Structural Behaviour of Glass Panels Under Soft-body Impact

Glass is a commonly used material in modern architecture not only for building enclosures but also for glazed barriers preventing building occupants from falling out of balconies or different levels inside buildings. The paper reports some results of an on-going research project involving testing of glass balustrades and infill panels mounted with different fixing methods, such as linear clamps, local clamp fixings, and point fixings through holes in glass. A reduced numerical model for prediction of strength of glass under soft body impact is also presented. In the experimental study toughened and heat-strengthened glass, as well as two interlayer materials of different stiffness, were used

The multiphysics modeling of heat and moisture induced stress and strain of historic building materials and artefacts

The basic structure of historic sites and their associated interior artefacts can be damaged or even destroyed by climate change. The evaluation of combined heat and moisture induced stress and strain (HMSS) can predict possible damage-related processes. In this paper, the development of one- and two-dimensional HMSS models of building materials and artefacts in COMSOL Multiphysics Version 4, a commercial finite element software, is presented. The validation of the numerical models is revealed using analytical, numerical and experimental solutions. As a result, the HMSS model was shown to be an adequate predictive tool to determine possible damage-related processes in building assemblies and artefacts

Analysis of tensile behavior of recycled aggregate concrete using acoustic emission technique

Recycled concrete aggregate (RCA) was processed from reinforced concrete edge beams sourced from a demolished bridge in Sweden. This material replaced different ratios of coarse aggregate in a benchmark concrete. The tensile behavior of the developed concrete mixes was characterized via monotonic and cyclic uniaxial tensile tests performed on notched cylinders. Such tensile tests allow for the quantification of the fracture energy and softening behavior of the concrete. Moreover, acoustic emission (AE) measurements were conducted in conjunction with the cyclic tests to characterize e.g. micro‐crack initiation and development, as well as crack localization. The tensile behavior of the various materials was found to be similar with minimal variation in the results. However, the softening behavior suggests that the RCA materials are slightly more brittle compared to both the mother and benchmark materials, which could be indicative of differences in the interface transition zones. The corresponding AE measurements also indicated similarities between the micro‐crack initiation and development for these mixes. It can be constituted that if the concrete used to produce RCA is of high quality and from one source, the resulting RAC will have adequate tensile properties with minimal variation, despite the aggregate replacement ratio

Structural performance of GFRP connectors in composite sandwich façade elements

To take structural aspects into consideration in the SESBE research project, focusing on the development of “smart” façade elements a systematic testing and modelling program has been developed for the verification of the structural performance of the façade sandwich elements. The present paper mainly focuses on the verification of the mechanical performance of the glass fibre reinforced polymer (GFRP) connectors of the novel type of façade element composed of reactive powder concrete (RPC) panels with foam concrete insulation between them. Because of the reduced thickness of the large façade elements, the performance of the connectors is critical for the entire structural concept. The first series of the testing programme concerning connector performance are presented here. The results suggest that sufficient strength and ductility of the connectors can be ensured using GFRP in the proposed thin light-weight façade elements

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

Usability of Textile Reinforced Concrete: Structural Performance, Durability and Sustainability

Textile reinforced concrete (TRC) is an innovative high performance composite material consisting of open multi-axial textiles embedded in a fine-grained concrete matrix. Despite the fact that TRC-based research has revealed many promising attributes, it has yet to reach its recognition due to a lack of available design tools, standards and long-term behaviour. To be able to reach this next stage, consistent test methods and reliable models need to be established to reduce uncertainty and the need for individual and extensive experimental studies. This thesis aims to investigate structural performance, durability and sustainability aspects of TRC for its usability in the built environment. The structural performance was experimentally and analytically evaluated for the individual material constituents, material interaction, as well as global TRC components. The linking of the structural performance of these various levels was investigated by means of non-linear finite element analysis (FEA). The durability of TRC was characterized according to the influence of accelerated ageing based on alkali resistance on the structural performance of textile reinforcement. Furthermore, the environmental sustainability of TRC was evaluated in comparison to conventional RC using a Life Cycle Assessment (LCA).The experimental quantification of the structural performance on the material and interaction levels was found to be decisive to understand the composite behaviour. In general, the bond behaviour in TRC has been identified as a critical feature affecting the global behaviour. Particularly for carbon textiles, the bond behaviour needs to be improved; an enhancement of the load bearing behaviour was successfully observed using surface coatings, short fibres, and high performance concrete. Linking the experimental data from the material and interaction levels to the global level in FEA led to promising results such that further insight on the actual failure behaviour could be gained. The accelerated testing was generally too aggressive for textiles made of basalt and AR-glass leading to extensive degradation; however, carbon textiles were found to be a promising alternative as they have superior durability properties in an alkaline environment without undergoing any strength loss. Through accelerated testing, it was found that the exposure time, temperature and test solution need to be material specific. The applied sizing or coating on the textiles also had a considerable influence on the extent of degradation. Based on the conducted LCA, the reduction of the concrete cover in a TRC panel significantly decreased its environmental impact compared to traditionally reinforced solutions. Ultimately, the experimental and modelling approaches developed in this work can be applied to further characterize the short- and long-term behaviour of TRC for the built environment

Sustainability and Flexural Behaviour of Textile Reinforced Concrete

Concrete reinforced with conventional steel is one of the most commonly used building materials, yet it has historically shown disadvantages in terms of durability and vulnerability to corrosion attack. Various remedial methods have been applied to overcome the shortcomings of this building material, such as increasing the concrete cover, which, however, leads to an increased self-weight of the structure. Over the past decade, Textile Reinforced Concrete (TRC), encompassing a combination of fine-grained concrete and non-corrosive multi-axial textile fabrics, has emerged as a promising novel alternative offering corrosion resistance, as well as thinner and light-weight structures such as foot bridges and fa\ue7ade elements.This thesis aims to preliminarily investigate the sustainability and flexural behaviour of TRC while bearing in mind its possible use for future buildings. The sustainable potential of TRC was evaluated using Life Cycle Assessment (LCA) with a cradle-to-gate perspective, such that conventional steel reinforced concrete and TRC were compared. It was revealed that TRC significantly decreased the cumulative energy demand and environmental impact of a reinforced concrete element; basalt fibre reinforcement yielded the least cumulative energy demand while carbon fibre gave the least environmental impact. Using TRC in the form of sandwich panels was also shown to yield a lower environmental impact compared to conventional reinforced concrete panels.Moreover, experimental studies were conducted to investigate the load-carrying capacity in bending and overall structural behaviour of TRC in both one-way and two-way action. It could be concluded that one-way slabs reinforced by one layer of carbon textile mesh had superior load-carrying capacity and ductility in comparison to specimens reinforced by one layer of alkali-resistant glass or basalt. The testing of two-way slabs demonstrated that among basalt and AR-glass reinforced specimens, basalt had a slightly higher flexural capacity. Furthermore, a 2D non-linear finite element model developed based on the one-way experiments, correlated rather well with the experimental results after calibration. Lastly, analytical calculation methods developed for conventionally reinforced concrete structures were used to evaluate the experimental results. The analytical results were shown to both under and over predict the flexural capacity in one-way and two-way action.Overall, experimental studies encompassing a greater study sample, optimized reinforcement ratios and application of fibre coatings are recommended to obtain further enhanced performance. The experimental programs, presented in this thesis, are valuable as they contribute to the expansion of fundamental knowledge related to TRC while promoting the prospective use of this novel material

Usability of Textile Reinforced Concrete: Structural Performance, Durability and Sustainability

Textile reinforced concrete (TRC) is an innovative high performance composite material consisting of open multi-axial textiles embedded in a fine-grained concrete matrix. Despite the fact that TRC-based research has revealed many promising attributes, it has yet to reach its recognition due to a lack of available design tools, standards and long-term behaviour. To be able to reach this next stage, consistent test methods and reliable models need to be established to reduce uncertainty and the need for individual and extensive experimental studies. This thesis aims to investigate structural performance, durability and sustainability aspects of TRC for its usability in the built environment. The structural performance was experimentally and analytically evaluated for the individual material constituents, material interaction, as well as global TRC components. The linking of the structural performance of these various levels was investigated by means of non-linear finite element analysis (FEA). The durability of TRC was characterized according to the influence of accelerated ageing based on alkali resistance on the structural performance of textile reinforcement. Furthermore, the environmental sustainability of TRC was evaluated in comparison to conventional RC using a Life Cycle Assessment (LCA).The experimental quantification of the structural performance on the material and interaction levels was found to be decisive to understand the composite behaviour. In general, the bond behaviour in TRC has been identified as a critical feature affecting the global behaviour. Particularly for carbon textiles, the bond behaviour needs to be improved; an enhancement of the load bearing behaviour was successfully observed using surface coatings, short fibres, and high performance concrete. Linking the experimental data from the material and interaction levels to the global level in FEA led to promising results such that further insight on the actual failure behaviour could be gained. The accelerated testing was generally too aggressive for textiles made of basalt and AR-glass leading to extensive degradation; however, carbon textiles were found to be a promising alternative as they have superior durability properties in an alkaline environment without undergoing any strength loss. Through accelerated testing, it was found that the exposure time, temperature and test solution need to be material specific. The applied sizing or coating on the textiles also had a considerable influence on the extent of degradation. Based on the conducted LCA, the reduction of the concrete cover in a TRC panel significantly decreased its environmental impact compared to traditionally reinforced solutions. Ultimately, the experimental and modelling approaches developed in this work can be applied to further characterize the short- and long-term behaviour of TRC for the built environment

Assessment of Fire Exposed Concrete with Full-field Strain Determination and Predictive Modelling

A condition assessment of civil engineering structures is typically performed after the occurrence of a fire incident to determine the remedial actions required out of a structural point of view. A condition assessment is based on the mapping of damage on the given structure, which is traditionally executed via methods that yield indirect results related to surface and/or geometric properties. To be able to predict the accurate fire resistance performance of a given structure, it is most suitable to apply a mapping method which can be directly coupled to the change in material properties of concrete at high temperatures. The aim of this study is to explore the potential of applying an innovative damage mapping methodology directly coupled to the change in material properties of concrete at high temperatures. This methodology consists of optical full-field strain measurements based on Digital Image Correlation (DIC) coupled with a predictive model based on finite-element analysis (FEA). An experimental study was firstly conducted to expose concrete slabs to a standard fire curve. Subsequently, compression tests were performed on drilled cores taken from the damaged induced specimens, all while optically measuring the full-field strain on a specimen surface. As a preliminary step, an FE model of a fire exposed core was developed based on input data from standard temperature-dependent properties. The analysis consisted of a sequentially coupled thermal stress analysis to solve the multiphysics problem. The model was able to capture the temperature distribution in the concrete with enough certainty given the choice of input data. The resulting strain along the height of the core was also comparable to the experimental optical strain measurements, particularly as the distance increased from the fire exposed surface. These results can be practical when assessing the required strengthening actions to restore the load carrying capacity and durability of the concrete structure