Self-Centring Earthquake-Resilient Hybrid Steel-Concrete Shear Walls with Rocking Beams

Project Information

SC-HYBWalls

Grant agreement ID: 101027745

DOI

10.3030/101027745

Project closed

EC signature date 28 February 2021

Start date 1 February 2022

End date 26 March 2024

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 212 933,76

EU contribution

€ 212 933,76

Coordinated by

UNIVERSITY COLLEGE LONDON
United Kingdom

Periodic Reporting for period 1 - SC-HYBWalls (Self-Centring Earthquake-Resilient Hybrid Steel-Concrete Shear Walls with Rocking Beams)

Reporting period: 2022-02-01 to 2024-01-31

Summary of the context and overall objectives of the project

Conventional seismic-resistant structures are designed to experience significant inelastic deformations under moderate to strong earthquakes. Inelastic deformations due to damage to structural members, and residual story drifts and deformations that cannot be retrieved after earthquakes. Structural and non-structural damage results in direct and indirect losses such as repair costs and costly downtime during which the building is repaired and cannot be used or occupied. In addition, residual deformations make often buildings more expensive to repair than to rebuild. Hence, the main objective defined for the SC-HYBWalls project was the development of minimal-damage/high-resilient structural systems that couple the advantages of self-centring and hybrid steel-concrete structural systems responding to the safety and socio-economical needs of modern societies. The project aims to:
• address the disadvantages of conventional self-centering solutions;
• experience minimal damage that can be rapidly and easily repaired (i.e. achieve high resilience) during moderate ground motions controlling both structural and non-structural components;
• minimize the probability of collapse (i.e. protection of human life) under very strong and rare earthquakes;
• allow the immediate occupation of the building after ground motions (i.e. avoid downtime);
• facilitate and expedite the construction.
The project's objectives were achieved through the development, design, and testing of a novel self-centering device equipped with friction dampers. The friction-damped self-centring (FDSC) device was integrated into steel coupling beams that connect reinforced concrete walls to each other or to steel columns at their sides, forming an innovative seismic-resilient structural system named SC-HYBWalls. The comprehensive investigations conducted in this project demonstrated the enhanced seismic performance and resilience of buildings taking advantage of SC-HYBWalls. Simulation of the response of buildings featuring SC-HYBWalls to a number of earthquakes highlighted the proposed system's efficiency in providing effective self-centring capabilities and significantly reducing earthquake-induced residual deformations.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Developing a self-centering device that can be integrated as a prefabricated component into hybrid Lateral Load Resisting Systems (LLRSs) was the first goal achieved in this project. Several SC configurations featured different damping mechanisms and structural details were explored to address the shortcomings of the available self-centering structural solutions. To achieve an optimized and practical design for the intended Friction-Damped Self-Centering (FDSC) device, simplified analytical investigations, detailed 3D finite element simulations, and full-scaled experiments were conducted in this project.
In this research project, the Friction-Damped Self-Centering (FDSC) device was implemented in two types of Lateral Load Resisting Systems (LLRS), categorized as hybrid coupled walls. These systems were developed to introduce the innovative SC-HybWalls, which were designed to enhance seismic performance and resilience. In the SC-HYBWalls configuration, reinforced concrete (RC) walls are interconnected or linked to pairs of side steel columns at each level through steel coupling beams featuring FDSC devices.
The efficiency of the novel FDSC device in improving the seismic performance and resilience of the two types of innovative LLRS proposed in this project was validated in the subsequent phase. This phase began with the design of several archetype SC-HYBWalls of both types, covering a range of key design parameters typical in structural engineering practice. Finite element models were next developed for the architype SC-HYBWalls. Nonlinear dynamic analyses were conducted to simulate the response of these archetypes to numerous ground motion records to account for record-to-record variability. The results of these simulations demonstrated that SC-HYBWalls significantly reduce residual earthquake deformations and mitigate damage concentration, a common failure mode in reinforced concrete (RC) walls, thereby enhancing energy dissipation capacity and the distribution of plasticity. These findings underscore the SC-HybWalls' capability to facilitate immediate reoccupation of buildings after moderate earthquakes and expedite repairs that might be needed following strong earthquakes. Hence, implementing SC-HYBWalls as LLRS in multi-story buildings can lead to significant savings in repair time and costs, and minimize or eliminate downtime after major seismic events.
Some findings from this research project have been presented at three international conferences: ANIDIS-ASSISI in Turin, Italy (2022), Eurosteel in Amsterdam, Netherlands (2023), and SECED in Cambridge, UK (2023), with details published in their respective proceedings. The latest results will also be presented at the World Conference on Earthquake Engineering (WCEE) in July 2024. Additionally, three peer-reviewed journal papers are planned to disseminate the project's outcomes. The first paper has already been submitted and is currently under peer review at the Journal of Structural Engineering. The other two papers are in preparation.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

The research project progressed beyond the state-of-the-art by developing for the first time an innovative self-centring hybrid steel-concrete system (SC-HYBWalls) optimized to achieve simultaneous structural and non-structural damage control (i.e. Resilience). Furthermore, the self-centering and energy dissipative components of SC-HYBWalls were designed as pre-fabricated compact devices (modules), offering a fast construction process as an important asset modern societies require. The implementation of the proposed prefabricated solution eliminates uncertainties associated with on-site pre-tensioning of bolts and bars. Such uncertainties can compromise the structural performance of self-centring solutions that require on-site pre-tensioning, raising concerns about the effectiveness of state-of-the-art self-centring configurations. Therefore, this research project provided a solid contribution to earthquake and structural engineering and to the construction industry by addressing the shortcomings of available self-centring solutions for building structures.
The resistance and stiffness of the proposed friction-damped self-centring (FDSC) device are adjustable. This feature allows for achieving self-centring phenomena and simultaneously reducing earthquake-induced structural and non-structural damages, which distinguishes FDSC devices from other available self-centring solutions. The effectiveness of SC-HYBWalls in mitigating damage concentration significantly expedites and facilitates the repair process, ensuring faster building reoccupation when immediate occupancy is not possible after severe ground motions. Consequently, the application of SC-HYBWalls significantly impacts the structural construction industry by addressing (1) the demand for safer buildings that can withstand severe earthquakes with minimal casualties; (2) the socio-economic need for building structures that are cost-effective and quick to construct, with minimal downtime after extreme events.
Furthermore, a straightforward design procedure was developed in this project to design seismic-resilient SC-HYBWalls. This enables structural engineers to design the proposed structural systems in practice.