produced by 1000 and 1200 kilograms of TNT at a distance of 5 and 10 meters from the structure. The results showed that by decreasing the amount of blast material and also increasing the distance of TNF from the structure, the damaging effects and also the maximum response of the structure reduced; and therefore, the structure went to the safe level (IO). The results also indicated that the A1 state is the best positioning for the controlled system, in which the maximum displacement of the roof, the maximum rotation of the structure is less than these values for the original structure (the structure with the conventional braces system). Also, the A1 state can be chosen as the best candidate for placement of the controlled system since it reduces the weight of the bracing system more than 16% rather than this value for the original structure.