Solutions From Concept To Completion
Structural Engineering
Site Solutions From Concept To Completion
Civil Engineering
Solutions Where Land Meets Water
Marine + Coastal
Solutions From Procurement To Completion
Construction Engineering
Structural + Mechanical Specialists
Entertainment Engineering
Consultation, Design + Inspection
Facade + Building Envelope
Soil + Foundation
Geotechnical Engineering
Investigation + Litigation Support
Forensic Engineering
Arts + Entertainment
Live Performances
Museums + Art Displays
Studios + Sound Stages
TV + Film Production
Theme Parks + Playplaces
Colleges + Universities
Private + Specialty Schools
Public K-12
Solar Energy
Transmission Infrastructure
Wind Energy
Oil + Gas
Senior Care
Outpatient Facilities
Heavy Industrial
Warehouse + Distribution Centers
Industrial Ports + Terminals
Ports + Coastal
Berths, Piers + Wharves
Ferry Landings, Ship Terminals
Floating Structures
Ports + Terminals
Marinas + Breakwaters
Transfer Stations
Public Infrastructure
Bikeways + Trails
Garage + Parking Facilities
Parks + Public Spaces
Recreational Spaces
Utility Infrastructure
Water + Wastewater
Real Estate Development
Community Facilities
Multifamily Residential
Ports + Terminals
Rail Transportation
Roads + Highways
Ropeway + Linear Infrastructure
Floating Harbor Wetland
Multimodal Processing Plant
416 + 420 Kent Dynamic Highrise
Wittpenn Bridge
Tiffany Crane
LaGuardia Airport Terminal B
NYC Ferry
Orlando Airport LED Displays
A leading full-service engineering firm renowned for our trusted, high quality, and innovative approach to solving complex challenges.
Expert Insight

Monumental Stairs Vibration Serviceability

THE HALL AT LIVE! Innovative Approach
Brad Fallon, PE
Senior Engineer

Monumental stairs are a major architectural feature in high-end designs of all types of commercial, institutional, and residential/mixed-use developments. As designers continue to push the envelope of material properties, producing ever-more beautifully complex, slender, and awe-inspiring forms, the tendency of these forms to resonate (or vibrate) in response to human activity, is becoming an increasing concern. As a result, mitigation of vibration issues has become a primary driver of the structural design of stair systems in many cases.

+ Oscillating Force

Monumental Stairs Vibration Serviceability
Differential Movement Model

All framed structures, including stairs, have an inherent natural frequency defined by their material composition, shape, and support system. Human activities, such as walking, running, and jumping also occur on these structures at a certain speed and frequency. When the frequency of human activity produces oscillating forces that match the natural frequency of the structure, vibration resonance occurs. This resonance will produce accelerations that can be palpably sensed by stair users. The sensation produced is generally uncomfortable and in extreme cases alarming.

Slender monumental stairs, consisting of heavier treads and guardrails combined with slender stringers and very little damping provided by non-structural finishes, often have very low natural frequencies. Consequently, this trait makes them more susceptible to vibration issues caused by human movement because there is a higher probability that the walking frequency of the stair users will match the natural frequency of the stair, driving vibrations. The subtle motions of these structures and the transmission of that movement to other parts of the building, can create vibration serviceability issues. This produces complaints of occupant discomfort and in extreme cases, potential safety concerns.

To best avoid vibration performance issues and the need to stiffen the structure post-construction, stair designers must be able to predict the dynamic properties and vibration response of monumental stairs under users’ loads during the design phase. Identifying and mitigating these issues long before fabrication and installation can save time and money, all while upholding the original architectural vision for the design.

Vibration Analysis
+ Design of Monumental Stairs

Historically, vibration behavior was predicted using a series of conservative empirical mathematical formulas based on structural characteristics such as mass and natural frequency. In 2016, the American Institute of Steel Construction (AISC) published an updated consensus procedure based on cutting-edge research by Brad Davis, Ph.D. The paper evaluated expected vibration responses of high-performance steel structures using finite element analysis, which analyzes the response characteristics of a structure using three-dimensional computer modeling. This procedure permits design engineers to more closely predict how a structure will behave in the real world in response to vibrations by using sophisticated structural analysis software, such as SAP2000. Programs like this can predict the magnitude of accelerations due to human-induced vibration.

“McLaren is at the forefront of using these new techniques to evaluate vibration response and has been collaborating with the architects and contractors who design and build these high-end monumental stair structures,” says Brad Fallon, PE, structural engineer specializing in the design of building structural components as well as the analysis of existing structures. “This analysis is performed as part of our design process and anticipated acceleration levels in relation to common threshold values reported back. If the analysis indicates a particular concern for vibration resonance, we can use our process to quickly evaluate design options to minimize impact to the overall architectural vision.”

The Author

THE HALL AT LIVE! Innovative Approach

Brad Fallon, PE

Brad Fallon, PE, is a structural engineer out of McLaren Engineering Group’s Baltimore office has 12 years of structural engineering analysis and design experience. Recently, Fallon used finite element modeling technique for the design of a monumental stair system for a well-known corporate headquarters in New York City. Additionally, he specializes in detailed design of structural systems and the preparation of contract drawings and specifications. Fallon has worked on facilities of various sizes and complexity ranging from aquariums to multi-story medical, residential, and mixed-use structures, as well as power plants, pedestrian bridges, and casinos. His project portfolio spans nationwide and includes: Two Light Tower (Kansas City, MO), Inmar Headquarters at PTRP (Winston-Salem, NC); Live! Maryland Casino & Hotel (Hanover, MD); National Aquarium (Baltimore, MD), and Teachers Village Workforce Housing (Newark, NJ).His NYC healthcare engineering work and oversight includes projects for the City’s top area systems including Mount Sinai Healthcare Facility, Northwell Health; New York Presbyterian Hospital; Beth Israel Medical Center; Lutheran Hospital; Lawrence Hospital and more.