EVALUATION AND RETROFIT OF CIRCULAR REINFORCED CONCRETE SILOS BUILT IN LIMA, PERU IN THE 1970’S DECADE

Abstract

The assessment of two circular reinforced concrete (RC) silos built in the 1970’s decade is presented. The methodology implemented is described, including the data collection, testing, analysis requirements, structural model, evaluation results, and retrofitting design. The RC silos were designed in the 1970’s decade with very low seismic demand and insufficient engineering details. The evaluation of this special type of existing structure has reported stability and strength severe issues that need to be improved.The national and international codes, as well as guidelines, were consulted to define the most appropriate seismic demand, the gravitational, and eventual loads. Moreover, the load combinations criteria, the evaluation and diagnostic requirements, the structural design criteria, and some adequate retrofitting techniques.The main retrofit strategy was oriented to improve the stability of the silos against overturning, reducing the normal stresses on the ground, and strengthening the RC walls subjected to the axial and bending combined effects due to the current requirements. The retrofit design implemented was able to respond to the described issues by an extension of the foundation and RC jacketing of the silo walls.A rational approach to evaluating and retrofitting this type of non-conventional RC structure was developed. In addition, a cost assessment based on a comparison of concrete and steel reinforcement volume between the existing silo and the strengthening components is presented.

Keywords

• circular silos
• reinforced concrete
• non-conventional structure
• evaluation
• seismic retrofit