ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.
Issue link: http://www.aspiremagazinebyengineers.com/i/485551
PARTNER SPOTLIGHTOSSING Take Advantage of Precasters’ Expertise Contractor-alternate design, new casting and erecting techniques help meet growing challenges as owners tap into full range of precasters’ knowledge and skills by Heinrich O. Bonstedt, Central Atlantic Bridge Associates In highway and bridge construction, a continuum of options and variations exists that impact each stakeholder, including owners, designers, contractors, and suppliers. Taking advantage of all of the skills and knowledge of each member of the team ensures the creation of a high-performance structure that is efficient, cost-effective, quick to complete, and aesthetically pleasing. In many cases, offering a “contractor-alternate design” approach achieves this goal. In this format, contractors can supplement the owner’s design effort. It allows contractors to adjust the plans to take advantage of new techniques and their own skills and equipment to optimize the design at the lowest possible bid. Contractors offer the logical choice to maximize efficiency in the design and construction. They have traditionally taken the lead in value engineering and engaging design professionals. Providing this option allows the contractor to provide extensive preconstruction services, such as estimating, value engineering, and constructability review, and they can then manage and create a comprehensive integration of supply channels. Further, the contractor assumes the risk and liability for defects and related problems. Using the contractor-alternate design approach ensures the contractor can take full advantage of the knowledge of the precaster and other key subcontractors, leveraging their techniques and state-ofthe- art facilities to maximize efficiency and design. This factor can be significant, as long delays can occur between design completion and bidding, locking projects into approaches that have been much improved in that interval. Precasters are skilled at valueengineering projects after designs are available, and the contractor-alternate design approach maximizes those adaptations by bringing the precaster into the process earlier. BIM Aids Designs The use of three-dimensional building information modeling (BIM) software ensures precasters can consider every option and every possible component configuration to produce the most efficient design in terms of piece count, sizes, weights, and other factors. This works especially well with total-precast concrete designs, where all the components can be fit together comprehensively and supplied by one source, minimizing communication problems. An example can be seen in the Ashcom Cove Creek Bridge in Bedford County, Pa. The bridge features one span of five 120-ft-long precast concrete bulb-tee girders and a total-precast concrete structure, including footings, piers, abutments, and deck panels with integral parapets, all designed and evaluated with BIM software. The changes reduced traffic detours from 7 months to 8 weeks and saved more than $125,000. The new version provided a one-for-one replacement of the original cast-in-place concrete design, maintaining similar connections with few adjustments. Bridges for Life Precast concrete designs also can help owners improve durability and lower long-term maintenance costs. Precast concrete continually adapts with new concrete mixtures and new casting techniques that create longer lasting designs with lower life-cycle costs. As a highly engineered product, precast concrete continues to develop higher strength and more durable concrete as precasters test new materials and practices. Such factors as self-consolidating concrete, lightweight concrete, cementitious formulations, pozzolan concentrations, improved reinforcement coatings, high-performance grout, and prefabricated welded-wire reinforcement are increasing the capabilities of precast concrete at an increasing rate.