Experimental Research On Seismic Performance Of Reinforced Concrete Combined Short Column With Concealed Steel Bracings

Reinfored concrete short columns have great stiffness, but low ability of deformatioin and energy dissipation, which may result in damage and even collapse of the structures because of their poor ductility during earthquakes. In this article, the author introduces new measure to improve the seismic performance of short columns, by adding the gradient bracing in common reinfored concrete short columns, the performance can be improved. Corresponding seismic experimental research and theoretical analysis have been done. The experiment indicates that reinforced concrete combined short columns with concealed steel bracings have good mechanisms for energy dissipation.The main contents and results are listed as fellows:1. Reinforced concrete combined short columns with concealed steel bracings have been introduced for the first time. Systemic experimental research on the seismic performance of 7 specimens of rectangle section short columns with 1/3 scale has been done by low-cyclic reversed loading tests, including 3 short columns shear- span ratio (1.75) and 4 ultra short columns shear-span ratio(1.5).2. Based on experimental research, the following seismic performance of the specimens have been analyzed systematically: bearing capacity, stiffness, energy dissipation, hysteretic capacity and the influence of designed parameters such as axial compression ratio and shear-span ratio, revealing the mechanism of steel bar or shaped steel bracing to improve seismic performance of short column.3. The simplified mechanical model and the calculative formulas of the reinforced concrete combined short columns with concealed steel bracings have been established. The calculating results accord well with the experimental results.Main researchful conclusions are listed as follows:1. Compared with common short column, the seismic performance of reinforced concrete combined short column with concealed steel bracings has been greatly improved, its late stiffness has good stability, and the hysteretic curve of combined short column with concealed steel bracings is plumber than that of common short column.2. Short column with steel bar bracings, shaped steel bracings and steel bar-shaped steel bracings all can have good seismic performance.Compared with others, the seismic performance of short column with steel bar-shaped steel bracings is better.3. The cracks of short column with bracings distribute closely and their distributing area is larger. The energy dissipation of short column with bracings is bigger, what's more, the main inclined crack of it tends to develop towards the angle of bracings.