Seismic Control Behavior Of A New Ring Spring-SMA Cables Re-centering Damper

One of the widely used seismic resistance measure is to ad d energy dissipation devices in buildings.However,the building structures with traditional dampers may produce large residual deform ation under strong earthquakes.In view of this,development of seismic dampers with re-centering performance has becom e one of the hot research topics of the earthquake resistant engineering.Shape Memory Alloy(SMA)is a new kind of s mart materials,which has the characteristics of shape m emory effect,superelasticity and high damping.SMA can be used as ener gy dissipation elements with good re-centering ab ility and durability.The ring spring is a compressible spring that is superposed by a combination of pairs of inner and outer rings,in which frictional force is generated by the mutual extrusion of the inner and outer rings.Based on such characteristics,the rin g spring has compact configurations and can absorb a lar ge amount of ener gy.A new type of re-centering damper consisting of a ring spring and SMA cables is developed in this thesis,in which the main function components have re-centering as well as ener gy dissipation characteristics.Thus,it has im portant theoretical significance and engineering value.The main research contents of this dissertation are as follows:(1)A ring spring with a diam eter of 200 mm was fabricated and processed into a damper.The hysteresis behavior of the fr iction spring damper was experim entally studied.The influence of displacem ent amplitude and loading frequency on the friction damper were investigated and analyzed.Then the finite element model of ring spring was established by ABAQUS softwa re,and the loading and unloading simulation was carried out to verify the test results.(2)SMA wires(diam eters of 0.5mm,1mm a nd 1.5mm)and SMA cables(stranded by seven SMA wires with a diam eter of 1mm)made from NiTi-SMA were tested through tension experim ent.The ef fects of dif ferent loading frequencies,displacement amplitudes,loading-unloading cycles and d iameter of wire on th e mechanical properties of the SMA wires and cables were systematically investigated.(3)A ring spring-SMA cables re-c entering damper(RSD)was designed and produced.The hysteresis behavior of th e hybrid damper wa s tested through quasi-static cycling experiment.The finite element model of RSD is established with ABAQUS software,and the num erical simulation is carried out to ver ify the experimental results.(4)A 9-story Benchmark steel frame was selected as the research object,and the RSD was applied to the cross brac ing of the structure to f orm a steel frame-braced frame.The finite elem ent model is established by using ETABS software to carry out dynamic elastoplastic time history analysis,and then to evaluate the seismic behavior of the controlled steel frame.