Tuesday, March 9, 2010

Who Says Parking Can't be (kinda) Cool?

As part of its plan to expand graduate research facilities and living quarters on campus, Virginia Tech has identified the need for compact, infill development and therefore the necessity of several new stacked parking structures. To minimize cost and the disruption caused by taking a whole parking lot out of service, the University has opted for a design/build project delivery method for the first of the new parking structures to be constructed. This delivery method will be combined with precast concrete panel construction to improve the speed and productivity of the construction crews on site. The project will be completed in a little under 1 year, and will add hundreds of new spaces to the existing parking stock on campus. The following are some photos of the ongoing construction:

This color-coded macro plan for the site was developed as part of a group project calling for routine observation of the construction process. Here we have diagrammed the general phasing of construction, beginning with site leveling, grading and foundation construction and proceeding with three structure phases and one phase of facade construction.  Crane locations and access roads, as well as materials storage have also been estimated here. This is an interpretation of the project plan and is by no means an official macro plan from the contractor on the project.

Next we have a view from a neighboring building of the south side of the site. The structural elements on this side have all been put in place and elements of the facade are beginning to be brought in on flatbed and assembled via a small mobile crane. The drainage pond for the site is also visible here, as well as the gravel access road that has been built to circumvent the site and allow easy access of materials and equipment. A secondary entry point to the site has been created here to facilitate the delivery of facade elements separately from precast structural elements.

This shot shows a view of the north side of the site from the main access point to the site. Here you can see the strip footings that were poured during phase 1 construction, and get an idea of how the precast concrete elements fit together. The mobile crane in this photo is in the process of lifting a precast slab element into place. There are five basic precast shapes that have been made to fit together to form columns, beams, girders, slabs and exterior elements. This increases repetition and productivity, and therefore reduces total construction time and cost for the project.

Here you can see a precast slab element waiting to be placed on the structure. The basic process calls for at least two slab sections to be at the ready for the crane to place so as to maximize the productivity of this expensive piece of equipment. A site worker informed me that about 15 of these pieces are delivered and placed in an average day by Tindall Concrete Contractors. These pieces come preformed with hook pieces for crane lifting, and have steel plates embedded at precise locations to allow integration with the rest of the structure through welding. A lift for this piece takes approximately 20 minutes.

Here we have a nice shot of the crane lifting a slab section from the flatbed truck, as well as site/foundation work that needs to be in place before precast panel erection can take place. Notice the idle equipment in the background.

Here is a shot of the second mobile crane on the south side of the site lifting a piece of facade into place to be welded by crewmen. This is happening simultaneously to the structural erection happening at the north side of the site to speed production and reduce total construction time for the project. It can be relatively difficult to plan lifts for multiple cranes on a single site, however, due to the distance between cranes and nature of lifts being made, there doesn't seem to be much danger here. Notice also the idle equipment on this side of the site as well.

Hopefully this photo journal of the construction site has helped shed some light on this innovative construction delivery method that should be incorporated into the playbook of every designer, engineer and contractor.

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