BIM for Efficient Project Execution

Introduction?

BIM or Building information model is a relatively new technology used in Design of built assets. They comprise of federated models prepared by different design teams which include model files, documents and structured data creating a digital replica of the building. BIM allows all disciplines to work on separate 'federated' models brought together to create single, complete model of the building at key stages.?

One of the benefits of adopting BIM is the potential for avoidance of clashes, ensure spatial co-ordination between different components of the Project including Structure, MEP Services such as Ducts, Piping systems, Electricals and fittings?

In this case study our focus is to give a clear understanding to our partners on how we can use BIM to solve site execution related issues and explain how we were able to achieve clash free and timely work completion. This case study was selected being an ongoing project and final results can be clearly verified.

Client Brief:

We were approached by one of the leading Healthcare provider in our?city to find solution to a MEP co-ordination issue at their ongoing site.

They had recently incurred losses on both time and cost, after executing basement and ground floor, in spite of having several agencies on board expensive rework and demolition of civil work occurred, ceiling heights also needed to be lowered in many areas up to 2.2mtrs and the end result was far from satisfactory.

They asked us to prepare coordinated 2D CAD drawings across all disciplines and issue good for execution shop Drawings for execution at site. We suggested the best way forward will be to model them in 3D using BIM and take Output drawings for execution ?

Site execution Requirements :

The client wanted the execution at the site to proceed without clashes and also to improve ceiling levels if possible, work execution has to be completed fast so clear working drawings with all dimensions were necessary.

Therefore our BIM team was assigned the Job of planning the Implementation

Our Strategy:

We understood that best strategy would be to 3D model the complete Project using BIM Software, Clear all Clashes in the Model itself and take 2D Drawing outputs from the Clash cleared model for execution at site. We agreed to complete one floor as a pilot project and if we are able to achieve the goals we will proceed BIM solution for all other floors.

We also suggested that all partners undertaking the execution at site need to be made aware of the complete coordinated model and so a collective online presentation was needed. To ensure the workability of the drawings each vendor was asked to Verify and Approve (VET) the 2D output drawings?before execution commenced.

So what's CAD and BIM??

Here is the basics: CAD is Computer Aided Design Generally a two-Dimensional Drafting system BIM is Building Information Modelling the latest 3D integrated workflow system

Challenges:

The project was executed in a very fast pace and several agencies were involved for implementation of such as Contractors for HVAC, Electrical, Plumbing, Medical Gas systems, Fire protection, Low voltage etc. Levels and Positions of all elements needed to be maintained during installation for proper Installation and maintenance.?

General Observations:

• We found that there is an Industry Standard sequence for Installing each service (levels) depending on ease of implementation, ability to access and service them and reduce interference from one another.?For example, Electrical and low voltage cables need to be positioned at a higher level and fire sprinkler pipes at the next lower level, HVAC ducts maybe parallel or below these and Water supply pipes will be further below. Drainage pipes have to be at lowest level as these are laid to 1:100 slope and exits at lowest levels. These are the limiting factor in finalising levels of Ceiling?
• All Valves and Machines installed in the ceiling need to be accessible for maintenance and these are to be located correctly during execution.
• There are specific services which needs welding or bracing and these needs to be completed in all respect before pulling cables or installing PVC or Rubber coated materials.

BIM Execution Plan:

We decided to use the software Autodesk Revit and clash detection tool proposed was Navisworks manage. The 3D models are created primarily in 3 different groups as below and linked together for convenience of working simultaneously. BIM 360 was used to work simultaneously on the different disciplines by various team members at the same time. A team strength of 3 members was assigned with a total period of 16days scheduled for model completion and 7 days for the 2D outputs.

• Architecture Model
• Structure Model – Linked to the Architecture Model
• MEP Model – Linked to both Architecture and Structure

Because the client requirements are Shop drawing outputs with sufficient information suitable for execution at site, it was decided to model the project at Level of Detail LOD400 which is Good for Construction Standard for execution.

Sequence of Modelling:

The following is the sequence of modelling we did for the Project

Complete Architecture Model is created from 2D Plans , structural model is created next and finally both these files are linked to MEP Model for creation of individual?MEP disciplines for co-ordination

Images of Typical 3d Outputs:

Clash Detection and Resolution:

Clashes occurs for various reasons when multiple disciplines were involved. Even after modelling in the correct sequence several clashes were detected by Navisworks Clash detection utility. This is because even though visible clashes were eliminated several new clashes occurred while Ceiling heights in certain areas were improved.

We conducted online 3D co-ordination workshops with all stake holders and Contractors to explain the various elements of the 3D Coordinated Model and resolve all minor clashes before execution can begin.?

Coordination Workshop 1 at Site

In this workshop we took the inputs from the various execution partners on the way forward to resolve the clashes after their inputs were considered. MEP Clash resolution was conducted on the BIM Model and clashes brought down to less than 100. Clashes were cleared using following principles?

• Shifting or diverting service lines right or left
• Routing the service route above or below another service?
• All turns are maintained with minimal or 45degree offset?
• Rerouting Drainage lines maintaining 1:100 slope ?
• Resizing HVAC Ducts – Reducing depth, increasing width maintaining 1:4 aspect ratio

Coordination Workshop 2 Online

In this coordination workshop we communicated how various clashes were resolved while modifying the model with all partners and after their inputs were considered and clashes were brought down to zero after the final clash resolution modelling

Finally clash free coordinated model at LOD 400 Level and thereafter Good for Construction 2D drawings were completed and ready for execution at site?as per the agreed execution schedule

For work execution 2D drawings are needed with correct dimensions and clearances need to be made available, therefore CAD and PDF Outputs are taken from the final coordinated BIM Model with dimensions and tags for all services as below

• HVAC layout?
• Water Supply layout?
• Drainage Layout?
• Electrical & ELV Layout?
• Fire Protection Layout?

Vetting of Drawings:

For execution to commence all partners should have clear understanding of their individual work so to ensure compliance Individual service drawings were sent to respective parties for Verification and Vetted before execution started. This ensured the workability and clear time schedule for execution at site.

Following are some 2D drawings outputs for various disciplines Extracted from the BIM model in CAD and PDF format were shared to all contractors for execution at site

Sequence of Execution at Site:

For Installation of various elements of MEP without causing damage to any of the individual services during execution a correct sequence of need to be followed as below

• All Welded pipes such as Chilled Water, Sprinkler and Medical Gas systems are?to be installed first and pressure tested. After this the insulation and finishing of the lines can be completed.
• Next stage is Installation of Plastic Pipes, Wires and other suspended non welded components?
• All positions given in the 2D coordinated plans need to be correctly followed

Conclusion

What we Achieved

• Produced 2D Clash Free Shop drawings for Individual Disciplines
• Able to Achieve Faster and Conflict free work completion for all Contractors
• Achieved more than 2.4mtrs Ceiling Height in service intensive areas up from 2.2mtrs before, achieved up to 2.6mtrs Ceiling heights in some areas.
• Later Corresponding floors were modelled and executed without any clashes?

Pros and Cons:

BIM allows architects, engineers and contractors to create a Digital Twin of the project they want to execute and also predict potential construction hazards and prevent them by adjusting the design.?

BIM Modelling software is relatively new and requires skilled trained manpower to carry out model construction. The system also require new software to be installed, along with slightly more capable PC's to process the larger amount of data required.

BIM Software is becoming cheaper and SAS models are available users are now able to make their investment in BIM in a phased and economical manner.

Clashes and clash clearance:

We found the best way to avoid clashes is to not create them in the first place, So our focus was on producing clash free models at each stage.

Architectural and Structural models were completed for the entire building first and Drainage for the level just above was completed before modelling ceiling mount services. Modelling was done as per the sequence trying best to avoid clashes at each stage.

Way forward:

Vast Majority of the Industry Professionals in the developed nations have implemented BIM for Designing, Engineering and Building all kinds of Construction Projects. BIM Implementation in India is relatively slow and needs lot more progress to make the design and construction industry more efficient.?Present scenario in India can be compared to investment in traditional earth excavation methods versus earth moving machinery.?

Virtual models of buildings are much more efficiently Simulated, Built, Operated and Maintained.

Our success in this project clearly shows that investment in BIM technology, with correct Infrastructure and team Excellent Savings in time, manpower and cost can be achieved for even most complex of projects.

About the Author:

Author is a Professional Consulting Engineer with over 3 decades of design experience as Principal of Tritech Engineering founded in 1995. He is also a Professional Member of India BIM Association and also Partners with Autodesk (USA) as Academic Partner for BIM & CAD training. He has memberships in ISHRAE, IPA and ELCA of India.?

He can be contacted at [email protected]?