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This paper describes the new 600 MW Karuma hydropower project in Uganda, which was completed in 2022. More than 70% of the project's structures were built underground to enhance resilience. Complexities relating to structural analysis and design, advanced engineering technologies, climatic considerations, deep excavations and tunnelling are presented. Key challenges experienced during construction, remedial measures undertaken, lessons learned and a proposed post-construction renewable energy option are also discussed. [ABSTRACT FROM AUTHOR]

The development of transport requires new transport routes. When designing and implementing them, we cannot avoid the construction of tunnels in our mountainous country. One part of the static design of the tunnel is the assessment of the structure on fire. The fire of cars in road tunnels can be modeled more and more accurately thanks to improving numerical models (CFD simulations, Fire Dynamics Simulator FDS [1]) as well as an extreme increase in computer performance. The results of these investigations are applied to the surface of the structure as a function of temperature varying over time. We can use more load fire curves. In the calculation of the effects of fire on a reinforcement in the mathematical model does not occur in common calculation procedures, but a homogeneous concrete cross-section is considered. In the article we compare the solution of a homogeneous reinforced concrete cross-section with the crosssection in which the reinforcing steel bars are modeled. When considering the higher thermal conductivity of steel, it is possible to assume faster heat spreading inside structural elements. The article discusses the extent to which the modeling of concrete reinforcement bars affects the resulting temperatures, but also the relative increase in the complexity of the problem, which is associated with an increase in the required computational time to solve the problem. The paper analyzes the reinforced concrete cross-sections of concrete columns and compares the differences obtained in the calculation as a homogeneous cross-section and a real cross-section with reinforcement. [ABSTRACT FROM AUTHOR]

This paper describes the innovative temporary works used for abutment construction of a moveable bridge in London's Docklands. Completed in 2019, the 27 m span Water Street Bridge and its approach causeway connect the Canary Wharf estate to the new Wood Wharf development on a reclaimed island site. Using strand-jacking, grout-bag seals, heavy temporary steelwork and innovative use of permanent works, the contractor-designed solution for delivering the bascule span abutment transformed a marine operation into a land-based one. The challenging logistics required careful planning and collaboration with all stakeholders to meet the programme and client brief, ensuring a safe, high-quality outcome. [ABSTRACT FROM AUTHOR]

The Suzhou Taihu New City major underground space development was one of the largest and most complex foundation projects in China. It had a footprint area of 93 000 m2 with a depth of 18 m into soft ground. The complexity was increased further by its proximity to existing sensitive assets, which include a metro station and flood defence structure. These challenges were overcome by using multiple innovative excavation and support techniques, including mini-pits, reserved soil berms, compartmentalised excavations, composite slope stabilisation, the observational method and a 'time–space effect'. [ABSTRACT FROM AUTHOR]

Design of slabs without shear reinforcement is, in practice, based mainly on empirical codified methods, derived on the basis of a large number of tests. However, the vast majority of these tests involves simply supported beams, with substantial amounts of longitudinal reinforcement, subjected to three- or four point bending. This paper presents the results of a significant experimental programme comprising eighteen simply supported - cantilevered slabstrips without stirrup reinforcement, and with a light amount of longitudinal reinforcement. Stirrups in the surrounding parts founded a shear critical region located in the hogging region of the simple span. All beams failed in shear within this shear critical region, the slenderness of which was fixed for all the beams. The influence of the concrete strength, which is of special interest in relation to lightly reinforced members, was investigated by varying the concrete strength systematically within the test series. The influence of the concrete strength and mix with respect to crack roughness was further studied using a large number of concrete cores prepared with coloured epoxy. The cores were all extracted from various zones containing critical and "non-critical" shear cracks. Photogrammetric measurements (digital image correlation) and optical fiber measurements were conducted in the shear critical region on all tested specimens, and detailed analysis on the propagation and kinematics of critical cracks are presented. [ABSTRACT FROM AUTHOR]

A significant part of geotechnical structures such as parts of tunnels, adits, retaining walls, etc., is made of reinforced concrete. In reinforced concrete structures there are often cracks in places where they were not considered in the design. It is up to the engineer performing the fault diagnosis to determine the nature of the cracks, the cause of the occurrence and the follow-up measures to prevent their further development or eventual sanitation. The principles of conventional methods of visual diagnosis of such structures are simple, but possible disturbances may occur in inaccessible places. Typically, performing visual diagnostics requires stopping the operation in the surrounding areas of structure under investigation to ensure the safety of the persons performing it. As a result, a device that ensures continuous monitoring of cracks even in hard-to-reach areas or in locations with increased operation has been developed. This device can continuously monitor the evolution of the crack over time, store the evaluated data chronologically or send it to the server, and notify the competent authorities about changes. [ABSTRACT FROM AUTHOR]

This paper discusses the influence of different curing conditions on the compressive strength of concrete test specimens monitored for 365 days. Five cures were analyzed. Statistical tests were applied (variance analysis and Fisher's) in order to evaluate the data. According to results, different curing conditions influence the compressive strength of concrete. The main novelty of this article is that the curing conditions affect the concrete compressive strength significantly only for ages over 28 days. Furthermore, this study shows that concrete specimens saturated with water have superior strength to concrete cured in a standard environment (moist chamber). The compressive strength of concrete decreases, respectively, with the following types of curing investigated: water tank, moist chamber, tank with water and lime, laboratory internal environment and external environment. The compressive strength gain over time also varies for each condition. The lower values found for the external environment confirm the greater difficulty of controlling the water loss on this environment, resulting in decrease of compressive strength. [ABSTRACT FROM AUTHOR]

The paper tells the story of 25 years of technology developments and engineering challenges in the European offshore wind sector. Since the world's first offshore wind farm at Vindeby in Denmark in 1991, the offshore wind industry has developed into a significant business across north-western Europe and beyond. The paper describes the early development of the wind industry in Denmark, followed by a focus on the evolution of offshore foundation concepts, their applicability and their pros and cons. [ABSTRACT FROM AUTHOR]

There are many century-old plain-concrete-arch railway bridges in Iran in need of seismic assessment. Given the logistical difficulties of conducting field tests, the use of computer models is being investigated as an alternative. Three-dimensional finite-element models were created for two bridges that had already been physically tested. After calibration with the test results, the modelled bridges were then subjected to a modelled earthquake to evaluate their behaviour under seismic loading. The results demonstrate that seismic response depends entirely on the geometrical and material properties, and that bridges perform better in a transverse direction. [ABSTRACT FROM AUTHOR]

A tired 1960s engineering and science library building at the University of Nottingham, UK has been transformed into a sustainable, state-of-the-art, multi-function educational and social facility. Redevelopment of the George Green library involved complete refurbishment of the existing structure and building a new extension with a new unifying facade. Major engineering interventions were necessary to transform the existing building along with significant repairs to damage that only became apparent as works progressed. The new facility shows that, with architectural and engineering ingenuity, old buildings no longer fit for purpose do not necessarily have to be demolished. [ABSTRACT FROM AUTHOR]

China's construction boom over the past few decades has led to growing demand for high-rise and 'mega-scale' buildings. Such structures feature sophisticated building services, unique elevations, seamless connection to infrastructure and high safety levels. Design and construction challenges include hazard mitigation against extreme actions and environments, integrated structural frameworks and facades, complex connections and overall constructional efficiency. Civil and structural engineers add value, enhance engineering efficiency and achieve overall environmental and cost-effectiveness for modern mega-buildings in China. This paper introduces the design and construction of four of such projects. It reviews the evolution of modern mega-buildings, including aspects of integrated engineering design, construction technology, value engineering and overall sustainability. [ABSTRACT FROM AUTHOR]

Completed in March 2015, Sai Ying Pun station is one of three large, new stations on the £1·3 billion West Island line project in Hong Kong. It is a massive, multi-disciplinary construction, with a 228 m long station cavern connected by way of a 1100 m network of passenger and ventilation adits to four entrance shafts up to 76 m deep. This paper focuses on the engineering design and construction challenges associated with delivering the monumental entrances, each of which is unique in its complexity. The entrances had to accommodate circulation and evacuation routes, plant, ventilation ducts, launch shafts and re-provisioning for original land use within a congested, steeply sloping urban environment. The relation of the entrances to the station and adit delivery, as well as the impact on existing buildings, is also discussed. [ABSTRACT FROM AUTHOR]

The Moorgate shaft at Crossrail Liverpool Street station is one of the deepest in London, UK. Construction of the base slab to the 42 m deep shaft required close collaboration between the client, designer, contractor and suppliers to give assurance that the slab was watertight. Dense reinforcement was detailed to ensure ease of fixing within the tight confines of the shaft and allow for the tolerance on the diaphragm walls. The concrete design was developed to ensure that it met the requirements for placing and structural strength while achieving good control on the temperature developed. The concrete mix was trialled for temperature development and initial set to allow relaxation of the original specification. The pour plan was developed with the co-operation of all the site teams to ensure appropriate contingency measures were in place. Temperature monitoring was carried out to ensure that mitigation measures could be applied to control placed concrete temperature against predetermined trigger levels. [ABSTRACT FROM AUTHOR]

A stunning new concrete, stainless steel and glass spiral staircase has recently been installed in the historic Somerset House in central London, UK. The elegant modular design - inspired by the structural system of the traditional spiral cantilever stairs in the grade 1 listed public building - has been made possible by the use of proprietary ultra-high-strength fibre-reinforced concrete for the 104 stair treads and intermediate landings. This paper describes the design, analysis and construction of the new staircase and in particular the engineering properties - and possibilities - afforded by using super-strong, ductile concrete. [ABSTRACT FROM AUTHOR]

The Shard in central London is 310 m high, making it the tallest building in western Europe. Designed for client Sellar Property Group, it is a 'vertical city', containing shops, offices, restaurants, hotel, apartments and a public viewing gallery. This paper describes the design and construction of the building, which has a concrete core, steel-framed floors to level 40, concrete floors to level 69 and a steel 'spire' at the top. Various innovative construction techniques were used to save time and improve safety, including building the three-storey basement and core top-down, installing plunge columns to high levels of accuracy, and using modular construction for the spire. [ABSTRACT FROM AUTHOR]

The Auditorium Oscar Niemeyer in Ravello, southern Italy is an iconic new concrete building perched above the Amalfi coast. The €16·7 million, 400-seat venue was completed in 2010 and provides a much-needed venue for this world heritage site's wealth of renaissance-inspired art and cultural events. The main structural feature is a 35 m vaulted roof supported on a slab cantilevering 12 m out from supporting walls, giving the building the appearance of floating in air. This paper reports on the many multi-disciplinary design and construction challenges involved in delivering this unique and geometrically complex building on a steep and confined site. A key issue was the need to respect the architectural vision while achieving an efficient and sustainable design. [ABSTRACT FROM AUTHOR]

Ground penetrating radar analysis of reinforced, layered concrete bridge decks requires fast, fully three dimensional modeling for analysis and inversion of measured data. However, numerical methods are often computationally expensive and impractical for real-time use. 2D modeling is fast, but lacks a comprehensive analysis of the problem. Here, we develop and test an analytic method to effectively simulate layered concrete bridge deck reinforced by a grid of rebars, excited by air-coupled GPR. The Green's function analysis in combination with the method of moments (MoM) is utilized to efficiently model the scattering effects of the rebar buried inside a stratified bridge deck. The results are validated well with finite difference frequency domain (FDFD) method. [ABSTRACT FROM PUBLISHER]

Two centuries of mining Bath limestone in Somerset, UK left a huge underground void just beneath the village of Combe Down. As its thousands of rock pillars degenerated, a growing collapse risk led to one of the country's largest local government civil engineering projects of the past decade. This paper explains how Bath and North East Somerset Council worked closely with the local community to develop a solution which involved carefully pumping over 600 000 m of foamed concrete into the mine with minimal social and environmental impact. The project also set several new good-practice benchmarks for public-sector construction. [ABSTRACT FROM AUTHOR]

Strata SE1 is a new 43-storey, 148 m tall reinforced concrete residential tower leading the sustainable regeneration of the Elephant and Castle area in London, UK. With a curved triangular footprint and three 9 m diameter wind turbines, the tower has been designed economically and built quickly on a confined city centre site. This paper describes the design and construction of the project, which used a system of 'walking columns' to achieve its tapered shape, with slabs acting as struts and ties. Headed reinforcement bars were used within the ties - one of the first applications in a UK building. [ABSTRACT FROM AUTHOR]

The world's tallest structure - the 828 m high Burj Khalifa building in Dubai - has set a new benchmark for engineering super-tall buildings. In particular, it significantly raised the bar for high-performance-concrete construction, with its massive reinforced-concrete core and wings extending nearly 600 m above ground level. This paper describes the how the extreme concreting challenges were overcome on the project, including successfully pumping and placing high-performance concrete to unprecedented heights as well as preventing excessive cracking and shrinkage in the hot and arid conditions. Practical advice is provided for future projects. [ABSTRACT FROM AUTHOR]

There has never been a greater need for buildings, tunnels and other infrastructure to be assessed for damage following fires. Even after a severe fire, structures are often capable of being repaired rather than demolished. This paper describes the role of forensic engineers in the investigation of fire-damaged structures constructed in concrete, steel and masonry. Forensic-engineering procedures described include on-site inspection and testing techniques, laboratory testing and structural fire analysis. The design and implementation of repairs is also discussed. [ABSTRACT FROM AUTHOR]

The collapse of a record-breaking 240 m span prestressed-concrete bridge in the Pacific Island nation of Palau occurred without warning in 1996. The parties involved were subject to a confidentiality agreement, so no definitive statement has been made as to the cause of the collapse. This paper reports on a study carried out using information in the public domain. Iit concludes that a repair carried out six weeks before the collapse was not to blame, but did expose weaknesses in the original design. is recommended that the construction industry should not shelter behind confidentiality clauses but, like the aircraft industry, publish its mistakes so lessons can be learned. [ABSTRACT FROM AUTHOR]

The London tunnels of section 2 of the Channel Tunnel Rail Link—now known as High Speed 1—carry the new railway from the eastern edge of London into the centre at St Pancras, a distance of approximately 20 km. The scheme required civil engineering and particularly mechanised tunnelling to be pushed to the limits of technology. Successful delivery of the works required strong emphasis on proactive risk management and a single team approach throughout the design and construction phases. This in turn led to an unusual but effective procurement approach. Together these factors have resulted in the successful delivery of a major new transport asset with little disruption to the everyday life of Londoners. [ABSTRACT FROM AUTHOR]

Tunnelling under the Thames estuary was considered to be the greatest risk to section 2 of the Channel Tunnel Rail Link project—now known as High Speed 1. However, it was delivered safely and ahead of programme by the application of risk management and sound engineering by the tunnel-boring machine manufacturer and contractors. This paper describes the award-winning design and construction of the 3.6 km long, twin-bore crossing. [ABSTRACT FROM AUTHOR]

A major new water treatment plant on a mountainside overlooking Tai Po in Hong Kong sits on top of a steep floodprone watercourse, 500 m of which has had to be buried deep under the works in a substantial culvert. This paper describes the challenging design and construction of the 8 m wide concrete-arch culvert, which for the past seven years has successfully contained and dissipated high-speed, boulder-laden storm flows of up to 80 m3/s. The Lin Au culvert incorporates a series of four chutes and stilling basins as well as providing overflow facilities for the treatment works above it using a variety of drop structures. The structural integrity of the culvert is critical, both to support the massive overlying fill platform of the new treatment works as well as to protect it from being washed out by up to 60 MW of hydraulic energy. [ABSTRACT FROM AUTHOR]

In contrast to the FFT, which only gives the frequency content of the whole signal without revealing its relation to time, the application of the Hilbert-Huang Transform (HHT) gives a time-frequency representation of the data. Examples of on-site measurements are shown, where HHT succeeds in identifying short transient signals, which could not be identified using FFT. Furthermore its application for filtering the signal and its capability to analyze data from nonlinear systems are demonstrated. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

The viaduct carrying the first section of the £5.2 billion Channel Tunnel Rail Link over the River Medway near Rochester is a uniquely styled bridge. The 1.25 km long 25-span prestressed concrete box girder has become a symbol for the new railway and the 152 m main span has extended the limit for high-speed train crossings. This paper reports on its design and construction, which used both balanced cantilever and push-launched techniques. The viaduct was awarded the Concrete Society Award for Civil Engineering in 2002. [ABSTRACT FROM AUTHOR]

The £50 million Hungerford Bridge millennium project in London provides two stunning new cable-stayed footbridges across the Thames, one on each side of Charing Cross railway bridge. Effectively it recreates Brunel's 1846 suspension footbridge to Hungerford market, the piers of which remain in the railway bridge structure. Heightened fears over unexploded bombs in the river bed led to a major redesign just after work started but a switch to the NEC contract helped ensure a smooth completion. [ABSTRACT FROM AUTHOR]

The Gateshead Millennium Bridge over the River Tyne in north-east England is a unique tilting bridge for pedestrians and cyclists. Opened by the Queen in May 2002, the inspirational 105 m span structure subsequently became the first bridge to win the Royal Institute of British Architects' 2002 Stirling Prize for `building of the year'. This paper provides an overview of what has become known as the `blinking eye' bridge and of the processes adopted to achieve and deliver it not least the spectacular superstructure installation. [ABSTRACT FROM AUTHOR]