The Original Decon® Studrails®

Studrails® are a proven, cost-effective solution to punching shear at slab-column connections. Studrails® dramatically decrease labor costs, as well as reduce clutter and congestion at the slab column connection. Recently added applications for Studrails® include foundation slabs and post-tension anchorage zones.

Flat plate construction is a mainstay of structural design in North America and around the world. This system is usually used for condominiums, hotels, office buildings, hospitals, and other structures. Designs are often governed by punching shear capacity at the slab column connections. If punching shear is not accounted for in the design, high shear load can cause a catastrophic brittle failure, as shown below:



Prior to the introduction of Decon® Studrails®, stirrups were often used to enhance the punching shear capacity. However, testing has shown measurable anchorage slip at bends, reducing their effectiveness in thin-slab construction. As a result of anchorage slippage, the full capacity of the stirrups cannot be developed in thin slabs. Each rebar stirrup cage takes several man-hours to fabricate and install, a significan factor in project scheduling and costs.

Stirrup installations congest the slab-column connection, adding significant complications to the placement of longitudinal reinforcement and P/T tendons, hampering utility installations and driving up overall construction costs.

Decon® Studrails® are a proven, cost effective solution to punching shear. Developed and tested at the University of Calgary since the 1970s, Studrails® now provide unmatched punching shear enhancement in thousands of buildings around the world.

Studrails®, with their 10:1 head-to-stem cross-sectional area ratio, anchor securely in the slab, eliminating slippage and providing greater resistance to punching shear.

Studrails® can be installed around the slab column connection in 5 minutes or less, providing substantial reductions in installation time and labor costs.

Special chairs supplied with the Studrails® ensure proper concrete cover.

Studrails® reduce clutter and congestion at the slab column connection; rebar, P/T tendons and other embedments can simply be dropped into position between the stud heads.

Applications of Decon® Studrails®

See the difference an uncongested slab can make.

Decon® Studrails® are commonly used in post tensioned or reinforced concrete slabs, with direct loading on columns. Drop panels, beams and column capitals may be eliminated, allowing the efficient use of fly-forms. The combination of Studrails® and fly-formwork will decrease the story turnaround time allowing fast-tracking of the construction schedule.

By installing Decon® Studrails® in raft foundations, you can increase the punching shear capacity at the base of columns, as well as in pile caps. This results in a significant reduction in slab thickness, and a substantial savings in related material, excavation and pumping costs.

Use Decon® Studrails® in place of hairpins to eliminate congestion in post-tensioned tendon anchorage zones. One Studrail® with up to 15 studs replaces a series of individual hairpins, resulting in significant time and labor savings. The superior anchorage enables the Decon® studs to develop their full yield strength by eliminating slippage.

Superior Seismic Performance

Tested and Proven

During an earthquake, rapid deterioration of the concrete slab can result if proper shear reinforcement is not provided. Under cyclic loading, unbalanced moments are transferred from the slab to the critical section around column capitals. These connections have been proven to fail in an explosive manner during those load reversals.

Decon® Studrails® are superior in withstanding these moments and maintain connection stability long after other systems have failed. They absorb energy with their ductile behavior. Lab test results show Studrails® provide superior ductility and lateral drift capacity when compared with conventional stirrups.

Without shear reinforcement	With Decon® Studrails®

The results clearly show Decon® Studrails® maintain strength in the connection with their special heads and secure anchorage. They resist the development of punching shear cracks and are vital for building applications in seismic regions due to the increased energy absorption and higher drift capacity. They have been extensively tested and proven in thousands of applications around the world.

Design Specifications

Decon® Studrails® are composed of special studs either studwelded or mechanically crimped to a steel base rail using a patented procedure. To develop the full yield strength of the studs in tension, the chart shows the standard dimensions which are necessary.

Specifications for Decon® Studrails®

The shear studs used in the fabrication of Studrails® are Low Carbon Steel, C1010 to C1020 in accordance with ASTM-A108. The strength and ductility requirements are:

Yield strength: 51,000 psi minimum (350 MPa)
Tensile strength: 65,000 psi minimum (450 MPa)
Elongation in 2 in.: 20% minimum
Reduction of Area: 50% minimum

The rails used in Studrails® are Low Carbon Steel Type 44W with the following strength and ductility requirements:

Yield strength: 44,000 psi minimum (300 MPa)
Tensile strength: 65,000 psi minimum (450 MPa)
Elongation in 8 in.: 20% minimum

The studs are welded in accordance with American Welding Society (AWS) D1.1 and CSA Standard W59 as certified by the Canadian Welding Bureau.

The table above shows the size of studs that are available. The overall height of the stud is dependent on the slab thickness and the required concrete cover.

Studrails® should be specified in the project documents under "Section 3200 – Concrete Reinforcement". The engineer should use wording similar to the following:

Shear Reinforcement at the slab column connection as shown on the drawings and details, shall be Studrails® as manufactured by Decon®. The complete and finished Studrail® shall be ICC ES evaluated and welding has to take place in an ICC ES approved and audited facility. Studrails® shall conform to the latest update of ASTM A1044.

Studrails® have been successfully installed in more than 30 countries

Decon® Studrails® are a proven, cost effective solution to punching shear. Studrails® now provide unmatched punching shear enhancement in thousands of buildings located in more than 30 countries around the world.

In North America, Decon® Studrails® have been used in a wide variety of buildings from Miami, FL to Anchorage, AK. Projects have included condominiums, office buildings, hotels, casinos, parking garages, hospitals and other buildings as diverse as houses and storage silos. Flat plate construction is widely used – particularly with post-tensioned slabs – and Decon® Studrails® are a key component of these designs.

Installation Case Studies

	This photo shows a typical edge slab column connection during reinforcement placement at a Montreal, PQ office building. The Decon® Studrails® are fastened to the forms first; the post-tensioning tendons and rebar can simply be inserted between.
	This photo shows the placement of post-tension tendons through a typical slab-column connection at an office building in Redmond, WA. The Decon® Studrail® design should provide enough space between the stud heads to allow the tendons, rebar, conduit etc to be simply dropped into position.
	This photo shows a luxury condominium under construction in Naples, FL. There were several slab-column connections on each level with high shear stress. To allow the simplicity of the flat plate design, Decon® Studrails® were used at these locations.
	This photo shows a typical interior slab column connection at a student residence in St. Paul, MN. The openings are not an obstacle since the Studrails can simply be placed alongside them to create a continuous stress path to the column.
	This photo shows an apartment building in San Mateo, CA. The seismic resistance is provided by the use of shear walls. Decon® Studrails® gave the slab-column connections adequate ductility to accommodate any induced drift during a seismic event.
	This photo shows one of a series of time-share condominiums constructed on Hilton Head Island, SC.

Installation Made Simple

The installation of Decon® Studrails® is very quick and easy. Instead of the hours required to form a column capital or fabricate stirrup cages, Studrails® can usually be placed around a slab-column connection in less than 5 minutes.

The sketch on the right shows a typical arrangement of Studrails® around the column. Either end of the Studrail® is placed adjacent to the column face. The dimension from the end of the base rail to the first stud will define the required distance of the first stud from the column face. The Studrails® are placed at the column corners.

Studrails® must remain vertical within the slab. If more than two Studrails® are required on a single column face, they should be evenly spaced.

The following simple steps are required for installation of the Studrails®:

1. Attach the special chairs to the base rails of each Decon® Studrail® and place one chair top over the chair at each end of the Studrail®.
2. Position the Studrail® properly on the formwork as per standard placement drawings.
3. Nail the chairs to the formwork through the blind nail holes in each chair leg.
   Repeat steps 1-3 for each Studrail®.
4. After the Studrails® are in place, the balance of the rebar, P/T tendons, conduit and other embedded items are ready to be positioned. Since the top of each Studrail® is open, it is a simple matter of dropping these items between the stud heads.

Using the alternate chairs is just as simple. The only difference is that the alternate chair slides into the pre-punched holes in the base rail of each Decon® Studrail®.

The installation process is simple and fast. The quality control during our manufacturing process assures proper and crucial positioning of the Decon® studs and the accompanying chairs ensure the correct concrete cover.