Experimental Study On Reinforced Concrete Coupling Beams With Different Volume Fraction Of Steel Fibers

In recent years, with the rapid development of hight-rise buildings,the structure of reinforced concrete coupled shear walls be used in practical engineering more extensive. Especially with the development of the theory about concrete, the strength of concrete is also increasing, which makes the shear walls' capacity and seismic capabilities greatly enhanced. From the damage of the earthquake we can find that as an important part in the shear wall structure the coupling beams is More vulnerable.during the strong earthquake, the coupling beams as the first line of defensean for the stability of structural yield before the shear wall's yield will play its plastic deformation and dissipation the seismic energy as much as possible, thus effectively reducing the damage of the main structure.So how to improve the performance of the coupling beams has been extensive attention of experts.For the current research of the coupling beams, we have no the uniform test method in various literatures,and although many improvements have been made to improve the coupling beams' performance, but its all has their own shortage. Steel fiber can significantly improve the concrete's ability of tensile, bending, shear and many other mechanical Performance, and the steel fiber also can improve the ductility and toughness of concrete to increase the deformation capacity of reinforced concrete structures and seismic capabilities.If reinforced concrete beams or walls have been added the steel fiber,the bearing capacity and seismic capacity of the coupled shear wall structure will be greatly improved.In this dissertation,a reinforced concrete compling beam without steel fibers and five reinforced concrete compling beams with different volume fraction of steel fibers have been concreted to study the behavior of earthquake resistant and the load-bearing capacity through the horizontal cyclic loading test with a realistic method.In order to study the the performance of coupling beams with steel fibers,in this paper, the work have been done as following:(1)Designed the experimental which can let the coupling beams be tested as actual situation,based on relevant theory and the practical application designed a reasonable testing program and finished tie work of the 6 coupling beams'production.(2)Test the six coupling beams with the method of horizontal cyclic loading tests,record the trial's carried out situation and the development of the concrete's crack in the loading path.The skeleton and load-displacement have been drew based on the result of the test,and we can find from that increasing the volume fraction of steel fiber can change the situation of the pinching effect.when the volume fraction of steel fiber is 1.5% the load-displacement of the compling beam has become more full.(3)Deeply analysed the result of the different fiber volume fraction in the coupling beams on the bearing capacity,ductility and the ability of seismic energy dissipation.Eventually reached,add the steel fibers in the reinforced concrete compling beam can significantly improve the ductility, energy dissipation and stiffness. with steel fiber volume fraction increases, the ductility, consumption energy performance and stiffness are become more reasonable.Especially when the fiber volume fraction is 2%, the effect of these types of performance improvement are better. Also the bearing capacity and lateral displacement along the beams' length have been calculated and analyzed.