Structural Engineering and Built Environment Performance
11:25 - 13:05 | Meeting Room 103 (Level 1)
Chair: Prof. Rebecca Dalli Gonzi
Mr Loai Al-Mawed
Department of Construction and Property Management, Faculty for the Built Environment
Additive manufacturing of concrete, known as 3D concrete printing, has become a focus of modern construction and research worldwide. The concrete used in this technology has a strict requirements for printability, including flowability, extrudability, and buildability. The common solution to meet these requirements is to increase the amount of cement in the mixture. As a result, the cement content needed for 3D concrete is higher than in conventional concrete, which limits the sustainability of this technology. Recently, researchers have proven that alkali-activated materials (AAMs) ae considered a promising alternative to cement. AAMs effectively utilise industrial by-products, such as fly ash and slag, creating a demand for alternative sources. Meanwhile, large amounts of construction and demolition (C&D) waste, including excavated limestone and quarry waste, negatively impact the environment. Recycling C&D waste as a silica- and alumina-rich precursor for geopolymer concrete can reduce reliance on traditional by-products and minimise waste disposal. This experimental study investigates the feasibility of utilising construction and demolition waste consisting of waste ceramic tiles and demolished concrete as primary precursors for geopolymer concrete.
The research led to the development of geopolymer concrete based entirely on construction and demolition waste, lightweight geopolymer concrete and 3D-printed lightweight geopolymer concrete, applied in the production of cladding panels for building retrofit applications.
Mr Raphael Farrugia
Department of Civil and Structural Engineering, Faculty for the Built Environment
The purpose of this paper is to study the behaviour of Flanged Cruciform Sections (FCS) subjected to uniform end moment to determine their elastic critical buckling stress and provide guidelines which can be implemented by structural designers. These sections are particularly effective as vertical load-bearing elements in high-rise structures due to their significant axial load resistance and efficiency in bi-axial bending. Despite their utility, research on their stability remains limited, and their buckling behaviour is not fully addressed in current standards.
As existing experimental data on flanged cruciform sections subject to uniaxial moment is limited, a robust parametric study was conducted using the Finite Strip Method package CUFSM as well as the Finite Element Analysis package ABAQUS. This study includes a critical buckling eigenvalue analysis of a comprehensive range of cross-sectional geometries for varying member slenderness.
The analysis identifies a continuum of stability failures governed by slenderness, that transitions from local to interacting distortional and torsional modes. A set of formulas for local buckling stresses is developed based on an interactive model that accounts for the rotational restraint between the web and flanges. Additionally, a novel design method based on elastic foundation theory is proposed to analyse the critical distortional and overall buckling stress as an interaction between the distortional and torsional modes.
The proposed analytical model is developed into a guideline for structural designers. Compared with Eurocode 3, the new method is found to provide significantly improved accuracy and consistency in resistance predictions.
Ms Lucia Buhagiar
Department of Civil Structural Engineering, Faculty for the Built Environment
The Maltese built landscape is characterised by over 300 churches. These monuments house priceless works of art and are architectural monuments in their own right. Crucially, more than half of these structures are constructed of unreinforced masonry (URM).
URM buildings are particularly susceptible to damage during seismic events. Churches, due to their geometric and architectural properties, are among the most seismically vulnerable historical constructions. Although the local society often exhibits complacency, Malta has suffered damage to many churches during past seismic events. There is a severe lack of data regarding the specific types and levels of damage incurred. Consequently, there is significant uncertainty regarding the seismic risk to churches in the Maltese Islands.
This research aims to formulate a methodology to determine the seismic vulnerability of URM churches in Malta. The research will follow a stepwise approach starting from the Guidelines published by the Italian Ministry for Cultural Heritage (2006). The first step is to adapt the internationally used rapid assessment form for the Maltese context, where the biggest challenge is the lack of seismic event damage data.
Once calibrated, the new seismic vulnerability assessment form will eventually be used to analyse a select number of case studies obtained from an inventory of churches in the Maltese Islands. The results of these case studies will be validated using numerical modelling. The validated form will then be used to assess the remaining case studies, and the results will ultimately be used to quantify the seismic vulnerability of Maltese URM churches.
Perit Etienne Magri
Department of Environmental Design, Faculty for the Built Environment
Façades with high glazing ratios in a cooling-dominated climate pose substantial challenges due to overheating and excessive daylight. The growing demand for energy to keep indoor temperatures comfortable is a concern, while glare and privacy are often dealt with retrospectively by installing indoor blinds. These often obstruct views and offer minimal thermal performance benefits. Although fixed external shading can help prevent overheating and glare, this lacks flexibility, and motorised options frequently develop problems over time due to their mechanical components. This paper discusses the thermal and visual performance of a prototype dual dynamic insulated glazing unit comprising two independently switchable (solar Polymer Dispersed Liquid Crystal and Suspended Particle Device) interlayers designed to control visible light transmittance and solar insolation into an indoor space while providing for privacy on demand. Using two identical mock-up offices set up as environmental field test chambers, the thermal and visual performance of the different states of the switchable glazing prototype is compared to that of a conventional insulated glazing unit under identical field test conditions, with and without conventional internal and external shading devices. Results show that the dynamic insulated glazing unit has the potential to provide for an improved indoor thermal and visual environment when compared to conventional glazing with indoor blinds. By allowing for a high degree of adaptability without any moving parts, building occupants are given complete control over the façade’s characteristics, with a technology capable of being fully integrated with building automation and management systems.
Mr Kevin Degiorgio
Department of Mechanical Engineering, Faculty of Engineering
This study revisits and discusses methods found in the literature for determining the plastic load for preventing of excessive deformation of a component under the action of a monotonically increasing load. The literature review focuses on the advantages and challenges of using existing plastic load determination methods. In this study, as a development from the literature, a novel method is presented that suggests the ratio of plastic work to elastic work induced by a monotonically increasing load can be used to determine the component’s plastic load. The proposed new method is applied to a number of test cases, from which it is observed that the results compare well with those obtained using methods reported in the literature. Furthermore, the novel method is easy to apply and addresses some application challenges of other methods.