Experimental Campaign Design

GLOBAL SYSTEM GOAL

To evaluate the ultimate collapse mechanisms, time-dependent dynamic instability, and spatial load redistribution of a complete 3D EPSB-RC structural system under realistic, multi-level earthquake excitation.

TARGET MECHANISMS

• Torsional Coupling: Exploiting severe geometric asymmetry (Center of Mass vs. Center of Rigidity) to induce massive dynamic torsional moments ($M_t$).
• Spandrel & Lintel Mechanics: Observing damage progression (diagonal tension / flexural hinging) in short coupling beams bridging windows and doors.
• System Identification: Tracking period elongation ($T_1$) and equivalent viscous damping degradation ($\xi$) via white noise excitation.

ENGINEERING CONTEXT

The design intentionally introduces severe spatial asymmetry. E4 is a solid shear wall, while E1, E2, and E3 feature distinct fenestrations. This skews the Center of Rigidity (CR) away from the Center of Mass (CM).

SETUP SUMMARY

• Footprint: $3000 \times 3000 \text{ mm}$.
• Height: 2 stories ($H_{tot} = 6750 \text{ mm}$).
• Diaphragms: Cast-in-place RC slabs ensuring absolute in-plane rigidity.

MASS SIMULATION

Because EPSB-RC walls are highly optimized, supplementary steel/lead ingots are bolted to the slabs to scale the total seismic weight ($W$) to match realistic $0.10 f_{ck}$ stress levels in the 1st-story ribs.

ENGINEERING CONTEXT

To systematically drive the structure from the elastic domain through to ultimate collapse using spectrally matched natural accelerograms (PEER NGA-West2).

LOADING SEQUENCE

• White Noise (0.05g RMS): Extracts evolving natural frequencies before and after every major run.
• SLE (Serviceability): Verifies elastic uncracked behavior.
• DBE (Design Basis): Maps controlled plastic hinging.
• MCE (Max Considered): Evaluates ultimate collapse prevention and structural robustness.

3D DIGITAL IMAGE CORRELATION (DIC)

Mandatory for 3D dynamic testing. As the entire building translates, rocks, and twists simultaneously, physical LVDTs are fundamentally flawed.

• Eliminating "Cosine Errors": Traditional LVDTs attached to stationary reference frames lose accuracy as the target points move out-of-plane (torsional warping). DIC inherently calculates true 3D spatial coordinates ($X, Y, Z$), entirely eliminating cosine errors.
• Focus Zones: Cameras will map the complex shear lag at the 3D corner joints and the dynamic web crippling in the asymmetric door/window spandrels.

HYBRID SENSOR DEPLOYMENT

While DIC maps the external strain fields, internal mechanical sensors are strictly required to monitor the "Interface Integrity Constraint".

• Internal Interface LVDTs: Must be anchored through the EPS into the concrete core at the base of the solid E4 wall to measure delamination/slip under violent dynamic reversals.
• Triaxial Accelerometers: Deployed at the geometric center and extreme corners of every slab to map absolute accelerations and the exact torsional yaw ($\ddot{\theta}_z$).
• String Potentiometers: Used to measure global inter-story drifts ($\Delta_{story}$), acknowledging minor acceptable tolerances for twisting.