The Earthquake-Resistant Experimental Researches On Top Story Knee Joint Of Concrete Structures With Short Shear Wall And Unbonded Tendons Prestressed Floor

In this paper, by means of revered cycle loading tests on the two specimens of concrete structures with short shear wall and unbonded tendons prestressed floor, it analyzes the behavior of this concrete structure system under cyclic loading . At first it studies mainly the bearing seismic capacity and bars' detail arrangement of four top story knee joints for the concrete structure system. At last, it brings forward the method of designing for top story knee joint.From analysis of load-displacement relation of the tests, it studies the seismic behavior of top story knee joint for the concrete structure system under cyclic loading. Analyzing results is that it can satisfy the bearing seismic capacity by designing properly for top story knee joint of the concrete structure system. At the same time, it provides an applicable method of designing for top story knee joint .Experimental results of top story knee joint for short shear wall type "L "are collected , summarized and analyzed by the finite element method . The firstly ,it is introduced for analyzing force transfer mechanism of top story knee joint from plane loading ,and analyzing top story knee joint's influence on seismic behavior of the concrete structure system under cyclic loading . Under positive moment and negative moment , it clarifies that the shear of top story knee joint is mainly transferred by the truss mechanism , the shear transferred by diagonal strut is reduced significantly ,but the confinement mechanism may be neglected .The secondly , it discusses the characteristic of top story knee joint from space loading under cyclic loading .The lastly , based on the seismic behavior of joint , method of designing is presented for top story knee joint . Section of beam is usually alike and thin as shear wall for this concrete structure system . There are the longitudinal steels of beams and shear wall ,bars and unbonded prestressed reinforcements of concrete slab in joint .This causes difficulty of bars details arrangement in joint . Accordingly it analyses different detailing arrangement of longintudinal reinforcement in the top story knee joint influence on the seismic behavior of the concrete structure system .it's results show that the arrangements can satisfy the bearing capacity under cyclic loading by designing properly details arrangement of reinforcement in joint . Additionally seismic anchorage and lap splices schemes are presented for the longitudinal in the top story knee joint . Experimental results of the longitudinal steels' strain in short shear wall type "L " are collected and analyzed in different loading stages . It discusses neutral axial variety of control section for short shear wall type "L " in different loading stages .It is evident conclusion that it's majority is single direction moment under negative moment ,and that it is mainly moment and torque under positive moment .At last it gives some suggestions of designing methods for short shear wall . Finally this paper studies that prestressed with unbonded tendons plays the role in the concrete structure system , and some suggestions of arrangement and designing method are taken into account .