A technical guide for equipment manufacturers on evaluating structural integrity, mounting stiffness, and dynamic response of critical electrical and mechanical systems under seismic stress.
Understanding Structural Integrity Testing Standards
Structural Integrity Testing Standards provide the framework for determining how equipment and supporting structures should be evaluated under specified loading conditions. For seismic qualification, the relevant requirements depend on the equipment category, industry, installation location, and expected seismic demand. Testing methods may involve Shake tables or a Seismic simulator to reproduce earthquake-like motion and assess how equipment performs under controlled conditions. When selecting a Seismic shake table, engineers also need to consider the equipment’s weight, mounting arrangement, required acceleration, and operating conditions.
Several standards and technical references are commonly considered when planning qualification activities. These help engineers decide which testing approach is suitable and how results should be evaluated to support reliable equipment performance.
Important Standards and References
- IEC 60068-3-3:2019
This international standard provides guidance on seismic test methods for equipment, primarily electrical and electronic equipment. It discusses dynamic testing approaches and the relationship between seismic environments and qualification testing. Its 2019 second edition replaced the earlier 1991 edition. <Cite refs={[“turn486638search3”]}/>
- IEEE/IEC 60980-344:2020
This standard addresses seismic qualification of equipment important to safety in nuclear facilities. It provides methods and documentation requirements for demonstrating that equipment can meet specified performance requirements during or after defined seismic demands. <Cite refs={[“turn486638search1”,“turn486638search7”]}/>
- IEEE 693-2018
This recommended practice focuses on seismic design of electrical substations. It covers seismic criteria, qualification methods, equipment performance, installation, and documentation. Amendment 693a-2024 is also listed by IEEE. <Cite refs={[“turn486638search11”]}/>
- ASCE/SEI 7
ASCE 7 provides structural design requirements, including provisions for nonstructural components and their supports and attachments. It is relevant when evaluating how equipment and its mounting arrangements interact with the building structure.
One important distinction: a standard does not automatically apply to every industrial installation. Engineers should identify the governing building code, project specification, authority requirements, and applicable equipment qualification standard before developing a test programme.
A facility may also need to demonstrate more than physical survival. If a control panel or emergency pump is expected to operate during an earthquake, its functional performance must be considered as part of the qualification requirements.
Equipment Mount Seismic Evaluation: Why Installation Matters
An equipment manufacturer may successfully test a machine under specified earthquake conditions, but that result does not guarantee it will perform equally well after installation.
The mounting arrangement is a major part of the equation.
Equipment Mount Seismic Evaluation examines how machinery, cabinets, electrical panels, and other components are attached to their supporting structures. It considers the forces transferred through mounting brackets, anchor bolts, base frames, and foundation connections.
Take an industrial water treatment facility as an example. It may have large pumps installed on concrete foundations, with electrical control cabinets positioned nearby. During an earthquake, both the equipment and its supporting structures may move.
If the mounting arrangement is inadequate, several problems may occur:
- Anchor bolts may experience excessive loading.
- Equipment may slide or overturn.
- Base frames may experience deformation.
- Connected pipes and cables may become damaged.
- Nearby equipment may create additional impact risks.
This is why Equipment Mount Seismic Evaluation should consider the complete load path, from the equipment’s centre of mass through its base and anchorage to the supporting structure.
What Engineers Should Check
A practical evaluation should include:
Equipment weight and centre of gravity: These influence the forces and overturning moments developed during seismic movement.
Anchor bolts and connections: Engineers should examine bolt size, material, embedment, spacing, and connection details.
Foundation condition: Concrete strength, foundation dimensions, and existing damage can affect mounting performance.
Flexible connections: Electrical cables, hydraulic lines, and piping should accommodate expected movement without creating additional hazards.
Nearby equipment: Potential collisions with surrounding machinery, walls, or structural members should also be considered.
Equipment Mount Seismic Evaluation should not be treated as a separate activity from equipment qualification. Both need to be coordinated because even a well-tested component can be vulnerable if installed incorrectly.
FEMA’s earthquake-resistant design guidance highlights the importance of securing nonstructural equipment and systems, particularly where their continued operation is important for safety and emergency response. <Cite refs={[“turn486638search24”,“turn486638search29”]}/>
Dynamic Shake Table Testing Methods for Industrial Equipment
Analytical calculations are useful, but some equipment requires physical testing to demonstrate how it responds to simulated earthquake motion.
This is where Dynamic Shake Table Testing Methods become important.
A shake table reproduces controlled movement on a test platform where equipment or representative specimens are mounted. Throughout the testing process, engineers utilise data acquisition systems paired with sensors to track how the equipment responds.
Depending on the qualification requirements, the test may involve different directions of motion, acceleration levels, frequencies, and duration.
How Shake Table Testing Works
A typical testing programme involves several stages.
- Define the test requirements
Engineers identify the expected seismic demand, equipment operating condition, required functionality, and applicable acceptance criteria.
- Prepare the equipment
The test specimen is installed on the platform using a mounting arrangement representative of its intended field installation. Sensors are positioned to capture relevant movements and responses.
- Apply the required motion
The table reproduces the specified seismic input. This may involve a required response spectrum or another defined motion profile, depending on the applicable test method.
- Monitor equipment performance
Engineers measure acceleration, displacement, vibration, and other relevant parameters. Where continued operation is required, the equipment may be monitored while it is energised or operating.
- Inspect and evaluate the results
After testing, the equipment is inspected for damage, loose connections, deformation, leakage, and functional problems. The recorded results are compared with the established acceptance criteria.
Choosing the Right Testing Equipment
Not every facility requires the same shake table configuration.
Some applications involve small electrical components, while others require larger machinery or complex assemblies. The table’s payload capacity, available movement, acceleration, frequency range, and control capabilities must match the test requirements.
For larger industrial equipment, the specimen’s size and weight can also make full-scale testing difficult. In such cases, engineers may consider a combination of analytical evaluation, subsystem testing, and representative component testing.
Modern Shake tables can use advanced control systems and hydraulic actuation to reproduce demanding motion profiles. A Seismic shake table may be particularly useful when evaluating equipment that needs to withstand defined earthquake movements.
Dynamic Shake Table Testing Methods are not simply about making equipment vibrate. The input motion, installation arrangement, measurement accuracy, and acceptance criteria all need to be properly controlled.