Seismic Behavior Experimental Study On The New Joints Of The Sinusoidal Web Steel Beams-concrete Column

Composite Frames consisting of reinforced concrete columns and steel beams(RCS) has the characteristics of reasonable stress, material saving, shorter construction period and is easy to ensure the quality, compared with the flat web beams, the sinusoidal web beams are more economic and have higher bearing capacity. Using the sinusoidal web beams instead of the flat web beams will be an important development direction of composite frames consisting of reinforced concrete columns and steel beams. The seismic behavior of beam to column joints is very important to the structure. In this paper, experimental study was carried out to study the seismic behavior of the new type end plate bolted connection of sinusoidal web steel beams-concrete column, which is put forward by the research group, hope to provide reference for the scientific research and application in the future.The new joints connect the sinusoidal web beams and precast concrete columns with high-strength bolt through the end plate. In order to ensure that the contact surface stress is uniform, filling the gap between the column steel tube and the steel beam end plate with high performance composite grouting material, until it reaches the strength, then preloading the bolts. Design and production of four full-scale joint specimens, three of them were strengthened in different ways on the sinusoidal web, the other one without any treatment. Low cyclic loading tests were carried out for four joint specimens, force-deformation-failure processes were observed and test data were recorded.Through the observation of experimental phenomena and test data processing, the hysteretic curve, skeleton curve, ductility and energy dissipation capacity of the joint specimens were analyzed and contrasted. The test results show that: the different measures taken on the web can improve the ultimate bearing capacity of specimens; all of the specimens showed good energy dissipation capacity; reinforcing steel plate at the end of beam can realize plastic region shift, and, the bolted end plate connection with bolt preload is up to the requirement of the rigid joint.According to the specimen actual deformation characteristic and failure process, combined with the existing theory and achievement, causes of sinusoidal web beams buckling failure in the experiment were analyzed in this paper. Analysis shows that sinusoidal web beams shear buckling in the experiment, because of the span is too small to meet the design requirements for "strong shear weak bending". Existing research shows that sinusoidal web has higher shear buckling load than the flat web, but, when the sinusoidal web buckling, bearing capacity decreases seriously, because of its no post buckling strength, in actual engineering design the stability bearing capacity of shear should be ensured to avoid sinusoidal web beams shear buckling. At the same time, according to the experimental data and theoretical calculation, the design calculation method considering the post buckling strength of the reinforcing steel plate at the end of the beam is put forward.