Retrofitting Solution for Soft Story Mitigation in Reinforced Concrete Frame Buildings: A Socio-technical Approach Using Numerical Optimization

Abstract

This research provides a practical and feasible retrofitting solution for soft story in reinforced concrete (RC) buildings with masonry infill walls for example in Nepal through numerical analysis. It is well understood that stiffness and strength of the soft story floor can be increased significantly by adding RC shear wall in the frame opening of the ground floor, making lateral deformation of that floor negligible. With this consideration, the authors have developed a numerical optimization framework for optimizing the RC shear wall in the open floor of soft story building incorporating socio-technical aspects from their previous publication [Timsina, K., Gadagamma, C. K., Numada, M. and Meguro, K. [2019b] “Development of a numerical optimization framework for solving soft-story problem in reinforced concrete frame buildings,” Seisan-Kenkyu]. The objective function for numerical optimization is cost minimization with the constraints of usability, performance, and complexity from a detailed field study. In this paper, the numerical optimization framework is developed and solved using the sequential quadratic programing (SQP). The whole scheme has been incorporated inside the 2D-Applied Element Method (AEM). The retrofitting solution thus obtained from the numerical optimization has been analyzed using the incremental dynamic analysis to know the capacity of the frame structure in earthquake ground motion. It shows that the retrofitting method can significantly enhance the soft story frame’s capacity and ensure the dwellers’ interests are not compromised.