VIRTUAL DESIGN AND CONSTRUCTION OF PLUMBING SYSTEMS PROJETO E CONSTRUÇÃO VIRTUAL DAS INSTALAÇÕES HIDROSSANITÁRIAS João Bosco Pinheiro Dantas Filho -
[email protected] Universidade Federal do Ceará
Bruno Maciel Angelim -
[email protected] FortBIM
Joana Pimentel Guedes -
[email protected] Universidade Federal do Ceará
Marcelo Augusto Farias de Castro -
[email protected] Universidade Federal do Ceará
José de Paula Barros Neto -
[email protected] Universidade Federal do Ceará
Abstract Coordinate mechanical, electrical and plumbing (MEPF) projects is a great challenge. The inability in identify conflicts in 2Ddrawings create delays in construction process due the identification of conflicts on field when the budget it's already approved; produces rework and influence the productivity of all the involved on the process. Building Information Modelling (BIM) can help AEC industry to find possible problems before the beginning of the construction work. Nevertheless, BIM benefits related to project compatibility are associated with level of detail (LOD) of the resulting model of the virtual construction phase (VDC). The paper is focused in presenting a case study about VDC uses and benefits allied with constructability analysis by civil construction industry and also present our findings in researches about the requests for information (RFI). For paper development were made literature reviews, interviews with the people involved in the process and qualitative analysis, used to evaluate the different types of RFI generated for the water/sanitary project facilities. Through reduction of RFI after the virtual construction, a table of recommendations was elaborated so that would be possible the identification and prevention of RFI and so, with that, would be possible a more proactive posture about RFI. Resumo Coordenar projetos MEPF é um enorme desafio pois a incapacidade de identificar conflitos em desenhos 2D gera atrasos no processo de construção e aumento da carga de administração devido a identificação de conflitos em campo quando o orçamento já está aprovado; gera retrabalho para corrigir problemas que não foram identificados na fase de projeto e interfere na produtividade de todos os participantes do processo. Building Information Modeling (BIM) pode auxiliar a encontrar possíveis problemas antes de iniciar a obra. Porém, os benefícios do BIM relacionados à compatibilização de projetos estão associados ao nível de detalhe do modelo resultante da fase da construção virtual (VDC). O objetivo deste artigo é apresentar o estudo de caso da utilização e benefícios do VDC aliado a análise de construtibilidade pela indústria da construção civil, apresentando nossos achados em pesquisas RFI. Para o desenvolvimento do artigo foram elaboradas revisões de literatura, entrevistas e análises qualitativas para avaliar os diferentes tipos RFI geradas pelo projeto de instalações hidrossanitárias. Através da redução de RFI após a VDC foi elaborada uma tabela de recomendações possibilitando a identificação e prevenção. Dessa forma, contribuímos para que seja adotada uma postura pró-ativa em relação a identificação de conflito. Keywords VDC, Constructability, Request for Information, Conflit Identification, Lean Design
VIRTUAL DESIGN AND CONSTRUCTION OF PLUMBING SYSTEMS. 1. Introduction Coordinate mechanical, electrical and plumbing (MEPF) projects is a great challenge. The inability in identify conflicts in 2D-drawings create delays in the construction process and the increase of the administration burden due the identification of conflicts on field when the budget it's already approved; produces rework to correct problems unidentified in the project phase and influence the productivity of all the involved on the process [1]. Building Information Modelling can help the AEC industry to find possible problems before the beginning of the construction work [2]. Nevertheless, BIM benefits related to project compatibility are associated with level of detail [3] - currently named level of development of the resulting model of the virtual construction phase (VDC). Researches shown that publications about this theme are mainly focused in conceptualization and that are few examples of analysis about the benefits of BIM to MEPF systems [4]. The paper is focused in evaluate requests for information (RFI) associated with water/sanitary facilities of a BIM model with the level of development 400 (LOD 400) [3]. Thus it is expected to add on the improvement of water/sanitary facilities projects, as well as assist the virtual construction team on notice and identify project problems.
2. Construction Analysis Constructability is a concept that emerged in the late 1970's [5,6] and evolved over many studies [5-9]. It can be defined as the use of the construction knowledge and planning experience of project, engineering, construction and supply for the project optimization [10]. A constructability analysis framework is proposed with the purpose to reduce the construction problems caused by projects and, with this, make the company more competitive [11]. When associated with the project process, constructability enhances quality and productivity in so far as reduces time, waste and costs, promoting a better building development with the insertion of the constructor on the project process [12]. Constructability analysis associated with BIM is a relatively new approach and offers that new evaluation of construction methods can be performed in a more efficient and uninterrupted way. Currently, it's made with the virtual exam of the BIM model [5]. Implement constructability on the project process requires a complete disassemble of traditional idea compartmentalization and the project team need more building feedback than the constructors can give [13].
3. Virtual Design and Construction Virtual Design and Construction (VDC) concept can be defined as the use of multi-disciplinary computer models that include product, construction, organization of construction team, operation team and performance requirements aiming support public and explicit objectives to integrate project, engineering, construction, operations, business strategies, etc. [14]. The creation of project alternatives in 4D models and the prediction of its project behaviors are the main VDC goals [15]. Studies show that VDC is a Lean process activator and improve the construction project delivery performance. [16]. VDC is the way to enhance construction project managing and its utilization demand a significant protocol alteration, mentality and traditional behaviors in construction industry [16,17].
4. Methodology This paper classifies itself as exploratory and descriptive. The analysis unity of the paper is the prototyping BIM process and presents a perspective from a practical BIM implementation. It is used a qualitative methodology. It was started with the question "How VDC can contribute to the improvement of MEPF projects?” Immediately it was done a literature review for the theme and methodology with a view to, from the results and conclusions, it was possible comprehend each contribution so that the basis for the data analysis of this paper could be developed. Case study was the research strategy used. This strategy applies when "why" and "how" questions are made; and when the focus is about contemporary phenomenon within the real life context [18]. The case sorting occurred whereof information oriented selection [19] to maximize information utility that this case could provide to the research's objectives. It was selected a critical case to obtain information that allows logical deductions such as: "If this is (not) valid for this case, so can (not) be applied to other cases". The criteria for the choice of the case were: it should have VDC use on project coordination. This paper was based on multiple evidence sources: semi-structured interviews taped and transcript with the managing virtual construction analyst, civil engineer responsible for the 3D model; documents analysis of project coordination reports, communication between contractor and BIM analyst, and analysis of the 3D navigation model of the construction through Autodesk Navisworks Freedom (Image 1) software. Data collection was performed considering the following operational means that corroborate to the validly and reliability of the data collected: use of multiple evidence sources; revision of the interview report by the interviewed; development and use of the case study data base. Data collection was made through fundamental theory that was incorporate to the case study with another se study as a way to treat the data and interpret them. The data analysis focused in patter recognition, construction of explanations and use of logical models, in witch was compared between an empirical pattern obtained through case study and another of prognostic basis obtained in literature review. Analytical qualitative strategy was developed with help of software to organize, manage and analyze qualitative information. Data categories focused for the paper methodology is the ones that can be observed in case studies presented by Eastman et al. [20].
5. Results 5.1. Enterprise Description It's a construction of a residential building with 15.925,67 m² of floor area and an estimated cost of R$ 38 million. After the pre-executive conclusion of the architecture, structure and facilities projects, the construction/incorporation company chose for the execution of an intermediary phase named virtual pre-construction. In this phase a BIM model was created with LOD 400, which made possible the constructability analysis with the objective to guarantee in advance that the construction systems can be executed in a more efficient way regarding time and cost. In order to achieve BIM benefits visualized by the client, it was released for the virtual construction team, past projects, the company's constructive methods. The constructive method contains execution information's constructive work that aren't explicit in projects, but that must be considered in pre-construction phase. An example of this type of information is the facilities' sequencing. In this case the enterprise was virtually built in the same way that it is in fact build. Thus, sanitary facilities were modelled first and served as base line for further analysis of possible conflicts with the remaining facilities.
5.2. Case Study's Virtual Pre-Construction Through coordination model analysis it was identified 167 RFI related to building facilities (or MEPF - mechanical, electrical, plumbing and fire protection). From this total, 51 were associated specifically with the plumbing systems project. It's part of plumbing systems hydraulic, sanitary, ventilation and drainage plumbing. Image 1 shows the RFI’s distribution identified with highlight the plumbing systems project, qualitative analysis' subject.
Image 1 – Identified RFI distributions.
The interview's analysis showed that the project's virtual construction process was developed in three stages. Architecture's and structure's 3D models were created on stage 1. On stage 2 the facilities' model was made and the constructability analysis was elaborated through a 3D coordination model that contained all the projects, and a report was produced with all the identified RFI. The projects' designers perform the projects' analysis and review and release new versions. From this point is initiated stage 3, in which the virtual construction team examines the newest projects' versions in order to verify if the pointed problems were solved or not. In this stage an approach between designers and the virtual construction team occurs pursuing the validation of project's information and the resolution of most RFIs. After modelling the most recent projects' versions a final report was released to the construction/incorporation company. This report brings all the unattended RFI and/or new questions that emerged from the solutions adopted. This study adopts RFI's classification in six analyzed categories: project's correction, project's omission; validation of information, project's modification, and divergence of information and project's verification. Table 1 presents the definition of each classification and demonstrates the practical evidence identified for the coordination model's analysis. Understanding this classifications associated with evidence as they happen can contribute so that virtual construction teams can have a referential or problems' categories check list in which they can look for, as well as can serve as reference so plumbing systems design teams would be able to avoid their occurrence, specially teams with BIM based projects.
Table 1 – Six types of RFI identified from VDC in MEPF Systems RFI Types
Description
Few examples
Project's Correction
Problems associated with presented solution's execution or version incompatibility.
It wasn't possible connect the relief ventilation w.c. suite master 10ºTYPE. Pluvial plumbing project with 1,42m exit height below curb when it should be at best 0,10m to make possible the gutter flowage.
Project's Omission
Absence of specific project for some areas.
SS2 floor's project didn't calculate drainage. Provide hydraulic designs for pool, body of water's and founts.
Validation of Information
In low complexity cases, when the project is partially neglectful about plumbing's route, the virtual construction team suggests a solution to designer's validation.
Validate hydraulic supply to the garden's faucet, unindicated in the ground floor's project. Pathway of the discharge piping from the drainage well partially omitted.
The solution adopted isn't wrong, but the analysis shows an opportunity of a better solution in order to avoid undesired situations.
Modify the route supply of PW from lookout w.c. Drainage plumbing has its initial point in the pool area, causing insufficient height (h=1,59m) for the parking area.
Project mistake associated with lack of attention where, two or more different drawings (plan, vertical scheme and isometric drawing) present different information.
Confirm the type of plumbing: floor plan indicates PPR, DI13 indicates CPVC type. Floor plan a construction detail has different information about the utilized material (PVC or PPR?).
Low complexity issues where the project can be mistaken or not. Opportunity for project's enhancement.
Verify the ventilation need for siphoned cash at sauna's shower. Verify the possibility of changing the inclination from 1% to 0, 5%.
Project's Modification
Diversion of Information
Project's Verification
Image 2 shows a case of correction witch the specified distance between ventilation and sanitary pipes (blue and black, respectively) that don't permit the connection's execution between them using a "Y" connector. Minimal distance verified by virtual construction in order to support execution was 330 mm between axes of 100mm plumbing.
Image 2 – Needed correction of the distance between ventilation and sanitary pipes.
Image 3 demonstrates divergence of information where the highlighted plumbing has a different specification on the floor plan drawings and isometric detail.
Image 3 – Difference of diameter information between plans isometric detail drawings.
Image 4 shows a project's modification where the beginning of the pipe occurred in lower slab due to the bottom of the pool located above the underground parking lots. Because of this and mandatory slopes every extension was virtually built with insufficient height for vehicles to maneuver. Based on that the project team analyzed the context and proposed new route of facilities aimed at enabling the use of underground and avoid inconvenience to users.
Image 4 – Insufficient height causing necessary modification.
Image 5 demonstrates project's omission that has been built virtually completely and was not detected the existence facility for floor drainage. This is a case of a simple mistake easily detectable if considered in the project's checklists thus can be prevented from becoming a RFI on future projects.
Image 5 – Omitted underground drainage.
Image 6 shows design validation where it is identified that the path of the discharge pipes was partly undefined in the projects. Given this and the low complexity of the issue the virtual construction team modeled a proposed pathway and requested validation and inclusion thereof in the projects.
Image 6 – Needed validation for the path of the discharge pipes.
It was noticed the all items related as verification, variance and modification were eliminated, and items related as omission and validation were reduced to only 1 occurrence. The questions related as project's corrections were all considered by designers, but when the modifications were implemented, caused new conflicts. It is observed that the commitment with the project's improvement didn't lead them to perfection, but delivered a small number of questions, already identified, to be analyzed and resolved by construction team. Image 7 shows the substantial RFI reduction in each category.
Image 7 – RFI classified reduction in each stage
Identify conflicts is a reactive approach while avoid conflict is proactive, thus, we have to develop ways to improve the design process in a way to reduce the occurrence of future conflicts [21]. Table 2 summarizes the recommendations to identify and avoid these RFI types in the plumbing systems design process or during the virtual construction. Table 2: How to identify and avoid MEPF Systems problems RFI Types
How to avoid/identify
Project's Correction
Verify connection feasibility between sanitary and ventilation plumbing; Verify the plumbing vertical alignment passing through floors from the roof; Verify coincidence between the rainwater output level and gutter level; Verify coincidence between the sanitary plumbing output level (considering mandatory inclinations) with the sewage systems.
Divergence of Information
Verify drawing differences (plan, vertical scheme and isometric detail) analyzing route, specified materials and dimensions (diameter);
Project's Modification
Verify height of plumbing considering mandatory slopes, level of associated floors, internal height and quote and lining existence;
Project's Omissions
Verify/request hydraulic design for poll, water body and fountains; Verify/request drainage design for garden, covered slabs and undergrounds;
Validation of Information
Verify feasibility of isometric details, layout and the supply network (hydric derivation); Verify the existence of level differences in drawings;
Project's Verification
Verify if, considering mandatory slopes, they can be reduced (change 1% for 0, 5%); Verify the ventilation need in sanitary plumbing and siphoned cash
6. Conclusion The results demonstrate the VDC's contribution for the improvement of plumbing system projects. Even though each project has its unique characteristics, is noticed that the results valid for it can be used as a guide to the adoption of a proactive posture towards conflict identification, according to proposed by Tommelein e Gholami [21]. In many cases the 3D construction model reveals the execution impediments that are not possible visualize in 2D drawings. 3D environment uses real sized pieces, tubes and equipment, obeying the necessaries slopes and space and structure limitations. Information requirement are financially valuable to the constructor and it is considered that generated RFIs in this specific case can contribute for the improvement of conception, production and managing processes of new water/sanitary facilities projects as long as considered during the integrated design process in which participants are committed to eliminate future RFIs, making the hole process leaner.
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