Experimental and numerical analysis of directional added mass effects in partially liquid-filled horizontal pipes

The change of pipe natural frequencies due to added mass effects has been investigated in two cylindrical horizontal pipes from empty to completely water filled cases with various intermediate partially-filled conditions. The added mass coefficients of the three first vertical and horizontal modes of vibration have been determined with both experimental modal analysis and finite element analysis (FEA) acoustic-structural numerical simulations, which showed good agreement. The vertical and horizontal added mass coefficients present different behaviors as a function of the water level. Moreover, the pipe cross sectional dimensions determine the magnitude of these effects. For generalization to any pipe size, dependency of the directional added mass coefficients with new vertical and horizontal added mass estimators has been found. These estimators can be used in practical situations with horizontally mounted cylindrical pipes as a reference to predict and quantify air content.Postprint (author's final draft

Accelerated life testing study of a novel tidal turbine blade attachment

This paper describes the setup and some results of an accelerated life testing study of a tidal turbine blade attachment, which involved high-cycle fatigue testing of a tidal turbine subsystem at the Large Structure Laboratory of the National University of Ireland Galway (NUI Galway). Tidal turbines are in an early stage of development, which implies that there is no standard design and many different approaches are emerging in the market. The subsystem described in this paper is a 3/8 scaled down part of a 10-blade hubless turbine, developed by OpenHydro, a company specialising in the design, manufacture, installation, and maintenance of marine turbines generating renewable energy from tidal streams. The subsystem consists of a blade and a sector of the rotating ring. The sample was installed on an existing 10¿m¿×¿6¿m¿×¿6¿m reconfigurable test frame and was loaded with a servo-hydraulic actuator controlled by an advanced software system, which allowed for an accurate sinusoidal load-controlled high-cycle fatigue test. The sample was loaded at four different levels to accumulate damage representative of a typical tidal turbine deployment life. The main objective of the test was to analyse the structural behaviour of the attachment system solution (blade-rotating ring) under fatigue load, particularly the internal structural welds, and to validate previously developed numerical models. To address all the requirements and to obtain valuable data, a large experimental test was set up. A total of 110 channels in a multi-channel data acquisition system were used to simultaneously acquire strain, displacement, and load data. Accurate measurements of temporal deformations and movement in a 3D field at the rear side of the ring were also acquired using a Digital Image Correlation system. The mechanism of failure was expected to be fatigue crack propagation at locations pre-determined in a structural analysis of the system.The authors would like to acknowledge the support of Science Foundation Ireland through the National Centre for Marine and Renewable Energy Ireland (MaREI) (Grant No. 12/RC/2302). The authors would also like to acknowledge Mr. Colm Walsh for his support and contribution during the testing campaign. The last author would also like to acknowledge the support of Science Foundation Ireland through the Career Development Award programme (Grant No. 13/CDA/2200).Peer ReviewedPreprin

DairyWater: striving for sustainability within the dairy processing industry in the Republic of Ireland

peer-reviewedThis Review describes the objectives and methodology of the DairyWater project as it aims to aid the Irish dairy processing industry in achieving sustainability as it expands. With the abolition of European milk quotas in March 2015, the Republic of Ireland saw a surge in milk production. The DairyWater project was established in anticipation of this expansion of the Irish dairy sector in order to develop innovative solutions for the efficient management of water consumption, wastewater treatment and the resulting energy use within the country's dairy processing industry. Therefore, the project can be divided into three main thematic areas: dairy wastewater treatment technologies and microbial analysis, water re-use and rainwater harvesting and environmental assessment. In order to ensure the project remains as relevant as possible to the industry, a project advisory board containing key industry stakeholders has been established. To date, a number of large scale studies, using data obtained directly from the Irish dairy industry, have been performed. Additionally, pilot-scale wastewater treatment (intermittently aerated sequencing batch reactor) and tertiary treatment (flow-through pulsed ultraviolet system) technologies have been demonstrated within the project. Further details on selected aspects of the project are discussed in greater detail in the subsequent cluster of research communications

Engineering in Communities Learning by Doing

Purpose The purpose of this paper is to focus on a number of initiatives in civil engineering undergraduate programmes at the National University of Ireland, Galway (NUIG) that allow students to complete engineering projects in the community, enabling them to learn by doing.Design/methodology/approach A formal commitment to civic engagement was undertaken by the NUIG in 2001 with the establishment of the Community Knowledge Initiative (CKI) to work on mainstreaming civic engagement (service learning) within the curriculum across the institution. Today, the majority of undergraduate and postgraduate degree programmes in the College of Engineering and Informatics at NUIG have embedded service learning into their curriculum. These initiatives allow students to work with and in local communities, international communities and multidisciplinary groups as part of their academic courses. The paper investigates and shows that community-based projects can enhance student learning and engagement in a number of ways. At NUIG, these projects are framed by a research orientation, commitments to civic engagement and building university-community partnerships, city-university partnerships and partnerships with other official agencies, so that community users can provide real learning problems and contexts for students and researchers and benefit from the results.Findings It was found that the students got a sense of pride and satisfaction out of the knowledge that their work may be helping communities and that learning is not just to get marks to pass the exam! The projects can increase the students sense of ownership of their own learning. Learners are more motivated when they can see the usefulness of what they are learning and when they can use that information to do something that has an impact on others.Research limitations/implications The work represents work done in one institution affecting a region in a country. This can be extended to include more institutions and other regions. This paper presents evidence from the aforementioned projects that by creating service-based learning the students energy in learning can have a positive impact on the community.Practical implications The energy and enthusiasm of learners can be better utilised (and increased) by setting assignments as real community-based projects.Originality/value This lies in the design of projects and assessment involving education providers and public for the benefit of learners and the society at large.peer-reviewe

Numerical model for steel brace members incorporating a fatigue model

The aim of this paper is to develop a robust numerical model for cold-formed steel square and rectangular structural hollow sections for use as axial loaded members in earthquake engineering applications. Pseudo-static cyclic physical tests of cold-formed steel brace specimens using axially loading are used to develop and calibrate a robust numerical model that mimics the results from the tests. A nonlinear fibre based beam-column element model which considers the spread of plasticity along the element is used. This numerical model includes a low cyclic fatigue model, which wraps the nonlinear fibre based beam-column element material in order to capture fracture in the braces. New parameters to be used for the fatigue model are introduced in this paper. Comparisons of the maximum tensile force (Fmax), initial buckling load (Fc), number of cycles to fracture, the total energy dissipated (Wtot) and the energy dissipated at the first cycle of ductility of 4 (Wl=4) between the numerical models and the physical tests are carried out. In general, the models captured the salient response parameters observed in the physical tests. It is found that the numerical model gives a good prediction of the maximum measured tensile force (Fmax) and initial buckling load (Fc) with the mean values being 0.93 and 0.95 of those measured in the physical tests, respectively. The corresponding coefficients of variation (CV) are 0.11 and 0.08, respectively. Moreover, the mean values of the total energy dissipated (Wtot) and the energy dissipated at the first cycle of ductility of 4 (Wl=4) for the numerical model are found to be 1.12 and 0.98, of those measured in the physical tests, respectively. The corresponding coefficients of variation (CV) are 0.13 and 0.20, respectively. Furthermore, the numerical model was validated using another set of independent physical tests. This validated brace element model can be used in future numerical models of concentrically brace frames buildings to predict the performance of the complete structures under earthquake loading.peer-reviewe

Evaluating the structural capacity of concrete elements through in-situ instrumentation

The difficulty in predicting the long term load capacity of concrete elements is well documented. Time dependent effects such as creep and shrinkage coupled with varying loading events, particularly during construction, can all have an adverse effect on the long term performance of a concrete structure. This paper proposes a method that utilises in-situ instrumentation to predict the load carrying capacity of concrete members. During the construction of the Engineering building at the National University of Ireland, Galway over 260 sensors were embedded in a number of key concrete elements. The sensors are being continually monitored with the use of automatic datalogging equipment and the data is being used to monitor changes in geometric and material properties along with the subsequent time dependent deterioration of the elements. The paper will illustrate how the in-situ data from the demonstrator building can be used to estimate the real time behaviour of the concrete elements and how these elements might respond to future changes in use and potential retrofitting. A cost analysis will show how such a monitoring system can be used to reduce the uncertainty levels involved when retrofitting concrete buildings.peer-reviewe

Earthquake resistant hollow and filled steel braces

THESIS 7552The earthquake resistance of many building structures is provided by steel bracing members. Although the use of tension-only concentric bracing is common, the behaviour of these systems is not fully understood, and international design guidance differs. Hollow section members are often employed as bracing elements, for both structural and aesthetic reasons. The purpose of this thesis is to investigate the seismic behaviour of such members. The influences of mortar infill and of member slenderness are addressed, mainly through experimental studies

Brace response and assessment: computation, experiments and design (BRACED)

ReportThe BRACED project investigated the ultimate behaviour of concentrically braced frames(CBFs). The research programme was designed to validate empirical models for theductility capacity of hollow section bracing members and recent proposals for theimproved detailing of gusset plate connections, to identify active yield mechanisms andfailure modes in different brace member/connection configurations, and to provideessential data on the earthquake response of European CBFs. The central element of anintegrated experimental and numerical research programme is a series of shake tableexperiments on full-scale model single-storey CBFs designed to Eurocode 8. Twelveseparate experiments were performed on the Azalee seismic testing facility at CEA Saclayin the March-May 2013. The properties of the brace members and gusset plate connectionswere varied between experiments to examine a range of feasible properties and toinvestigate the influence of conventional and improved design details on frame response.Each experiment examined the response of the test frame and brace-gusset platespecimens to table excitations scaled to produce elastic response, brace buckling/yieldingand brace fracture. These experiments were supported by complementary quasi-staticcyclic tests on a simplified version of the shaking table test frame that retained all of theimportant characteristics of that structure, including overall dimensions, beam-to-columnconnections, brace properties and gusset-plate connection design. Correlative pre-testpredictions and post-test simulations using pushover and time-history analysis were alsoperformed using the OpenSees seismic analysis software. The outputs of the researchprogramme represent a unique set of data on the ultimate earthquake response of CBFswith realistic brace members and connections. The principal experimental outcomesinclude measurements of elastic frame stiffness and its evolution with brace damage,measurements of the displacement ductility capacity of the brace specimens; anevaluation of the influence of brace connection configuration and gusset plate detailing onframe stiffness, damping and ductility; and observations on the contributions of brace andconnection yielding to overall inelastic deformation of CBFs. The numerical modelling hasvalidated a methodology of modelling this class of structure in OpenSees, while theproject as a whole supports an assessment of Eurocode 8 design guidance for CBFs

Improving the Delivery of a Construction Management Study-Abroad Course in Ireland through Student Feedback

International study abroad offers limitless opportunities for students to learn outside of the traditional university setting. By living and learning in a foreign country, the student\u27s exposure to a different culture can help them experience history first-hand and discover new ways of thinking/living. Recent trends show that the number of U.S. college students participating in study-abroad courses offered by their university is increasing. Apart from the exposure to different cultures, many study abroad courses do not provide a focused subject area related to a discipline of study chosen by the individual student. This paper describes an overall view of an international construction management study-abroad course conducted in Ireland by both American and Irish faculty members. The results of student surveys that were used to assess the course learning objectives and provide suggestions for improvement are also presented. These suggestions can be used by faculty members to develop or improve similar construction-focused study-abroad courses

The creation of a living laboratory for structural engineering at the National University of Ireland, Galway

The recently completed New Engineering Building (NEB) at the National University of Ireland, Galway (NUIG) is a new state of the art academic facility on the university's north campus. The building unites all five engineering disciplines within the university and at 14,250m2 is now the largest engineering school in Ireland. It represents a milestone in the construction of engineering educational facilities by incorporating the use of numerous types of sensors to create an interactive learning environment for engineering students. Not only will it be a centre of education, but the building itself will act as a living laboratory and teaching tool. This paper outlines the instrumentation of the structural elements within the building and the part they will play in the teaching and understanding of structural engineering within the university.peer-reviewe