Page 65 - Colorado Construction & Design Magazine - Spring 2023

Ahead of the Curve
Unique Precast, Prestressed Concrete Bridge Girders to Define a New Bridge Near Vail
By Jim Schneider | Executive Director | PCI Mountain State
In Colorado, I-70 is an iconic and commonly used passage that takes travelers to and from the Denver Metro area up to mountain towns like Breckenridge, Vail and beyond. It is a stretch of highway that must be sufficiently durable and robust to handle the heavy load of traffic it receives each year, while also being sufficiently elegant and inviting to cater to the large number of visitors and tourists that come to vacation in those mountain towns.
The Colorado Department of Transportation (CDOT) recently set out on an initiative to construct a bridge nestled in the curves of Vail Pass in Colorado. With its notable qualities of durability and flexibility, precast, prestressed concrete is an ideal choice for this kind of construction. It’s no wonder that CDOT looked to precast for this high-profile bridge project near one of the state’s most upscale, popular mountain towns.
Local producer and longtime CDOT partner Plum Creek Structures stepped up to tackle the complex requirements of this project. “The project is up at the westbound Vail path, and it’s a roughly 550-foot-long bridge with five spans,” explains Kevin Kovac, President of Plum Creek Structures. “The product CDOT chose was a curved precast trapezoidal girder. The radius set on the girders was a 1680 radius, which is almost straight.”
“We conceivably may have been able to go with a straight girder, but aesthetics is a factor for this project,” explains Dan Werner, Chief Engineer of Plum Creek Structures. “The town of Vail wanted a certain look and that was a main driver in the decision to go with the curved girder. It’s hard to get that bend, but we knew there were ways to do it. It would take some effort and some work, but we knew we could do it.”
One of the few precasters in the country
that produces curved precast trapezoidal girders, Plum Creek got to work coming up with the best approach to create the materials needed for this ambitious project. It would require some out-of-the-box engineering
and production.
Pre and Post
The bridge construction consisted of piers and abutments with diaphragms, but these were different because the team had to use post-tensioning method (PTM) since the girders were curved, and pre-tensioning was impossible. Post-tension work is usually done on-site for precast curved bridges. This did require some adjustments on the production side. Precast had to work in tandem with posttensioning being done at the precast yard.
“The bridge is three girders wide and five spans, so there are 15 beams,” Kovac explains. “They are six-foot-deep sections, averaging about 115 feet in length. For hauling purposes and handling purposes, they are each individually post tensioned. When we pour them, it’s all precast with mild reinforcing. Once they’re stripped, they have to cure for a certain amount of time and a post tensioner comes in to push strand through a series of ducts, stress it, grout it and ship it.” www.ccdmag.com | news@ccdmag.com
Ryan Development Build to Suit Lafayette, CO
Project Stats
Primary Market: Office
Size: 380,500 sq ft
Project Total Cost: Not disclosed
Project Schedule: 180 crane days – two cranes on the job
Precast Construction Start: 9/02/21
Precast Completion: 2/23/2022
Total Precast (Y/N): Y
Project Overview A Global Medical Equipment manufacturer sought to consolidate their multiple locations across Boulder County into one 380,500 sq ft state-of-the-art facility, a significant construction project for the area. The campus includes two connected five-story buildings that accommodate lab and office space supporting over 1,100 employees.
Ryan Companies brought on Wells early in the project to work alongside the design team to develop the precast construction documents,
and to lock in the building aesthetic early in
the process. Wells’ scope of work included engineering, detailing, manufacturing, delivery as well as installation of the precast products, and the Wells Sealants and Restoration team performed
all caulking, sealants, and waterproofing including some blind-side waterproofing for the office building. A unique and rare application of insulation was applied in the elevator shafts to function as a vapor barrier for the structure.
Wells offers a comprehensive full line of structural and architectural prefabricated building solutions in addition to erection and sealant services to support this total precast building solution. The building utilizes Wells full array of prefabricated building solutions including double tees, beams, columns, precast stairs and landings, cores walls and exterior architectural load bearing & cladding elements. The enclosure features light and dark gray wall panels/spandrels with integral reveals to create depth and visual interest. All exterior precast elements had an acid-etch finish. The building design was intricate with a very modern aesthetic and integrated square bullnoses — differing from the usual round bullnose design — as well as miter joints at every corner for clean, contemporary angles. The round columns that decorate the front of the building were challenging to manufacture, as they took three separate concrete pours to make a single column. The time and effort put into each prefabricated building component shows, resulting in a stunning design.
To make sure this development was a success, Wells utilized team members from across the country, showcasing a collaborative effort to build the project. Two Wells field crews — one from Minnesota and one from Colorado — worked side by side in connection with two cranes, resulting in a shorter installation duration.
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