Behavior Of Multi-partition Steel-concrete Composite Column-steel Beam Stiffener Plate Connection Under Combined Moment And Tention

Multi-partition special-shaped steel-concrete composite column structures have unique advantages and great application prospects.From the architectural level,they can be designed the same thickness as walls to improve building utilization.From the structural level,they can achieve higher bearing capacity and energy absorption without increasing the section size of columns and improve the degree of equipment.At this time the connections used most in composite structures are out-ring connections and inner-plate connections.However,out-ring connections failed to meet the concepts of special-shaped structures while inner-plate connections lead to difficulties of concrete pouring.To avoid the problems mentioned above,stiffener plate connections were studied.When the middle column is removed in a frame structure,the loads supposed to be sustained by the removed column are consequently spread to the adjacent beams through the connection.In this case,the beam-to-column connection is subjected to combined sagging moment and tension instead of negative bending moment.To guarantee the application of steel-concrete composite column-steel beam stiffener plate connections,their mechanical behaviors in column-removed conditions should be promised.Because of the lack of studies on stiffener plate connections,the behavior of multi-partition rectangular section steel-concrete composite column-steel beam stiffener plate connections under combined moment and tension were investigated.The main works are listed as follows:(1)With beam-to-column assemblies with two half-span beams models and static test methods,the experiment of four multi-partition rectangular section steel-concrete composite column-steel beam stiffener plate connections with reduced scale(1:2)under combined moment and tension were conducted.The main factors varied in the tests were the type and geometric dimensions of stiffener plates.The deformation development process,stress development process of key points and failure mode of specimens were analyzed.The results indicate that loads above the removed column formerly can spread to adjacent beams effectively through stiffener plate connections.At the beginning,the beam-to-column assemblies resist the upper load through the flexural mechanism,but with the increasing deformation the flexural mechanism remains table and the catenary mechanism provides more resistance force,which improves the resistance ability greatly.The geometric dimensions of the stiffener plates can affect the behaviors of the connections.(2)The finite element software ABAQUS is applied to analyze the behavior of stiffener plate connections under combined moment and tension in column-removed conditions.The geometric and material non-linear behaviors are considered in the analysis.With the reasonable choices of constitutive relationships,unit types,contact,interaction,boundary conditions and loads,the behaviors can be simulated precisely.The results of the experiment and related researches are used to validate the accuracy of finite element analysis results.(3)The finite element software ABAQUS is applied to analyze the behavior of stiffener plate connections with full scale.The models were simplified coMPared to the experiment.The typical stiffener plate connection is analyzed to study its working mechanism more clearly.The main factors that influence the connection behaviors are: the strength of beam,the thickness of steel column welded to the stiffener plates,the strength,thickness and geometric dimensions of the stiffener plates.Each factor is studied in detail.Finally some designing advice were put forwards based on the experiment results and FEA analyzes.