serviceability design of floor structures | i8 Figure 2 3D structural model for the Shared Lab Building The structural engineer should urge the architect to locate corridors along columns or beam lines for a better vibration performance and for a minimization of the footfall effect. Lower vibration levels can be achieved by altering the structural framing, for example, reducing the column or beam spacing, or increasing the slab thickness or beam depth. Another approach to deal with the vibration problem is to use special isolation devices in conjunction with a stiff structure for a better performance. The induced pulse force acting on a floor due to a person walking has a shape that may be idealized as shown in Figure 1 (Ebrahimpour, Hamam, Sack, & Patten, 1996; Galbraith & Barton, 1970; Murray et al., 1997; Ungar, Zapfe, & Kemp, 2004). The dynamic forces applied to the ground by a walking person can be measured directly by experiments using instrumented force plates or platforms. Prediction methods The most popular method to predict vibration response is the AISC method. The methodology of the AISC Guide focuses on the estimation of footfallinduced vibrations that result at the center of the bay due to walking in the middle of that bay. The AISC Design Guide 11 estimates the response of concrete floors to footfall vibration as follows. The maximum velocity of the floor is: Idealization of footfall pulses Vibrations generated by people walking are controlled by the stiffness and fundamental frequency of the floor, the path of the walker, the walker’s pace rate (paces/min), and the person’s weight. The forces associated with footfall have been shown to have both harmonic and impulsive components. where fn is the fundamental frequency (Hz), Xmax is the maximum dynamic floor displacement, Xstatic is the static deflection, Am is a dynamic amplification factor, and to is the pulse rise time and decay time. A more accurate verification method to assess structural vibrations resulting from human footfall is the finite element model and time history analysis. The method will be discussed in the subsequent sections. Figure 1 Idealized footstep force pulse (walking pace 100 step/min, person weight 84 kg, dwell duration 0.37 sec) 41