Building Information Modeling advances structural engineering

BIM (Building Information Modeling) is a term used to describe a design and construction process in which some or all of a building's information is available in one model. It is an evolving concept; one that will continue to change as the capabilities of existing technologies improve. Consulting structural engineers recently enjoyed added benefits from new communication advances in computer software. These advances include direct digital exchange capabilities between software applications as well as new advances in 3-D modeling. BIM is rapidly evolving into a new and enhanced platform for project delivery. In the past, engineers used one software application to draw plans, and another one to design the structure. These various design, modeling and drafting software packages were unable to exchange design data with each other. As a result, engineers had to input data at every phase of the design. These packages, which come from different vendors, required multiple models which slowed down the work process and created various modeling limitations. For that reason, engineers experienced difficulties and their designs were often considered overly conservative and poorly coordinated and often associated with cost overruns and project delays. BIM is helping overcome these difficulties. BIM offers structural engineers the following new benefits: 1. Live tracking of material quantities - offering instantaneous evaluation of design quality. 2. Reduced design and production schedules, due to the ability to import architectural plans into the design software. 3. Reduced modeling errors. 4. Improved coordination between architects and engineers. 5. Elimination of RFI's, and reduced schedules for approved shop drawings resulting in less time spent on communication and reviews. 6. Improved tracking of shop drawings and of shop fabrication performance. At Wexler Associates, BIM has been used for the last five years, and many millions of sq. ft. of new buildings have benefited from BIM each year. With proven in-house BIM capabilities, Wexler's office provides the following new project delivery benefits: 1. Structural designs with live tracking of material quantities. These designs are done through direct import of architectural drawings and without the need to create a model from drawings, reducing production time significantly. 2. In-house structural steel, cast-in-place concrete and precast plank shop drawings and calculations. These shop drawings are done through the exchange of files, again without the need to start new models, saving significant time and reducing errors. 3. Plant monitoring of production through linked software. 4. Field monitoring of erection through bar codes and linked software. In some cases, at least 2 months are saved in the production of shop drawings, and fewer personnel are needed to track shop drawings and to coordinate. Shop drawings are issued only once approved, ready for fabrication and they are issued for record information only. Through direct digital transfer, the shop drawing information can be downloaded directly to the fabricator's computer numeric control (CNC) equipment which automates many of the fabrication processes. One recent example includes a one million s/f retail project including parking, loading docks, fire lanes, pedestrian plazas, bridges and movie theaters. Using BIM, 10,000 tons of structural steel was designed in four weeks. A similar project done by traditional means could take months if not years to reach the fabrication stage. Another example is a residential project in downtown NYC. The owner approached Wexler's office, asking for a redesign to save steel costs. Because of live tracking of material quantities, a redesign was guaranteed to produce savings in excess of one million dollars. Upon completion of design and shop drawings, the project was delivered on time and on budget. A third example is an eighteen story housing project located in Long Island City. Using BIM, the steel design and shop drawings were completed several months ahead of schedule and with no RFI's and no extra costs To summarize, Building Information Modeling is an important improvement to the way architects, engineers, contractors and fabricators have been working. It provides coherent and consistent drawings and a clear visualization of the building design. BIM greatly decreases errors made by design team members, followed by direct reduction in time required to complete design and construction. Wexler Associates' use of BIM provides better structural plans at lower costs to the owner and saving time. At Wexler Associates, we believe BIM will become the standard for design and construction within the near future. Neil Wexler, PhD, PE, is president, chief structural engineer and founder of Wexler Associates, New York, N.Y.