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The Filigree Wideslab method is a process for construction of concrete decks that successfully integrates "factory precast" and field-construction technologies. This is accomplished by constructing concrete floor decks from two interconnected concrete placements, one made in a factory, and the other done in the field.
History
[edit]The Filigree Wideslab method was developed over 40 years ago by Harry H. Wise of Mid-State Filigree Systems, Inc. as a more efficient and economic construction process than conventional cast-in-place technologies.[1]
Description
[edit]The process begins by manufacturing thin precast concrete panels (typically 2.25" thick) with the deck's bottom reinforcement included. The panels are then shiped to a jobsite and erected on temporary shoring.
Subsequently, the deck's top reinforcing steel is placed on top of the precast panels at the site, and concrete is poured over the entire assembly to achieve the final thickness of the deck. This completes the construction process.
Advantages
[edit]This process effectively accelerates the construction of structures by eliminating the need for costly and time consuming field forming, and the placing of bottom reinforcement. The Filigree Wideslab panels are often manufactured with polystyrene blocks, or "voids", that reduce the quantity of field-placed concrete. This reduced the quantity and cost of field concrete, and it reduces the overall weight of the structure, further reducing the costs of columns and foundations.[2]
The soffits of the panels have a smooth uniform finish as a result of casting them in polished steel molds. This reduces the labor cost and time typically required to grind and patch the soffits of cast-in-place concrete decks to achieve an acceptable aethetic finish.
The Filigree Wideslab method of deck construction can be applied anywhere conventionally poured-in-place concrete is specified. It can be used for flat plate, beam and slab or wall-bearing concrete structures. Any strength requirements needed for poured-in-place construction can be readily met with the Filigree method.
Design Methods
[edit]A concrete deck using the Filigree method of construction is designed using vertually the same techniques as are used for cast-in-place decks as prescribed by the American Concrete Institute document ACI318-05[3]. Specifically, Section 17, titled "Composite Concrete" permits the use of precast concrete elements to be attached to cast-in-place concrete provided the requirements of this section are adhered to.
The system is designed as a one-way continuous span slab supported on continuous span beams. An analysis of the slab take into account the width of the beams, as the deeper beams behaveas slab haunchs, proving greater stiffness to the slab near a support.
The top reinforcement design for the slabs should be done at both the beam cewnterlines, and at the beam faces. This is because the negative slab moments are typically much less a a beam face, allowing a reduction in the top reinforcment required.
The beams are designed with a frame analyse that includes the stiffness of the columns. Punching shear stress is checked
References
[edit]- ^ "Alternative Concrete", Construction-Today Magazine, March 2009, p.106
- ^ http://www.filigreeinc.com
- ^ ACI Committee 318 (2008). ACI 318-08: Building Code Requirements for Structural Concrete and Commentary. American Concrete Institute. ISBN 0870312642.