Pittsburgh Flexicore Realizes the Value of BIM for Concrete Manufacture
For more than 50 years, Pittsburgh Flexicore Co. has been a leading manufacturer of precast, pre-stressed concrete components, and structures in the northeastern United States. In that time, the company has manufactured over 25 million square feet of hollow core products for approximately 4,000 projects, and become a premier supplier of products from beams and columns to stairs and wall panels.
The company has seen numerous changes to the way precast concrete components are designed, manufactured and erected—though perhaps no change as profound as the industry’s current shift to building information modeling (BIM).
Karen Laptas, P.E. and chief engineer with Pittsburgh Flexicore, explains, “New technologies, such as BIM, are reshaping and redefining our industry. Adopted correctly, these technologies have the ability to help us complete tasks faster, for less money, and with greater quality.”
Like most precast manufacturing companies, Pittsburgh Flexicore production process relies on 2D drafting, along with various estimating tools and automated production processes to manufacture products with relative speed and ease. Efficiency is key to success with just two engineers and one estimator/project manager to handle drawing checks, production and erection tasks.
Laptas says, “We’re a small lean company, which is one of the reasons we search out highly efficient and accurate tools. We had heard BIM required some significant changes in conventional practices, so we decided to start small. In the early stages, our primary goal was to combine developing the Tekla Structures-based modeling program with our everyday engineering tasks.”
These tasks included working with an estimator to determine layout, design and connection details, developing submittal packages, and creating production tickets and erection reports. In order to achieve this goal, the company began modeling selected projects that would develop the custom component catalog, reports, and general layout and production drawings. The first job was to fabricate simple concrete beam supports for a client.
Components and Connections
“In this first foray into BIM, our team went from sales to engineering, approval and production in two days,” says Laptas. “Production gave a solid feedback on the drawings. They particularly liked the 3D sketch that our detailers provided with the shop drawings.”
The Tekla Structures profile editor tool allows users to sketch variable cross sections. These cross sections can be as simple as I-beam profiles or as complex as hollow-core profiles. The tool allows you to sketch the profile, dimension it accurately and then use it throughout the current model and any subsequent models. Once created, the profiles can be adjusted from a dialog by simply changing dimensions or returning to the sketch editor. This tool gives the user the flexibility to create a customized library of profiles.
The company’s next BIM-enabled job focused on a church expansion. For this effort, staff engineers modeled the necessary concrete components and connections. The structural framing of the addition consisted of 10-inch hollow-core floor slabs setting on a combination of steel columns and beams, and concrete masonry unit and cast-in-place walls. Pittsburgh Flexicore modeled the entire structure in Tekla Structures based on architectural and structural 2D drawings.
All seemed to go well until the slabs arrived at the site. Laptas recalls, “When crews went to set one of the hollow-core planks on a steel beam, they found that the hollow-core plank was 4 inches too short. With the help of the model, we were able to determine that the steel erection drawings were incorrect, and then help the erector figure out how to reset the beam. Of course, if the entire project team had grasped the concept of collaborative model earlier, we with could have avoided a costly erection error.”
The church expansion project also allowed Pittsburgh Flexicore to begin development of custom component catalog for use within Tekla Structures. Currently, the catalogue contains custom parts such 8-inch, 10-inch and 12-inch hollow-core sections, beam and column profiles, as well as field and embed plates and hardware. Engineers also created custom intelligent seam components for varying connection conditions such as hollow-core slab to masonry or a hollow-core slab to a steel beam. Laptas says, “The custom component catalog will continually evolve as we detail increasingly complex projects. Every modeler keeps a log of the components (parts, details, connection, seam) along with notes of how to improve the components if they are used again.”
Along with building the custom component catalog, the company was able to refine its general arrangement drawings, sections and detail sheets and shop drawings and develop customized reports. It wasn’t long before Pittsburgh Flexicore customers and project partners began to realize a noticeable return on investment.
Adamson Stadium, the home of the California University of Pennsylvania football and track & field team, in California, Pennsylvania, is undergoing some major renovations including the rehabilitation of the over 50-year-old precast concrete stadium structure. Pittsburgh Flexicore was called in to provide a precast system that would help raise the platform connecting the existing upper level stadium to a new masonry elevator tower. The system consisted of beams, L spandrels, spandrels and slabs.
“It was a small but complicated addition with hidden and slip connections. The contract drawings were difficult to understand until we built the Tekla model—then everything made sense to us and the rest of the project team,” recalls Laptas.
The Tekla Structures Model Reviewer was particularly helpful in communicating with the general contractor, architect and engineer about how the various connections met the design requirements. Laptas explains, “In addition to producing general arrangement and section and details drawing, we were able to produce shop drawings, embed and erection plate drawings along with customized production and erection reports.”
True BIM Coordination
With increasing expertise, the Pittsburgh Flexicore team was ready to handle its most challenging BIM project to-date. The firm was selected to be part of the design team for a seven level, multiuse structure, which would contain over 3,000 hollow-core planks. The first three levels call for hollow-core planks set on a Versa System. The remaining level calls for hollow-core planks set on steel stud walls and concrete masonry unit walls. The architect and structural engineer developed drawings using AutoCAD, while Pittsburgh Flexicore created a 3D model from the preliminary drawings using Tekla Structures.
Laptas says, “We overlaid our model on top of the AutoCAD model and were able to see and communicate conflicts between the architect and engineering drawings clearly. Over the course of a month, we worked closely with the rest of the project team to refine the permit drawings based on our 3D model.” To shorten the RFI cycle, Pittsburgh Flexicore used the Tekla Structures Model Reviewer, a free downloadable tool, extensively to support coordination activities. The team can use redlining tools in the Model Reviewer to identify and annotate locations of interest, while the contractor can use the model to fly directly to these locations. Consequently, any changes, issues or RFIs can be easily discussed using the 3D model as a visual aid. The owner received permits and financing shortly after, and construction is scheduled to begin shortly.
Laptas concludes, “The first five months of BIM adoption have been exciting. We are very pleased with the speed of adoption internally and are sold on the quality and communication advantages the technology provides to our company and customers. 2D is on the way out; BIM is in and we’re ready to take advantage of everything BIM has to offer in terms of efficiency, collaboration and quality.”
With the new technologies reshaping the construction industry in mind, Pittsburgh Flexicore set out to implement BIM principles throughout its sales, estimating, production and erection business practices with the help of Tekla Structures software.