###### Abstract
Overall, the dynamic problem is represented by a moving SMD biodynamic pedestrian model (with frequency \(f_{m}\)), which interacts with a substructure characterized by mass \(M_{s}\), fundamental vibration frequency \(f_{1}\), damping ratio \(\zeta_{\text{s}}\), and thus possible sensitivity to vibration issues (Figure 1b). Even more complex, bipedal, and three-dimensional biodynamic models could also be used for sophisticated HSI calculations, see for example [10; 11; 12; 13]. As a common assumption of these literature formulations, low-frequency pedestrian systems (usually represented by laboratory prototypes) or rigid contrast systems are taken into account regardless of other structural parameters of interest, like, for example, the mass of structure \(M_{s}\) in relation to pedestrians (and thus possible additional HSI interaction with occupants). For the SMD models in [5; 6], for example, the experimental calibration of input biodynamic parameters was carried out on an 11.63 m long prototype footbridge with \(f_{1}=4.27\) Hz and \(\xi_{\text{s}}=1\%\). A prototype of a walkway consisting of a massive steel-concrete composite deck was used for the laboratory investigations reported in [7]. Rigid platforms were also used for the SMD validations reported in [5; 7; 8]. In this paper, a selection of existing SMD approaches is taken into account for structural performance assessment. The attention is primarily given to glazed floors which are mostly characterized by specific fundamental vibration frequency \(f_{1}\) and mass \(M_{\text{s}}\) parameters, compared to other construction typologies. To facilitate the comparative analysis, four  
Figure 1: Biodynamic pedestrian model: (**a**) schematic representation of Spring-Mass-Damper (SMD), Single Degree of Freedom (SDOF) model (figure reprinted from [8] with permission from Elsevier®, copyright license number agreement 5458701302374, December 2022) and (**b**) example of presently developed numerical model for Human-Structure Interaction (HSI) analysis. different SMD proposals from earlier studies (SMD-1 to SMD-4, in the following, see [5; 6; 7; 8]) are applied to four different floor configurations (F#1 to F#4, in the following), under normal walking scenarios of a single pedestrian. In doing so, two different glazed floor systems (F#3 and F#4) are analyzed and addressed towards two different concrete configurations (F#1 and F#2). From the total of 100 numerical analyses/configurations, the attention is focused on typical performance indicators of primary interest to characterize and assess the vibration response of structures (like acceleration peak, RMS acceleration and CREST factor). In terms of F#1 to F#4 floor systems, most importantly, various combinations of vibration frequency \(f_{1}\) and structural mass \(M_{s}\) are taken into account. For the concrete floors (F#1 and F#2), for example, the \(M_{s}\) term is generally high compared to pedestrians, regardless of the vibration frequency \(f_{1}\) (i.e., \(>\) or \(<\)8 Hz). In the case of structural glass systems like F#3 and F#4 solutions [14; 15], on the other side, basic structural components are typically characterized by structural mass \(M_{s}\) which can often be relatively low compared to occupants, and by vibration frequency \(f_{1}\) which is not necessarily \"low\" [16; 17; 18], see Figure 2. Dedicated studies are thus recommended to address HSI phenomena on glazed floors, especially under unfavourable operational and ambient conditions (see for example [19; 20]). In general terms, regardless of the structural floor typology, the analysis of input SMD parameters show, at first, that major modifications can be found in terms of pedestrian characterization, even under similar walking conditions and sub-structure dynamic parameters. As such, relevant effects can be expected about the performance indicators of primary interest for structural analysis and vibration serviceability assessment.