Pushover-based probabilistic seismic capacity assessment of RCFs retrofitted with PBSPC BRBF sub-structures

•A new type of external retrofitting sub-structure combining the system-level upgrading and precast-assembly technology.•An efficient numerical model based on OpenSees verified by the experiments.•Three span-story RCFs (low, medium, high), three retrofitting scenarios (full, odd, even), and three force patterns (CF, TF, UF).•A pushover-based PSCA procedure for the sub-structure considering uncertainty.•Recommendations of average median thresholds and logarithmic standard deviations for SD, MD, ED and CP states.•Sensitivity evaluation and comparison of uncertain factors for the PSCA results. A new external retrofitting sub-structure is introduced in this paper, namely, precast bolt-connected steel-plate reinforced concrete buckling-restrained-brace-frame (PBSPC BRBF). The numerical model is proposed considering the joint mechanical behavior, postcast concrete effects, and interfacial shear performance, and the results are validated via an experimental study. The probabilistic seismic capacity assessments (PSCAs) are performed on the deficient reinforced concrete frames (RCFs) retrofitted with PBSPC BRBFs based on a pushover method. The structural and load uncertainties (e.g., the material parameter and load value) are analyzed, and the Latin hypercube sampling (LHS) method is adopted for the 1-span-3-story, 3-span-6-story and 5-span-8-story frames, respectively. The histograms, probability density functions (PDFs) and PSCA curves for all conditions are provided, and the average median values or logarithmic standard deviations (SDs) are recommended. The sensitivity analysis is also performed, and the tornado diagrams and stack columns are presented. The research provides the thresholds of damage measures for different limit states of the RCFs retrofitted with the external sub-structures, and the corresponding conclusions can be further combined with probabilistic seismic demand analyses to constitute the integrated fragility framework.