The Study On Structural Capacity And The Effective Width Of Negative Moment Area Of Composite Truss Beam

As a kind of composite structures, steel-concrete composite beams are more and more widely applied in large space or span, bridges, high-rise buildings, industrial buildings and other structures in recent years. Steel-concrete composite beams and concrete-filled square steel tubular column have very high value of studying and applying. The design of beam-column joints is extremely critical in composite frame structures. Because the internal force between beam and column is transferred through the joints, the safety and reliability of joints is the premise of normally working of the entire structure. There are several joints forms recommended in the relevant codes. However, the joint forms are various in practical engineering. The experiment and theoretical study on joint area are more and more at present. The researchers have accumulated much more experience and achievements, but further research analysis is still necessary.The relevant research of concrete-filled square steel tubular column joint areas is mostly on the study of mechanical performance. However, the research on deformation of steel column and the effective width of the concrete slab in the negative moment region is not enough. Steel truss-concrete composite beam is a new kind of composite structures, the research and application of it is highly valuable. Based on related literatures and some actual project, the study object is the joint between concrete-filled steel tubular column and steel truss-concrete composite beam. This paper designed the specimen and created full scale structure models for finite element simulation. Firstly, I did the study on the steel column wall deformation affected by the sleeve reinforcement’s axial force in the negative moment region, analysed the influence of different structure forms on its deformation. Then, I did the calculation of several different b/t of models, analysed the influence of different b/t on its deformation. Finally, I set up the connection models between steel truss-concrete composite beams and concrete-filled steel tubular column, studied the influence of different loading means, reinforcement ratio, concrete slab width, degree of shear connection and the additional longitudinal reinforcement on the mechanical performance of composite beams under negative bending moments and joints region deformation of steel concrete column. In addition, I came up with several influencing factors on the effective width of composite beam. At the same time, I analysed the influence of reinforcement ratio, wide span ratio, the shear connection coefficient and edge constraint effect on the effective width.The study of additional sleeve reinforcement’s effect on deformation of steel tube column and steel truss-concrete mechanical performance and the effective width in the negative moment region has certain guiding significance for the design of beam-column joints in practical engineering. To some extent, it can promote the development and application of composite structures.