Assessing the structural behaviour of square hollow glass columns subjected to combined compressive and impact loads via full-scale experiments

Glass is largely used in buildings as a novel construction material. Due to the intrinsic mechanical properties of such material, however, specific design recommendations are demanded in order to offer appropriate \u201cfail-safe\u201d requirements. This is especially true in the case of load-bearing structural glass elements where redundancy, stability and residual resistance should be guaranteed. In this regard, based also on a past research effort, the paper experimentally investigates the structural performance of full-scale square hollow glass columns, whose resisting cross-section consists of four adhesively joined laminated glass panes. Impact tests are carried out on in-plane compressed specimens, including both a reference undamaged column and a deliberately, preliminary broken specimen. The effects of multiple impact test configurations (inclusive of various release configurations for the impact mass as well as type of impact body) are hence emphasized, with critical discussion of the observed overall results and failure mechanisms

Structural characterisation of adaptive facades in Europe \u2013 Part I: Insight on classification rules, performance metrics and design methods

Adaptive facades are increasingly used in modern buildings, where they can take the form of complex systems and manifest their adaptivity in several ways. Adaptive envelopes must meet the requirements defined by structural considerations, which include structural safety, serviceability, durability, robustness and fire safety. For these novel skins, based on innovative design solutions, experimentation at the component and / or assembly level is required to prove that these requirements are fulfilled. The definition of appropriate metrics is hence also recommended. A more complex combination of material-related, kinematic, geometrical and mechanical aspects should in fact be properly taken into account, compared to traditional, static facades. Accordingly, specific experimental methods and regulations are required for these novel skins. As an outcome of the European COST Action TU1403 \u2018Adaptive facades network\u2019 - \u2018Structural\u2019 Task Group, this paper collects some recent examples and design concepts of adaptive systems, specifically including a new classification proposal and the definition of some possible metrics for their structural performance assessment. The aim is to provide a robust background and detailed state-of-the-art information for these novel structural systems, towards the development of standardised and reliable procedures for their mechanical and thermo-physical characterisation

Low velocity impact performance investigation on square hollow glass columns via full-scale experiments and Finite Element analyses

Taking advantage of two full-scale experimental tests carried out on square hollow glass columns under low velocity impacts, the paper aims to further assess via Finite Element models the structural performance of such structural systems. In them, the resisting cross-section consists of four adhesively bonded laminated glass panes. Adhesive joints are also used for the connection between glass columns and top/bottom restraints. As a result, careful consideration in the analysis and design of these innovative systems is required, to guarantee appropriate fail-safe design principles for a typically tensile brittle material, as well as to account for possible accidental or exceptional loading conditions. Simplified but computationally efficient FE models are validated in the paper towards the available full-scale test results. Key aspects in the observed overall performances under low velocity impact are then emphasized, with careful consideration for several loading configurations, including variations in the release distance for the impacting mass as well as in the type of impact (hard/soft body). In conclusion, a FE sensitivity analysis is also carried out, giving preliminary evidence of the effects of some main input parameters on the overall performance of the examined systems, including possible localized damage in glass, as well as geometrical and mechanical features in the column restraints

Numerical Modelling of Adhesive Connections Including Cohesive Damage

Adhesive connections offer a number of benefits in structural applications, especially in the case of brittle adherends such as glass. There, a multitude of materials can be used to provide structural bonding between glass and/or metal components, giving evidence of different mechanical behaviours as well as structural performances. This paper reports on a Finite Element numerical investigation carried out on small-scale adhesive joint specimens. Taking advantage of a past experimental study performed at CTU in Prague - focused on both material tests and small-scale adhesive connections subjected to shear loading - the numerical modelling approach is validated by taking into account a selection of shear tests on glass-to-steel adhesive joints. The typical specimen is composed of two glass plates bonded to two steel plates with a gap between them and four adhesive joints per one specimens. Finite Element numerical analyses are presented, as obtained from full 3D solid models representative of the specimens components. While careful consideration is spent for the mechanical description of materials, a key role is indeed assigned to cohesive surface interactions, being representative of any possible damage occurring at the interface between the adhesive layers and the bonded substrates. The sensitivity of FE results to input parameters responsible of damage initiation and propagation is discussed, based on past experimental observations

Structural characterisation of adaptive facades in Europe - Part II: Validity of conventional experimental testing methods and key issues

Given their intrinsic features, adaptive facades are required to strictly satisfy rigid structural performances, in addition to typical insulation, thermal and energy requirements. These include a minimum of safety and serviceability levels under ordinary design loads, durability, robustness, fire resistance, capacity to sustain severe seismic events or other natural hazards, etc. The overall design process of adaptive facades may include further challenges and uncertainties especially in the case of complex assemblies, where even multiple combinations of material-related phenomena, kinematic effects, geometrical and mechanical characteristics could take place. In this context, experimental testing at the component and/or at the full-scale assembly level has a fundamental role, to prove that all the expected performance parameters are properly fulfilled. Several standards and guideline documents are available in the literature, and provide recommendations and procedures in support of conventional testing approaches for the certification and performance assessment of facades. These documents, however, are specifically focused on ordinary, static envelopes, and no provisions are given for the experimental testing of dynamic, adaptive skins. In this regard, it is hence expected that a minimum of conventional experimental procedures may be directly extended from static to dynamic facades. However, the validity of standardized procedures for adaptive skins is still an open issue. Novel and specific experimental approaches are then necessarily required, to assess the structural characteristics of adaptive facades, depending on their properties and on the design detailing. In this paper, existing fundamental standards for testing traditional facades are first recalled and commented. Special care is spent for the validity and reliability of conventional testing methods for innovative, adaptive envelopes, including a discussion on selected experimental methods for facade components and systems. Non-conventional testing procedures which may be useful for adaptive skins are then also discussed in the paper, as resulting from the research efforts of the European COST Action TU1403 \u2018Adaptive facades network\u2019 - \u2018Structural\u2019 Task Group

An insight on possible classification and metrics, experimental testing and numerical modelling for adaptive facades - Activity report from the \u2018Structural\u2019 Task Group

Adaptive facades are getting more and more widespread in modern buildings. These facade systems, among many others, need to fulfil the requirements of several structural considerations, such as structural safety, serviceability, durability, robustness and fire safety, being typically defined for standard facades and building enclosures in general. The paper discusses special structural characteristics that need to be taken into account when designing adaptive facades, and summarises some recent efforts of the activities carried out by the \u2018Structural\u2019 Task Group within the European COST Action TU1403 \u2018Adaptive Facades Network\u2019

Structural Characterisation and Performance Assessment

Modern adaptive facades can significantly improve energy and thus cost, efficiency of both new and refurbished buildings by responding to the changes in the outdoor conditions. Furthermore, they can provide healthy and comfortable indoor environment to the building occupants, by adjusting the response to their needs. As the main function of facades is to separate the indoor from the outdoor environment, their performance has a major impact to the building\u2019s energy usage is extremely important for reaching the European Commission\u2019s ambitious climate and energy targets by 2020, as well as to follow the 2050 energy roadmap goals. However, another important function of facades is to transfer various design loads (to the building skeleton) and to accommodate movements due to the same actions, being characterized by different features as in the case of self-weight, wind, earthquake loads, as well as thermal actions, extreme mechanical loads, etc. Depending on the type and level of adaptivity of a given facade, such a structural demand could lead to challenges during the overall design process. On the other hand, structural adaptivity can lead to a more efficient static and dynamic response under varying loading conditions, i.e. increase resistance in case of extreme events and/or provide fail-safe collapse mechanisms, thereby enhancing structural robustness. This document collects some major outcomes and feedback from the \u201cStructural\u201d Task Group within the WG2 - COST Action TU1403