Shear strength prediction for concrete encased steel short columns: Calibration based on current design codes

Abstract

Due to the brittle failure process of shear failure, the accurate strength prediction of concrete encased steel (CES) short columns significantly influences the seismic assessment. In current design codes, the superposition method is widely employed, namely that the shear strength of a CES short column can be regarded as the sum of the shear strength of the RC part and that of the steel shape. However, the existing test results indicated that the RC part suffered a significant loss in shear strength during its post-peak period, and the steel shape could exhibit outstanding toughness, namely that these two parts cannot reach the corresponding shear strength simultaneously, which may lead to a deviation in the shear strength prediction. This paper reviews and assesses the calculation methods in current design codes using existing test results. Then, the traditional superposition method is calibrated in terms of the interaction between the RC part and the steel shape, and the shear contribution of these two parts can be decoupled by evaluating the corresponding peak strength point and the strength loss during the post-peak period. Finally, a comparison with a database consisting of the test results of 43 CES short columns is reported to verify the applicability of the proposed calibration. It can be concluded that the calibrated method can produce reasonable predictions, and the strength overestimation caused by the negligence of the interaction between the RC part and the steel shape in current design codes can be effectively captured to facilitate the practical design.