Experimental Study On Degradable Prefabricated Brace Apply To Primary-secondary Structures

Brace is an important lateral resisting component in primary-secondary structures,in which the primary structure composed of brace,primary beam and primary column is the main lateral resisting system and load-bearing system.At present,buckling-restrained brace is often used in the primary-secondary structures,however,there still exists extremely high bearing capacity after yielding,which make adjacent primary column bear large axial force,brittle damage may occur.So,this dissertation proposed a new type of fabricated degradable brace,which can provide stiffness for the structure under frequent earthquakes,degrade immediately after yielding under rare earthquakes,and reduce the axial force of adjacent primary column.The mechanical property of the brace was studied through numerical simulation and experiment.The specific research contents are as follows:By comparing the changes and differences of the axial force and damage of the primary column of primary structure with different types of braces under the horizontal displacement loading,it is clear that the buckling-restrained brace has adverse influence on the bearing characteristics and damage development of the main column under the action of rare earthquakes.Aiming at this problem,this dissertation proposed a new type of fabricated degradable brace,and elaborated the structural characteristics and working principle of the fabricated degradable brace.The mechanical properties of the fabricated degradable braces are analyzed theoretically.The calculation methods of the bearing capacity,the force transmission path and the stiffness of each stage were discussed,and the ideal bearing capacity curve model was established.The effects of different parameters of the fabricated degradable brace on its mechanical properties were studied by numerical simulation.The effect rule of the initial deflection,width,steel yield strength and length of the core steel plate on the brace performance were analyzed in detail.The results showed that the peak bearing capacity and initial stiffness of the brace reduced with the increase of the initial defects of the core steel plate;the smaller the yield strength of the core steel plate,the smaller the peak bearing capacity of the brace,and the faster the bearing capacity degenerated;if the width of the core steel plate is too large,the plasticity range of the core steel plate will be reduced and the development will be uneven,and the energy consumption of the brace will be reduced.;the peak bearing capacity and the initial stiffness will decrease as the length of the core segment increases.Based on the fabricated degradable brace proposed in this dissertation,three fabricated degradable brace test pieces with different core steel plate thicknesses were designed and manufactured,on which the quasi-static test was carried out,the influence of different core steel plate thickness on hysteresis performance,bearing capacity characteristics and the energy consumption capacity was analyzed.The test results showed that the prefabricated degradable brace had degradable capacity under tension and compression,and the tension bearing and compression bearing capacity showed symmetry,while the tensile and compressive stiffness was different,the energy consumption capacity of the degradable brace depended mainly on core steel plate,it was significantly improved after buckling of core steel plate;the thicker the core plate is,the higher the energy consumption capacity is.