Experimental Study On Short-span Coupling Beams With Efficacious Detailing

Coupling beams are important elements in coupled walls. They are ligaments forpassing force between single shear walls. So strength, stiffness, ductility and energydissipating capacityof coupling beams can affect shear walls' performance directly. Theshort-span coupling beams are usually adopted in the coupled walls or core-walls toassure the lateral stiffness of structures. Test investigations show that if these kinds ofcoupling beams are designed with seismic design methods of normal frame beams, thepremature shear failure can not be prevented, so the ductility demand of structures can'tbe satisfied. So far domestic and foreign researchers have not yet found out an effectivereinforcement scheme for convenient construction and guaranteeing the occurrence ofshear failure after coupling beams attaining displacement ductility required. Seismicdesign method of coupling beams with small aspect ratio was one of importantproblems catching notice at the newly revised structure design codes just completed. Aiming at this important problem to be urgently settled in engineering design, theresearch group of the author have carried out a series of test investigations on couplingbeams with small aspect ratio. Firstly, the Master Zhang Binbin's tests further verifiedthat the design methods in The Code for Design of Reinforced Concrete High-riseStructure (JGJ3-2002) can not satisfy basic seismic requirement. At the same time, ourresearch group find that some acceptable improved reinforcement scheme suggested bydomestic and foreign researchers can not attain satisfying ductility performance. At the basis of the summary of reinforcement scheme already put forward, the MasterCao Yunfeng brings forward a reinforcement scheme with good applicability inengineering, namely the reinforcement scheme of adding diagonal bars and rhombicinclined bars on the basis of traditional reinforcement. The tests proved that thereinforcement scheme can obtain favorable displacement ductility and plastic energydissipation capacity for the coupling beams with the small aspect ratio of 1.0. TheMaster Zhao Jielin tested five specimens with the span to depth from 0.8 to 1.25, andproved the reinforcement scheme is available, at the same time, he try to apply thestrut-and-tie model to this kind of reinforcement scheme, and made some progress. To go deep into the research further, this thesis concentrates on some aspectsfollowing: 1) Prove the availability of this kind of reinforcement scheme through more tests. III重庆大学硕士学位论文 2) Make tests of coupling beam with the span to depth of 1.5. 3) Use the finite element program of ANSYS to simulate the specimens of this kindof reinforcement scheme. 4) Sum up the results of the research group and build a formula to calculate thecarrying capacityof the coupling beams. The results show that :1) The coupling beam with the span to depth of 1.5 also havegood ductility (>5.0) and energy dissipation. 2 The finite element analysis reconfirmedthe force characteristic of rebar in the coupling beam. 3)The paper gives a formula ofthe coupling beams' carrying capacity under the foundation of Zhao JieLin's results,and the results indicate that the theoretic calculation value show good agreement withthe test value.