Reliable slab-to-wall connections are critical in hollowcore diaphragm systems. Whether resisting out-of-plane wind pressures, suction forces, or in-plane diaphragm loads, these connections must safely and predictably transfer horizontal shear.

The March–April 2026 issue of PCI Journal features a research study titled “Embedded Plate Connection between Hollowcore Slabs and Concrete Walls,” evaluating a new end-bearing connection assembly designed specifically for hollow-core applications

Molin Concrete was proud to serve as the precast partner supporting this research initiative.

The Challenge with Traditional Connections

Hollowcore slabs are manufactured through an extrusion process, which limits the ability to cast embedded anchors during production. As a result, many current slab-to-wall connections rely on:

• Post-installed dowels
• Welded steel angle connections
• Field welding
• Masonry bond beams

While widely used, these approaches can introduce field variability and limited experimental data for certain loading scenarios.

A New Embedded Plate and Stud Assembly

The connection studied in this research consists of:

• A steel embed plate installed within a hollowcore void
• A welded steel stud
• A post-installed screw anchor connecting the slab to a cast-in-place wall

Because the embedded hardware is installed during production, field installation is simplified to drilling and placing a screw anchor. No field welding is required.

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Two Phases of Experimental Testing

The study evaluated performance through two structured phases:

Phase 1:

Direct loading of the embedded plate assembly installed within a hollowcore slab under:

• Out-of-plane pressure
• Out-of-plane suction
• In-plane loading

Phase 2:

Full slab-to-wall subassembly testing using cast-in-place walls, with and without confinement reinforcement. Testing was conducted to failure to determine governing mechanisms and compare results with ACI 318-19 design predictions.

Key Findings

Some of the most significant conclusions included:

• The embedded plate assembly demonstrated conservative performance relative to predicted capacities.
• In full subassembly tests, failure consistently occurred as concrete breakout in the supporting wall, not failure of the embedded hardware.
• The connection eliminated the need for field welding while maintaining predictable performance.
• Code-based predictions using ACI 318-19 were conservative compared to observed capacities.

These findings suggest the system provides adequate and reliable performance for hollow-core slab-to-wall end-bearing applications.

Why This Matters for Designers

For structural engineers designing hollowcore diaphragm systems, connection detailing often drives constructability and risk.

This research contributes experimental data supporting:

• Predictable shear transfer mechanisms
• Simplified installation
• Reduced field welding
• Code-aligned performance

When diaphragm forces must be transferred reliably, connection detailing deserves careful consideration.

Molin’s Role

Molin Concrete supported this research as the precast partner, contributing full-scale hollowcore specimens and production expertise. Collaborations like this allow research to move beyond theory and reflect real-world production and installation conditions.

Read the Full Study

The complete research article is available in the March–April 2026 issue of PCI Journal:

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