Challenge For Civil Engineers Research Articles

Optimal Multi-Type Sensor Placement for Structural Identification by Static-Load Testing.

Assessing ageing infrastructure is a critical challenge for civil engineers due to the difficulty in the estimation and integration of uncertainties in structural models. Field measurements are increasingly used to improve knowledge of the real behavior of a structure; this activity is called structural identification. Error-domain model falsification (EDMF) is an easy-to-use model-based structural-identification methodology which robustly accommodates systematic uncertainties originating from sources such as boundary conditions, numerical modelling and model fidelity, as well as aleatory uncertainties from sources such as measurement error and material parameter-value estimations. In most practical applications of structural identification, sensors are placed using engineering judgment and experience. However, since sensor placement is fundamental to the success of structural identification, a more rational and systematic method is justified. This study presents a measurement system design methodology to identify the best sensor locations and sensor types using information from static-load tests. More specifically, three static-load tests were studied for the sensor system design using three types of sensors for a performance evaluation of a full-scale bridge in Singapore. Several sensor placement strategies are compared using joint entropy as an information-gain metric. A modified version of the hierarchical algorithm for sensor placement is proposed to take into account mutual information between load tests. It is shown that a carefully-configured measurement strategy that includes multiple sensor types and several load tests maximizes information gain.

Briefing: Resource scarcity and resource security – a suppressed civil engineering challenge

While natural and manufactured resources provide the raw materials with which civil engineers work, the term ‘resources’ should always be considered in its wider interpretation and then in the context that resources are in many cases limited. That they should be used wisely (resource efficiency) is beyond contention – we do this as a matter of course – yet considerations of where and how resources are obtained and refined for use are far less likely to feature in a civil engineer's psyche. Similarly, considerations of resource availability for others now, and importantly in the future, and the vulnerability of these resources to future supply disruption (e.g. for geopolitical reasons) are likely not to be in the forefront of our thinking when conducting our routine business. The ICE Research, Development & Innovation towards Engineering Excellence panel has chosen this topic as one of pressing importance across all the sectors that comprise civil engineering. Accordingly, the panel is promoting this topic for Research & Development Enabling Fund (R&DEF) proposals. This briefing note describes the prior work of the panel in exploring the extent of this issue, along with insights from current research, to raise awareness, encourage R&DEF proposals and prime debates on this topic.

Static Analysis of Interlocked Water Tower

In the areas prone to natural disasters, ability of lifeline systems from catastrophic damages is one of the most important challenges in civil engineering. One of the most important structures is elevated water tanks. Most of the damages observed to these structures under seismic events are due to the improper design and wrong selection of supporting system. This paper investigates the suitability of interlocking system for staging of an elevated water tank of higher capacity. As a preliminary study the performance of concrete interlock panelled tower under static condition is analyzed by considering the standard earth gravity under full and empty conditions. The study concludes that the new system can perform in a similar way as that of the conventional system.

Evaluation of French motorway network in relation to slime mould transport networks

France has developed a high quality motorway system that has been rapidly rationalised and matured in the late 20th century yet has been founded on ancient, Roman infrastructures. The development of the motorway system is thus an iterative method associated with hierarchical ‘top-down’ processes taking into consideration factors such as population density, network demand, location of natural resources, civil engineering challenges and population growth. At the opposite extreme to this approach is the development of transport networks within simple biological systems which are typically decentralised, dynamic and emerge from simple, local and ‘bottom-up’ interactions. We examine the notion, and to what extent, that the structure of a complex motorway network could be predicted by the transport network of the single-celled slime mould Physarum polycephalum. This comparison is explored through its ability to ‘deduce’ the French motorway network in a series of analogue and digital experiments. We compare Physarum network and motorway network topology in relation to proximity graphs and assess the trade-off between connectivity and minimal network length with a bottom-up model of a virtual plasmodium. We demonstrate that despite the apparent complexity of the challenge, Physarum can successfully apply its embodied intelligence to rationalise the motorway topology. We also demonstrate that such calculations prove challenging in the face of significant obstacles such as, mountainous terrain and may account for the missing route between Nice, Grenoble, Avignon and Lyon. Finally, we discuss the topological findings with respect to circle and spoke city planning infrastructures and certain species of web-building spiders.

Weigh-in-motion implementation in an old metallic railway bridge

The structural assessment of old metallic bridges is a challenge for civil engineers. This is mainly due to difficulties in identifying material properties and vehicle characteristics. A great number of these bridges were built with materials that are no longer used in modern structures and are presently subjected to loads very different from the ones considered in the design. In this context, structural monitoring can be an important tool to characterize the structural behavior and to support the safety assessment. In this paper, the steps taken to implement a Bridge-Weigh-in-Motion algorithm for traffic characterization in a railway bridge are presented. For that purpose, a long term monitoring system based on strain gauges was installed in the Portuguese Trezói Bridge. The measurements from a period of approximately two years were used to obtain axle loads, axles spacing and velocities of the trains that crossed the bridge during this period, enabling the accurate characterization of the real traffic conditions. This was achieved applying a method for traffic characterization based on the research developed by Moses (1979) and also based on the recent research developed by Liljencrantz et al. (2007) and Quilligan (2003), which was enhanced by an optimization algorithm implemented to minimize the error of the simulated response when compared to the measured response of the structure, thus allowing the estimation axle loads, axle spacing and speed.

Experimental modal analysis of masonry arches strengthened with graphene nanoplatelets reinforced prepreg composites

Strengthening of masonry structures with different engineering materials has become a challenge for civil engineers with the advancements in engineering technology. This study mainly focused on dynamic parameters of masonry arches, which were strengthened with nanoparticle reinforced prepreg composites. For this purpose, the prepreg composites were produced with carbon fiber and epoxy system which was reinforced with graphene nanoplatelets particles that was 1wt% of the epoxy system. Afterwards, four different strengthening alternatives were performed at the extrados and intrados of the masonry arches. Finally, dynamic characteristics such as mode shapes and modal frequencies of unstrengthened and strengthened arches were determined through experimental modal analysis (EMA) and numerical analysis.

Some new and interesting caverns in tunnels and along stretches of the Croatian Highways (Dinaric Karst, Croatia)

During the construction of almost all the tunnels in the Croatian Dinaric Karst in the last 50 years thousands of caves have been encountered that represented the major problems during the construction works. Geological features (fissures, folding, faults, etc.) are described in this contribution, together with the hydrogeological conditions (rapid changes in groundwater levels). Special engineering geological exploration and survey of each cave, together with the stabilization of the tunnel ceiling, and groundwater protection actions according to basic engineering geological parameters are also presented. In karst tunneling in Croatia over 150 caves longer than 500 m have been investigated. Several caves are over 300 m deep, and 10 are longer than 1000 m. Different solutions were chosen to cross the caves depending on the size and purpose of the tunnels (road, rail, pedestrian tunnel, or hydrotechnical tunnels). This paper presents interesting examples of stabilization of ceilings in big cave chambers, construction of bridges inside tunnels, deviations of tunnels, filling caves, grouting, etc. A complex type of karstification has been found in the cavern at the contact between the Palaeozoic clastic impervious formations and the Mesozoic complex of dolomitic limestones in the Vrata Tunnel and at the contact with flysch in the Ucka Tunnel. However, karstification advancing in all directions at a similar rate is quite rare. The need to have the roadway and/or tunnel above water from a spring is the biggest possible engineering-geological, hydrogeological and civil engineering challenge. Significant examples are those above the Jadro spring (Mravinci tunnel) in flysch materials or above the Zvir spring in Rijeka (Katarina tunnel), and in fractured Mesozoic carbonates.

Side Near Surface Mounted (SNSM) technique for flexural enhancement of RC beams

Abstract The rehabilitation of existing Reinforced Concrete (RC) structures constitutes one of the leading challenges in civil engineering. The crucial reasons for the strengthening of RC structures comprise frequent increases in design loads, engineering errors in design or workmanship issues during construction, changes in code and functional requirements. This paper introduces an innovative approach comprising the Side-Near-Surface-Mounted (SNSM) technique, which incorporates Carbon Fiber Reinforced Polymer (CFRP) and steel bars as strengthening reinforcement. Experimental and analytical investigation was adopted to explore flexural strengthening of RC beams with them. Analytical models are presented to predict the ultimate load, crack spacing and deflection. Four-point bending tests were performed up to failure on the rectangular RC beams strengthened with different ratios of SNSM reinforcement. The failure characteristics, yield and ultimate capacities, deflection, cracking behavior, ductility and energy absorption capacities were evaluated. The SNSM technique significantly enhanced the flexural behavior of the beams. The yield and ultimate load carrying capacities of the beams increased by a factor of 2 and 2.38 times, respectively. The cracking loads improved more notably (3.17 times). Predicted results from the analytical models showed good agreement with the experimental results, which confirmed proficient implementation of the proposed SNSM technique.

Whole Life Care of Infrastructure – A Serious Challenge for Civil Engineers

Infrastructure undergoes a number of phases during its whole service life: from planning, design, construction, operation (or service), rehabilitation and final demolition end of life. One of the most challenging issues facing civil engineering profession is the intelligent management of infrastructure to ensure its safe and serviceable operation and function. This paper will present a paradigm for the whole life care of infrastructure. Based on recent research and findings in corrosion affected concrete structures during its whole life of service, methods and models to be used in the paradigm will be outlined. Discussion on challenges in each area will also be provided. This paper will advocate that whole life care of infrastructure is the future trend for civil engineering progression.

From wasteland to world-class centre: Barangaroo South, Sydney, Australia

Barangaroo South is a A$6 billion (£4 billion) transformation of a former container port in Sydney, Australia, into a business, residential and leisure precinct. Due for completion in 2020, it features three commercial towers up to 49 storeys providing more than 490 000 m2 of gross floor area. It is set to become one of Australia's first large carbon dioxide-neutral developments. This paper provides an overview of the civil engineering challenges facing the project and the innovative solutions adopted, including remediation of past contamination, basement retention and foundation construction in reclaimed land, groundwater control, design of foundations and transfer structures over the proposed rail tunnels, and superstructure design.

Civil Engineering Grand Challenges: Opportunities for Data Sensing, Information Analysis, and Knowledge Discovery

This paper presents an exploratory analysis to identify civil engineering challenges that can be addressed with further data sensing and analysis (DSA) research. An initial literature review was followed by a web-based survey to solicit expert opinions in each civil engineering subdiscipline to select challenges that can be addressed by civil engineering DSA research. A total of 10 challenges were identified and evidence of economic, environmental, and societal impacts of these challenges is presented through a review of the literature. The challenges presented in this paper are high building energy consumption, crude estimation of sea level, increased soil and coastal erosion, inadequate water quality, untapped and depleting groundwater, increasing traffic congestion, poor infrastructure resilience to disasters, poor and degrading infrastructure, need for better mining and coal ash waste disposal, and low construction site safety. The paper aims to assist the civil engineering research community in setting an agenda for data sensing and analysis research to address these challenges.

Work harder on yourself than you do on your job: a new challenge for civil engineers

Civil Engineering is as challenging as any profession and has much to contribute to society, yet its prestige and influence have waned. Denise Bower, Ian McGill and Nancy Madter introduce the work of the ICE Capacity Building Panel and ask what more civil engineers could do to improve themselves.

Experimental FRP/SRP–historic masonry delamination

Abstract The preservation of the architectural heritage presents one of the important challenges in civil engineering due to the complexity of the geometry of the structures, the variability of the materials used and the loading history of the buildings. This objective increases for existing constructions in the seismic area. External bonding of fiber or, more recently, steel reinforced polymer composites has become a popular technique for strengthening historic monumental masonry buildings. The performance of the interface between composites and masonry is one of the key factors affecting the behaviour of strengthened structures: shear walls, arches and vaults. This paper aims to present the results of an experimental study to evaluate the bond between fiber reinforced polymer (FRP) – glass and carbonFRP – and steel reinforced polymer (SRP) with historic masonry: pull–push shear tests on FRP/SRP-to-historic brick bonded joints specimens were carried out. Modes of failure are discussed in detail and analytical results are compared with experimental data. Experimental strains recorded on FRP/SRP strips were processed to evaluate shear–slip laws of tested specimens; energy fracture and failure load values are compared with theoretical values by simplified models for shear stress–slip. Finally, a simple model of FRP/SRP design suitable for practical application to historic masonry is proposed.

Quantitative Interpretation of Half-Cell Potential Measurements in Concrete Structures

The interpretation of half-cell potential measurements in reinforced concrete structures can be a major challenge for civil engineers. The main reason for this is that half-cell potential mapping provides information to predict the probability of corrosion in concrete, but it does not give clear insight on the rate and the nature of corrosion. Although for general uniform corrosion, half-cell data can provide valuable information about the probability of corrosion. In the case of localized corrosion, the predictions of half-cell measurements can be misleading. The main objective of the present work is to provide practicing engineers a tool that they can use to better interpret the results of half-cell potential measurements. This tool quantitatively relates the potential readings on the surface of the concrete to the rate of probable localized reinforcement corrosion through concrete resistivity, cover thickness, and temperature, allowing the engineers to gain supplementary information from half-cell tests. Experimental comparisons presented in this paper demonstrate the potential benefits of the proposed approach when typical half-cell measurements may not be able to predict the localized corrosion mechanism.

Engineering ‘the aerodrome of democracy’, Canada 1939–1944

The British Commonwealth air training plan was created to address the critical shortage of trained flyers that existed at the outbreak of World War II. As the expansion of existing training facilities in areas likely to be subject to enemy attack was unlikely to be satisfactory, an agreement was reached between Great Britain, Canada, Australia and New Zealand to provide training facilities in Canada. Initial requirements were for 58 airfields, one to be complete by May 1940, 37 by the end of 1941 and the remaining 20 by April 1942. The extent of this civil engineering challenge is highlighted by the fact that, in 1939, the Royal Canadian Air Force possessed only five airfields. However, not only were the original targets achieved, they were surpassed in both scope and time. On completion, 88 ‘main’ airfields were in use; as most of these airfields required at least one ‘satellite’ field with many of the facilities of the main fields, the grand total was 176 airfields. In the words of President Roosevelt, Canada had become ‘the aerodrome of democracy’. As airfields were constructed in every province of Canada, planning and logistical problems were immense. Standardisation of design for airfield layout, prefabrication of components for hangars and other airfield structures, a centralised management organisation and the application of what, today, we would describe as modern construction project management techniques all helped Canada's civil engineers to successfully complete this Herculean task.

Climate change and civil engineering challenges

The greatest challenge facing civil engineers today is how mitigate and adapt to climate change. However, as discussed in this paper, there are still considerable uncertainties about the trends of some critical aspects of climate change and thus doubts about the mechanisms controlling them. In developing future strategies, a major contribution of civil engineers will be through providing practical and financial evidence about projects and systems which work and do not work. Engineers also know about risk, which is intimately related to system design. The paper concludes that the UK engineering profession needs to be more closely involved in developing effective integrated policies, working with scientists, business and government agencies.

Improved suboptimal Bang–Bang control of aseismic buildings with variable friction dampers

One of the challenges in civil engineering is to find an innovative means of suppressing the structural vibration due to earthquake and wind loadings. This paper presents an approach for effectively suppressing vibrations of a structure with variable friction damper using a new Bang–Bang control input. A continuous function of story velocities is used to represent the improved control to reduce chatter, high frequency switching and avoid instability. With a genetic algorithm, the amplitudes of control and preloading friction forces individually prescribed in the controller and damper are optimized for enhancing the seismic performance of buildings. The control strategy for the friction damper is proposed for a three story building with one variable friction damper installed at the first story for seismic reduction. The numerical results indicate that a better reduction of peak response accelerations of floors can be achieved than those of the unmodified controller, and the adaptability of the control system is also improved greatly by comparison with the reduction ratios of the structural response energy excited by different earthquake intensities.

UK power: an everchanging challenge for civil engineers

This paper provides an overview of Britain's continually evolving electricity supply industry and how it got to where it is today. In an ever-changing social, political and technical environment, the industry has gone from private to public ownership and back again, and the benefits of a partial return to distributed generation are now becoming apparent. Continually rising demand and an increased emphasis on sustainability and security are now leading to further restructuring. All of this continues to supply a rich variety of challenges and opportunities for civil engineers, whose role in developing, upgrading and maintaining the nation's power-system infrastructure remains as vital as ever.

Modernising the UK's west coast main line railway

In December this year the rail journey from London to Glasgow will be 44 minutes shorter. It will mark substantial completion of the £8 billion, ten-year programme to modernise the UK's west coast mainline, one of the largest railway projects in the world. Over half the 650 km long, 160-year-old heavily trafficked route has already been upgraded to carry new 200 km/h tilting trains, two years ahead of schedule, and gauges have been increased for European 2·9m freight containers all the way to Glasgow. Work on all final contracts is now underway with completion scheduled for 2009. This paper provides an overview the project, its unique civil engineering challenges and the innovative working practices and technological solutions adopted.

Pisa goes critical

The Leaning Tower of Pisa is not just a quaint curiosity but a magnificent architectural treasure. Over the years its inclination has been increasing inexorably to the point where it is about to fall over. Moreover the stresses in the masonry induced by the lean have brought it close to structural failure. Stabilisation of the tower represents the ultimate civil engineering challenge. This paper describes the history of the tower and the mechanics of its behaviour, understanding of which has proved vital in the development of stabilisation measures. Early stabilisation was first achieved by placing temporary lead weights on the foundation masonry on the opposite side from the lean. Long term stabilisation commenced in February 2000 using a controversial method of soil extraction to reduce the inclination by about 10% – not enough to be visible but enough to substantially increase the safety. A long, tense journey lies ahead of the tower.