PSI - Issue 64

Gabriella Maselli et al. / Procedia Structural Integrity 64 (2024) 1743–1751 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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So far, there is no consensus on the selection of impact categories, nor are there harmonised methods or frameworks for conducting S-LCA, except that the steps of S-LCA are often, but not always, considered equivalent to those of LCA, i.e. ‘ cradle to grave ’ (Larsen et al., 2022). Unlike LCC and LCA, S-LCA is not yet considered or applied in the building sector to assess the social impact of building construction or renovation. 4. Research Methodology If it is becoming more and more urgent to search for new circular and sustainable materials in the field of civil engineering, it is equally necessary to characterise models for evaluating economic and technical life-cycle performance right from the testing phase of new products. In other words, when a building realised with innovative materials is being tested, it is necessary to assess whether it can represent a better alternative to conventional structures, firstly satisfying structural and technical, then economic criteria. Therefore, the aim of this work is to define a standardised and exportable approach based on the LCC to jointly evaluate the structural and economic performance of alternative designs of equivalent structures made of different materials. Therefore, this approach allows to: (i) estimate the life cycle costs of innovative structures; (ii) identify among several design alternatives the one that performs best both technically and economically, considering the entire life cycle. Thus, if two or more structural materials with comparable mechanical properties are taken as a reference, the proposed evaluation model allows the economically best alternative to be identified, taking into account the costs that need to be borne from realisation to disposal. The structure of the analysis approach is based on the following steps: 1. Evaluation of the technical-mechanical characteristics and structural analysis of the building; 2. Identification, classification and estimation of all life cycle costs of the structure; 3. Estimation of the life cycle cost of each design alternative; 4. Sensitivity analysis and/or risk analysis; 5. Comparison of the performance of the design alternatives. In step (1), after having identified the construction materials, the pre-dimensioning of the main members is carried out by means of simplified static diagrams, to then proceed to the verification phase of the structural typology under examination by means of a linear dynamic analysis capable of taking earthquake stresses into account. Phase (2) consists in defining a Cost Breakdown Structure (CBS) useful to identify and estimate the following cost categories, as suggested by the Royal Institution of Chartered Surveyors (RICS, 2016): (i) Design and construction cost; (ii) Operation cost; Item (i) includes construction costs, furniture and equipment, site costs or opportunity costs of the site already in ownership. In addition to these costs, there are design, consulting, legal and other professional fees. These costs, partially or totally, may be incurred with debt capital, or through financing. Operation costs (ii) include expenses for personnel salaries and wages and expenses for heating, cooling, ventilation, lighting, hot water and equipment. Maintenance costs (iii) are divided into ordinary and extraordinary. The former are all costs for ordinary maintenance and repairs, annual maintenance contracts and salaries of maintenance personnel. Extraordinary maintenance costs concern: the replacement of components of a plant and/or structure at the end of its useful life, with a one-off expense if the life cycle of the plant/structure is less than the period of analysis of the entire work; refurbishment for functional alteration or upgrading. Occupancy costs (iv), if any, are related to functional use, security and insurance, as well as personnel, material and other expenses necessary to perform the functions of the building. End-of-life costs (v) relate to the recovery or demolition of the work and affect the residual value. The latter is (iii) Maintenance cost; (iv) Occupancy cost; (v) End of life cost.