Study On Mechanical Properties Of Short Coupling Beams With Different Reinforcement Under The Earthquake

The shear wall coupling beam is the first line of seismic fortification in the tall buildings,it's an important part to ensure the overall safety of the building structure under the action of earthquake,it plays an important role in structural safety.The short coupling beam usually refers to the beam with the span-to-height ratio less than 2.5,it follows the structural design principle of "strong wall and weak beam",its strength,stiffness and deformation performance have great influence on the seismic performance of the coupling shear wall.Code for design of concrete structures(GB50010-2010)and Technical specification for concrete structures of tall builcling(JGJ3-2010)just roughly put forward three design concepts,didn't specify its seismic performance.In order to study the stress state of short coupling beams under the earthquake,in this paper,three beams with different forms reinforcement are designed,which are diagonal brace reinforcement,concentrated diagonal reinforcement and cross oblique reinforcement.The finite element software was used to simulate the loading test of the specimen under cyclic loading,through studying three beam specimens with different forms reinforcement of crack development,the load-displacement and the strain distribution of steel bars,and then analysis the seismic performance of short coupling beams.The reach show that judging from the crack development trend,the three short coupling beams experienced 3 stages:bending failure,shear failure and bending shear failure.The three short coupling beams mainly happen shear deformation under the action of earthquake,which accords with the principle of "strong shear and weak bending",and the shear area is mainly concentrated in the middle position with good seismic performance.The shear strength of the stirrups is not the dominant effect,the diagonal reinforcement is subjected to tensile force in the whole range and bear most of the shear effect.The short coupling beams with brace reinforcement and concentrated diagonal reinforcement form a role which similar to the cross column in the middle of the beam,and effectively improve the bearing capacity.Compared to other two kind beams,the hysteresis curve of the beam with cross oblique reinforcement is full,the ductility and energy dissipation capacity are the best,the stiffness degradation is more balanced,the ability that structure relies on themselves plastic deformation to reduce the earthquake damage is more better.