Flexible blast resistant steel structures by using unidirectional passive dampers

• Reviewing self centering energy dissipaters and introducing a new SCED called UPD.
• UPD applies force only when the frame moves far from its initial position.
• UPD remains inactive and unloaded when the frame moves toward the initial position.
• In a flexible frame equipped with UPD, most of the energy is dissipated by damper.
• After the blast loadings, the frame with UPD returns back to its initial position.

Application of passive yielding dampers in structures for attenuation of blast effects is a complicated topic and needs more research works. If a structure is designed to have high lateral flexibility, the applied passive energy absorbers can dissipate the most internal blast energy. But in this condition, the frame will find re-centering problem after dissipation of energy and will never come back to its original configuration. In fact the restoring force of this high flexible frame will not be adequate to return the devices back to their initial dimensions. Therefore, the absorbers lock up the structure at its deflected form which is a very vulnerable condition. This problem has been solved in this research by manufacturing of a new unidirectional passive damper (UPD) which has different behaviours under tensile and compressive loadings. This new damper applies force to the frame and absorbs the energy just in the case that the frame is moving away from its original equilibrium position. When the frame moves toward its equilibrium position, the device becomes inactive and provides no obstacle to the movement of the structure. By application of UPD in a flexible frame, a blast resistant system is achieved in which the internal energy is mainly dissipated by the absorbers.