Experimental Study And Numerical Simulation Of Prestressed Self-centering RC Frame Joints

Earthquake is one natural disaster with great destructive power.In addition to threaten human's life,earthquake causes great economic losses to the society.The economic losses include two parts: direct economic loss and indirect economic loss.In the direct economic loss,it includes rebuilding costs,repair costs,demolition costs,etc.While in the indirect economic loss,it includes the all losses caused ty the interrupt of structural function.People not only hope that the buildings will not collapse during the quake,but also want a slight structural damage and small economic losses.There is no damage or slight damage for the assembled prestressed self-centering reinforced concrete structure after earthquakes.So the structure can be used as soon as possible and economic losses are greatly reduced.This kind of structure was widely concerned by researchers.In the past researches,small size buckling restrained braces were susally chosen as external dampers,which lead to complicated construction in structural node.In this study,the ordinary steel angles were used as external dampers at structural nodes.The corresponding experimental and numerial studies were performed.During the study,the mechanical performance of the node in the direction that without dampers is also concerned.The main contents in this thesis are as follows:(1)A self-centering reinforced concrete(RC)column with a scale of 1:1.5 was designed and manufactured(including the node connecting the column and foundation).In the specimen,the restoring force is provided by the prestressed steel strands,while the energy dissipation capacity is provided by the external steel angle.(2)Pseudo-stastic experiments were carried out to test the mechanical performance of the self-centering RC column-foundation node and beam-column node.The influence of loading direction and axial compression ratio on performance of the specimens(self-centering ability and energy dissipation capacity)was addressed.Especially,the state of the prestressed steel strands was observed during the tests when the specimens reached their limited displacement.This was performed to affirm if the self-centering ability was reduced at this moment.The expemental tests were compared with that from the corresponding research literatures.And it can be demonstrated that steel angle has silimar energy dissipation capacity with buckling restrained brace.(3)Mechanical performance of the specimens was simulated by the finite element software of OpenSEES.The methods were addressed including how to simulate the self-centering nodes and how to define the values of the constitutive models.