How to Limit Vibration in a Steel Structure

Steel forms the framework for modern buildings.

Vibration due to human activity or natural factors such as earthquakes, wind and waves has become the dominant design issue facing modern steel structures. In order to limit the vibration impact on any structure, engineers must identify the source of vibration, analyze the maximum vibration load the structure can withstand, isolate the vibration from the structure and strengthen the structure itself.

Things You'll Need

• Access to a wind tunnel in a research laboratory
• Access to a shaking table in a research laboratory
• Scaled down laboratory model of steel structure
• Accelerometer
• Seismometer
• Expert helpers specializing in earthquake, wind and structural engineering

Instructions

1. Identify the sources of vibration. Examine the impact of earthquake ground motion and wind pressure on similar structures in the region of your design if it is a building or other exterior structure. Investigate the positioning of walkways, elevators and heavy machinery close to a sensitive microelectronic or nanotechnology process.

2. Use instrumental recordings of past earthquakes or wind motion and analyze their effects on your structural design. Position accelerometers and seismometers around your manufacturing site and record the vibrations produced by human and vehicle traffic and heavy machinery. Analyze the effects of the recorded ground motion on the steel structure that supports your manufacturing process.

3. Build a scaled-down model of your structure for laboratory testing. Test your model for earthquake motion response on the shaking table and wind impact response in the wind tunnel. Analyze the results to determine the maximum load for your structure and incorporate this into your design.

4. Isolate vibrations from your manufacturing process by shifting walkways and elevators as far from it as possible. Include lead-rubber bearings or other earthquake motion dampers into the design of your structure’s base. This system isolates the structure from the ground motion below and acts as a shock absorber. Find a sheltered location for your structure to minimize wind impact.

5. Minimize the span of horizontal beams in your structure. This will reduce any bending or flexing in response to the impact of wind, ground motion or pedestrian and vehicle traffic. Strengthen the vertical supports of your steel structure to accommodate expected forces from ground motion, wind or waves.

Tips & Warnings

• Enlist the help of earthquake, wind and fluid mechanics experts at all stages in your structural design.

References

• Tecumseh Group: Eng-Tips Forums; Pipelines, Piping and Fluid Mechanics Engineering Forum; Steel Structure Vibration Absorbing!
• Mitsubishi Heavy Industries: Steel Structures & Civil Engineering Technologies
• Thorlabs: Sources of Vibration
• University of Buffalo: Advanced Earthquake Resistant Design Techniques

Resources

• Northeast Window and Door Association: Architectural Testing; Determining Wind Loads on Buildings – What’s the Big Deal? Craig H. Wagner
• Modern Steel Construction: Challenging Vibration in Engineered Structures; Brian Breukelman; Mar 2004
• A Beginner’s Guide to Structural Engineering: Chapter 2 – Materials; Steel Materials; T. Bartlett Quimby; May 2011
• American Institute of Steel Construction: Designing with Structural Steel; A Guide for Architects; 2002; pp. 9-16
• Structure Magazine: Structural Design of Steel Pipe Support Structures; Kasi V. Bendapudi; Feb 2010