Decision-making approaches for optimal seismic/energy integrated retrofitting of existing buildings

Abstract

Given the ambitious targets of carbon emission reduction set for the very near future, it is now expected that retrofitting operations on existing buildings aim both at reducing their operational energy consumption and at improving their seismic performance. Indeed, it is now well acknowledged that, if a sole energy efficiency upgrade is provided to a given building, in case of an earthquake occurrence, double economic and environmental losses will be experienced due to both the lost investment for energy retrofitting and the repair and retrofitting activities for post-earthquake damage. Moreover, social losses may also be experienced in terms of casualties, injured or homeless due to the seismic and structural deficiencies of the existing structure. To aid thus the process of a coupled seismic/energy renovation of the existing building stock, several multi-criteria decision-making (MCDM) approaches have been developed for the identification of optimal retrofitting solutions for buildings. Such procedures typically consider a range of economic, social, technical, and, more recently, environmental aspects that are assumed to be of interest to decision makers (e.g., installation cost, duration of works, architectural impact, need for specialised workers, etc.). The present study demonstrates the application to a case-study school building of two different MCDM approaches, which account for seismic vulnerability and energy efficiency, as well as related environmental impacts of buildings. The main differences between the two procedures are explored in terms of considered decision-making parameters and corresponding weights, rankings of retrofitting options and identification of the optimal retrofitting strategies.

A Comparative Analysis of Retrofitting Techniques for Seismically Vulnerable Historical Building

“…Historical buildings often possess intricate architectural details, delicate materials, and unique construction methods that can be easily damaged by seismic forces. By implementing base isolation, these buildings can be effectively protected without altering their original design or compromising their historical integrity [7]. The isolators accommodate ground movements and prevent these movements from being directly transmitted to the building's structure, thereby preserving both structural and non-structural components such as facades, ornaments, and interior finishes.…”

“…Steel braces provide lateral support and increase the stiffness of the wall, reducing its susceptibility to seismic-induced deformations. Steel ties and anchors can be embedded within the masonry to improve the connection between individual units, enhancing the wall's overall integrity and loadbearing capacity [7]. The use of steel elements is particularly effective in providing localized reinforcement to areas of the wall that are most vulnerable to seismic forces, such as corners and intersections.…”

“…Steel bracing systems work by creating a rigid framework that restricts lateral movements and distributes seismic forces more evenly throughout the structure. This is achieved through the installation of diagonal steel braces, which can be configured in various patterns such as X-bracing, K-bracing, or chevron bracing [7]. These braces are strategically placed within the timber frame to provide maximum support and to absorb and dissipate seismic energy, thereby reducing the stress on the timber components and preventing excessive deformation.…”

“…However, the installation of steel bracing systems does require careful planning and engineering expertise. The integration of steel braces into existing timber frames must be executed with precision to ensure that the braces effectively contribute to the building's seismic resistance [7]. Additionally, considerations must be made regarding the potential impact on the building's load paths and connections, as well as the need for regular maintenance to ensure the long-term effectiveness of the bracing system.…”

“…Seismically vulnerable historical buildings are valuable cultural assets that require specialized retrofitting techniques to enhance their structural integrity and mitigate earthquakeinduced damage [4]. Retrofitting techniques for such buildings involve a nuanced approach that balances structural reinforcement with the preservation of historical authenticity [7].…”