Optimization of Inspection Period in Natural Stone Claddings

Cláudia Ferreira,Ana Silva,Ilídio S Dias,Jorge De Brito,Inês Flores-Colen

doi:10.3390/app10228236

Abstract

In condition-based maintenance plans, the schedule of inspections is an important step. Condition-based actions are performed according to prescribed condition criteria (i.e., condition, cost, availability, among other factors), and the main purpose of inspections is to evaluate the façade’s condition and plan its correction in order to reduce the risk of failure of the cladding. Therefore, the main goal of this study is to implement multi-objective optimization to understand whether there is an optimal time interval for performing the inspections. For that purpose, a Petri-net condition maintenance model is used to assess the influence of different maintenance plans on the overall degradation of natural stone claddings. In this model, the maintenance activities can only be performed after an inspection has been carried out. The definition of the best maintenance policy results in a conflict of objectives. Owners/managers seek to achieve a maintenance strategy that minimizes service life costs and maintain the cladding in a safe and minimal degradation condition. Multi-objective optimization procedures are capable of considering several conflicting objectives. In this paper, the objective functions considered are minimization of the service life costs, maximization of the efficiency index, maximization of the service life, and minimization of the total number of replacements over the time horizon.

Highlights

As the first line of defense against the environmental agents, the claddings are the most susceptible element to degradation [1]
It is assumed that the degradation process follows a Weibull distribution, and, in Table 2, the optimal parameters of the degradation process are presented in terms of the mean and standard deviation of the sojourn time in each degradation condition
Regarding the design variable constraints (Equation (3)), and based on Section 2.1.2, it is assumed that the time interval between inspection varies between 1 and 20 years

Summary

Introduction

As the first line of defense against the environmental agents, the claddings are the most susceptible element to degradation [1]. For many years, little or no attention has been paid to their maintenance [2] since building owners/managers assumed that this element plays a more decorative than structural role [3]. Over the last years, this belief has been changed, and stakeholders start to understand that appropriate and continuous maintenance is the most economical way to ensure the long-term durability of assets and improve the quality and aesthetic perception of the cities without compromising the assets’ reliability or safety [6,7]. Nowadays, decision-makers on service life management of the built environment are confronted by high demands of deteriorated assets and lower financial and human resources [8].

Objectives

Methods

Results

Conclusion