Accelerate post-installed rebar design with PROFIS Engineering’s Concrete to Concrete module. Whether you are designing slab or wall extensions, structural joints, or concrete overlays, this module supports a wide range of design methods per CSA A23.3:19 and research-based methods including: 

• Development length
• Lap splices
• Anchoring to concrete
• Shear fiction
• Anchoring to concrete to design for bar yield
• Hilti Method for Interface Shear

Why Use the Concrete-to-Concrete Module?

Traditionally engineers have designed post-installed rebar using anchor design provisions or by applying the same development length equations used for cast-in reinforcing bars. In 2015, the ICC-ES Acceptance Criteria for Post-installed Adhesive Anchors in Concrete Elements (AC308) was updated to allow post-installed rebar with adhesive to be qualified as equivalent to cast-in reinforcement for development length calculations.
 
While designing for the full yield strength is often desirable, limited concrete thickness can make full development length unfeasible. The Concrete-to-Concrete module addresses this challenge by offering research-based alternatives that enable shorter embedment depths. Two research-based options, Anchoring to Concrete for bar yield and Hilti Method for Interface Shear can result in shorter embedment depths compared to development length calculations.
 
Learn more: Hilti Post-installed Reinforcing Bar Design Guide

Anchoring to Concrete for Bar Yield

The method leverages the CSA A23.3:19 anchoring to concrete provisions to compare the CSA A23.3:19 concrete breakout and bond strength equations against the nominal yield strength of the steel. The software iteratively calculates the shortest embedment depth that ensures both concrete breakout and bond strengths exceed the steel’s yield strength. This alternative design method is based on the work of Charney et al. published in the study "Recommended Procedures for Development and Splicing of Post-installed Bonded Reinforcing Bars in Concrete Structures".
 
Learn more: Design for Yield using Anchoring-to-Concrete Provisions for Post-installed Reinforcing Bar

Hilti Method for Interface Shear

Based on research by Palieraki et al. (ACI Structural Journal V.119 No. 3, 2022), this method calculates interface shear strength by summing the contributions of friction and dowel action, along with modification terms that account for additional influencing factors. It requires a minimum embedment depth of eight times the bar diameter, which is often shorter than the development length.
 
Learn more: Interface Shear Transfer Design using the Hilti Method for Post-installed Rebar Design

 
Designing for Fire-Rated Applications

While ACI 216.1 provides guidance for evaluating fire resistance of cast-in reinforcement, it does not address post-installed bars with adhesive systems. In 2022, AC308 was updated to include testing provisions for fire exposure. Hilti has completed this testing for both HIT-RE 500 V3 and HIT-FP 700 R adhesives. PROFIS Engineering incorporates these fire design parameters, enabling engineers to evaluate development lengths under fire exposure and simulate heat effects based on application geometry.
 
Learn more: Hilti Post-installed Reinforcing in Fire Conditions Design Guide
 

Getting Started

This is the first dialog box after starting a design in the Concrete to concrete module.



Step 1: Select Connection Type
 
Extensions/Lap Splice

• Uses lap splice design method for embedment depth

 
Learn more: Extension Design using CSA A23.3:19 Provisions for Post-installed Reinforcing Bar

Structural Joints

• Supports multiple design method options and any combination of moment, tension, and shear loads.

 
Learn more: Structural Joint Design using CSA A23.3:19 Provisions for Post-installed Reinforcing Bar
 
Shear doweling/Concrete overlay

• Designed for shear loads only
• Offers CSA A23.3:19 shear friction or Hilti’s research-based Interface Shear Method

Step 2: Select Application Type
 
The Connection type selection affects the list of applications such as Slab to slab or Wall to slab. The application selection affects the starting geometry of the concrete and the starting rebar layout. These may be adjusted in the 3D view or the left input section.​ When the connection is designed for fire exposure, the Application selection affects how heat sources are simulated in the software.

Learn more: Designing Post-Installed Rebar for Fire Conditions Using PROFIS Engineering.
 
Step 3: Select Load Type
PROFIS Engineering supports design for static, seismic, and fire load types. When starting a new design, the initial dialog asks whether the structural element should be evaluated for fire exposure and/or seismic loads. If selected, the module automatically populates the load table with the chosen load types, streamlining the design process.
 
Step 4: Define Concrete and Reinforcement Properties

• Select concrete compressive strength.​
• Edit the concrete geometry. Note that the new concrete section needs to be the same size or smaller than the existing concrete section.
• For beam connections, select reinforcement layers and define the number of bar per layer.
• For column connections, select reinforcement arrangement and define number of bars in each direction.
• Select adhesive, rebar strength, and bar size.

 
Step 5: Input Loads

• Add factored loads in 3D view or in the table​.
• With a Premium license, add multiple load combinations and import loads from excel.

 
Step 6: Select and Review Design Method Options



The available design methods depend on the selected connection type and load conditions. The figure above is a screenshot from the software when Structural Joints is selected as the connection type and a shear load has been inputted. The first three checkbox options enable the four design method selection options.
 
Allow for research-based design methods selection enables:​

• Anchoring to concrete to design for bar yield ​
• Hilti method for interface shear

 
Design for yield selection enables: ​

• Development length ​
• Lap splice length​
• Anchoring to concrete to design for bar yield​

 
Splice to existing reinforcement selection enables:

• Lap splice length

 
For moment and/or tension loads only, the design method options are:

• Development length
• Lap splice length
• Anchoring to concrete to design for external loads
• Anchoring to concrete to design for bar yield

 
Anchoring to concrete to design for external loads is the phrase used to describe designing post installed reinforcing bar like an anchor by comparing the demand load to each failure mode such as steel strength, concrete breakout strength, and bond strength. This design option is similar to the Anchoring to concrete module in the PROFIS Engineering Suite.
 
For shear loads only, the design method options are:

• Shear friction (CSA A23.3:19 Ch. 11) + Development length (CSA A23.3:19 Ch. 12)
• Shear friction (CSA A23.3:19 Ch. 11) + Anchoring to concrete to design for bar yield
• Hilti method for interface shear

 
For combined moment/tension and shear loads:
There are options for considering the use of the same or different rebar for each load type. These options are available in the Calculation Data section on the New concrete tab.

When calculating the shear friction capacity, the software offers three options for defining the area of concrete (Acv) and the area of reinforcement (Avf):

• The default assumption selection uses only the compression zone of the cross- section based on the internal moment capacity to determine Acv and Avf.
• The full cross-section selection uses the full cross-section of the new concrete for Ac and all modeled rebar for determining the Avf.
• The user defined option allows manual input of Acv and Avf values offering flexibility to use different rebar than what is modeled. 

 
Standard vs. Premium features in PROFIS Engineering
All PROFIS Engineering users, whether using the free Standard version or the paid Premium version can take advantage of designing with all design methods, cloud-based file storage, and automatic software updates.
 
PROFIS Engineering Premium users gain additional productivity features such as:

• Running multiple load combinations
• Importing loads from excel
• Saving design templates and favorite inputs
• Sharing project files and folders

 
Learn more: Compare versions of PROFIS Engineering
 
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