Simulated earthquake test response status test

Seismic Qualification via Simulated Earthquake Testing – Reliable Response Evaluation for Brazilian Infrastructure

As an independent testing engineering laboratory with ISO/IEC 17025 accredited capabilities, we provide Brazilian project owners, structural engineers, and procurement specialists with state‑of‑the‑art seismic simulation services. Our dynamic testing platform reproduces real earthquake ground motions to evaluate the structural response, functional integrity, and dynamic behaviour of critical components. All protocols are designed to align with ABNT NBR 15421 (Seismic action – Procedure) and international qualification standards, ensuring that your equipment and structures meet the rigorous safety expectations of Brazilian regulatory agencies, including ANEEL (electricity sector) and ANP (oil and gas), as well as mining and industrial project requirements.

Test Specimens We Commonly Evaluate

Our seismic simulation laboratory accommodates a broad spectrum of specimens, ranging from small electromechanical relays to large sub‑station components. Typical test articles include:

• Electrical and control panels – low‑voltage switchgear, motor control centres, and distribution boards
• Instrumentation and protective relays – digital protection relays, transducers, and communication racks
• Mechanical and process equipment – pumps, valves, pressure vessels, and support skids
• Structural assemblies and substructures – steel frames, bracing systems, and precast concrete elements
• Piping systems and supports – pipe hangers, expansion joints, and anchored pipe segments
• Electrical raceways and cable trays – ladder trays, conduits, and junction boxes
• HVAC modules and emergency systems – air handling units, generator sets, and battery racks

Shaking Table Input Motion – Time History & Response Spectrum Generation

• Artificial and recorded ground motion synthesis – We generate input accelerograms based on site‑specific seismic hazard levels defined in NBR 15421, including type 1 and type 2 response spectra. Our control system allows the reproduction of historical earthquake records (e.g., scaled El Centro, Kobe, or synthetic signals) with a frequency range typically from 0.5 Hz to 50 Hz and peak acceleration capacity up to 5 g, depending on table payload.
• Multi‑axis simultaneous excitation – Full tri‑axial (X, Y, Z) simultaneous motion is applied to simulate the most realistic dynamic loading. We perform bi‑directional and uni‑directional runs as required, with real‑time closed‑loop control ensuring that the actual table response matches the target demand spectra within the tolerances defined by IEC 60068‑2‑57 (test methods for seismic effects).
• Sine‑beat and sine‑dwell testing – For equipment qualification, we apply sine‑beat inputs to assess low‑cycle fatigue effects and resonance build‑up. Dwell tests at identified resonant frequencies are conducted for a defined number of cycles to verify the specimen’s ability to withstand persistent oscillatory forces, following IEEE 693 (Recommended Practice for Seismic Design of Substations).

Dynamic Response Characterisation – Modal Analysis & Resonance Search

• Low‑level sine sweep (resonance search) – Before the main seismic event, we conduct a low‑amplitude frequency sweep (typically 0.2 g peak) from 0.5 Hz to 100 Hz to identify natural frequencies and mode shapes of the specimen. This modal survey, performed per ISO 7626‑1, provides critical data on dynamic stiffness and damping ratios, helping engineers avoid destructive co‑incident frequencies.
• High‑level response verification – During the full‑level seismic run, we continuously monitor the acceleration, displacement, and strain response at predefined measurement points. The output time histories are processed to determine peak floor response acceleration, relative displacement between connected parts, and absolute acceleration amplification factors.
• Transfer function and frequency response estimation – Using Fast Fourier Transform (FFT) analysis, we derive transfer functions between table input and specimen response. These results are compared with pre‑test analytical models (e.g., finite element predictions) to validate or update structural models, ensuring that the ‘response status’ – defined as the specimen’s dynamic stability and integrity – is fully quantified.

Performance Criteria & Functional Verification During/After Excitation

• Structural integrity and permanent deformation check – We inspect for visible damage, yielding, fastener loosening, or fracture based on NBR 15421 acceptance criteria. Dimensional measurements using calibrated callipers and gauges verify that residual displacements are within specified project tolerances.
• Operational continuity (functional testing) – For active electrical and mechanical equipment, we perform electrical continuity, insulation resistance (per IEC 60216), and mechanical operation (valve stroke, relay trip/close) both during the seismic event (where safe and monitored) and immediately after. This ‘response status’ confirms that the unit remains fully operational – a critical requirement for ANEEL‑regulated power generation and transmission assets.
• Leak integrity and pressure retention – For pressurised vessels and piping, we measure leakage rates and pressure decay under static hold conditions before and after testing, following API 579 or ASME BPVC guidelines, to ensure that seismic loads do not compromise containment safety.

Instrumentation, Data Acquisition & Uncertainty Quantification

• High‑precision accelerometry – We deploy tri‑axial ICP® accelerometers with sensitivity up to 1,000 mV/g and a flat frequency response up to 5 kHz, strategically placed on the table platen, the mounting interface, and critical mass points of the specimen. Displacement is monitored via LVDT sensors and high‑speed laser interferometers with sub‑millimetre accuracy.
• Strain gauge monitoring – Bonded foil strain gauges (120 Ω) are installed at high‑stress locations to capture dynamic strain time histories. Data are sampled at rates up to 2 kHz per channel using a 24‑bit simultaneous sampling system, ensuring no phase distortion between channels – essential for accurate relative displacement and stress calculation.
• Measurement uncertainty and traceability – All primary sensors are calibrated with traceability to national metrology standards. We report the expanded uncertainty (k=2) for peak acceleration (±3 %), frequency (±1 %), and displacement (±2 mm), meeting the rigor required for forensic or acceptance testing under ISO/IEC 17025.

Report Acceptance & Compliance with Brazilian Regulatory Framework

Our seismic test reports are issued as comprehensive, data‑rich documents that include test setup photographs, sensor location diagrams, input response spectra, recorded acceleration time histories, computed amplification factors, and a detailed ‘pass/fail’ disposition based on pre‑agreed performance criteria. These reports are fully aligned with the technical requirements of ABNT NBR 15421 and are widely accepted by ANEEL for substation equipment qualification, by DNIT (National Department of Transport Infrastructure) for bridge components, and by state environmental agencies requiring seismic safety demonstrations for industrial installations. We provide bilingual (English/Portuguese) executive summaries to facilitate submission to Brazilian certifying bodies and project review teams, ensuring that your seismic response status is documented, defensible, and ready for regulatory approval.