Matrix‐Based Analytical Method for Failure Mode Identification and Uniform‐Failure Seismic Design of Prestressed Column

ABSTRACT Resilient seismic design requires that structures exhibit excellent seismic performance and small residual deformation. Unbonded prestressed reinforced concrete (UBPRC) columns, with prestressed strands serving as self‐centering components, can effectively reduce residual displacement, which is of great significance for the seismic resilience of bridges. Compared with a traditional reinforced concrete column, the presence of prestress may change the failure mode of the UBPRC column. To quantitatively study the failure mode of UBPRC columns, two failure modes in the complete damage state were defined, and a matrix‐based analytical model was proposed. First, two failure modes were defined: crushing of the core concrete and tensile fracture of the longitudinal steel bars. On this basis, the uniform‐failure state was defined as the two failure modes occurring almost simultaneously. Then, an analytical model for the failure mode, including eight structural and material parameters, was proposed. The failure mode can be identified by inputting the values of these parameters into the analytical model. According to the proposed analytical model, the effects of various parameters on the failure mode of UBPRC columns were investigated. The parameter design was carried out using transverse and longitudinal reinforcement ratios, and the prestressing force ratio as examples, based on the uniform‐failure state. The proposed analytical model can be applied to identify the failure modes and to perform preliminary parameter design of the UBPRC column.