Construction has been suffering from a productivity crisis for many years in Italy. The new design tools and the most advanced construction techniques are struggling to spread in an extremely atomized reality. Among the most popular research areas is the attempt to industrialize the structural elements. In the past this was done through the prefabricated reinforced concrete structures and today through the x-lam. However, the cast-in-situ reinforced concrete structures are the most widespread in residential construction. This construction technique involves three activities: formwork, laying of reinforcing bars and casting. The laying of the reinforcing bars and the casting of the concrete have been the subject of various innovations. On the other hand, despite advanced formwork systems are considered more efficient, the traditional formwork methods, which require inefficient wooden boards cut and nailed on site, are still used. Therefore, the first purpose of this paper is to identify the spread of advanced formwork systems and to compare them with the traditional one. To investigate this, a survey comprised of 50 professionals and a case study were conducted, so using both qualitative and quantitative approaches, the specificities of formwork and global impact were analyzed. The results obtained suggest that the advanced systems significantly reduce execution times and costs ensuring greater safety for the workers and better finishings quality for the concrete elements, although these systems are not very widespread. Despite their proven importance, almost all the choices relating to formwork projects are usually left to the executing companies at a late stage of the process. This practice is not acceptable from the point of view of the designers’ responsibilities nor from the point of view of the construction phase efficiency. Therefore, a workflow identifying the responsibilities, the information, and decision-making milestones within the project, and a Construction Site Information Model showing the design and communication effectiveness of the BIM approach in the ergotechnical field are proposed. For this purpose, the most recent technical regulations concerning digitized information management have been followed. Special focus was paid to the Level of Information Need, which is the new way to defining the information needs for technical and construction objects. Finally, following the goal of optimizing the use of formwork on site, it has been noticing that the great variability of productivity of reinforced concrete works, combined with the low reliability of deterministic programming methods, makes difficult to organize storage, supplies, equipment and work areas. So, a probabilistic algorithm is proposed for calculating the duration of a few activities in series. Based on the Monte Carlo method, this tool is built for the needs of reinforced concrete works, and it takes into account the uncertainty of team performance and weather interruptions. The intention is to make the methods of risk management accessible to the small realities that make up the Italian construction world. To ease the process, a user friendly interface is proposed to simplify the use of the algorithm assuming it is automated and implemented in small software.
Il settore edile in Italia soffre da anni una crisi di produttività. I nuovi strumenti di progettazione e le tecniche più avanzate di costruzione faticano a diffondersi in una realtà estremamente atomizzata. Tra gli ambiti ricerca più percorsi vi è il tentativo di industrializzazione degli elementi strutturali, prima con le strutture in c.a. prefabbricate, ora con il legno multistrato. Tuttavia, in ambito residenziale, rimane maggioritario l’impiego del calcestruzzo armato gettato in opera, la cui realizzazione si articola in tre attività principali: casseratura, posa dei ferri d’armatura e getto. La posa dei ferri e il getto del calcestruzzo sono stati oggetto di diverse innovazioni: realizzando le gabbie in ferriera per le armature, preparando il calcestruzzo in centri di betonaggio specializzati e utilizzando pompe in grado di svuotare le autobetoniere in pochi minuti per il getto. Per quanto riguarda la casseratura invece, sebbene esistano da anni sistemi avanzati che promettono di migliorarne la produttività, viene ancora oggi spesso realizzata con metodi tradizionali basati su tavole di legno tagliate e chiodate in opera. Pertanto, il primo scopo del presente elaborato è quello di individuare la diffusione dei sistemi di casseratura avanzata e di metterli a confronto con quella tradizionale. Per farlo viene prima proposto un sondaggio che ha coinvolto più di 50 addetti ai lavori e poi un caso di studio, analizzando le specificità delle casseforme e il loro impatto globale sul cantiere seguendo un approccio sia qualitativo che quantitativo. I risultati ottenuti dimostrano che, sebbene siano poco diffusi, i sistemi avanzati riducono sensibilmente i tempi di esecuzione e i costi, sia diretti di lavorazione che indiretti di cantiere, garantendo maggiore sicurezza per gli operai e finiture qualitativamente migliori per gli elementi gettati. Nonostante la loro dimostrata importanza, la quasi totalità delle scelte relative alle opere di casseratura viene solitamente demandata alle imprese esecutrici in una fase avanzata del processo. Tale prassi non è accettabile né dal punto di vista delle responsabilità dei progettisti né da quello dell’efficienza della fase costruttiva. Pertanto, viene proposto un flusso di lavoro che individui all’interno del progetto i responsabili, le informazioni e i momenti di decisione e un modello Co.S.I.M. basato sul caso di studio che mostri l’efficacia progettuale e comunicativa dell’approccio BIM in ambito ergotecnico. A questo scopo è stata seguita la più recente normativa tecnica riguardante la gestione informativa digitalizzata, dalla ISO 19650 alla EN 17412-1, focalizzando l’attenzione sul Level of Information Need, ovvero il nuovo approccio alla definizione del fabbisogno informativo per gli elementi tecnici e cantieristici. Infine, seguendo il proposito di ottimizzare l’impiego in cantiere delle opere di casseratura e avendo notato dall’esperienza sul campo che la grande variabilità di produttività delle opere in c.a., combinata alla scarsa affidabilità dei metodi di programmazione deterministici, rende difficile organizzare stoccaggi, forniture, attrezzature e aree di lavoro, viene proposto un algoritmo probabilistico per il calcolo della durata di poche attività in serie. Tale strumento, basato sul metodo Monte Carlo, costruito per le esigenze delle opere in c.a., consente di tenere conto dell’estrema incertezza della resa delle squadre e degli stop dovuti alla pioggia. Lo scopo è quello di portare i metodi propri del risk management anche nelle piccole realtà che costituiscono il mondo dell’edilizia italiana, in modo che le scelte dei progettisti e delle imprese siano basate su valutazioni più complesse e meno semplicistiche. Per questo viene anche proposta una possibile interfaccia user-friendly che possa rendere semplice l’utilizzo dell’algoritmo nel caso in cui questo venga automatizzato e implementato in un piccolo software.
Sui sistemi di casseratura negli appalti edili. Confronto, gestione informativa digitalizzata e progettazione ergotecnica
Cantelmo, Andrea
2020/2021
Abstract
Construction has been suffering from a productivity crisis for many years in Italy. The new design tools and the most advanced construction techniques are struggling to spread in an extremely atomized reality. Among the most popular research areas is the attempt to industrialize the structural elements. In the past this was done through the prefabricated reinforced concrete structures and today through the x-lam. However, the cast-in-situ reinforced concrete structures are the most widespread in residential construction. This construction technique involves three activities: formwork, laying of reinforcing bars and casting. The laying of the reinforcing bars and the casting of the concrete have been the subject of various innovations. On the other hand, despite advanced formwork systems are considered more efficient, the traditional formwork methods, which require inefficient wooden boards cut and nailed on site, are still used. Therefore, the first purpose of this paper is to identify the spread of advanced formwork systems and to compare them with the traditional one. To investigate this, a survey comprised of 50 professionals and a case study were conducted, so using both qualitative and quantitative approaches, the specificities of formwork and global impact were analyzed. The results obtained suggest that the advanced systems significantly reduce execution times and costs ensuring greater safety for the workers and better finishings quality for the concrete elements, although these systems are not very widespread. Despite their proven importance, almost all the choices relating to formwork projects are usually left to the executing companies at a late stage of the process. This practice is not acceptable from the point of view of the designers’ responsibilities nor from the point of view of the construction phase efficiency. Therefore, a workflow identifying the responsibilities, the information, and decision-making milestones within the project, and a Construction Site Information Model showing the design and communication effectiveness of the BIM approach in the ergotechnical field are proposed. For this purpose, the most recent technical regulations concerning digitized information management have been followed. Special focus was paid to the Level of Information Need, which is the new way to defining the information needs for technical and construction objects. Finally, following the goal of optimizing the use of formwork on site, it has been noticing that the great variability of productivity of reinforced concrete works, combined with the low reliability of deterministic programming methods, makes difficult to organize storage, supplies, equipment and work areas. So, a probabilistic algorithm is proposed for calculating the duration of a few activities in series. Based on the Monte Carlo method, this tool is built for the needs of reinforced concrete works, and it takes into account the uncertainty of team performance and weather interruptions. The intention is to make the methods of risk management accessible to the small realities that make up the Italian construction world. To ease the process, a user friendly interface is proposed to simplify the use of the algorithm assuming it is automated and implemented in small software.File | Dimensione | Formato | |
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https://hdl.handle.net/10589/177589