Vibration Analysis and Dynamic Characterization of Structural Glass Elements with Different Restraints Based on Operational Modal Analysis

Abstract

Given a series of intrinsic features of structural glass systems (i.e., material properties, type of restraints, operational conditions, etc.), special care should be spent at the design stage, to ensure appropriate fail-safe requirements, but also in the service life of these innovative building components and assemblies. In this paper, the dynamic characterization of simple monolithic glass elements is presented, based on non-destructive laboratory experiments and Operational Modal Analysis (OMA) techniques, including Finite Element (FE) numerical simulations, classical analytical models, and video-tracking approaches. It is shown, in particular, how the actual restraint condition (i.e., flexibility of supports, with respect to ideal boundaries) can affect the vibration parameters of a given glass member (frequency and damping capacity). This turns out in possible variations of its overall structural performance, including stress-strain-related effects, hence suggesting the need for even further dedicated studies and methods for the reliable analysis and design of structural glass assemblies and complex systems under dynamic loads.

Reliability of Field Experiments, Analytical Methods and Pedestrian’s Perception Scales for the Vibration Serviceability Assessment of an In-Service Glass Walkway

“…A series of steel tendons and frame members were then used to support the glass plates, for up to ≈140 square meters of transparent walking surface. The research outcomes presented in this paper follow and extend the preliminary experimental investigation summarized in [16], where the vibration performance of monolithic glass samples under soft impact was assessed as a function of flexible mechanical supports (Figure 1b), including analytical calculations derived from classical dynamic theories [17] and Finite Element (FE) parametric studies (ABAQUS [19]). In addition, the current investigation aims at further exploring Figure 1.…”

“…In addition, the current investigation aims at further exploring Figure 1. Dynamic performance of glass members: (a) Sensitivity of polyvinyl butyral (PVB®) stiffness to humidity/loading frequency (reproduced from [15] with permission from Elsevier, license n. 4585281507083, May 2019) and (b) flexible restraints (reproduced from [16] under CC BY 4.0 license). This paper focuses on the vibration serviceability assessment of an in-service glass walkway in Italy.…”

Safety Issues in the Seismic Design of Secondary Frameless Glass Structures

“…While Z and H can be rationally estimated, and the fundamental period T 1 of the full building can be calculated based on approximate formulations, the reliable estimation of T a can represent a severe challenge for designers. It was shown for example in [33][34][35] that-even for simple independent glass elements with a beam behaviour-the local detailing of restraints can have marked effects on the vibration period T a (and also damping capacity). When more detailed calculations are available, the use of maximum R a values from Figure 5a could result in extremely conservative assumptions, thus in over-design of glass members.…”

Vibration experiments for diagnostic investigations on a glass suspension footbridge

“…Besides such a series of primary safety requirements, an additional key aspect in operational conditions is represented -under ordinary loads -by maximum vibrations, requiring dedicated calculation methods (i.e., [4]). In most of the cases, the optimal vibrational condition can be considered satisfied as far as the fundamental frequency is minimum 8 Hz.…”