Assessment of existing reinforced concrete (RC) structures after an earthquake is a challenging task that must somehow relate qualitative and quantitative observations in the plastic hinge regions and the associated residual deformation capacity of damaged structures. Having an estimate available for the remaining drift capacity will result in more economical and informed decisions regarding demolition or strengthening options. This study aims to develop a practical methodology to estimate the maximum drift demand of an RC column based on the residual crack width. For this purpose, fiber-based frame elements are used to model the RC column considering appropriately concrete behavior in compression and tension stiffening effects. Afterwards, the accuracy and reliability of the proposed methodology are demonstrated by validating the computational approach with two cyclic experimental results from literature and new test data for a one-bay one-story RC frame conducted within the course of this study. A comprehensive parametric study is performed for RC columns with different axial loads, longitudinal and transverse reinforcement ratios, and ground motions to exhibit the stochastic behavior. The study identifies the axial load ratio as the predominant parameter. Key findings include strong correlations between maximum drift ratios and total residual crack widths, as well as maximum compressive strains, with regression analysis yielding equations for accurate drift ratio estimation. Simple predictive models are proposed to estimate the maximum deformation demands based on observed residual crack widths. Residual cracking exceeding 5 mm poses significant risk for the columns with axial load ratios above 0.4, with 90% probability of exceedance 2% drift ratio.

Significant infill wall damage in reinforced concrete frame buildings was observed in the past earthquakes. A vast number of numerical approaches have been proposed to estimate the non-linear behavior of infilled frames at different scales. Mesoscale lattice models were successfully used in the past to simulate the behavior of reinforced concrete member response. In this study, two-dimensional mesoscale lattice approach with an extended calibration technique was consistently applied to simulate the response of unreinforced Aerated Autoclaved Concrete (AAC) masonry infilled reinforced concrete frames. Two AAC infilled walls were tested for the purposes of this study. The objective of the tests were to investigate the effect of infilled wall-frame interaction with and without openings and validate the proposed numerical approach. In addition to the tests conducted, two tests were used from the literature for further validation. The maximum error of load capacity estimation from the simulations was less than 15% for all the examined tests. The proposed lattice model was capable of estimating crack propagation in the infill walls with reasonable accuracy. The frame-infill wall interaction was successfully simulated with providing a realistic representation of strut formation. Finally, a parametric study was conducted to examine contact length and strut width as a function of lateral deformation. The results show that the infill wall-frame contact length is significantly dependent on the lateral deformation demand levels and properties of interaction region.