Upside-down Stud Rails

Posted on January 15, 2022 in: Technical

Jim Klinger, concrete construction specialist The Voice Newsletter January 2022

Imagine, if you will, the following scenario.  You are scheduled to start installing rebar and PT for an elevated concrete slab tomorrow.  The plywood deck has been swept clean, and the MEP crew has moved out of your way.  You get a call from your stud rail (also known as PSR, or punching shear resistor) supplier, who informs you that supply chain issues are preventing him from delivering the product to your jobsite on time.  Or...

Imagine, if you will, the following scenario.  You have scheduled a 500-plus CY placement for the day after tomorrow.  The rebar and PT has been completed and is awaiting inspection.  You get a call over the radio from your field foreman that your crew has forgotten to install the stud rails required at just about every column on the floor.

In both cases, all may not be lost, and the placements might not have to be cancelled.  As it turns out, the “stud” part of the stud rail is needed to prevent the slab cracking that typically occurs during a punching shear failure.  The stud itself does not care if it is right-side up or up-side down.  The “rail” part of the stud rail is merely a convenient means of spacing the studs.  In other words, it is entirely acceptable for the stud rails to be installed after the rebar and PT have been installed, just as long as the spacing and placement tolerances are kept within the bounds indicated on the construction documents.

Reference:  Concrete Q&A, ACI Concrete International, January 2022

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