Experimental Campaign Design

MESO-SCALE GOAL

To transition from isolated material characterization to sub-assembly analysis. This phase empirically isolates the phenomenological bifurcations unique to the EPSB-RC "screen-grid" topology prior to full-scale lateral testing.

TARGET MECHANISMS

• Truss-to-Vierendeel Transition: Quantifying the "Shear-Softening" penalty in sparse grids under pure diagonal compression fields.
• The Solid Shoe Effect: Validating the localized kinematic boundary stiffening ($\Gamma > 1.2$) provided by a monolithic RC kicker vs. continuous EPS formwork.
• Kinematic Decoupling: Utilizing advanced instrumentation to mathematically separate total drift into flexure, sliding shear, and rigid-body rocking.

ENGINEERING CONTEXT

While standard codes use smeared compression fields, the discrete voided topology forces a stepped "zig-zag" stress path. This test applies diagonal compression to induce a diagonal tension shear field ($\tau_{xy}$), isolating pure shear compliance without global flexural moments.

SETUP SUMMARY

• Standard: Adapted ASTM E519 / E519M.
• Specimens: $1300 \times 1300 \times 150 \text{ mm}$ panels, rotated $45^\circ$.
• Topology Grid Matrix: Dense ($a/b=1.0$), Standard ($a/b=1.33$), and Sparse ($a/b=2.0$).

EXPECTED OUTPUTS

The ultimate in-plane shear capacity ($V_u$) and quantification of the analytical Shear Capacity Efficiency factor ($\psi_{shear}$).

ENGINEERING CONTEXT

To evaluate plastic hinge formation at the base cold joint under simulated seismic demands, and definitively validate the "Solid Shoe" Boundary Effect ($\Gamma > 1.2$) where a monolithic RC base shortens the effective Vierendeel buckling length.

SETUP SUMMARY

• Specimens: $1300 \times 1300 \text{ mm}$ wall cast onto a $1900 \times 500 \times 400 \text{ mm}$ rigid RC foundation block.
• Protocol: ACI 374.1 reversed cyclic lateral drifts (FEMA 461) coupled with a constant $10\% N_{Rd}$ axial pre-load.

EXPECTED OUTPUTS

Moment-rotation hysteresis, base shear slip degradation, and structural energy dissipation capacities for the "Solid Shoe" vs. Standard CFS Track boundary detailing.

3D DIGITAL IMAGE CORRELATION (DIC)

Required to map the tensile strain fields and identifying the onset of flexural cracking preceding global failure. DIC is absolutely immune to sensor damage during explosive concrete spalling.

• "Virtual LVDTs": Within the DIC software, exact pixel displacements between nodes are tracked. Hiraishi (1984) kinematic equations are applied to these virtual sensors to decouple drift into flexure, diagonal shear, and sliding shear.
• The EPS Blindspot Constraint: If the EPS formwork is left on the wall, the DIC cameras only see the foam. It cannot track internal concrete damage.

PHYSICAL MACRO-ELEMENT LVDTs

Mandatory for continuous tracking of interfacial behavior and instances where DIC optical lines of sight are obscured.

• Through-Thickness Anchoring: To track the concrete core while the EPS is attached, horizontal LVDTs must be drilled through the foam and anchored directly into the RC webs. Otherwise, they only measure superficial foam crushing.
• Interface Separation: Specialized transverse LVDTs monitor the "Interface Integrity Constraint" by physically measuring the out-of-plane peeling between the EPS and the concrete lattice.
• Vulnerability: X-configuration LVDTs on bare concrete are highly prone to buckling/destruction during diagonal shear explosive failures.

HORIZONTAL/VERTICAL PANEL JOINTS

If the EPSB-RC system evolves into large pre-cast segments, connection verification is required to guarantee diaphragm action and monolithic equivalent behavior (EN 1992-1-1).

• Mechanism: Grouted sleeve connections, welded plates, or cast-in-situ concrete stitches bridging the reinforcement.
• Verification: Full transfer of axial, shear, and bending forces across the lapped joints under simulated seismic drifts.

WALL-TO-SLAB / ROOF CONNECTIONS

Evaluates load transfer capacity and deformation compatibility under combined vertical loads and lateral diaphragm forces (wind/seismic inertia).

• Setup: T-shaped or L-shaped sub-assemblies representing a wall segment connected to a $1.5 \text{ m}$ slab span.
• Failure Modes Monitored: Anchorage pull-out, slab edge cracking, or dowel connector yielding.