Researches On Passive Control Of Knee Braced Frame With SMA Damper

Knee brace is a new type of structure as it provides lateral stiffness for structures in small earthquakes and produce energy consumption when yielding in large earthquakes. Super elastic shape memory alloy is a new type of smart materials with large deformation recovery function, which also has properties that are high damping property, fatigue resistance and durability. The SMA damper and knee brace are combined to make an energy dissipation device to realize vibration control of frame structure in this thesis. The main contents are as follows:(1) A new SMA damper is designed using super elastic property of SMA. The structure and working principle are discussed in detail. The advantages of the damper are that all internal SMA wire is always in tension when the damper is in tension or in pressure and the maximum strain of SMA can be controlled.(2)The SMA wire and knee brace are combined to constitute a dual energy dissipation line in structure, namely energy dissipation is generated in SMA in small earthquakes and generated in knee brace in strong earthquakes.(3) The secondary development of SMA constitutive model using UMAT subroutine on ABAQUS platform is finished. A SMA damper knee brace mechanical model is built by establishing a SMA mechanical model(4) Taking a fifteen layer and a three layer frame as example, vibration response and the post-earthquake structure self reset in the knee braced frame with SMA damper are calculated,respectively.The results show that the inter layer displacement and horizontal displacement can be effectively suppressed in the energy dissipation system, and energy dissipation system can drive the structure reset after the earthquake with the acceleration increased.