Novel Design Proposal for the Seismic Retrofit of Existing Buildings with Hybrid Steel Exoskeletons and Base Sliding Devices

Ljuba Sancin,Claudio Amadio,Chiara Bedon

doi:10.2174/1874149502115010074

Abstract

Background: Existing Reinforced Concrete (RC) structures and brittle buildings are often exposed to seismic events that may have significant resistance and displacement demand compared to their actual capacity. Accordingly, an optimal retrofit intervention can ensure enhanced and safe structural performances for them. Among the techniques that have been addressed for the retrofit of existing RC frames, steel exoskeletons can notoriously improve the seismic performance of existing buildings due to their input stiffness, ductility and resistance. In this paper, the attention is focused on the interaction of steel exoskeletons with RC frames and the consequent details to achieve a more effective design of the retrofit intervention. Objective: Based on parametric calculations, a new hybrid design concept that takes advantage of traditional steel exoskeletons with additional base sliding devices (at the foundation level of the RC frame to retrofit) is addressed in this paper. Methods: As shown through SDOF and 2D-MDOF calculations, the definition of the optimal operational conditions (and thus mechanical configurations) for the so-assembled hybrid solution can maximize the potential of the retrofit intervention, with marked benefits in terms of ductility, resistance, and overall efficiency, ensuring very low damage in the existing building. Results: Given that the used base sliders are bidirectional, it is expected that the proposed solution could be efficiently extended to 3D structures, once the exoskeleton systems are optimally designed along the two principal directions of the hybrid structure to retrofit. Conclusion: The potential of the hybrid approach is shown based on parametric analyses. Furthermore, general design recommendations are proposed for the hybrid solution.

Highlights

IntroductionExisting Reinforced Concrete (RC) structures and brittle buildings, as known, are often required to withstand seismic events that may be significantly high in magnitude (and require high resistance / displacement demand), compared to their actual capacity
Existing Reinforced Concrete (RC) structures and brittle buildings, as known, are often required to withstand seismic events that may be significantly high in magnitude, compared to their actual capacity
The attention is focused on the response of the RC frame, the steel exoskeleton and the hybrid system

Summary

Introduction

Existing Reinforced Concrete (RC) structures and brittle buildings, as known, are often required to withstand seismic events that may be significantly high in magnitude (and require high resistance / displacement demand), compared to their actual capacity. An optimal retrofit intervention can ensure enhanced structural performance [1, 2]. In this regard, many research studies have been dedicated to several techniques that may be suitable for different existing structures [3 - 7], and especially for RC buildings [8 - 10]. Existing Reinforced Concrete (RC) structures and brittle buildings are often exposed to seismic events that may have significant resistance and displacement demand compared to their actual capacity. Among the techniques that have been addressed for the retrofit of existing RC frames, steel exoskeletons can notoriously improve the seismic performance of existing buildings due to their input stiffness, ductility and resistance. The attention is focused on the interaction of steel exoskeletons with RC frames and the consequent details to achieve a more effective design of the retrofit intervention

Methods

Results

Conclusion