bluuebunny/crossref_metadata_2025 huggingface dataset:
MỘT SỐ KẾT QUẢ NGHIÊN CỨU BƯỚC ĐẦU VỀ ĐỘNG LỰC TRẦM TÍCH LƠ LỬNG TRONG MÙA LŨ TẠI VÙNG BIỂN VEN BỜ CỬA SÔNG HẬU
Authors: Tien Nguyen Ngoc , Thanh Nguyen Trung , Dang Vu Hai , Vinh Vu Duy
Published: July 2016

Các mối tương tác biển - đất liền trong vùng ven bờ bị chi phối chủ yếu bởi các quá trình thủy động lực như sóng, dòng chảy, lưu lượng nước sông, thủy triều trong đó thủy triều đóng vai trò quan trọng. Tại các khu vực có lưu lượng phù sa lớn như vùng ven biển sông Hậu, các quá trình này càng trở nên rõ rệt khi phân tích từ số liệu khảo sát trong thời kỳ mùa lũ (tháng 9) thuộc chương trình hợp tác khoa học và công nghệ giữa Việt Nam và Hoa Kỳ (2013 - 2015) và đề tài độc lập mã số VAST-ĐLT.06/15-16 (2015 - 2016). Trong chuyến khảo sát này, mục đích là điều tra sự lắng đọng và phân bố theo không gian, thời gian của hàm lượng trầm tích lơ lửng. Ngoài ra, chúng tôi còn khảo sát ảnh hưởng của dòng triều trong mối tương quan với hàm lượng trầm tích lơ lửng. Độ muối (đơn vị PSU - Practical Salinity Unit), hàm lượng trầm tích lơ lửng (đơn vị đo NTU - Nephelometric Turbidity Units) được đo bằng thiết bị Compac-CTD (Depth temperature conductivity chlorophyll turbidity), và thiết bị đo độ đục OBS-3A (Turbidity and Temperature Monitoring System). Kết quả nghiên cứu cho thấy hàm lượng trầm tích lơ lửng tương quan với vận tốc dòng chảy. Tốc độ dòng chảy khi triều lên đến 60 cm/s ở lớp mặt và 40 cm/s ở đáy tạo nên sự tăng nồng độ trầm tích lơ lửng trong cột nước ở tầng đáy 24 NTU và 8 NTU tại tầng mặt. Trong pha triều lên, quá trình vận chuyển và lắng đọng trầm tích lơ lửng bị chi phối bởi dòng triều dài hơn so với mùa khô. Điều này cho thấy sự bất đối xứng của elip thủy triều và dẫn đến sự lắng đọng trầm tích lơ lửng trong các mùa là khác nhau. Từ kết quả phân tích có thể thấy vùng biển ven bờ cửa sông Hậu, hàm lượng trầm tích lơ lửng chịu sự chi phối bởi dòng chảy triều và thủy triều là rất lớn, do đó quá trình lan truyền, xáo trộn nước sông và biển có sự khác biệt đáng kể trong các điều kiện triều và điều kiện mùa.
ĐẶC ĐIỂM ĐỊA HÌNH ĐÁY VÀ TRẦM TÍCH TẦNG MẶT VÙNG BIỂN QUẦN ĐẢO THỔ CHU
Authors: Trung Pham Ba
Published: July 2016

Quần đảo Thổ Chu được cấu tạo bởi các đá trầm tích (cao 176 m), có thế nằm ngang. Xung quanh đảo được giới hạn các sườn dốc mài mòn và đỗ vỡ sụp lở. Hình thái đường bờ là các vách dốc, mài mòn và các tảng lăn với kích thước khá lớn, bị mài mòn yếu, ít bị thay đổi, thảm thực vật trên đảo còn nguyên sinh. Độ sâu trung bình quần đảo Thổ Chu khoảng 20 - 30 m, có rãnh sâu có độ sâu -96 m và có rất nhiều đồi ngầm phần lớn được phủ san hô. Đặc điểm trầm tích tầng mặt được phủ bởi các kiểu trầm tích hạt thô: Cát chứa graven, cát chứa bùn sét (và graven), cát chứa bùn sét, bùn sét.
HIỆN TRẠNG THÀNH PHẦN LOÀI VÀ NGUỒN LỢI ĐỘNG VẬT ĐÁY VỊNH LAN HẠ - CÁT BÀ
Authors: Dat Dinh Thanh , Chieu Hoang Dinh , Hoa Luu Xuan
Published: July 2016

Một chuyến khảo sát đã được tiến hành vào tháng 7 năm 2014 tại 15 trạm trong vùng rạn san hô vịnh Lan Hạ - Cát Bà. Kết quả đã ghi nhận được 210 loài động vật đáy thuộc 55 họ, 22 bộ của 3 ngành. Động vật thân mềm Mollusca (lớp chân bụng (Gastropoda) chiếm 114 loài, lớp hai mảnh vỏ (Bivalvia) 67 loài); da gai (Echinodennata) 27 loài; chân khớp (Arthropoda) 2 loài. Có 4 loài động vật đáy thuộc danh mục Sách Đỏ Việt Nam. Các loài chiếm ưu thế lớn như Barbatia lima, Septifer bilocularis là các loài có giá trị kinh tế thấp, các loài có giá trị kinh tế cao lại có sinh lượng rất thấp. Sự phân bố của các loài động vật đáy trên các rạn san hô ở vịnh Lan Hạ - Cát Bà là không đồng đều, phụ thuộc vào kiểu nền đáy rạn và mức độ được bảo vệ của các rạn. Các rạn san hô được bảo vệ tốt hơn có số lượng loài phân bố nhiều hơn (như Vạn Bội, cửa Cát Dứa 1, Tai Kéo, Giỏ Cùng). Hiện trạng nguồn lợi và đa dạng sinh học động vật đáy trong các vùng rạn thuộc vịnh Lan Hạ - Cát Bà đang có nguy cơ suy giảm về thành phần loài, đặc biệt là sinh lượng. Trữ lượng ước tính tức thời của một số loài động vật đáy có sinh lượng lớn khoảng 88 tấn, trong đó trữ lượng của hải sâm đen ở thời điểm khảo sát chỉ bằng 49,79%; trai ngọc môi đen 91,01%; ốc đụn đực 74,79% so với năm 2012.
STUDY CURRENT STATUS OF TDS DISTRIBUTION IN THE PLEISTOCENE AQUIFER IN COASTAL ZONE OF NAM DINH PROVINCE
Authors: Thu Trinh Hoai , Trung Nguyen Nhu , Thang Do Van , Manh Vu Van , Hang Nguyen Thu
Published: July 2016

Saltwater intrusion has occurred in coastal aquifers in Nam Dinh province, Vietnam, which causes many negative effects on economic activities and especially residential life. Determining fresh-saltwater distribution is therefore necessary for authorities to have fundament to release policies and solutions promptly to prevent this issue. Based on the analysis of samples, 3 regression equations of each couple of the conductivity, total dissolved solids (TDS) and chloride concentration were formulated and displayed on graphs, these can be applied to calculate TDS from available conductivity or chloride concentration values in any areas. Calculating all input data, a variogram was created, which indicates the spatial correlation between points. Then, Kriging interpolation was applied in map-making process. Finally the spatial distribution of fresh and saltwater was delineated. Freshwater regions are located in the southern part and a small area in the north of Nam Dinh province.
ALGORITHM DEVELOPMENT OF SATELLITE IMAGE PROCESSING TO DETECT THE CONCENTRATION OF SUSPENDED PARTICULATE MATTER IN COASTAL WATERS OF RED RIVER DELTA
Authors: Thao Nguyen Van , Vinh Vu Duy , Ve Nguyen Dac , Canh Pham Xuan
Published: July 2016

In this research, a set of optical data measured in the coastal waters of Red River Delta is used to develop the empirical algorithm for detecting the concentration of suspended particulate matter (SPM). The result of the study shows that the relationship between water-leaving reflectance and the concentration of SPM follows polynomial function with correlative coefficient (R2) > 0.9. Landsat-8 OLI and VNREDSAT-1 satellite images were used to apply this algorithm for detecting the concentration of SPM in the coastal waters of  Red River Delta. The concentrations of SPM from image processing and numerical model are much close to each other. The study result will be a valuable reference for studying on water quality in coastal area from remote sensing.
STUDY ON PATHOGEN OF LUMINOUS DISEASE VIBRIO HARVEYI ON LARVAE AND JUVENILE OF MUD CRAB (SCYLLA SERRATA) IN HATCHERY
Authors: Muu Tran The , Sang Vu Van
Published: July 2016

Luminous disease is known as the most popularly dangerous disease in the hatcheries of mud crab (Scylla serrata) in northern provinces. Without any treatment, the mortality caused by this disease may reach 50 - 100% after 2 - 3 days infected. In this study, Vibrio harveyi has been identified as the main pathogen which causes the disease in larvae and juvenile of mud crab by using method for bacteria identification (bio-chemical reaction and comparision of the gene 16S rDNA) as well as artificial disease infection. In addition, we have developed successful prevention and treatment for this disease as follows: potasium permanganate, chlorine, formaline used for treatment of water, crab spawners, living food (artemia), utensils and equipment, after that one of the three different kinds of antibiotics can be used: Neomycine, Erythromycine or Doxycyclin. For prevention, the dose of 2 ppm/day can be applied for 3 consecutive beginning days of each development stage (Zoea, Megalope and juvenile), and 3 ppm/day can be applied for 3 consecutive days for disease treatment.
Call to Action on Herbicide Resistance Management
Authors: Coble Harold D. , Schroeder Jill
Published: July 2016

Management of herbicide resistance can be most effectively accomplished if every person and organization involved in agricultural production takes an ownership position and participates in solving the growing problem of weed resistance to herbicides. Growers and other pest management practitioners are keys to effective herbicide resistance management since they make the final decisions on practices used. However, many other people and organizations have an important role to play as well. Agricultural input supply networks, including chemical companies, are a widely used information source for growers' decisions through company marketing efforts. Government agencies may influence decisions through regulations or incentive programs. University scientists through their research, education, and outreach programs may impact management decisions, and organizations such as professional societies, farm and commodity groups, public interest organizations, and the agricultural press play roles as well. It is critically important that all of these groups impacting herbicide resistance management decisions are sending the same message and that message is based on sound science. The time to act is now.
Economic Returns to Herbicide Resistance Management in the Short and Long Run: The Role of Neighbor Effects
Authors: Livingston Michael , Fernandez-Cornejo Jorge , Frisvold George B.
Published: July 2016

A bioeconomic model is used to estimate how managing glyphosate resistance to horseweed affects short- and long-run profits in corn, soybean, and corn-soybean rotation systems. Model results found that resistance management reduces profits in the first year of implementation, but increases profits in the second and subsequent 18 yr. In all three systems, long run gains begin to outweigh short-run costs (and resistance management “pays for itself”) by the second year. Over a 20-yr horizon, the estimated annual average profit advantage from managing resistance exceeded $158 ha–1($64/acre) for corn, $137 ha–1($55/acre) for corn-soybean, and $55 ha–1($22/acre) for soybean. Seed immigration from a neighbor's field can reduce these gains, but this reduction is negligible if the neighbor also practices resistance management. If the neighbor did not manage resistance, however, the grower's estimated annual profit advantage fell to roughly $123 ha–1($50/acre) for corn, $60 ha–1($24/acre) for the corn-soybean rotation, and virtually zero for soybean. Methods applied in this study identify corn and corn-soybean rotations as cases where resistance management “pays for itself' quickly and significantly, even if the neighbor does not manage resistance. Continuous soybean presents a more challenging case that may require additional programs and incentives to encourage collective resistance management among growers. Even for continuous soybean, however, joint grower–neighbor resistance management can pay for itself within 2 yr.
Rethinking Outreach: Collaboration Is Key for Herbicide-Resistance Management
Authors: Asmus Amy , Schroeder Jill
Published: July 2016

Effective outreach is critical to achieving success in managing herbicide-resistant weeds. Interdisciplinary collaboration is needed to adapt information delivery and to engage communities to address the herbicide-resistance problem. Weed scientists must partner with the production community to adapt herbicide-resistance practices for local needs, to work collaboratively with state and regional stakeholders to create effective resistance-management practices, and to provide an overarching national message as to the causes of, and solutions to, resistance.
Exploring the Potential for a Regulatory Change to Encourage Diversity in Herbicide Use
Authors: Powles Stephen B. , Gaines Todd A.
Published: July 2016

An overreliance on herbicides in several important grain- and cotton-producing regions of the world has led to the widespread evolution of herbicide-resistant weed populations. Of particular concern are weed populations that exhibit simultaneous resistance to multiple herbicides (MHR). Too often, herbicides are the only tool used for weed control. We use the term herbicide-only syndrome (HOS) for this quasi-addiction to herbicides. Growers and their advisers focus on herbicide technology, unaware of or ignoring basic evolutionary principles or the necessary diversity provided by other methods of weed control. Diversity in weed control practices disrupts resistance evolution. Significant challenges exist to implementing diversity, including how to address information so that producers choose to alter existing behaviors (HOS) and take calculated risks by attempting new and more complex strategies. Herbicide resistance management in the long term will require creativity in many sectors, including roles for growers, industry, researchers, consultants, retailers, and regulators. There can be creativity in herbicide registration and regulation, as exemplified by the recent U.S. Environmental Protection Agency program that encourages herbicide registrants to register products in minor crops. We propose one idea for a regulatory incentive to enable herbicide registrants in jurisdictions such as the United States to receive an extended data exclusivity period in exchange for not developing one new herbicide in multiple crops used together in rotation, or for implementing stewardship practices such as robust mixtures or limitations on application frequency. This incentive would provide a mechanism to register herbicides in ways that help to ensure herbicide longevity. Approaches based only on market or financial incentives have contributed to the current situation of widespread MHR. Our suggestion for regulatory creativity is one way to provide both financial and biological benefits to the registering company and to the overall stakeholder community by incentivizing good resistance management.
Community-Based Approaches to Herbicide-Resistant Weed Management: Lessons from Science and Practice
Authors: Ervin David E. , Frisvold George B.
Published: July 2016

When herbicide-resistant weeds are highly mobile across farms, delaying resistance becomes a common-pool resource (CPR) problem. In such situations, it is in the collective long-term interest of farmers to conserve an herbicide's usefulness. Yet, each farmer has an individual short-run incentive to use the herbicide without considering effects on resistance. This study considers the potential for community-based (CB) approaches to address problems of herbicide-resistant weeds. Here, growers actively participate in designing, financing, and implementing programs, usually in collaboration with industry, government, and universities. CB approaches have certain advantages over top-down regulatory or subsidy-based approaches. Scholars and practitioners have developed effective governance mechanisms for many CPRs that could aid in developing effective resistance management programs. Successful CB management programs for insect pest eradication and areawide invasive weed control offer additional lessons about the potential and challenges of such efforts. Lessons from these examples can inform the design and implementation of successful, voluntary programs for herbicide-resistance management. Key research, education, and outreach priorities to help implement successful CB programs are identified at the close.
Human Dimensions of Herbicide Resistance
Authors: Ward Sarah
Published: July 2016

Herbicide resistance has become a major topic of international research in weed science, with a steady stream of presentations and papers on various aspects of the biology of herbicide resistant weeds. Diverse sources—including WSSA—have generated an equally steady stream of recommendations for preventing and managing herbicide resistance. The situation in the field, however, continues to deteriorate, with new cases of herbicide resistant weeds being reported at an increasing rate. We know what to do, but why aren't we doing it?
Steel bridge design and construction: a Southern African experience
Authors: Dundu Morgan
Published: July 2016

Bridge design and construction has gone through several phases in Southern Africa. The first phase was dominated by steel. During this phase, revolutionary steel bridges were constructed. This happened despite the fact that steel was not manufactured in this region. The use of structural steel in these bridges exploited its advantageous properties of economically carrying heavy loads over long spans with minimum dead weight. After this phase, the choice of material used in bridges changed to concrete. During the past 20 years, steel has staged a strong comeback. The aim of this paper is to explain why the bridge industry has experienced different phases in construction. Selected case studies of vehicle and foot steel bridges are presented and discussed to substantiate the competitiveness of steel as a bridge construction material.
Mechanical issues to consider when designing a moving bridge
Authors: Thorogood Michael
Published: July 2016

With the excitement and enthusiasm often encountered when starting work on a new design commission for a moving bridge, the mechanical, electrical and hydraulic equipment associated with operating the bridge can get overlooked at the outset, meaning that the project as a whole suffers further down the line. Issues such as the space allocated for the mechanism, life of equipment, location of gates and barriers often get overlooked at the start of a project and then have to be addressed in a less than ideal way later. This paper discusses some of the key issues that require addressing both at the early conceptual stages but also as the project develops and key details and decisions are made that can determine the success of the project as a whole. It goes on to look at the considerations needed during installation, commissioning and handover.
Movable bridges: condition, modelling and damage simulations
Authors: Catbas F. Necati , Gokce Hasan Burak , Gul Mustafa , Frangopol Dan M.
Published: July 2016

Movable bridges are unique structures due to the complex interaction between their structural, mechanical and electrical systems. While these systems provide versatility to movable bridges, their intricate interrelation also creates intermittent operational and maintenance challenges. First, the authors examine movable bridges in Florida with their inspection data. The review of common problems serves as a basis for the selection of a real-life bridge and the simulations that are the main contributions of this particular paper. Next, the representative bascule-type movable bridge is described. As span lock failure is identified as one of the most frequently observed movable bridge problems, a finite-element model of the representative bridge is created to simulate this type of failure. Before conducting the span lock damage simulations, the finite-element model is calibrated globally using modal frequencies from ambient vibration tests and locally using strain data from field load tests. Finally, changes in the static and dynamic characteristics are examined to detect issues such as span lock failures, which are critical to ensure the safe operation of bascule-type movable bridges.
The environmental impacts of fibre-reinforced polymer composites in construction
Authors: Zhang Chao
Published: July 2016

Fibre-reinforced polymer composites have gained increasing popularity within the bridge engineering sector, mainly due to the financial benefits often associated with their use. As concerns grow over climate change and depletion of natural resources, it is important that the environmental – in addition to cost – implications of their use should be considered. This paper conducts, within the general framework of life cycle assessment, a review of the literature on various aspects of this topic. The environmental credentials of this relatively new class of materials are examined at the material level in terms of embodied impacts and based on two case studies, for bridge decking applications. Aspects such as end-of-life disposal and use of alternative, bio-based materials are also discussed. Based on the work in this paper, better understanding of the environmental impacts of fibre-reinforced polymer composites in construction can be gained and areas of further research identified.
An overview on recycling and waste in construction
Authors: Barritt John
Published: July 2016

Good practices in the recycling and reuse of construction waste can prevent valuable resources being lost to landfill and enable EU member states to meet the European Commission Waste Framework Directive target of 70% recovery by 2020. When regulation and taxation makes recovery the lower cost option to landfill, where extensive treatment infrastructure exists, when recycled materials meet established standards and specifications, and construction clients and contractors create the demand pull for resource-efficient construction, this 70% target is easily exceeded, as is the case in the UK. Although there is scope for further improvement in recycling construction waste in the UK to optimise quality and broaden applications for recovered resources, this is no longer the major challenge in improving resource efficiency in construction. UK construction practices still create too much waste in both the design and build phases of construction; stopping waste is the lower cost option to recycling waste, and is more resource efficient.
Book review
Authors: Chian Siau Chen
Published: July 2016

Centrifuge Modelling for Civil Engineers
Longitudinal shear strengthening of composite bridge beams
Authors: Zanardo Giovanna , Shayan Ahmad , Scanlon Robert F.
Published: July 2016

A number of composite concrete bridges (i.e. bridges with precast prestressed concrete beams designed to act structurally in combination with a cast-in-situ concrete slab) were constructed in Western Australia in the 1960s and 1970s. Newer editions of bridge design codes have altered the requirements to which these bridges were designed. Recent assessments made on the basis of the new requirements have indicated that these structures exceed current stress limits in longitudinal shear and therefore need strengthening. To implement effective non-destructive retrofit strategies, Main Roads Western Australia (MRWA) initiated a testing programme to investigate the application of non-intrusive strengthening schemes comprising epoxy-bonding of carbon-fibre reinforced polymer (CFRP) and glass-fibre reinforced polymer (GFRP) products to reduced-scale specimens representing the connection between concrete elements in a bridge deck. A total of 32 specimens were tested. The tests were specifically designed to assess the strength of the connection under the small deformations generated in bridge decks under service conditions. The performance of the tested specimens has been compared in terms of relative slip and separation between the connected concrete blocks at peak force. The results have provided insight into the key variables that govern the strength of retrofitted connections under longitudinal shear (e.g. concrete roughness at the interface, concrete strength, reinforcement at the interface, anchorage/bonding, fibre direction, weaving pattern and thickness of the epoxy-bonded fibre composites). While the results were obtained for a specific Australian problem, they might have application to similar situations elsewhere.
Recycling cigarette butts in lightweight fired clay bricks
Authors: Kadir Aeslina A , Mohajerani Abbas
Published: July 2016

Several trillion cigarettes are produced worldwide annually, resulting in tonnes of cigarette butt waste. Cigarette butts accumulate in the environment due to the poor biodegradability of the cellulose acetate filters. Results from a study on recycling cigarette butts into fired clay bricks are presented. Five different soil–cigarette butts mixes with different percentages of cigarette butts were used. The physico-mechanical properties of manufactured bricks including compressive strength, flexural strength, density, water absorption and thermal conductivity are discussed. The results show that the density of fired bricks was reduced significantly, by up to 30%, depending on the percentage of cigarette butts incorporated into the raw materials. Similarly, the compressive strength of bricks decreased according to the percentage of cigarette butts included in the mix, and the estimated values of thermal conductivity were also reduced significantly. The results also show that the mixing time has a considerable effect on the properties of the fired clay bricks tested. Furthermore, the leachate test results revealed only trace amounts of heavy metals. It was concluded that cigarette butts can be regarded as a potential addition to the raw materials used in the manufacture of lightweight fired bricks and, furthermore, that recycling cigarette butts in bricks is a very practical and potentially significant contribution in terms of a sustainable solution to one of the serious environmental pollution problems in the world.
The 1862 gold fields water supply scheme: Victoria, Australia
Authors: Harper B. C. S.
Published: July 2016

A major water supply scheme to support mining at two significant alluvial gold fields in the colony of Victoria, Australia was undertaken in the 1860s. It involved a large clay core embankment dam on the Coliban river and aqueducts to serve the mining communities at Castlemaine and Sandhurst. In a new colony lacking hydrological records, estimation of the river flow and the flood characteristics presented a challenge to the designer Joseph Brady. The paper examines Brady's approach to estimating these hydrological parameters and the reaction of other engineers in the colony to the design. The scheme was modified during construction to increase the volume to be delivered, but the higher level of supply could not be realised. Also the climatic conditions in the colony produced occasional floods with a higher crest than Brady's estimate. Additional spillway capacity was provided during construction, but the peak volumes were such that the dam had to be held below full capacity level to prevent destruction through overtopping. Problems with the scheme brought about a programme of hydrological surveys of river catchments in the colony. Examination of 50 years of Coliban records shows the acumen of the original design engineer Joseph Brady.
The Aneha scandal: building fraud in Japan
Authors: Gojo Wataru
Published: July 2016

Japan's building regulation system is composed of Building Standard Law (BSL) and Kenchikushi Law. Compliance to BSL is secured mainly by the building confirmation procedure and kenchikushi (building designer) qualification system. BSL has advanced structural requirements and a structural calculation program approval system. In 2005, the Aneha scandal, involving falsification of structural calculation documents, was uncovered. Around 100 hotels and condominiums were falsified utilising approved programs, 30 of which were deemed strikingly dangerous. Neither the chief designer nor the confirmation agency was able to discover Aneha's fraud, demonstrating that the Japanese building regulation system failed to protect public safety. Large-scale revisions were made to laws and regulations, including the introduction of a structural calculation review process, the publication of guidelines for confirmation/inspection, reformation of the approval scheme programme, and control over private confirmation agencies and kenchikushis. These were drafted and enforced in a very short period, which resulted in negative effects for the economy and the management/labour environment of practitioners. Some victims raised lawsuits for damages against local governments and agencies that had overlooked the falsification. It is suggested that more time should be taken between evaluating the choice of alternatives to cope with a problem and learning lessons from it.
Corrosion-resistant FRP reinforcement for bridge deck slabs
Authors: Tharmarajah Gobithas , Taylor Susan E. , Cleland David J. , Robinson Des
Published: July 2016

This paper discusses the beneficial influence of compressive membrane action in fibre reinforced polymer (FRP) reinforced in-plane restrained slabs in bridge deck slabs and the improved service performance when arching action occurs. Bridge deck slabs that are exposed to extreme environmental conditions can experience severe corrosion damage. Expansive corrosion in steel reinforcement significantly reduces the design life and durability of concrete structures; for example, on one short section of the M1 in Northern Ireland, nearly £1 million was spent last year on the maintenance and repair of bridges due to corrosion. Corrosion-resistant composite reinforcement such as basalt fibre reinforced polymer (BFRP) and glass fibre reinforced polymer (GFRP) provides a durable alternative to reinforcing steel. In this research, two BFRP reinforced slabs and two GFRP reinforced slabs were constructed using high-strength concrete with a target cube compressive strength of 65 N/mm2. The slabs represented typical full-scale dimensions of a real bridge deck slab 475 mm wide by 1425 mm long and 150 mm deep. The service and ultimate behaviour of the slabs are discussed and the results are compared with the relevant design guidelines.
Carbon calculator design tool for bridges
Authors: Smith David A. , Spencer Phillippa , Dolling Chris , Hendy Chris
Published: July 2016

BCSA and Corus engaged Atkins to develop a simplified carbon calculator design tool, which could be used to evaluate the carbon footprint of typical steel–concrete composite bridges. A key requirement was to allow rapid evaluation of a range of preliminary design options based on minimal calculated quantities for each option, using typical default assumptions. In addition, the tool needed to be flexible enough to allow the designer to enter more detailed data to override default assumptions and quantities should they become known more accurately. This paper describes the development of the design tool, assumptions used in setting the default parameters and commentary on the sources of information used for the carbon data. An illustration of its use in comparing a typical steel–concrete composite bridge with an equivalent concrete bridge is also provided. It is intended that the design tool will be used by bridge designers to help quantify the embodied and operational carbon dioxide of steel–concrete composite bridges at all stages in their life-cycle, facilitate reductions in the carbon dioxide footprint during construction and maintenance by allowing alternatives to be rapidly assessed, and benchmark projects to facilitate continuous improvement with respect to carbon dioxide.
Using Eurocodes and Aashto for assessing shear in slab bridges
Authors: Lantsoght Eva O. L. , van der Veen Cor , de Boer Ane , Walraven Joost C.
Published: July 2016

Reinforced concrete short-span solid-slab bridges are used to compare Dutch and North American practices. As an assessment of existing solid-slab bridges in the Netherlands showed that the shear capacity is often governing, this paper provides a comparison between Aashto (American Association of State Highway and Transportation Officials) practice and a method based on the Eurocodes, and recommendations from experimental research for the shear capacity of slab bridges under live loads. The results from recent slab shear experiments conducted at Delft University of Technology indicate that slabs benefit from transverse force redistribution. For ten selected cases of straight solid-slab bridges, unity checks (the ratio between the design value of the applied shear force and the design beam shear resistance) are calculated according to the Eurocode-based method and the Aashto method. The results show similar design shear forces but higher shear resistances in the North American practice, which is not surprising as the associated reliability index for Aashto is lower.
Reinforced-concrete beam hinge joint fatigue assessment
Authors: Cousins David Peter
Published: July 2016

A major highway underbridge has been subjected to a complex fatigue assessment to determine its present and future serviceability. Similar to approximately 100 other structures within Great Britain, reinforced-concrete deck hinge joints are positioned within longitudinal beams providing rotational flexibility. Concerns were raised as to the fatigue condition of the hinge joints considering repetitive rotations applied by traffic loading and pitting corrosion found on reinforcement bars. This paper describes the assessment work and associated research relating to this structure including finite-element analysis, laboratory models and space frame modelling of the structure. Comments are made on the applicability of current codes of practice for fatigue assessment of reinforced-concrete deck hinge joints.
Bridge model updating using distributed sensor data
Authors: Bentz Evan C. , Hoult Neil A.
Published: July 2016

One of the challenges of managing bridge infrastructure is developing numerical models that can be used to accurately assess highly redundant bridge systems. One way to refine the model is to use sensor data to perform model updating. However, conventional sensors provide limited data with which to update the model, given the many degrees of freedom associated with indeterminate structures, resulting in a large potential error. Distributed sensing technologies such as digital image correlation and fibre optic strain sensors have the potential to provide more extensive data sets for model updating. This paper presents a case study of a reinforced concrete bridge that was modelled numerically to predict the bridge performance. The bridge was then load tested, and distributed sensor data were acquired. Using the sensor data, the numerical model was updated and refined estimates of the bridge behaviour were obtained. The initial and final models produced estimates of bridge behaviour that differed by an order of magnitude, illustrating the importance of sensor data for some bridge assessments. Additionally, the model indicated that the stiffness of the bridge had increased with time owing to an increase in the elastic modulus of the concrete and the development of compressive stresses.
Multiple-span suspension bridges: state of the art
Authors: Collings David
Published: July 2016

This paper provides a state-of-the-art review of the design and construction of multiple-span suspension bridges. It starts with a brief introduction to the key issues associated with multi-span suspension bridges and then gives a historical review of this bridge form together with a list of multi-span suspension bridges constructed from 1800 to the present day. The paper looks at and compares the deflection characteristics of the classic suspension bridge with multi-span suspension bridges. The paper outlines the problems associated with this bridge form, primarily caused by increased flexibility, and the ways that they can be and have been overcome. Actual bridges where they exist (or formerly existed) are referred to and the paper also looks at some current and proposed future projects using multiple-span suspension bridges. Much of the recent work on this subject has been carried out in China, and translations of the abstracts of some recent Chinese papers are included in an appendix to the paper.
Strength properties of epoxy resin–soil–cement mixtures
Authors: Anagnostopoulos Costas A.
Published: July 2016

The use of new materials for soil strengthening is crucial for geotechnical engineering, especially in methods that are commonly used for ground improvement, such as deep mixing. The main objective of this study was to investigate the potential use of two-component water-soluble epoxy resins to improve the mechanical properties (compressive strength, splitting tensile strength, elastic modulus, shear strength parameters) of clay soils, because the efficacy of these resins on soil strengthening has not yet been properly investigated. The experiments were conducted using soil mixes with different epoxy resin-to-water ratios, solid-to-water ratios and cement content. The results of this study indicate that epoxy resin, when combined with cement, improves the mechanical properties of the clay soil significantly, and could provide a suitable solution for deep mixing method applications or other geotechnical operations. Based on the experimental results, a non-linear regression analysis was performed to correlate the mechanical properties of the mixes with epoxy resin, water, solid, cement content and curing time. The accuracy of the produced model was found to be satisfactory.
Crushed concrete in road structures – two decades of experience
Authors: Dettenborn Taavi , Forsman Juha , Korkiala-Tanttu Leena
Published: July 2016

Since the early 1990s, crushed concrete aggregate (CCA)/recycled concrete aggregate has been successfully used in Finnish road constructions. The aim of this paper is to analyse the long-term behaviour of CCA and to compare CCA with conventional mineral aggregates in road structures. The analysed trial sections consist of the road and highway pavements where CCA has been used in the base and subbase layers. The first studied Finnish trial section was constructed in 1995, which has enabled nearly two decades of follow-up studies. In total, five follow-up trial sections were studied. E-modulus of pavement layers was determined using the deflection data from falling weight deflectometer measurements. The studies revealed excellent long-term behaviour in the CCA build pavements and validated the suitability of chosen design parameters in previous guidelines. In this study, the sections consisting of maximum 50 mm particles of CCA in the base or subbase layer gained 10–25% larger bearing capacity in 13–15 years after construction than the reference pavements that were constructed with crushed rock. The increase of the CCA stiffness was faster in the first years after construction and in the 2–5 years little or insignificant increase in such stiffness could be observed.
Masonry mortar with nanoparticles at a low temperature
Authors: Kazempour Hooman , Bassuoni Mohamed T. , Hashemian Fariborz
Published: July 2016

This study explores a possible approach for alleviating the effects of low temperatures on masonry construction through the addition of nano-alumina (NA) and nano-silica (NS) in masonry mortar mixtures (used for joints) mixed and cured at 5 ± 1°C. Fresh (flow, air content, setting time) and hydration, hardened (compressive strength) and microstructural characteristics of the mortar mixtures were determined at different ages to capture the behaviour of masonry mortar at the low temperature. The type (NA or NS) and dosage (2, 4 and 6% by mass of masonry cement) of the nanoparticles had very pronounced effects on the trends of the various tests. The overall trends suggest that either 6% NA or 6% NS can alleviate the effects of low temperature on masonry mortar mixtures in terms of accelerating the kinetics of hydration and rate of hardening, and inducing (especially NS) progressive microstructural and strength development with time.
Alkali–aggregate reaction: performance testing, exposure sites and regulations
Authors: Lindgård Jan , Fournier Benoit , Rønning Terje F. , Thomas Michael D. A.
Published: July 2016

Several laboratory performance tests for alkali–aggregate reaction (AAR) have been used worldwide for about 20 years. However, a review performed one of the present authors in 2006 concluded that none of the test methods meets all the criteria for an ideal performance test. In the last decade, research has been performed in several countries with the aim to improve current AAR performance test methods and develop alternative tests. The Rilem (The International Union of Laboratories and Experts in Construction Materials, Systems and Structures) Technical Committee (TC) 258-AAA (2014–2019) is also focusing on this topic. The main purpose of this technical committee is to develop and promote a reliable performance-based testing concept for the prevention of deleterious AAR. Strong emphasis will be placed on the implementation of the Rilem methods and recommendations as national and international standards. It is crucial to link the results from the accelerated laboratory testing to field behaviour, primarily against field exposure sites. Some results from such exposure sites are included in this paper.
Effect of acrylic latex on the properties of cement grouts
Authors: Anagnostopoulos Costas A. , Patsios Angelos
Published: July 2016

The main objective of this comprehensive laboratory project was to investigate the potential use of acrylic latex to improve the physical and mechanical properties of thick superplasticised cement grouts. Experiments were conducted using different acrylic latex dosages with cement grouts that were prepared with water/cement ratios of 0·5, 0·4 and 0·33. The results indicated that the addition of acrylic latex of up to 5% significantly increases the 28 and 90 d strength, despite an extension of the setting time. The bleeding and resistance to acid attack of acrylic latex modified grouts were significantly improved. Grouts containing acrylic latex had much a higher viscosity and yield stress than the un-modified grouts. However, acrylic latex reduces the viscosity and yield stress of grouts that were prepared with water to cement ratios of 0·5 and 0·4 when added in small amounts. Based on the experimental results, non-linear regression analysis was performed to correlate the physical and mechanical parameters of the acrylic latex modified grouts and the descriptor variables.
Modelling rotational failure in confined geometries using DLO
Authors: Smith Colin C. , Gilbert Matthew
Published: July 2016

Discontinuity layout optimisation (DLO) is a generally applicable numerical limit analysis procedure that can be used to identify critical plastic collapse mechanisms in engineering problems. Considering the modelling of in-plane failure, the authors have previously presented a formulation capable of identifying rotational failure mechanisms in non-dilating media. However, the formulation presented did not explicitly address cases involving confined geometries, where curved slip lines could potentially intersect boundaries. In this paper, methods are outlined which permit efficient modelling of such cases. Details of the kinematic and equilibrium formulations are provided, which are then verified through application to various geotechnical and structural mechanics problems. It is shown that results of high accuracy can be obtained, both in terms of the predicted collapse load and the corresponding failure mechanism.
Modelling impact resistance of polymer-laminated steelwork
Authors: Kadhim Majid , Wu Zhangjian , Cunningham Lee
Published: July 2016

This paper reports on the numerical simulation of a series of steel beams strengthened with carbon-fibre-reinforced polymer laminates and subject to impact loads. Non-linear finite-element analysis was conducted using a proposed model validated by way of comparison with available experimental tests. The numerical model includes the effect of strain rate for steel using the Johnson–Cook model, while for the laminate and adhesive materials the Cowper–Symonds model is used. Several possible failure modes for the strengthened member can be captured using the model such as the global steel failure, polymer rupture and debonding between steel members and polymer laminates. The numerical results show that the use of externally bonded laminates decreases mid-span deflection of strengthened beams in the series by 11%. While having the same level of impact kinetic energy, it is found that a beam struck at a lesser velocity and with a larger mass of impactor tends to have higher deflection, for both strengthened and unstrengthened cases. Additional key parameters such as laminate thickness are also investigated in this study.
Modelling of tsunami-induced bore and structure interaction
Authors: Pringgana Gede , Cunningham Lee S. , Rogers Benedict D.
Published: July 2016

A series of three-dimensional smoothed particle hydrodynamics (SPH) and finite-element (FE) models, with a domain in the form of a water tank, were undertaken to simulate tsunami-induced bore impact on a discrete onshore structure on a dry bed. The fluid motion was simulated using the SPH-based software DualSPHysics. The tsunami-like waves were represented by solitary waves with different characteristics generated by the numerical paddle wavemaker. Numerical probes were uniformly distributed on the structure's vertical surface providing detailed measures of the pressure distribution across the structure. The peak impact locations on the structure's surface were specifically determined and the associated peak pressures then compared with the prediction of existing commonly used design equations. Using the pressure–time histories from the SPH model, FE analysis was conducted with Abaqus to model the dynamic response of a representative timber structure. The results show that the equations used to estimate the associated pressure for design purposes can be highly non-conservative. By gaining a detailed insight into the impact pressures and structure response, engineers have the potential means to optimise the design of structures under tsunami impact loads and improve survivability.
Air losses in compressed air tunnelling: a prediction model
Authors: Ahangar Asr Alireza , Javadi Akbar
Published: July 2016

Data (measurements) from a tunnel in Munich, Germany, were used to develop and validate a model to predict air loss volumes in the process of compressed air tunnelling. In the implemented case study, compressed air was used as a measure to control the groundwater followed by placing of a shotcrete lining as temporary support. Evolutionary polynomial regression (EPR) was used for modelling. EPR is a data-driven method based on evolutionary computing that aims to search for an explicit and structured polynomial model representing air losses. Comparisons made between the actual measurements and the model predictions showed robustness of the suggested model in learning and predicting the behaviour of the system. A sensitivity analysis was also performed on the developed model; this revealed the reliability of the model by correctly presenting the expected effects from air permeability of the soil despite the non-homogeneous and layered nature of the geo-materials involved in this case study.
Natural frequency analysis of offshore wind turbine monopiles
Authors: Ward Ian P.
Published: July 2016

A key requirement of offshore wind turbine foundations is that the fundamental frequency of the structure should lie within the required range stipulated by the turbine supplier. If this is not achieved then excessive turbine-induced dynamic stresses could be experienced by the foundation due to resonance. This paper describes an efficient procedure for calculating the natural frequency of a monopile foundation as might be used at the early design stage and through the project life cycle to ensure component compatibility and optimisation of the designed structure. The use of the procedure is demonstrated for an example structure and the methodology is used to explore how the design might be impacted by changes to key parameters. The results illuminate the need to understand the inter-relationship between the structure and the soil, and highlight the inadequacy of the current disjointed design process for tower and foundation.
Briefing: Arch bridges – unlocking their potential
Authors: Long Adrian , Nanukuttan Sreejith
Published: July 2016

Arch bridges are strong, durable, aesthetically pleasing and require little maintenance but very few have been built since the early 1900s. However, this trend has changed as more than 60 FlexiArch bridges have been installed since the system was launched in 2007. The FlexiArch uses precast concrete voussoirs, requires neither corrodible reinforcement, nor centring, can be installed in hours and is contractor friendly. Details of this innovative method of construction and installation of arch bridges are given and the enormous potential of the system for multi-span viaducts is also highlighted.