A BIM Based-Tool for Formwork Management in Building Projects

Abstract

Se diseñó e implementó una herramienta BIM para gestionar encofrados. Para ello, se realizó una revisión de la literatura así como de encuestas para determinar las preferencias de la industria de la arquitectura, ingeniería y construcción referente a la gestión de encofrados en edificaciones. Se determinó el nivel de desarrollo requerido para los modelos BIM de encofrados, la preferencia respecto a la opción de alquiler y nivel de automatización actual de estos procesos. Luego se automatizó la creación de modelos de encofrados y los principales flujos de trabajo de la gestión de encofrados.

Formwork represents between the 35% and the 60% of the total cost of the structural framing of a concrete building and is always part of the critical path of a project. Building Information Modeling (BIM) has been growing rapidly worldwide for building projects. However, modeling temporary structures using BIM is not very common. The current formwork management practice relies on the use of traditional tools like CAD, PDF editors and spreadsheets. A BIM formwork model during the preconstruction stages provides a powerful tool for decision making in formwork management (selecting formwork system, formwork supplier, and defining quantities to procure formwork systems). Relying only on rough cost estimates and field experience related to formwork can lead to like overestimating formwork budgets, renting surplus formwork, and paying for additional formwork elements/systems that are in jeopardy of being lost, damaged or even stolen. A review of the state of art, the state of practice and the results of survey used to gather data about AEC practitioners regarding formwork management preferences, indicated that: (1) BIM formwork modeling with LOD 100 and 200 is the preferred approach by practitioners, (2) renting formwork is the preferred mode, considering the contact area of the system instead of renting pieces of formwork, and (3) the use of traditional tools like CAD, PDF editors and spreadsheets involving minimum level of automation, is the general practice in formwork management. Based on these findings the thesis focuses on the design, development and testing of a BIM-based formwork management tool. The BIM-based tool has two phases: (1) the automation of BIM formwork modeling of the contact surface of formwork systems and populating BIM parameters related to formwork (formwork types, formwork weight, productivity, and timing) in the input BIM model, and (2) use of the resulting BIM model developed in phase 1 for formwork management tasks (quantity takeoffs, formwork demand profiles, cost analysis, estimation of Key Performance Indicators (KPIs) like reuse factor and formwork efficiency, and tracking formwork removal). The tool was tested on two case studies (a 20-story building and a 5-story building) both with 80 work zones and 46,650 m2 of floor-built area. The results of the KPIs for both case studies were similar as expected since both buildings have similar modular architectures. The BIM-based tool for formwork management presented in this thesis provides the following advantages: (1) Implemented independently of the formwork systems or formwork provider selected, (2) Time savings due to automation of repetitive tasks in Revit and focus on modeling formwork surface contact area (instead of modeling all formwork components), and (3) Reduction in human error since the BIM processes (formwork modeling, parameters management, and exchange of data between different platforms) are automated, reducing the need of manual entry of parameter values or manual 3D modeling.