College - Author 1

College of Architecture and Environmental Design

Department - Author 1

Architectural Engineering Department

Degree Name - Author 1

BS in Architectural Engineering

College - Author 2

College of Architecture and Environmental Design

Department - Author 2

Architectural Engineering Department

Degree - Author 2

BS in Architectural Engineering



Primary Advisor

Graham Archer, College of Architecture and Environmental Design, Architectural Engineering Department


Forced vibration testing is a tool used to characterize a structure’s dynamic properties. When subjecting a structure to a forced harmonic load, the results help define the structure’s fundamental frequencies and dominant mode shapes. However, when conducting testing, it is difficult to determine the contributions of each mode to the response at a given location in the structure. The recorded response from a forced vibration test is a combination of unknown modal constituents. Excitation may not result in the pure, single mode response that the experimenter desires, but may instead result in a combination of modal responses that obscure the recorded data or even weaken the overall response.

The phase angle is the lag in the response of the structure to the applied harmonic load. Often, engineers focus on the amplitude of the response but overlook the phase angle in their analysis. The investigation conducted herein used a configurable three-story MATLAB model capable of simulating forced vibration tests to determine the role of the phase angle in forced vibration testing. The results produced by the model were also used to analyze modal contributions to the structural response. A data-driven numerical approach and algebraic theoretical approach were both used to characterize the harmonic response. This study describes how the phase angle could indicate when modal contamination occurs, helping engineers filter forced vibration results and understand when a pure mode response is being achieved.

SeniorProjectModel.m (27 kB)
Forced Vibration Model