Civil Engineering Research Collection
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- PublicationDistributed acoustic sensing for seismic surface wave data acquisition in an intertidal environment(Society of Exploration Geophysicists, 2024-07)The application of distributed acoustic sensing (DAS) for shallow marine seismic investigations is assessed, in particular with respect to the collection of seismic surface wave data in an intertidal setting. Appropriate selection and directional sensitivity of fiber-optic cables is considered and the measured data is validated with respect to conventional seismic data acquisition approaches, using geophones and hydrophones, along with independent borehole and seismic cone penetration test (SCPT) data. In terms of cable selection, a reduction in amplitude and frequency response of an armored cable is observed, when compared with an unarmored cable. For seismic surface wave surveys in an offshore environment where the cable would need to withstand significant stresses, the use of the armored variant with limited loss in frequency response may be acceptable from a practical perspective. The DAS approach also has indicated good consistency with conventional means of surface wave data acquisition, and the inverted VS also is very consistent with downhole SCPT data. Observed differences in phase velocity between high tide (Scholte wave propagation) and low tide (Rayleigh wave propagation) are not thought to be related to the particular type of interface wave due to shallow water depth. These differences are more likely to be related to the development of capillary forces in the partially saturated granular medium at low tide. Overall, this study demonstrates that our novel approach of DAS using seabed fiber-optic cables in the intertidal environment is capable of rapidly providing near-surface S-wave velocity data across considerable spatial scales (multikilometer) at high resolution, which is beneficial for the design of subsea cables routes and landfall locations. The associated reduction in deployment and survey duration, when compared with conventional approaches, is particularly important when working in the marine environment due to potentially short weather windows and expensive downtime.
10 - PublicationReview of the system of testing, certification and accreditation of new building products(Construct Innovate, 2024-02-28)This report examines the existing Irish housing delivery system, with a comprehensive review of standards, testing, certification and accreditation. The report presents a concise literature review to draw insights from similar standards, testing, certification and accreditation systems in the United Kingdom (UK) and Europe. Additionally, interviews of construction professionals are undertaken to understand perspectives of industry on the current Irish system of standards, testing and certification. The methodology employed comprises extensive desktop research combined with semi-structured interviews of a cross-section of the construction sector. The aim is to gain a comprehensive understanding of the current situation and identify potential obstacles in the system of standards, testing, certification and accreditation that could be impeding the more efficient delivery of housing in Ireland. The findings highlight challenges embedded within the existing system. In Ireland, the key components of the construction of housing related to standards, testing and certification include; building regulations, building control regulations, technical guidance documents, national standards, European design/material/product standards, execution standards, testing standards, certification and accreditation, as well as construction product regulations. When adopting a novel or innovative construction product, material, or system, NSAI Agrément emerges as the most practical avenue for demonstrating compliance with Irish Building Regulations, especially in the absence of established national standards or harmonized European standards. During semi-structured interviews, several recurring challenges emerged, including a lack of understanding of the Agrément process and a lack of clear guidance. In response to these challenges, the report presents potential recommendations aimed at streamlining the approach to Building Regulation compliance for novel or innovative housing construction products. By comparing extensive research, semi-structured interviews with a cross-section of the construction sector, and comparative analysis, this report serves as a valuable resource for policymakers, industry professionals and stakeholders involved in the housing construction sector.
10 - PublicationBehavioural attitudes to modern methods of construction(Construct Innovate, 2024-02-04)The primary objective of this report is to investigate the psychology of change inherent in the broader acceptance and adoption of modern methods of construction (MMC) within the realm of housing delivery. Understanding the underlying factors that influence this transformation is important in shaping the future of the housing industry. As the residential construction industry undergoes transformation, it is important to foster trust and faith in compliant modern building techniques that supersede traditional methodologies. By identifying and addressing any potential barriers to acceptance of MMC, the report aims to provide insight from both the construction sector and wider public. To fulfil these objectives, an in-depth analysis was undertaken, incorporating both quantitative and qualitative approaches. Through semi-structured interviews with construction sector stakeholders two sets of surveys were designed, one for the public and the other for the construction sector. The surveys provided valuable data was gathered from the public and construction industry sector. This dual approach not only ensures the depth of understanding but also provides a holistic view of the challenges, perceptions, and expectations of the construction sector and public towards MMC. Some of the main findings indicate that in Ireland there is limited experience within the construction sector working on MMC projects, with Category 2 MMC emerging as the most prevalent. Public perception of MMC varies, with positive perceptions around terms like modular house and offsite house contrasting with negative perceptions related to rapid-build house and pre-fabricated house. The factors influencing the publics decision relating to residential property purchase are primarily related to considerations of Location, Price and Quality. The barriers to wider MMC adoption in the construction industry are identified as a lack of industry knowledge, difficulties changing from traditional construction, and lack of pipeline of MMC. Government involvement is deemed crucial, emphasising the need for guaranteeing project pipeline, supporting public procurement, and showcasing successful MMC projects.
11 - PublicationFast perturbation-dependent reliability curves in traffic networks(2023-07-23)Uncertainty characterisation and reliability analysis for high-fidelity models is often prohibitive due to the large analysis efforts it demands. This is particularly prevalent in highly complex systems that require costly simulations, such as that case of traffic networks. If reliability of traffic networks is to be evaluated for different perturbations, regardless of how it is defined, then prohibitive analysis times and efforts should be expected. Traffic networks are network systems composed of multiple sub-systems and components. When changes in the system intrinsic variables occur, these result in operational changes in the network that can only be understood in an holistic form. In the present work, a perturbation-dependent fast reliability assessment is proposed. It considers reliability as a variation in travel time to the reference time, which is often used to characterize reliability in traffic. In the present work it is discussed in a full probabilistic context, with reliability curves being characterised using a lower-fidelity model that uses a kriging-based sequential learning approach approach. This metamodeling approach enables the characterisation of different levels of reliability for a perturbation, through a N threshold modelling approach, that uses probability density functions and that sets reliability curves in a form of a fragility curve. With such implementation it is possible to enable a fast characterisation of reliability, and its probabilistic behaviour, in traffic. The implementation is researched in two reference traffic networks with uncertain demands, and results show that this technique can inform multiple purposes of decision-making, ranging from reduced order modelling tools to operational management of the system.
10 - PublicationComputational Modelling of Intra-Module Connections and Their Influence on the Robustness of a Steel Corner-Supported Volumetric Module(MDPI, 2024-03-21)This paper investigates the robustness of a single 3D volumetric corner-supported module made of square hollow-section (SHS) columns. Typically, the moment–rotation (M-θ) behaviour of connections within the module (intra-module) is assumed to be fully rigid rather than semi-rigid, resulting in inaccurate assessment (i.e., overestimated vertical stiffness) during extreme loading events, such as progressive collapse. The intra-module connections are not capable of rigidly transferring the moment from the beams to the SHS columns. In this paper, a computationally intensive shell element model (SEM) of the module frame is created. The M-θ relationship of the intra-module connections in the SEM is firstly validated against test results by others and then replicated in a new simplified phenomenological beam element model (BEM), using nonlinear spring elements to capture the M-θ relationship. Comparing the structural behaviour of the SEM and BEM, under notional support removal, shows that the proposed BEM with semi-rigid connections (SR-BEM) agrees well with the validated SEM and requires substantially lower modelling time (98.7% lower) and computational effort (97.4% less RAM). When compared to a BEM with the typically modelled fully rigid intra-module connections (FR-BEM), the vertical displacement in the SR-BEM is at least 16% higher. The results demonstrate the importance of an accurate assessment of framing rotational stiffness and the benefits of a computationally efficient model.
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