Efficient Rebar Detailing with 3D Solutions

There are many jobs within the architecture, engineering, and construction (AEC) industry that are not commonly recognized—a rebar detailer is one of them. However, most people have seen the work that rebar detailers do, they just do not know it. If you live in a condo building, have parked in a parking garage, or do your grocery shopping at a strip mall, you have seen the finished product of rebar detailers. The concrete poured at each of these locations will contain steel reinforcement—a vital element to the structural integrity of any concrete structure. The rebar detailer’s job is to ensure that the reinforcement can be placed accurately, which is a far more complex and involved activity than it sounds. However, with the right solutions, this time-consuming activity can be streamlined for increased output, precision, and cost-effectiveness.

Mastering the Art of Interpretation

The structural engineer is responsible for determining what reinforcement is needed in each component of the structure, starting with the footings and working up. The size, spacing, zoning, layering of bar, and other crucial data are used in calculations and rough drawings are created to illustrate what reinforcement is needed so that the concrete does not fail. However, the structural engineering drawings lack the detail that rebar placers require to do their job effectively.

Since the rebar placers are not able to work directly from the engineer’s output, it is the rebar detailer’s job to interpret the data and create the detailed drawings that clarify exactly where to place the bars prior to the concrete being poured. Rebar detailers are masters of interpretation: they must be able to understand the engineer’s calculations, drawings, and their intentions. They use their creativity and experience to create new drawings that a placer can read and comprehend, drawings that reflect the fabricated steel that has been sent to a site. This takes a significant amount of time, often requiring that new drawings are created from scratch based on the structural engineer’s drawings.

Managing Input from Many Different Stakeholders

Rebar detailers are also problem solvers. They put the pieces of the puzzle together to create the right drawing so that the rebar is fabricated and installed correctly. Communication and coordination between the engineer, general contractor (GC), rebar site foreman, and the fabrication shop is crucial to avoid errors and wasted time, money, and materials.

Detailers must always ensure they are working with the engineer’s latest set of drawings. However, rebar detailers typically interact directly through the GC, and do not communicate directly with the engineer. If information is missing or unclear, the detailer must send an enquiry to the engineer through the GC in the form of a request for information (RFI), which can take two weeks to receive a response. The engineer must also review the placing drawings for conformity prior to a pour, which takes at least two weeks. Should anything change, the GC must also be kept informed about any variations to the project that require a change to the contract price (either as an addition or a subtraction). In an ideal world, all drawings would be submitted to the engineer for approval and returned to the detailers in plenty of time to accommodate the pour date of the concrete. Yet often detailers receive the engineering drawings with the rebar expected to be on site soon after, creating additional time pressures when developing the detailing drawings.

Other parties are also involved in the process. For example, the rebar site foreman supplies the rebar detailers with on-the-job information, such as the maximum bar lengths they can handle on a particular site. They request drawing preferences such as number of drawings per piece, the date they need particular bars on site for a pour, how the bars should be supported, and other important details. The fabrication shop informs rebar detailers about maximum truck weights, minimum safe bending numbers, as well as lead time needed for a project. Managing these different inputs and keeping them informed consumes a large portion of a rebar detailer’s time.

Coordinating with Trades

Rebar detailers need to be concerned about structural steel components, such as embedded plates, steel columns and beams, and penetrations in the concrete for plumbing and mechanical equipment. It is crucial for a detailer to see how their pieces fit together—for example, where a column intersects a beam and ties into a slab. They can then resolve problems such as bar congestion, bar layering and spacing, hook dimensions, and lap locations, or a lack thereof. This is achieved by examining the drawings or models from the different disciplines and subcontractors and determining where these issues occur. However, this can be difficult to do effectively when working from 2D drawings or separate 3D models, so conflicts between components and rebar can still arise on site.

The Case for 3D Rebar Detailing

In this technological age, why isn’t 3D detailing more widely adopted? The value of 3D modeling and BIM software versus 2D CAD for rebar detailing is still debated. After all, many experienced rebar detailers can produce 2D detailing drawings as quickly as—or even faster than—creating a 3D rebar model, so why change? The benefits that 3D modeling and BIM offer reach much further than just faster detailing drawings. Modeling reinforcement in 3D can make the entire rebar detailing process much more streamlined and efficient, saving valuable time, money, and effort.

Improved Visualization

Rebar visualization is one of the biggest advantages; being able to see the finished product in 3D enables the detailer to better understand where clashes occur and make adjustments. In 3D, issues such as bars protruding out of the concrete, clashing with other rebar, or interfering with other factors (such as structural steel, mechanical or plumbing openings) can be clearly seen. In some tools—such as Allplan Engineering—the software can even automatically detect these collisions, drastically reducing the chances of errors within the rebar being missed. With 2D modeling, there is no way to detect these clashes between the disciplines until they happen on site. Sometimes clashes on site are not discovered until two or three days before a pour, causing significant amounts of wasted time and materials.

Increased Accuracy and Speed

Detailing reinforcement in 2D is time-consuming, costly, and prone to errors due to the amount of manual work and input required. A 3D solution like Allplan improves detailing accuracy and speed by automating many of the repetitive detailing tasks while keeping some of the familiar steps of a 2D workflow. Because of Allplan’s unique setup, it is possible to draw reinforcement in 2D while the 3D reinforcement is created simultaneously within the model, making it easier to transition from a 2D CAD program to a 3D rebar modeling solution. Alternatively, shapes can be reinforced quickly and easily using the built-in, automatic edge detection feature, with grips that allow each bar to be adjusted and fine-tuned if required. Simply adjust the reinforcement properties and watch the 3D model update to reflect the changes. Features such as Automated Python Parts (APPs) enable quick, easy, and customizable modeling of concrete objects with reinforcement already embedded within them for a complete model in a fraction of the time of 2D drawing.

Efficient Documentation

Once the model is created, reaching a completed set of detailing documentation is just as efficient. Bars are automatically numbered by the software, so that any required documentation – such as lists and schedules – can be quickly and easily created using built-in reporting tools. Not only does this save a significant amount of time, it also greatly increases the accuracy of the output. Allplan includes report templates that align to many different codes and standards, making the scheduling process a simple case of choosing the right template for the desired standard. However, reports can be easily customized to display the information that the detailer feels is most relevant to the project.

Enhanced Communication

Communication and coordination between the relevant parties is also improved by using a BIM solution. Tools such as Bimplus allow the models from each discipline to be combined and viewed for a complete visualization of the project, which can be adjusted to show the desired information. In addition, the time required for RFIs can be reduced by using a data management platform, as information can be shared and tasks can be assigned to various team members which improves communication between parties. The result is streamlined working processes with reduced wait times and improved transparency.

Efficiency = Increased Competitiveness and Profitability

As rebar design and detailing is a significant part of every project schedule, choosing the right software is a critical decision for rebar detailers who want to improve their efficiency, competitiveness, and profitability. Working efficiently means a greater output can be realized with the same resources, while still maintaining a high degree of accuracy.

Allplan helps rebar detailers overcome common issues to achieve this. We believe that a 3D modeling software vendor needs to understand the complexities of detailing rebar, and the workflow the detailers use when creating the placing drawings. We do, which is why Allplan has been specifically adapted and developed to include the essential tools that a detailer needs to effectively do their job.

Click here to learn more about Allplan for reinforcement.

Disclaimer: The views and opinions expressed in AECbytes sponsored articles are those of the sponsor and do not represent or reflect the views of AECbytes.