Role of In-Field Experimental Diagnostic Analysis for the Derivation of Residual Capacity Indexes in Existing Pedestrian Glass Systems

The use of simplified tools in support of the mechanical performance assessment of pedestrian structures is strongly attractive for designers due to practical efficiency, as well as for researchers in terms of innovation and the assessment of new proposals. On the side of design, the vibration serviceability requires that specific comfort levels for pedestrians are satisfied by taking into account conventional performance indicators and the class of use, or the structural typology for pedestrian systems’ object of analysis. A major issue, in this context, is represented by long-term performance of systems (especially pedestrian) that are based on innovative or sensitive materials and possibly affected by degradation or even damage, and thus potentially unsafe. Consequently, it is clear that, especially for in-service structures, the availability of standardized non-destructive protocols for a reliable (and possibly rapid) structural assessment can represent an efficient support for diagnostics. This perspective paper poses the attention on the residual capacity quantification of laminated glass (LG) pedestrian structures, and on the assessment of experimental and/or numerical tools for their analysis. To this aim, three modular units belonging to two different indoor, in-service pedestrian systems are taken into account like pilot studies. On the practical side, as shown, a primary role is assigned to Operational Modal Analysis (OMA) procedures, which are used on-site, to quantify their structural performance based on vibration response, including damage detection and inverse characterization of materials degradation. As shown, based on earlier detailed validation, it is proven that a rapid structural assessment can be based on a single triaxial Micro Electro-Mechanical System (MEMS) accelerometer, which can be used to derive relevant capacity measures and indicators. To develop possible general recommendations of technical interest for in-service LG pedestrian systems, the so-calculated experimental performance indicators are assessed towards various traditional design procedures and literature approaches of classical use for structural diagnostic purposes, which are presently extended to the structural typology of LG systems.