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Search Results: 1 - 10 of 963 matches for " bridge "
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A New Type of Bridge, Mobilebridge? to Super-Quickly Recover a Bridge  [PDF]
Ichiro Ario, Yuki Chikahiro
World Journal of Engineering and Technology (WJET) , 2015, DOI: 10.4236/wjet.2015.33C025
Abstract:

Many natural disasters cause not only critical situations for facilities and resident’s residents’ life, but also significant damage to economy. It is obvious that quick rescue action must be undertaken and that there are many problems due to the occurrence of secondary disasters at rescue worksite. Basing Based on the previous study of deployable structures and the concept of the multi-folding micro-structures, we propose a new type of foldable bridge in form of scissor structure called the Mobile-bridge?. In this paper, we discuss the vehicle passing test performed on the real-scale Mobile-bridge in order to evaluate its mechanical characteristics and application limits. Moreover, we verified the compatibility between the result of calculations and experiments by means of theoretical modelling. The results show that it is sufficient to treat the load as equivalent nodal forces applied at the joints without including the stiffness of the deck.

Identification of Bridge Movement Mechanisms  [PDF]
Matthew T. Yarnold
Engineering (ENG) , 2014, DOI: 10.4236/eng.2014.69059
Abstract:

Bridge behavior is highly dependent upon the movement mechanisms present throughout the structure. These mechanisms (e.g. bearing, joints, etc.) have a substantial impact on the long-term durability and potential safety of the structure. A major distinguisher between the varieties of movement systems is their operating timescale. In some cases, they function rapidly, within fractions of a second, and in other cases gradually over days, months or even years. However, in nearly all cases, the lifecycle of the movement system is shorter than that of the bridge assuring the need for future intervention. Breakdown of a movement system can produce unintended forces/deformations that progressively degrade the structure. Identification and tracking of movement mechanisms proactively address long-term durability by helping to avoid these unintended consequences. A general framework for characterization of these mechanisms was developed. This framework was applied to an operating bridge that includes several critical mechanisms operating over different timescales. As a result of this and other studies, recommendations are provided for identification of bridge movement systems.

 

Sixth Scale Model Studies of Masonry Arch Rib Behaviour at Different Eccentricities  [PDF]
Abbagana Mohammed, T. G. Hughes
Open Journal of Civil Engineering (OJCE) , 2018, DOI: 10.4236/ojce.2018.84038
Abstract: This paper reports a validation study involving sixth scale masonry model to replicate prototype tests carried out on five unit high masonry prisms. In order to test the applicability of small masonry models to real life problems, an investigation into masonry behaviour relevant to the serviceability requirement of masonry arch bridges was chosen as prototype test to validate the small scale masonry tests. Only representative masonry specimens were considered in the study; this corresponded to parts of an arch ring in a complete masonry arch. Two mortar designations; designation iv and designation v were used. These weak mortars tend to conform better to existing old structures. Loads were applied at four eccentricities of 0, 5, 9, and 14 mm from the centre of the specimens. This corresponds to e/d ratios of 0, 0.14, 0.25, and 0.39, where e is the eccentricity of the load and d the length of the transverse section of the specimens. The result shows that validation study corresponds with prototype study for low eccentricities; therefore, strength enhancement is seen over the concentric compressive strength. However, this does not apply at higher eccentricities as specimens were noticed to fail by elastic instability characterised by tension debonding of the top mortar joint.
A New Design for Anterior Fixed Partial Denture, Combining Facial Porcelain and Lingual Metal; PTU Type II
A. Pahlevan
Journal of Dentistry of Tehran University of Medical Sciences , 2005,
Abstract: A new design for replacing a missing anterior tooth is described. In this article, a lingually fixed partial denture, its advantages, disadvantages, indication and contraindications have been explained. The ability of this design to replace a single missing central or lateral incisor is discussed.
A New Design for Anterior Porcelain Fused to Metal Fixed Prosthetic Restorations; PTU Type III
A. Pahlevan
Journal of Dentistry of Tehran University of Medical Sciences , 2006,
Abstract: A new design for anterior fixed-partial denture (FPD) and crown is described. This article presents its advantages, disadvantages, indications and contraindications.The new design which has been exercised for 8 years provides esthetics and high strength for the restorations and the results have been satisfactory.
A New Design for Anterior Laminate Fixed-Partial dentures; PTU Type I
A. Pahlevan
Journal of Dentistry of Tehran University of Medical Sciences , 2006,
Abstract: A new fixed-partial denture design using laminates is described for the replacement of a missing anterior tooth. In this article advantages, disadvantages, indications and contraindications of the new design have been discussed. This method is best suited forcases with missing incisors and esthetically compromised abutment teeth.
Genetic Algorithms-based Optimization of Cable Stayed Bridges  [PDF]
Venkat Lute, Akhil Upadhyay, Krishna Kumar Singh
Journal of Software Engineering and Applications (JSEA) , 2011, DOI: 10.4236/jsea.2011.410066
Abstract: Optimum design of cable stayed bridges depends on number of parameters. Design of Cable stayed bridge satisfying all practical constraints is challenging to the designers. Considering the huge number of design variables and practical constraints, Genetic Algorithms (GA) is most suitable for optimizing the cable stayed bridge. In the present work the optimum design is carried out by taking total material cost of bridge as objective function. During problem formulation most of the practical design variables and constraints are considered. Using genetic algorithms some parametric studies such as effect of geometric nonlinearity, effect of grouping of cables, effect of practical site constraints on tower height and side span, effect of bridge material, effect of cable layout, effect of extra-dosed bridges on optimum relative cost have been presented. Data base is prepared for new designers to estimate the relative cost of bridge.
Investigation of Infrasound Radiated from Highway Bridge Owing to Moving Truck  [PDF]
Saiji Fukada, Hiroyuki Okada, Hirokazu Hama, Takeshi Mitsuda
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.412155
Abstract:

Several complaints arose from houses near an object bridge about rattling sounds caused by infrasound, a low-frequency noise in the 0 - 20 Hz frequency range. In Japan, conventional trucks with a rear leaf suspension have vibration frequencies of about 3.0 Hz; furthermore, their tire spring vibration frequency is 10 - 20 Hz. Infrasound is radiated from the bridge owing to the truck’s suspension spring vibration and/or tire spring vibration. In this study, the bridge vibrations were investigated using test trucks or conventional trucks to determine the cause of rattling sounds. It was found that the truck’s spring vibration caused excessive bending vibration in the object bridge; this in turn was transmitted to nearby houses as infrasound. Various preventive measures for infrasound were then considered, and their effectiveness was investigated through a simulation of the dynamic response using a running truck. The difference between each measure’s effectiveness as obtained by a comparison with each simulation’s result provided a clear picture about the infrasound reduction methods in consideration of both construction cost and working difficulty.

Synthesis and Characterization of Novel μ-Carbonato Tetranuclear Copper Complexes [(Pip)4nCu4X4(CO3)2] in Aprotic Media  [PDF]
Mohamed A. El-Sayed, Hoda A. Elwakeil, Ahmed H. Abdel Salam, Hemmat A. Elbadawy
Open Journal of Inorganic Chemistry (OJIC) , 2016, DOI: 10.4236/ojic.2016.61004
Abstract: In this work, novel oxidative coupling complexes, [(Pip)4nCu4X4(CO3)2] (n = 1 or 2, X = Cl or Br, Pip = piperidine), are synthesized from the reaction of well characterized Lewis base [(Pip)4nCu4X4O2] with carbon dioxide as a Lewis acid in CH2Cl2. These carbonato-derivatives are isolated as stable solids. They are easily soluble in aprotic solvents as CH2Cl2or phNO2. Cryoscopic measurements support tetranuclear structure for all of them. Electronic spectra in the near infrared with high molecular absorptivity may be explained for tetranuclear cuban structure to fulfil 3 halo-ligands for each copper centre in [(Pip)4nCu4X4(CO3)2]. The EPR spectra for [(Pip)4nCu4X4(CO3)2] complexes are axial type of spectra (dx2-y2 G.S) suggesting elongated tetragonal distortion for all of them. Cyclic voltammograms for [(Pip)4nCu4X4(CO3)2] are irreversible in character. These tetranuclear carbonato complexes show catalytical activity. They initiate the oxidation of 2,6-dimethylphenol (DMP) to 3,3’,5,5’-tetramethyl-4,4’-diphenoquinone (DPQ).
Safety Indications of Navigation Audit for Tankers to Develop a Bridge Inspection Method  [PDF]
Murat Hasan Ali Altun, Serdar Kum
Journal of Computer and Communications (JCC) , 2019, DOI: 10.4236/jcc.2019.71003
Abstract: A significant amount of world trade has been carried out by maritime transportation. In 2016, world maritime trade volume increased by 2% and reached 10.3 billion tons, 55,057 global ton-miles. There has been a significant increase in quantity and tonnage of tankers, with the requirement for well qualified and experienced personnel in the maritime industry. Therefore, employment has become a serious problem. Major Oil Companies (MOCs), port states, classification societies, and flag states have increased the number of inspections on tankers due to safety concerns. Tanker inspections are becoming more difficult and inefficient due to intensive cargo operations. Inefficient, subjective or substandard inspections/evaluations are usually leading to incorrect decisions, and causing an unfair market. In addition, corrective actions cannot be carried out properly, and decision making authorities cannot give the best decisions about vessels and their operator companies due to lack of scientific methods. In this study, details are identified such as finding the root causes, identifying the risks, understanding the possible consequences, and determining the working areas during the ship crews’, operators’, auditors’ and charterers’ working and ship selection periods. Pairwise comparisons were carried out by means of surveys on ship masters (captains), chief officers, deck officers, and superintendents. Five criteria—Crew, Equipment, Company, Structure, and ISM (International Safety Management) were weighted using Analytical Hierarchy Process (AHP). Finally, Bridge Safety Support System (BSSS) was developed according to criteria weights. In this way, best choices can be offered to ship charterers about which ship is better for a company’s interests. And, carrying out bridge inspections and corrective actions will be more reliable and effective for maritime transportation. Statistical data and vessel improvements will be obtained in BSSS. As a result, fair market conditions will be available in maritime industry with the help of this study.
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