STATIC PERFORMANCE OF THE HIGH-PERFORMANCE CONCRETE FILLED STEEL TUBULAR STUB COLUMN(Ⅱ): MECHANISM ANALYSIS AND LOAD BEARING CAPACITY

Distributions of stresses and strains of steel tube and concrete for high-performance concrete filled steel tubular stub column were investigated,it was found that longitudinal stress of concrete at mid-height cross-section distributed uniformly around the circumferential direction for the circular specimen,while longitudinal stress of concrete at mid-height cross-section located at corners was the biggest one for the square specimen.During loading process,steel tube at mid-height cross-section yielded firstly and then yield region developed gradually toward the two ends of the specimen.Analysis results of the typical calculations indicated that the circular steel tube could provide better confinement for concrete than the square steel tube,also,the circular steel tube confine the concrete uniformly around the circumferential direction while the confinement forces located at corners were the biggest ones for the square specimen.All of the specimens had the biggest confinement forces at the mid-height cross-section.Adhesive strength had little influence on the load bearing capacity of the specimens.Calculation formula of load bearing capacity for the normal concrete filled steel tubular stub column is also suitable for the high-performance concrete filled steel tubular stub column.There are no essential differences between the high-performance concrete filled steel tubular stub column and the normal concrete filled steel tubular stub column in aspect of static performance.