ShearailTM – Shear Stud Reinforcement

ShearailTM by Tendon Systems, LLC is ICC ( International Code Council) strength tested. ShearailTM shear stud reinforcement system is an advanced, engineered product.

ShearailTM provides significant building construction cost savings since drop panels and concrete shear capitals can be eliminated. This yields formwork and concrete savings and enables a faster construction schedule.

Stud shear reinforcement has emerged as the preferred method of increasing punching capacity in thin slabs. It has been used in thousands of buildings all over the world, including the United States and Canada. SherailsTM provide an uncongested and quickly installed alternative to closed stirrups or other less popular methods of punching strengthening. Post-tensioning or other slab reinforcement can simply be installed between the heads of the vertical studs.

Reduced installation time translates into reduced labor costs and faster turnaround time per pour. With the use of the design guidelines of ACI 421.1R99, ShearailsTM can eliminate the need for shear capitals, significantly reducing formwork costs and allowing the use of fly forms. The large 10:1 head-to-stem cross-sectional area ratio provides superior anchorage, allowing full utilization of the stud material.

Why ShearailsTM? Punching Shear is a significant design consideration in flat plate slabs. Often it is the controlling design criterion.

Public Life Safety Enhanced! Structural failures due to inadequate moment capacity usually exhibit advanced warning signs such as excessive slab deflections and concrete cracking. These warning indicators provide notice and the structure can be evacuated, shored and stabilized so public safety can be secured. Punching shear capacity failures, however, are abrupt and usually catastrophic and can lead to a progressive failure collapse and severe loss of life.

What are the Design Team’s Options to high punching shear?

  • Shear capitals, drop heads or drop panels, or
  • Thicker slab depths, or
  • Larger column size, or
  • Closed rebar stirrup reinforcement, or
  • Headed stud shear reinforcement ShearailsTM

Shear capitals, drop heads or drop panels are an effective solution, but compound the complexity of the formwork process, resulting in higher formwork expenditures when compared to a flat plate formed slab. Furthermore, the aesthetics of a drop capital on an exposed ceiling for condominiums, apartments and hotels usually preclude their use for these applications. Thicker slabs can work from a structural capacity standpoint, but this requires more concrete which increases concrete forming costs, column sizes, rebar and foundation requirements.

Larger column sizes would be an effective structural solution, but the additional size presents the Architect with larger columns that would encroach into adjacent rooms.

Closed rebar stirrup reinforcement has traditionally been used to increase the punching strength of flat plates but in slabs thinner than 10 inches it is difficult to achieve anchorage of the stirrups. The full capacity of a closed rebar stirrup cannot be achieved in thin slabs as a result of slippage at the stirrup bends. As a recognition of this limitation ACI-318-02 Building Code prohibited the use of rebar stirrups in thin slabs and has added additional detailing requirements in thicker slabs that make placement of rebar stirrups impractical due to the congestion created.

SOLUTION…ShearailTM Brand Shear Stud Reinforcement and eliminate those problems and costs!

Structures in areas of high seismic risk, moment reversals and high unbalanced joint moments can undergo premature punching failure. ShearailsTM can improve the lateral drift capacity of a column-slab joint by absorbing energy with their ductility and superior anchorage.

ShearailsTM are manufactured under strict quality control ICC manufacturing and testing certification program. With accurate field placement drawings prepared by Tendon System’s experienced engineering and drafting staff showing exact rail locations, the simplicity of SHEARAILTM installation is unsurpassed.

INSTALLATIONShearail-Figure-1.1

  1. Clip the provided chair to the rail. Place one chair 2 in.from each end of the rail and additional chairs on the rail as required.
  2. Position rails on formwork at the corner of every column but not closer than 2 in. from the slab edge or opening. Rails should be equally spaced along column face. (see Figure 1.1)
  3. Nail the chair to the formwork to ensure correct position is maintained during concrete installation. Rails should always be installed with the studs vertical.

PRODUCT SPECIFICATION

ShearailTM Studs meet or exceed all of the following requirements.

  • Yield Strength: 51,000 psi (350 MPa), minimum
  • Tensile Strength: 65,000 psi (450 MPa), minimum
  • Elongation: 20 percent in 2 inches (51mm), minimum
  • Reduction of Area: 50 percent, minimum

ShearailTM Rails meet or exceed all of the following requirements.

  • Yield Strength: 44,000 psi (300 MPa), minimum
  • Tensile Strength: 65,000 psi (450 MPa), minimum
  • Elongation: 20 percent in 8 inches (203mm), minimum
  • Reduction of Area: 50 percent, minimum