The product and design information contained herein are provided for general design assistance and preliminary product sizing. Complete calculations and details, including custom solutions shall be provided to meet project specific requirements.

The Load/Span tables have been developed to show general product performance and should be interpreted using sound engineering judgement.

Refer to “Choosing and Planning a Floor System” for additional information on the use of our products.


Readiness Center
Kapolei, HI

Readiness Center
Kapolei, HI


The design of precast building products is usually the responsibility of the manufacturer.

GPRM Prestress will provide the product, detail, and connection designs to the loading requirements provided by the Engineer of Record.

Load/Span tables are based on ACI 318-05 and applicable PCI recommendations.

Product may or may not be shored during construction. Typically, the more shallow sections, e.g. prestressed plank may require shoring. The deeper “stemmed” sections, e.g. double tees, do not.

General design parameters:

  • Strand. ½”. 270k low relaxation
  • Concrete. 6000 psi @ 28 days. 4000 psi @ release.
  • Topping. 4000 psi @ 28 days.
  • A 2 ½” composite topping slab is used in the analysis.
  • Simply supported spans are assumed.
  • A super-imposed dead load of 15psf is used in the analysis. The live load capacity is in addition to this load.
  • Dead load includes product and topping slab.

Load/Span combinations outside the tables can be achieved with specific design and detailing considerations.

Special load conditions, bearing details etc. can be accommodated with project specific solutions.


Product Product Description

Double Tee

The Double Tee product line includes both 10ft and 8ft sections as well as the 9ft wide triple tee module. Standard section depths up to 32” are available. These sections have large span, and high load carrying capacities. Examples using the 24” section include 65ft parking deck spans, and 40ft spans with HS-20 loadings.

The product is cast in “long line” forms allowing for high production capacities. Using a depressed strand profile should always be considered for most sections.

The Double Tee is the most versatile product for large and small deck penetrations. The 10ft unit can easily accommodate 4ft wide openings, with general penetrations having little impact on capacity. Standard stem penetrations can be provided in the Double Tee for running smaller utilities.

Dynacore TM

The Dynacore (hollowcore) product line is manufactured in a standard 4ft width. Standard depths are 6”, 8” and 10”, which provide economical spans to 50ft. Dynacore is a machine manufactured product using an extruded process with zero slump, high strength concrete. Once release strengths are achieved, units are cut from the continuous extrusion to project required lengths. Mild steel reinforcing, plates and inserts are not utilized with this product.

The extrusion process produces a machine finished top surface that does not receive additional roughening. Per ACI 318, the design of hollowcore slabs for composite action is usually limited to a horizontal shear strength of 80 psi. Full scale testing has confirmed this surface meets these requirements.

Small penetrations can be easily accommodated with site drilling once product is set. Large penetrations need to be well coordinated and detailed accordingly. 

Prestressed Plank

Prestressed Plank is produced in varying thicknesses to meet project requirements. A 3½" Plank is the recommended minimum with ½" strand, although 3" has been used. The 4" Plank is the most common thickness and should be used for smaller projects and for “infill” areas where other products may not suit. Plank widths are tailored to suit project requirements with 10ft being typical. GPRM Prestress will provide the most economical layout width on our shop drawings. When a thickness over 4” is required, other products should also be considered.

Beams & Soffits

Downloadable Files:

Prestressed beams and soffits are designed to complement the available flooring products. Utilizing the standard form sections will generally provide a more economical solution. The use of prestressing for these products assists with section depth, performance, and often eliminates the need for shoring.

Inverted “T” beams should be considered any time a Double Tee system is being used. This reduces both shoring and forming demands. “Standard” and “Lite” ITB sections are available to suit project needs and should be selected based on the DT and ITB spans, load conditions and erection considerations.

Other Products

Downloadable Files:

Additional products such as Walls, Columns, Spandrels, and Stairs are also available. These usually carry more project specific requirements and are therefore not presented as “standard” products. These products are commonly used as part of our “Total Precast Solutions” as well as custom applications. GPRM Prestress does employ some typical forms which should be utilized if possible for project economy.

Some best practice items are:
Consult GPRM Prestress. Availability of form sections and current details can produce real project economies.
Consider Prestressing. Prestressed walls and columns not only produce much more robust units for handling, they can also provide for more economical use of materials and achieve design solutions that may not available with mild steel reinforcing.

Standard products often have dimensional and detailing constraints due to casting methods and steel forms. The following pictures show some typical plant used to produce some of the products discussed.