93,389 research outputs found
Settlement rehabilitation of a 35 year old building : case study integrated with analysis and implementation
No full textThis paper presents a rehabilitation project concerning the settlement of a 35 year old building. The foundation system of the northwest wing of the building consists of strip footings and slabon-grade. Differential settlement results in significant cracking of the masonry partition walls located on the footing and hence rehabilitation of the footing is required to stabilize the foundation system. Geotechnical and structural investigations are conducted, including site borings and analytical modeling based on one-dimensional consolidation theory that is incorporated into a finite element analysis. The predictive model exhibits that the differential settlement does not cause noticeable distress for the primary structural members, whereas the continued settlement affects use of the building. Site implementation is performed with the pushpile method to terminate the continuous settlement of the foundation
Rehabilitation of a water distribution system using\ud sequential multiobjective optimization models
No full textIdentification of the optimal rehabilitation plan for a large water distribution system (WDS) with a substantial number of decision\ud
variables is a challenging task, especially when no supercomputer facilities are available. This paper presents an initiative methodology for the\ud
rehabilitation of WDS based on three sequential stages of multiobjective optimization models for gradually identifying the best-known Pareto\ud
front (PF). A two-objective optimization model is used in the first two stages where the objectives are to minimize rehabilitated infrastructure\ud
costs and operational costs. The optimization model in the first stage applies to a skeletonized WDS. The PFs obtained in Stage 1 are further\ud
improved in Stage 2 using the same two-objective optimization problem but for the full network. The third stage employs a three-objective\ud
optimization model by minimizing the cost of additional pressure reducing valves (PRVs) as the third objective. The suggested methodology\ud
was demonstrated through use of a real and large WDS from the literature. Results show the efficiency of the suggested methodology to\ud
achieve the optimal solutions for a large WDS in a reasonable computational time. Results also suggest the minimum total costs that will be\ud
obtained once maximum leakage reduction is achieved due to maximum possible pipeline rehabilitation without increasing the existing tanks
An experimental investigation of cyclically, axially loaded piles in sand
No full textBibliography: leaves 91-93.The research work involved the installation and cyclic load testing of large-scale pressure-grouted, instrumented piles in sand in the laboratory. The major objective of this experimental investigation was to establish the effects of the mean cyclic load level and amplitude on the pile behaviour during cyclic loading. Of particular interest was the study of the skin friction distributions along the pile shafts in order to understand the processes involved. Cyclic loading was limited to one-way loading in load-controlled mode. A literature review showed a lack of experimental data on the cyclic behaviour of large-scale pressure-grouted piles. The results of a number of small model tests in sand are discussed and the major trends of pile performances are highlighted to facilitate comparison of the observations made in this research. It was found that no definite testing procedure for cyclically-loaded piles is common to the various investigations. A research program and procedure of load applications was therefore developed to allow the isolation of the individual influences of the most significant cyclic parameters, the mean cyclic load level and the amplitude. In total 12 piles were installed using the same sand preparation and pile installation techniques. The tests only varied with regard to the applied loading procedur
Vertical Uplift Resistance of a Group of Two Coaxial Anchors in Clay
No full textThe vertical uplift resistance for a group of two horizontal coaxial rigid strip anchors embedded in clay under undrained condition has been determined by using the upper bound theorem of limit analysis in combination with finite elements. An increase of undrained shear strength of soil mass with depth has been incorporated. The uplift factor F-c gamma has been computed. As compared to a single isolated anchor, a group of two anchors provides greater magnitude of the uplift resistance. For a given embedment ratio, the group of two anchors generates almost the maximum uplift resistance when the upper anchor is located midway between ground surface and the lower anchor. For a given embedment ratio, F-c gamma increases linearly with an increase in the normalized unit weight of soil mass up to a certain value before attaining a certain maximum magnitude; the maximum value of F-c gamma increases with an increase in embedment ratio. DOI: 10.1061/(ASCE)GT.19435606.0000599. (C) 2012 American Society of Civil Engineers
Computational Determination of Air Valves Capacity Using CFD Techniques
No full text[EN] The analysis of transient flow is necessary to design adequate protection systems that
support the oscillations of pressure produced in the operation of motor elements and regulation.
Air valves are generally used in pressurized water pipes to manage the air inside them. Under certain
circumstances, they can be used as an indirect control mechanism of the hydraulic transient.
Unfortunately, one of the major limitations is the reliability of information provided by manufacturers
and vendors, which is why experimental trials are usually used to characterize such devices.
The realization of these tests is not simple since they require an enormous volume of previously stored
air to be used in such experiments. Additionally, the costs are expensive. Consequently, it is necessary
to develop models that represent the behaviour of these devices. Although computational fluid
dynamics (CFD) techniques cannot completely replace measurements, the amount of experimentation
and the overall cost can be reduced significantly. This work approaches the characterization of air
valves using CFD techniques, including some experimental tests to calibrate and validate the results.
A mesh convergence analysis was made. The results show how the CFD models are an efficient
alternative to represent the behavior of air valves during the entry and exit of air to the system,
implying a better knowledge of the system to improve it.This research was funded by the Program Fondecyt Regular, grant number 1180660.García-Todolí, S.; Iglesias Rey, PL.; Mora Melia, D.; Martínez-Solano, FJ.; Fuertes-Miquel, VS. (2018). Computational Determination of Air Valves Capacity Using CFD Techniques. Water. 10(10):1-16. https://doi.org/10.3390/w10101433S1161010Liou, C. P., & Hunt, W. A. (1996). Filling of Pipelines with Undulating Elevation Profiles. Journal of Hydraulic Engineering, 122(10), 534-539. doi:10.1061/(asce)0733-9429(1996)122:10(534)Zhou, F., Hicks, F. E., & Steffler, P. M. (2002). Transient Flow in a Rapidly Filling Horizontal Pipe Containing Trapped Air. Journal of Hydraulic Engineering, 128(6), 625-634. doi:10.1061/(asce)0733-9429(2002)128:6(625)Laanearu, J., Annus, I., Koppel, T., Bergant, A., Vučković, S., Hou, Q., … van’t Westende, J. M. C. (2012). Emptying of Large-Scale Pipeline by Pressurized Air. Journal of Hydraulic Engineering, 138(12), 1090-1100. doi:10.1061/(asce)hy.1943-7900.0000631Apollonio, C., Balacco, G., Fontana, N., Giugni, M., Marini, G., & Piccinni, A. (2016). Hydraulic Transients Caused by Air Expulsion During Rapid Filling of Undulating Pipelines. Water, 8(1), 25. doi:10.3390/w8010025Zhou, F., Hicks, F. E., & Steffler, P. M. (2002). Observations of Air–Water Interaction in a Rapidly Filling Horizontal Pipe. Journal of Hydraulic Engineering, 128(6), 635-639. doi:10.1061/(asce)0733-9429(2002)128:6(635)Vasconcelos, J. G., Wright, S. J., & Roe, P. L. (2006). Improved Simulation of Flow Regime Transition in Sewers: Two-Component Pressure Approach. Journal of Hydraulic Engineering, 132(6), 553-562. doi:10.1061/(asce)0733-9429(2006)132:6(553)Li, J., & McCorquodale, A. (1999). Modeling Mixed Flow in Storm Sewers. Journal of Hydraulic Engineering, 125(11), 1170-1180. doi:10.1061/(asce)0733-9429(1999)125:11(1170)Ramezani, L., Karney, B., & Malekpour, A. (2015). The Challenge of Air Valves: A Selective Critical Literature Review. Journal of Water Resources Planning and Management, 141(10), 04015017. doi:10.1061/(asce)wr.1943-5452.0000530Stephenson, D. (1997). Effects of Air Valves and Pipework on Water Hammer Pressures. Journal of Transportation Engineering, 123(2), 101-106. doi:10.1061/(asce)0733-947x(1997)123:2(101)Bianchi, A., Mambretti, S., & Pianta, P. (2007). Practical Formulas for the Dimensioning of Air Valves. Journal of Hydraulic Engineering, 133(10), 1177-1180. doi:10.1061/(asce)0733-9429(2007)133:10(1177)De Martino, G., Fontana, N., & Giugni, M. (2008). Transient Flow Caused by Air Expulsion through an Orifice. Journal of Hydraulic Engineering, 134(9), 1395-1399. doi:10.1061/(asce)0733-9429(2008)134:9(1395)Bhosekar, V. V., Jothiprakash, V., & Deolalikar, P. B. (2012). Orifice Spillway Aerator: Hydraulic Design. Journal of Hydraulic Engineering, 138(6), 563-572. doi:10.1061/(asce)hy.1943-7900.0000548Iglesias-Rey, P. L., Fuertes-Miquel, V. S., García-Mares, F. J., & Martínez-Solano, J. J. (2014). Comparative Study of Intake and Exhaust Air Flows of Different Commercial Air Valves. Procedia Engineering, 89, 1412-1419. doi:10.1016/j.proeng.2014.11.467Martins, N. M. C., Soares, A. K., Ramos, H. M., & Covas, D. I. C. (2016). CFD modeling of transient flow in pressurized pipes. Computers & Fluids, 126, 129-140. doi:10.1016/j.compfluid.2015.12.002Zhou, L., Liu, D., & Ou, C. (2011). Simulation of Flow Transients in a Water Filling Pipe Containing Entrapped Air Pocket with VOF Model. Engineering Applications of Computational Fluid Mechanics, 5(1), 127-140. doi:10.1080/19942060.2011.11015357Davis, J. A., & Stewart, M. (2002). Predicting Globe Control Valve Performance—Part I: CFD Modeling. Journal of Fluids Engineering, 124(3), 772-777. doi:10.1115/1.1490108Stephens, D., Johnson, M. C., & Sharp, Z. B. (2012). Design Considerations for Fixed-Cone Valve with Baffled Hood. Journal of Hydraulic Engineering, 138(2), 204-209. doi:10.1061/(asce)hy.1943-7900.0000496Romero-Gomez, P., Ho, C. K., & Choi, C. Y. (2008). Mixing at Cross Junctions in Water Distribution Systems. I: Numerical Study. Journal of Water Resources Planning and Management, 134(3), 285-294. doi:10.1061/(asce)0733-9496(2008)134:3(285)Austin, R. G., Waanders, B. van B., McKenna, S., & Choi, C. Y. (2008). Mixing at Cross Junctions in Water Distribution Systems. II: Experimental Study. Journal of Water Resources Planning and Management, 134(3), 295-302. doi:10.1061/(asce)0733-9496(2008)134:3(295)Ho, C. K. (2008). Solute Mixing Models for Water-Distribution Pipe Networks. Journal of Hydraulic Engineering, 134(9), 1236-1244. doi:10.1061/(asce)0733-9429(2008)134:9(1236)Huang, J., Weber, L. J., & Lai, Y. G. (2002). Three-Dimensional Numerical Study of Flows in Open-Channel Junctions. Journal of Hydraulic Engineering, 128(3), 268-280. doi:10.1061/(asce)0733-9429(2002)128:3(268)Weber, L. J., Schumate, E. D., & Mawer, N. (2001). Experiments on Flow at a 90° Open-Channel Junction. Journal of Hydraulic Engineering, 127(5), 340-350. doi:10.1061/(asce)0733-9429(2001)127:5(340)Chanel, P. G., & Doering, J. C. (2008). Assessment of spillway modeling using computational fluid dynamics. Canadian Journal of Civil Engineering, 35(12), 1481-1485. doi:10.1139/l08-094Li, S., Cain, S., Wosnik, M., Miller, C., Kocahan, H., & Wyckoff, R. (2011). Numerical Modeling of Probable Maximum Flood Flowing through a System of Spillways. Journal of Hydraulic Engineering, 137(1), 66-74. doi:10.1061/(asce)hy.1943-7900.0000279Castillo, L., García, J., & Carrillo, J. (2017). Influence of Rack Slope and Approaching Conditions in Bottom Intake Systems. Water, 9(1), 65. doi:10.3390/w9010065Regueiro-Picallo, M., Naves, J., Anta, J., Puertas, J., & Suárez, J. (2016). Experimental and Numerical Analysis of Egg-Shaped Sewer Pipes Flow Performance. Water, 8(12), 587. doi:10.3390/w812058
Wind loads analysis at the anchorages of the Talavera de la Reina cable stayed bridge
No full textThis paper describes wind tunnel tests performed on wind tunnel models of the Talavera de la Reina cable stayed bridge. The work describes the aeroelastic model construction and it is focused on the evaluation and analysis of the mean and peak wind loads at the tower foundation and the cable anchorages since these data can be very useful by the bridge manufacturer as a support for the bridge design. The work is part of a complete wind tunnel study carried out to analyze the aeroelastic stability of the bridge
Dynamic Analysis of an Offshore Wind Turbine: Wind-Waves Nonlinear Interaction
No full textAn offshore wind turbine can be considered as a relatively complex structural system since several environmental factors (e.g. wind and waves) affect its dynamic behavior by generating both an active load and a resistant force to the structure's deformation induced by simultaneous actions. Besides the stochastic nature, also their mutual interaction should be considered as nonlinear phenomena could be crucial for optimal and cost-effective design. Another element of complexity lies in the presence of different parts, each one with its peculiar features, whose mutual interaction determines the overall dynamic response to non-stationary environmental and service loads. These are the reasons why a proper and safe approach to the analysis and design of offshore wind turbines requires a suitable technique for carrying out a structural and performances decomposition along with the adoption of advanced computation tools. In this work a finite element model for coupled wind-waves analysis is presented and the results of the dynamic behavior of a monopiletype support structure for offshore wind turbine are shown. © 2010 ASCE
Sequence alignment and structure of the AscE-AscG<sub>1–61</sub> complex.
No full text<p>(A) Protein sequences of AscE and AscG from <i>Aeromonas hydrophila</i> AH-1 were aligned with related proteins from <i>Pseudomonas aeruginosa</i> (PscE and PscG) and <i>Yersinia pestis</i> (YscE and YscG) using CLUSTLAW <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0019208#pone.0019208-Thompson1" target="_blank">[43]</a>. The α-helical secondary structures, as determined in the crystal structures of AscE-AscG<sub>1–61</sub>, PscE-PscF-PscG and YscE-YscF-YscG, are shaded in grey. The residues involved in forming the hydrophobic interface between AscE and AscG<sub>1–61</sub> are boxed. Residues 62 to 116 from the C-terminal disordered region of AscG are bold-faced. (B) Ribbon representations of the crystal structure of the complex formed between AscE (blue) and AscG<sub>1–61</sub> (red) at two different views. The ribbon diagrams were generated using the software Chimera <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0019208#pone.0019208-Pettersen1" target="_blank">[44]</a>. (C) The simulated-annealing <i>F<sub>o</sub>-F<sub>c</sub></i> omit map in the conserved region of AscE in the AscE-AscG<sub>1–61</sub> complex. The map is contoured at a level of 2.0 σ. Residues Met2 to Ala12 of AscE and all atoms within 2 Å of Met2 to Ala12 of AscE were omitted prior to refinement. The figure was generated with the graphics programs “PyMOL” <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0019208#pone.0019208-DeLano1" target="_blank">[45]</a>.</p
Discussion of “Measuring Energy Efficiency in Urban Water Systems Using a Mechanistic Approach” by Leon F. Gay and Sunil K. Sinha
No full textSe analiza un artículo publicado en la Revista y se evidencia que los indicadores propuestos por los autores no tienen demasiado sentido. En su lugar se proponen indicadores alternativos.Cabrera Rochera, E.; Cabrera Marcet, E.; Espert Alemany, VB.; Pardo, MÁ. (2013). Discussion of "Measuring energy efficiency in urban water systems using a mechanistic approach" by Leon F. Gay nad Sunil K. Sinha. Journal of Infrastructure Systems. 19(6):503-505. doi:10.1061/(ASCE)IS.1943-555X.0000072S50350519
Integrated Non-Destructive Survey for the Prediction of Remaining Servicing Life of Airfield APRONs
No full textThe project of rigid pavements in airport aprons is a complex process considering several factors, spanning from the critical aircraft that is expected to park in the stand to the subgrade bearing strength. However, issues occurring during the construction phase or overloading of the pavement are likely to reduce the service life with respect to the design expectations. This work presents outcomes from a still on-going non-destructive monitoring activity carried out from 2008 over three park stands located in APRON 700 in Fiumicino Airport of Rome, Italy. In particular, the three stands were subjected over the years to different loadings that produced various rate of damage of the concrete slabs. The area was surveyed, at different time intervals, by visual inspection of the cracking (i.e., calculation of the pavement condition index), heavy weight deflectometer (HWD) testing, and ground penetrating radar. By comparing the outcomes from NDTs with the visual evolution of the damages over the area, it was possible to stress out the evolution pattern of the decays and to determine a reliable domain of service life by means of damaging versus time prediction curves. © 2021 Airfield and Highway Pavements 2021: Airfield Pavement Technology - Selected Papers from the International Airfield and Highway Pavements Conference 2021. All rights reserved
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