Figure 1 The solid model of the TMD

To address the vibration of a monumental staircase in an office building, the structural engineer of the project incorporated a 500 lb tuned mass damper (TMD) into the design.  DEICON designed, fabricated the TMD to be installed underneath the landing Figure 1 shows the tuned mass damper.

The dynamic attributes of the monumental staircase, namely the first natural frequency and damping ratio, were measured and used in tuning the tuned mass damper, targeting the first mode of vibration of the staircase.

Figure 2 shows the images of the TMD installed in the cavity underneath the landing and the TMD itself.The blue traces in Figure 3 depict the power spectral densities (PSDs) and time traces of the measured landing as well as step 7 accelerations without the TMD in place.  The red traces in Figure 3 show the same measurements as those of blue traces, except with the TMD installed.

Comparison of the red and blue traces in Figure 3 clearly  points to the effectiveness of the tuned mass damper in dampening its target mode, abating the vibration of the staircase.