Dissertations / Theses on the topic 'Concrete construction – Testing'
To see the other types of publications on this topic, follow the link: Concrete construction – Testing.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Concrete construction – Testing.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Loedolff, Matthys Johannes. "The behaviour of reinforced concrete cantilever columns under lateral impact load." Thesis, Stellenbosch : Stellenbosch University, 1989. http://hdl.handle.net/10019.1/67104.
Full textAbstract:
Microreproduction of original thesis.Thesis (PhD)--Stellenbosch University, 1990.
Some digitised pages may appear illegible due to the condition of the original microfiche copy.
ENGLISH ABSTRACT: see item for full text
AFRIKAANSE OPSOMMING: sien item vir volteks.
2
Chai, Hsi-Wen. "Design and testing of self-compacting concrete." Thesis, University College London (University of London), 1998. http://discovery.ucl.ac.uk/1317644/.
Full textAbstract:
Self-compacting concrete (SCC) can flow into place and compact under its own weight into a uniform void free mass even in areas of congested reinforcement. The research reported in this thesis examined the production of SCC with readily available UK materials, with the overall aims of evaluating test methods and establishing a suitable mix design procedure. There have been significant recent developments and applications of SCC in several countries, notably Japan. A literature survey gave an understanding of the advantages and properties of SCC, test methods and the range of constituent materials and their relative proportions for its successful production. A range of SCC mixes can be produced with the common features of a lower aggregate content than conventional concrete and the use of superplasticizers. Most mixes also contained one or more of pulverized fuel ash, ground granulated blast furnace slag and an inert powder filler. A four stage experimental programme was carried out: *tests on pastes to assess the effect of the types and proportions of the powders and superplasticizers on the rheology. *tests on mortars to determine suitable dosage of superplasticizers for high fluidity, low segregation and low loss of workability with time after mixing. Flow spread and funnel tests were used. *tests on fresh concrete to enable suitable types and quantities of coarse aggregate to be combined with these mortars to produce SCC. Fluidity and viscosity were measured using slump flow and V-funnel tests, and passing ability using L- and U-type tests. Two-point workability tests were also carried out, and a novel way of assessing segregation resistance was developed. *tests on hardened concrete to determine compressive strength, bond to reinforcement and drying shrinkage. A mix design procedure, based on a method suggested by Japanese workers, has been developed. This includes optimisation of the mix with a linear optimisation tool from a commercial spreadsheet package.
3
Chan, Denny Yuk. "Structural integrity assessment of cantilevered type concrete structures by instrumented impact hammer (IIH) technique & ultrasonic pulse velocity (UPV) technique." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21174088a.pdf.
Full textAbstract:
Thesis (M.Sc.)--City University of Hong Kong, 2005.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Aug. 31, 2006) Includes bibliographical references.
4
Mong, Seng Ming. "Non-destructive evaluation with ultrasonic pulse velocity (UPV) in concrete structure." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21175032a.pdf.
Full textAbstract:
Thesis (M.Sc.)--City University of Hong Kong, 2005.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 4, 2006) Includes bibliographical references.
5
Lau, Connie K. Y. "Non-destructive evaluation with ultrasonic pulse velocity (UPV) in concrete structure." access abstract and table of contents access full-text, 2005. http://libweb.cityu.edu.hk/cgi-bin/ezdb/dissert.pl?msc-ap-b21174441a.pdf.
Full textAbstract:
Thesis (M.Sc.)--City University of Hong Kong, 2005.At head of title: City University of Hong Kong, Department of Physics and Materials Science, Master of Science in materials engineering & nanotechnology dissertation. Title from title screen (viewed on Sept. 1, 2006) Includes bibliographical references.
6
Wong, Koon-Wan. "Non-linear behaviour of reinforced concrete frames /." Title page, contents and abstract only, 1989. http://web4.library.adelaide.edu.au/theses/09PH/09phw872.pdf.
Full text
7
Kenyon, Jonn Mark. "Non-linear analysis of reinforced concrete plane frames /." Title page, table of contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phk368.pdf.
Full text
8
Machado, Rafael Ignacio. "Experimental investigation of steel tubed reinforced concrete columns." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19457.
Full text
9
Fung, Wing-kun, and 馮永根. "The use of recycled concrete in construction." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B30517643.
Full text
10
Atrushi, Dawood Soliman. "Tensile and Compressive Creep of Young Concrete : Testing and Modelling." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2003. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18.
Full textAbstract:
The thesis deals with experimental and numerical modelling to characterize early age tensile and compressive creep and its associated stress relaxation - which are very important properties in stress simulation of early age concrete. For this purpose a comprehensive work was carried out involving construction of a new tensile creep test equipment and development of test procedures to generate basic experimental data.
The experimental program is subdivided into four series. Each of the series involves one varying parameter, which is relevant to the time-dependent behaviour of early age HPC. Most of the tests are repeated to check the reproducibility of the test results. The reproducibility of the test results for the BASE concretes confirmed that the experimental setup is reliable, and that it can be used to determine tensile creep of concrete at early ages.
An extensive test program has been performed on HPC, with w/b = 0.40. The primary parameters studied were concrete ages at loading (1, 2, 3, 4, 6 and 8 days), stress/strength levels (20-80%), and temperature levels (20, 34, 40, 57 and 60 oC) in addition to the effect of silica fume (0-15%) on tensile creep. The testing apparatus was new and significant efforts were devoted to develop reliable procedures in terms of accuracy and reproducibility. In parallel, compressive creep tests were conducted on a separate testing apparatus, and the results are compared to tensile creep behaviour.
It was found that the instantaneous deformation under tension is smaller than under compression, and that the corresponding creep curves also are different. Creep in tension is found to be lower initially, but an almost linear rate is soon established which is much higher than in compression. The consequence is greater creep magnitude and thus greater creep coefficient in tension than in compression. The tests on non-linearity showed that the proportionality limit between stress and sealed tensile creep strain is about 60% of the strength. Creep tests under isothermal temperatures showed that, as for compressive creep, the sealed tensile creep accelerates for temperatures higher than 20 oC. In addition, the maturity principle describes this effect reasonably well, for the tested loading ages of about 3 days.
The relatively large amount of experimental data, available in this study, has been used to investigate mathematical models. Comprehensive test results from the TSTM apparatus are analyzed with respect to creep and relaxation, where the effect of temperature on creep and relaxation is emphasized. Simulations of self-induced stresses are performed using the creep model denoted the Double Power Law (DPL). As solution method, the theory of linear viscoelasticity with aging is used. The model (M-DPL) is modified to take into account the effect of irrecoverable creep.
For increasing temperatures during the hardening phase, the transient creep, which takes place during heating is taken into account by an additional creep term. Its contribution to stress relaxation was found to be up to 10%. This transient creep term is considered to be irrecoverable during the subsequent temperature decrease. The modified model captures the various characteristics of sealed creep and describes the tensile behaviour at early ages more accurately than the original Double Power Law.
The effect of relaxation is found to be relatively large and significant in development of selfinduced stresses. Under isothermal temperature of 20 oC, the relaxation increases to about 40% of the fictive elastic stresses after 3 days and remains about constant after that. On the other hand, presentation of relaxation under realistic temperature histories is much more complicated, because the stresses change from compression to tension. This might also lead to increased tensile stresses because compressive creep reduces compressive stresses, but increases the subsequent tensile stresses. Underestimation of creep in this early period will lead to underestimation of the cracking risk.
Creep development at very early ages has an important effect in determination of the creep model parameters. After an evaluation of the test results using six loading ages (1, 2, 3, 4, 6 and 8 days) it was concluded that an optimal test program should include at least 3 loading ages, in which the loading ages 1 and 2 must be included.
Furthermore, the test results indicate that partial replacement of cement with silica fume (5-15%) increases the sealed tensile creep. However, the reference concrete without silica fume dose not fit to this systematic pattern.
11
Shams, Mohamed Khalil. "Time-dependent behavior of high-performance concrete." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/20682.
Full text
12
Labonte, Ted. "Construction and testing of Type II AASHTO girders using self-consolidating concrete." [Gainesville, Fla.] : University of Florida, 2004. http://purl.fcla.edu/fcla/etd/UFE0007000.
Full text
13
Cassidy, Eric Dana. "Development and Structural Testing of FRP Reinforced OSB Panels for Disaster Resistant Construction." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/CassidyED2002.pdf.
Full text
14
Chau, Siu-lee, and 周小梨. "Effects of confinement and small axial load on flexural ductility of high-strength reinforced concrete beams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B31997661.
Full text
15
Lam, Wai-yin, and 林慧賢. "Experimental study on embedded steel plate composite coupling beams." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B26643352.
Full text
16
Yuan, Lie Ping. "Partial interaction behaviour of bolted side plated reinforced concrete beams." Title page, abstract and contents only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phl7161.pdf.
Full textAbstract:
Includes bibliographical references (p. 185-189) Aims to determine the effect of partial interaction on the behaviour of the concrete beam, plate and bolt connector components of the composite plated beam. Develops design rules for the determination of the ultimate capacity for bolted plate reinforced composite beams.
17
Gao, Shanshan, and 高珊珊. "Coring process monitoring for strength of grout, concrete and rock in laboratory testing." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2010. http://hub.hku.hk/bib/B45530361.
Full text
18
Samman, Tamim Abdulhadi. "Indeterminate reinforced concrete frames subjected to inelastic cyclic deformation." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184307.
Full textAbstract:
Four full-size statically indeterminate reinforced concrete frames with two symmetrical bays were tested to obtain sufficient data to evaluate the adequacy of the current ACI-ASCE Committee 352 design recommendations, as well as to determine whether a relaxation of some of the limits in these guidelines can be justified. Each specimen contained three 8.5-foot-long columns, connected at mid-height by two 9-foot-long beams. Initially, a constant axial load was applied to each column. The specimens were then subjected to a displacement-controlled loading schedule to simulate the type of displacements a frame may experience during a severe earthquake. In designing the specimens, the latest recommendations of the ACI-ASCE Committee 352 and the ACI building code ACI 318-83 were satisfied except for the following modifications: (1) the flexural strength ratio (M(R)) in the second specimen was reduced from 1.4 to 1.2, (2) the shear-stress factors (γ) in the joints of the third specimen were increased from 12 and 15 to 15 and 20 for the exterior and interior joints respectively, and (3) the number of the transverse reinforcements inside the right exterior joint in the fourth specimen was reduced from 4 to 2 sets of hoops. The conclusion inferred from the results indicate that for drift levels within the elastic range, the elongations and the rotations of the beam regions near the faces of the columns, in addition to the joint shear strains, were not affected by the design values for the primary variables in the last three specimens. For larger excursions into the inelastic range, the relaxation of the current Committee 352 design recommendations in the last three specimens not only showed a significant effect in reducing the elongations and the rotations of the beams, or in increasing the joint shear strains but led to lower energy dissipation of the specimens. Consequently, the current design guidelines by the ACI-ASCE Committee 352 yield statically indeterminate frames which exhibit sufficient ductility.
19
Slapkus, Adam. "Evaluation of Georgia's high performance concerete bridge." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/19479.
Full text
20
Xu, Jiangong Barnes Robert W. "Nondestructive evaluation of prestressed concrete structures by means of acoustic emissions monitoring." Auburn, Ala, 2008. http://hdl.handle.net/10415/1429.
Full text
21
Gravina, Rebecca Jane. "Non-linear overload behaviour and ductility of reinforced concrete flexural members containing 500MPa grade steel reinforcement." Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phg777.pdf.
Full textAbstract:
Includes corrigenda (inserted at front) and list of publications published as a result of this research. Includes bibliographical references (leaves 192-199) Investigates the overload behaviour and modes of collapse of reinforced concrete flexural members containing 500MPa grade reinforcing steel and evaluates the adequacy of current ductility requirements for design according to AS 3600 to ensure strength and safety.
22
Shami, Haroon I. "Evaluating permanent deformation in asphalt concrete using Georgia loaded wheel tester." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/19606.
Full text
23
Lam, Wai-yin, and 林慧賢. "Plate-reinforced composite coupling beams: experimental and numerical studies." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B37311797.
Full text
24
Zaina, Mazen Said Civil & Environmental Engineering Faculty of Engineering UNSW. "Strength and ductility of fibre reinforced high strength concrete columns." Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/22054.
Full textAbstract:
The main structural objectives in column design are strength and ductility. For higher strength concretes these design objectives are offset by generally poor concrete ductility and early spalling of the concrete cover. When fibres are added to the concrete the post peak characteristics are enhanced, both in tension and in compression. Most of the available experimental data, on fibre reinforced concrete and fibre reinforced high strength concrete columns, suggest that an improvement in both ductility and load carrying capacity due to the inclusion of the fibres. In this thesis the ductility and strength of fibre reinforced high strength concrete are investigated to evaluate the effect of the different parameters on the performance of columns. The investigation includes both experimental and the numerical approaches with 56 high strength fibre reinforced concrete columns being tested. The concrete strength ranged between 80 and 100 MPa and the columns were reinforced with 1, 2 or 2.6 percent, by weight, of end hooked steel fibres. The effect of corrugated Polypropylene fibres on the column performance was also examined. No early spalling of the cover was observed in any of the steel fibre reinforced column tested in this study. A numerical model was developed for analysis of fibre and non-fibre reinforced eccentrically loaded columns. The column is modelled as finite layers of reinforced concrete. Two types of layers are used, one to represent the hinged zone and the second the unloading portion of the column. As the concrete in the hinged layers goes beyond the peak for the stress verus strain in the concrete the section will continue to deform leading to a localised region within a column. The numerical model is compared with the test data and generally shows good correlation. Using the developed model, the parameters that affect ductility in fibre-reinforced high strength concrete columns are investigated and evaluated. A design model relating column ductility with confining pressure is proposed that includes the effects of the longitudinal reinforcement ratio, the loading eccentricity and the fibre properties and content and design recommendations are given.
25
Venkata, Vijai Kumar. "Development and testing of hurricane resistant laminated glass fiber reinforced composite window panels /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p1426111.
Full text
26
Draper, Jeffrey Dean. "Neural networks and non-destructive test/evaluation methods." Thesis, College Park, Maryland : University of Maryland, College Park, 1992. http://handle.dtic.mil/100.2/ADA254802.
Full textAbstract:
Thesis (M.S. in Civil Engineering)--University of Maryland, College Park, 1992."A scholarly paper submitted to Assistant Professor Ian Flood." Description based on title screen as viewed on April 16, 2009. Includes bibliographical references (p. 49-52). Also available in print.
27
Werner, Carl Scott. "Cyclic Behavior of Screen Grid Insulated Concrete Form Components." PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/364.
Full textAbstract:
The principle of sustainability in the built environment has become much more significant in the past decade, resulting in a push to develop building systems that are more energy efficient, durable, and use fewer natural resources. For residential and light commercial buildings, insulated concrete forms (ICF) have enjoyed increasing popularity for their ability to meet these new demands. ICFs are a stay-in-place concrete formwork system for building structural walls that are also highly insulated, among other benefits. Screen-grid ICFs (SGICF) are a small subset of ICFs that tend to use less concrete than standard ICFs and are sometimes made of recycled materials. These traits make SGICFs attractive, but there is a lack of understanding of their structural characteristics due to their irregular internal concrete structure. Because of this, structures using SGICFs are limited to heights no higher than two stories. Further study should show whether SGICFs structures can safely built to greater heights. This investigation studied two types of SGICFs at a component level in order to gain understanding of their lateral force and drift ratio capacities under cyclic loading. Several variables, including steel reinforcement details, the type of concrete, and the presence of the forms, were altered to measure their impact on the performance of the systems. Test results suggested that the ICF formwork increased lateral strength by up to 100% and lateral deformation capacity by up 60% when compared to identical specimens tested with the formwork removed. Results also showed that confinement of the cement, either by mesh hoops, spiral wire, or fiber-reinforced concrete improved the drift ratio at failure up to 500% when compared to specimens with no confinement material. Computer models were created to gauge their ability to replicate the behavior of the experimental test results. The models typically overestimated the lateral load resistance of the samples by 50-100%, and even more in some cases, depending on the reinforcement. The models were not reliable in determining the drift ratio at which the sample was considered to have failed. In some cases the model failed at 50% lower lateral deformations than the test specimen, while in others the model did not fail at all. Future studies should explore refinements of the models to increase their accuracy and usefulness, as well as accounting for the contributions do to the form material. Future studies should also include using spiral wires, mesh hoops, or fiber reinforced concrete in full-scale walls to verify their efficacy in improving overall wall performance.
28
Aules, Wisam Amer. "Behavior of Non-Ductile Slender Reinforced Concrete Columns Retrofit by CFRP Under Cyclic Loading." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4804.
Full textAbstract:
In the Middle East region and many countries in the world, older reinforced concrete (RC) columns are deemed to be weak in seismic resistance because of their low amount of reinforcement, low grades of concrete, and large spacing between the transverse reinforcement. The capacity of older RC columns that are also slender is further reduced due to the secondary moments. Appropriate retrofit techniques can improve the capacity and behavior of concrete members. In this study, externally bonded Carbon Fiber Reinforced Polymer (CFRP) retrofit technique was implemented to improve the behavior of RC columns tested under constant axial load and cyclic lateral load. The study included physical testing of five half-scale slender RC columns, with shear span to depth ratio of 7. Three specimens represented columns in a 2-story, and two specimens represented columns in a 4-story building. All specimens had identical cross sections, reinforcement detail, and concrete strength. Two specimens were control, two specimens were retrofit with CFRP in the lateral direction, and one specimen retrofit in the longitudinal and lateral directions. A computer model was created to predict the lateral load-displacement relations. The experimental results show improvement in the retrofit specimens in strength, ductility, and energy dissipation. The effect of retrofitting technique applied to two full-scale prototype RC buildings, a 2-story and a 4-story building located in two cities in Iraq, Baghdad, and Erbil, was determined using SAP2000.
29
Lopez, Ibaceta Alvaro Francisco. "Seismic Performance of Substandard Reinforced Concrete Bridge Columns under Subduction-Zone Ground Motions." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/4977.
Full textAbstract:
A large magnitude, long duration subduction earthquake is impending in the Pacific Northwest, which lies near the Cascadia Subduction Zone (CSZ). Great subduction zone earthquakes are the largest earthquakes in the world and are the sole source zones that can produce earthquakes greater than M8.5. Additionally, the increased duration of a CSZ earthquake may result in more structural damage than expected. Given such seismic hazard, the assessment of reinforced concrete substructures has become crucial in order to prioritize the bridges that may need to be retrofitted and to maintain the highway network operable after a major seismic event. Recent long duration subduction earthquakes occurred in Maule, Chile (Mw 8.8, 2010) and Tohoku, Japan (Mw 9.0, 2011) are a reminder of the importance of studying the effect of subduction ground motions on structural performance. For this purpose, the seismic performance of substandard circular reinforced concrete bridge columns was experimentally evaluated using shake table tests by comparing the column response from crustal and subduction ground motions. Three continuous reinforced columns and three lap-spliced columns were tested using records from 1989 Loma Prieta, 2010 Maule and 2011 Tohoku. The results of the large-scale experiments and numerical studies demonstrated that the increased duration of subduction ground motions affects the displacement capacity and can influence the failure mode of bridge columns. Furthermore, more damage was recorded under the subduction ground motions as compared to similar maximum deformations under the crustal ground motion. The larger number of plastic strain cycles imposed by subduction ground motions influence occurrence of reinforcement bar buckling at lower displacement compared to crustal ground motions. Moreover, based on the experimental and numerical results, subduction zone ground motion effects are considered to have a significant effect on the performance of bridge columns. Therefore, it is recommended to consider the effects of subduction zone earthquakes in the performance assessment of substandard bridges, or when choosing ground motions for nonlinear time-history analysis, especially in regions prone to subduction zone mega earthquakes. Finally, for substandard bridges not yet retrofitted or upgraded seismically, the following performance limit recommendation is proposed: for the damage state of collapse, which is related to the ODOT's Life Safety performance level, the maximum strain in the longitudinal reinforcement should be reduced from 0.09 (in./in.) to a value of 0.032 (in./in.) for locations where subduction zone earthquakes are expected, to take into consideration the occurrence of bar buckling.
30
Salam, Jamal Mohamad. "Application of cyclic uniaxial compression testing to investigate the effects of preload and other factors on the structural properties of concrete affected by alkali silica reaction." Thesis, Queen Mary, University of London, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261641.
Full text
31
Sheats, Matthew Reed. "Rehabilitation of reinforced concrete pier caps using carbon fiber reinforced composites." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19490.
Full text
32
Garth, John Stuart. "Experimental Investigation of Lateral Cyclic Behavior of Wood-Based Screen-Grid Insulated Concrete Form Walls." PDXScholar, 2014. https://pdxscholar.library.pdx.edu/open_access_etds/1857.
Full textAbstract:
Insulated concrete forms (ICFs) are green building components that are primarily used for residential wall construction. Unlike most polystyrene based ICF variants, the Faswall ICFs used in these experiments were significantly denser because they were made from recycled wood particles and cement. The current design approach for structures constructed with this type of wall form only allows the designer to consider the contribution of the reinforced concrete cores. Previous research has shown that this approach may be conservative. This project experimentally evaluated the lateral structural response of these types of grid ICF walls under increasing amplitude of in-plane cyclic loading. Two different height-to-length (aspect) ratios (approximately 2:1 and 1:1) were investigated, as was the effect of simultaneous gravity load. Furthermore, the reinforced concrete grid was exposed for each aspect ratio in order to examine the contribution of the ICF blocks to the lateral response. Analyses of hysteretic behaviors and failure modes indicated conservatism in the current design approach for estimating lateral strength and ignoring the beneficial contribution of the ICF blocks to overall performance. The presence of the wall forms increased the lateral shear capacity of the walls by an average of 42% (compared to the walls with forms removed), while also increasing the deformation capacity by an average of 102%. Furthermore, by considering an additional gravity load of 10 kips-per-lineal-foot (klf), the shear resistance of the walls increased by 32% (versus walls only subjected to self-weight), on average, and the deformation capacity of the walls increased by an average of 19%. Comparisons of the experimental results to several design equations led to the recommendation of a design equation that was previously accepted for another type of ICF system.
33
Ghasemi, Sahar. "Innovative Modular High Performance Lightweight Decks for Accelerated Bridge Construction." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2248.
Full textAbstract:
At an average age of 42 years, 10% of the nation’s over 607,000 bridges are posted for load restrictions, with an additional 15% considered structurally deficient or functionally obsolete. While there are major concerns with decks in 75% of structurally deficient bridges, often weight and geometry of the deck further limit the load rating and functionality of the bridge. Traditional deck systems and construction methods usually lead to prolonged periods of traffic delays, limiting options for transportation agencies to replace or widen a bridge, especially in urban areas.
The purpose of this study was to develop a new generation of ultra-lightweight super shallow solid deck systems to replace open grid steel decks on movable bridges and as well serve as a viable alternative in bridge deck replacements across the country. The study has led to a lightweight low-profile asymmetric waffle deck made with advanced materials. The asymmetry comes from the arrangement of primary and secondary ribs, respectively perpendicular and parallel to the direction of traffic. The waffle deck is made with ultrahigh performance concrete (UHPC) reinforced with either high-strength steel (HSS) or carbon fiber reinforced polymer (CFRP) reinforcement. With this combination, the deck weight was limited to below 21 psf and its overall depth to only 4 inch, while still meeting the strength and ductility demands for 4 ft. typical stringer spacing. It was further envisioned that the ultra-high strength of UHPC is best matched with the high strength of HSS or CFRP reinforcement for an efficient system and the ductile behavior of UHPC can help mask the linear elastic response of CFRP reinforcement and result in an overall ductile system. The issues of consideration from the design and constructability perspectives have included strength and stiffness, bond and development length for the reinforcement, punching shear and panel action. A series of experiments were conducted to help address these issues. Additionally full-size panels were made for testing under heavy vehicle simulator (HVS) at the accelerated pavement testing (APT) facility in Gainesville. Detailed finite element analyses were also carried out to help guide the design of this new generation of bridge decks. The research has confirmed the superior performance of the new deck system and its feasibility.
34
Bothma, Jacques. "The structural use of synthetic fibres : thickness design of concrete slabs on grade." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85877.
Full textAbstract:
Thesis (MScEng)-- Stellenbosch University, 2013.ENGLISH ABSTRACT: Concrete is used in most of the modern day infrastructure. It is a building material for which there exist various design codes and guidelines for its use and construction. It is strong in compression, but lacks tensile strength in its fresh and hardened states and, when unreinforced, fails in a brittle manner. The structural use of synthetic fibres in concrete is investigated in this study to determine its effect on enhancing the mechanical properties of concrete. Slabs on grade are used as the application for which the concrete is tested. The material behaviour is investigated in parallel with two floor design theories. These are the Westegaard theory and the Yield-Line theory. The Westegaard theory uses elastic theory to calculate floor thicknesses while the Yield-Line theory includes plastic behaviour. Conceptual designs are performed with the two theories and material parameters are determined from flexural tests conducted on synthetic fibre reinforced concrete (SynFRC) specimens. Large scale slab tests are performed to verify design values from the two theories. Higher loads till first-crack were measured during tests with concrete slabs reinforced with polypropylene fibres than for unreinforced concrete. It is found that the use of synthetic fibres in concrete increases the post-crack ductility of the material. The Westegaard theory is conservative in its design approach by over-estimating design thicknesses. This was concluded as unreinforced slabs reached higher failure loads than predicted by this theory. The Yield-Line theory predicts design thicknesses more accurately while still accounting for the requirements set by the ultimate- and serviceability limit states. By using SynFRC in combination with the Yield-Line theory as design method, thinner floor slabs can be obtained than with the Westegaard theory.
AFRIKAANSE OPSOMMING: Beton word gebruik as boumateriaal in meeste hedendaagse infrastruktuur. Daar bestaan verskeie ontwerp kodes en riglyne vir die gebruik en oprig van beton strukture. Alhoewel beton sterk in kompressie is, het beton ‘n swak treksterkte in beide die vars- en harde fases en faal dit in ‘n bros manier indien onbewapen. Die gebruik van sintetiese vesels in beton word in hierdie projek ondersoek om die invloed daarvan op die eienskappe van die meganiesegedrag van beton te bepaal. Grond geondersteunde vloere word as toepassing gebruik. Parallel met die materiaalgedrag wat ondersoek word, word twee ontwerpsteorieë ook ondersoek. Dit is die teorie van Westegaard en die Swig-Lyn teorie. Die teorie van Westegaard gebruik elastiese teorie in ontwerpsberekeninge terwyl die Swig-Lyn teorie ‘n plastiese analise gebruik. ‘n Konseptuele vloerontwerp is gedoen deur beide die ontwerpsmetodes te gebruik. Materiaalparameters is bepaal deur buig-toetse uit te voer op sintetiesevesel-bewapende beton. Grootskaalse betonblaaie is gegiet en getoets om die akkuraatheid van die twee metodes te verifieer. Die betonblaaie wat bewapen was met polipropileen vesels het groter laste gedra tot by faling as die blaaie wat nie bewapen was nie. Die vesels verbeter die gedrag van beton in die plastiese gebied van materiaalgedrag deurdat laste ondersteun word nadat die beton alreeds gekraak het. Die Westegaard teorie kan as konserwatief beskou word deurdat dit vloerdiktes oorskat. Hierdie stelling is gegrond op eksperimentele data wat bewys dat onbewapende betonblaaie groter laste kan dra as wat voorspel word deur die Westegaard teorie. Die Swig-Lyn teorie voorspel ontwerpsdiktes meer akkuraat terwyl daar steeds aan die vereistes van swigting en diensbaarheid voldoen word. Deur gebruik te maak van sintetiese vesels en die Swig-Lyn teorie kan dunner betonblaaie ontwerp word as met die Westegaard teorie.
35
Zerkane, Ali S. H. "Cyclic Loading Behavior of CFRP-Wrapped Non-Ductile Reinforced Concrete Beam-Column Joints." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3000.
Full textAbstract:
Use of fiber reinforced polymer (FRP) material has been a good solution for many problems in many fields. FRP is available in different types (carbon and glass) and shapes (sheets, rods, and laminates). Civil engineers have used this material to overcome the weakness of concrete members that may have been caused by substandard design or due to changes in the load distribution or to correct the weakness of concrete structures over time specially those subjected to hostile weather conditions. The attachment of FRP material to concrete surfaces to promote the function of the concrete members within the frame system is called Externally Bonded Fiber Reinforced Polymer Systems. Another common way to use the FRP is called Near Surface Mounted (NSM) whereby the material is inserted into the concrete members through grooves within the concrete cover. Concrete beam-column joints designed and constructed before 1970s were characterized by weak column-strong beam. Lack of transverse reinforcement within the joint reign, hence lack of ductility in the joints, and weak concrete could be one of the main reasons that many concrete buildings failed during earthquakes around the world. A technique was used in the present work to compensate for the lack of transverse reinforcement in the beam-column joint by using the carbon fiber reinforced polymer (CFRP) sheets as an Externally Bonded Fiber Reinforced Polymer System in order to retrofit the joint region, and to transfer the failure to the concrete beams. Six specimens in one third scale were designed, constructed, and tested. The proposed retrofitting technique proved to be very effective in improving the behavior of non-ductile beam-column joints, and to change the final mode of failure. The comparison between beam-column joints before and after retrofitting is presented in this study as exhibited by load versus deflection, load versus CFRP strain, energy dissipation, and ductility.
36
Murahidy, Alexander Gustav. "Design, construction, dynamic testing and computer modelling of a precast prestressed reinforced concrete frame building with rocking beam-column connections and ADAS elements." Thesis, University of Canterbury. Department of Civil Engineering, 2004. http://hdl.handle.net/10092/2514.
Full textAbstract:
Following a major earthquake event, essential public amenities such as medical facilities and
transport networks need to remain functional - not only to fulfil their ongoing role in serving
the community but also to cope with the added and immediate demand of a population
affected by a natural disaster. Furthermore, the economic implications of wide spread damage
to housing and commercial facilities should not be discounted. A shift in design approach is
required that is consistent with current trends towards performance based building design. The
present aim is to achieve seismic energy dissipation during the earthquake event, without the
aftermath of damage to structural elements, whilst maintaining design economies.
Structures permitted to rock on their foundations and provide recoverable rotations at the
beam-column interfaces offer significant advantages over those using conventional ductile
detailing. A jointed construction philosophy can be applied whereby structural elements are
connected with unbonded prestressing tendons. Supplemental damping is provided by
replaceable flexural steel components designed to deform inelastically. For this research a
multi-storey test building of one quarter scale has been constructed and tested on an
earthquake simulator at the University of Canterbury. A computer model has been developed
and a set ofpreliminary design procedures proposed.
37
Ogura, Hiroki, Venkatesh Naidu Nerella, and Viktor Mechtcherine. "Developing and Testing of Strain-Hardening Cement-Based Composites (SHCC) in the Context of 3D-Printing." Molecular Diversity Preservation International (MDPI), 2018. https://tud.qucosa.de/id/qucosa%3A33325.
Full textAbstract:
Incorporating reinforcement into the practice of digital concrete construction, often called 3D-concrete-printing, is a prerequisite for wide-ranging, structural applications of this new technology. Strain-Hardening Cement-based Composites (SHCC) offer one possible solution to this challenge. In this work, printable SHCC were developed and tested. The composites could be extruded through a nozzle of a 3D-printer so that continuous filaments could be deposited, one upon the other, to build lab-scaled wall specimens without noticeable deformation of the bottom layers. The specimens extracted from the printed walls exhibited multiple fine cracks and pronounced strain-hardening characteristics under uniaxial tensile loading, even for fiber volume fractions as low as 1.0%. In fact, the strain-hardening characteristics of printed specimens were superior to those of mold-cast SHCC specimens.
38
Crane, Charles Kennan. "Shear and shear friction of ultra-high performance concrete bridge girders." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34745.
Full textAbstract:
Ultra-High Performance Concrete (UHPC) is a new class of concrete characterized by no coarse aggregate, steel fiber reinforcement, low w/c, low permeability, compressive strength exceeding 29,000 psi (200 MPa), tensile strength ranging from 1,200 to 2,500 psi (8 to 17 MPa), and very high toughness. These properties make prestressed precast UHPC bridge girders a very attractive replacement material for steel bridge girders, particularly when site demands require a comparable beam depth to steel and a 100+ year life span is desired.
In order to efficiently utilize UHPC in bridge construction, it is necessary to create new design recommendations for its use. The interface between precast UHPC girder and cast-in-place concrete decks must be characterized in order to safely use composite design methods with this new material.
Due to the lack of reinforcing bars, all shear forces in UHPC girders have to be carried by the concrete and steel fibers. Current U.S. codes do not consider fiber reinforcement in calculating shear capacity. Fiber contribution must be accurately accounted for in shear equations in order to use UHPC.
Casting of UHPC may cause fibers to orient in the direction of casting. If fibers are preferentially oriented, physical properties of the concrete may also become anisotropic, which must be considered in design.
The current research provides new understanding of shear and shear friction phenomena in UHPC including:
*Current AASHTO codes provide a non-conservative estimate of interface shear performance of smooth UHPC interfaces with and without interface steel.
*Fluted interfaces can be created by impressing formliners into the surface of plastic UHPC. AASHTO and ACI codes for roughened interfaces are conservative for design of fluted UHPC interfaces.
*A new equation for the calculation of shear capacity of UHPC girders is presented which takes into account the contribution of steel fiber reinforcement.
*Fibers are shown to preferentially align in the direction of casting, which significantly affects compressive behavior of the UHPC.
39
Quevedo, Valéria Ramos Baltazar. "Estudo de composição para concreto extrudável para pré fabricados." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/999.
Full textAbstract:
CapesBem estabelecido e amplamente utilizado nas indústrias de polímeros e cerâmicas, o processo de extrusão vem sendo também explorado pela indústria de concreto. Embora a indústria de pré fabricados estruturais de concreto utilize superplastificantes, ainda não existem ensaios específicos para caracterizar o comportamento no estado fresco de concretos utilizados para extrusão. Foi observado que, mesmo em empresas de grande porte, a avaliação consiste no ensaio de abatimento em tronco de cone e na experiência intuitiva de um funcionário ao manipular o concreto com uma pá manual. No entanto o lançamento do concreto nos moldes é realizado por máquinas extrusoras que possuem maior força e constância na aplicação. Assim, a extrudabilidade do concreto é baseada no ensaio de “slump test” e na avaliação pessoal do operador, sendo confirmado num lote piloto no próprio processo industrial. Este trabalho teve como base o processo de fabricação de telhas extrudadas autoportantes. Visando simular algumas condições do processo de produção, foi realizada uma adaptação do ensaio da caixa-L, no qual foi inserido um vibrador de mangote no reservatório da caixa. O ensaio consistiu em avaliar o comportamento do concreto ao ser inserido no reservatório da caixa-L e logo após a abertura da comporta, com e sem vibração prévia do concreto no reservatório, para assim melhor definir um procedimento de ensaio. Para uma análise reológica foi proposta a realização de ensaio de squeeze-flow, realizado com argamassa e concreto da dosagem de concreto para extrusão. Foram utilizadas as mesmas configurações do ensaio utilizado para a argamassa: máquina de ensaio do tipo universal, célula de carga de 2000 N, prato superior e amostra, ambos com 10 cm de diâmetro, deformação livre, e com o diâmetro do punção igual ao diâmetro da amostra. Ensaios para adaptação da altura da amostra (5 cm) foram realizados de modo a evitar que ao invés de se deformar por cisalhamento ocorresse a compressão simples da brita. Foi realizada caracterização das matérias primas e testes de compactação, que determinaram a melhor proporção entre a areia fina natural, areia artificial e brita nas seguintes proporções: 25%: 25%: 50% e 0%: 50%: 50%, em massa. Para cada uma destas proporções, foram determinadas composições para o concreto com valores de “m” variando de 4,0, 4,5 e 5,0, que reduzem a quantidade de cimento em até 16%. Utilizou- se aditivo superplastificante de 3a geração à base de Policarboxilato. Para definir os teores de aditivo, foi realizado ensaio de slump test, referência na indústria para escolha de composição, definindo assim as 16 composições para estudo. A realização do ensaio possibilitou criar uma metodologia para verificar o comportamento do concreto sobre vibração, fornecendo informações tais como: aparência, coesão, tixotropia e o perfil do fluxo. Isso pode permitir realizar ajustes reais de trabalhabilidade do concreto com base nas características do processo de produção e perfil da peça extrudada. A análise reológica verificou que as condições de fluxo sofridas pela argamassa não são mantidas para o concreto, principalmente quanto à coesão e aderência. Outros fatores também foram observados, como a segregação, exsudação e comportamento ao longo do tempo. Os resultados mostram que ocorrem diferenças significativas, sendo que algumas características apresentadas na argamassa não se reproduzem no concreto. Ensaios de resistência mecânica à compressão mostraram que todas as composições atendem ao valor mínimo previsto em norma e quanto à trabalhabilidade observou-se que as composições somente com areia artificial apresentaram falta de coesão, perceptível no ensaio de slump test. Definiu-se o ensaio de caixa-L adaptado com vibração prévia como melhor procedimento de ensaio. Os resultados mostraram que mesmo composições com abatimento nulo, que seriam descartadas pela indústria, apresentaram trabalhabilidade e fluíram com vibração, sendo que os teores de aditivo influenciaram no perfil e no tempo do escoamento.
A well established and widely used in the industries of ceramics and polymers, the extrusion process has been also explored by the concrete industry. Although the industry of prefabricated structural concrete using superplasticizers, there are still no specific tests to characterize the behavior in the fresh concrete used for extrusion. Although the industry prefabricated concrete structural use superplasticizers, there're not no specific tests to characterize the behavior of the fresh concrete used for extrusion. It was observed that, even in large companies, the evaluation consists of the slump test in truncated cone and the intuitive experience of an employee to handle the concrete with a shovel manual. However the concrete cast in molds is done by extruding machines that have greater strength and consistency in application. Thus extrudability of concrete is based on the testing of "slump test" and the personal evaluation of the operator, being confirmed in a pilot batch in industrial process itself. This work was based on the manufacturing process of extruded tiles freestanding. Aiming to simulate some of the conditions of the production process, there was an adaptation of the test box-L, which was inserted in the reservoir hose vibrator housing. The test consisted in assessing the behavior of the concrete to be inserted into the reservoir from the L-box and immediately after opening the gate, with and without prior vibration of concrete in the tank, so as to better define a test procedure. For a rheological analysis was proposed to carry out squeeze flow test conducted with concrete mortar and concrete strength for extrusion. We used the same settings as used for the test mortar testing machine universal type, load cell 2000 N, and sample top plate, both 10 cm in diameter, free deformation, and the punch diameter equal to the diameter sample. Assays for adjusting the height of the sample (5 cm) were made in order to avoid that instead of being deformed by the compressive shear occur in the gravel. Was performed characterization of raw materials and compression testing which determined the best ratio between the fine sand natural, artificial sand and gravel in the following proportions: 25%: 25%: 50% to 0%: 50%: 50% by mass. For each of these ratios were determined for concrete compositions with values of "m" ranging from 4.0, 4.5 and 5.0, which reduces the amount of cement up to 16%. We used superplasticizer 3rd generation based Polycarboxylate. To set the content of admixture slump test was performed test, the industry benchmark for the choice of composition, thereby setting the 16 estudo.Para compositions for each of these ratios were determined for concrete compositions with values of "m" varying from 4.0, 4.5 and 5.0, which reduces the amount of cement up to 16%. We used superplasticizer 3rd generation based Polycarboxylate. The main test possible to create a methodology to assess the behavior of concrete on vibration, providing information such as: appearance, cohesion, thixotropy and flow profile. This can make adjustments allow real concrete workability based on the characteristics of the production process and extruded profile part. The rheological analysis verified that the flow conditions experienced by the cement is not retained in the concrete, especially in regard to cohesion and adhesion. Other factors were also observed, such as segregation, exudation and behavior over time. The results show that significant differences occur, and some features disclosed in the mortar on the concrete not reproduced. Testing of mechanical strength showed that all compositions meet the minimum standards set out in and about the workability was observed that the compositions only with artificial sand showed a lack of cohesion noticeable slump test. Set up the test L-box pre adapted as best vibration test procedure. The results showed that even compositions with zero rebate which would be discarded by the industry had flowed workability and vibration, and the admixture levels and influence the time profile of the flow.
40
Graeff, Matthew Kent. "The Repair of Laterally Damaged Concrete Bridge Girders Using Carbon Fiber Reinforcing Polymers (CFRP)." UNF Digital Commons, 2012. http://digitalcommons.unf.edu/etd/592.
Full textAbstract:
In recent years the use of carbon fiber reinforcing polymers (CFRP) to repair damaged structural components has become more accepted and practiced. However, the current reference for designing FRP systems to repair and strengthen reinforced concrete (RC) and prestressed concrete (PSC) girders has limitations. Similarly, very few resources address solutions for the debonding problem associated with CFRP laminates or the use of CFRP laminates to repair structural members with pre-existing damage. The included experimental program consists of testing both RC and PSC girders with simulated lateral damage and CFRP repairs. A total of 34 RC beams were statically tested under a 4-point loading until failure and had cross-section dimensions of 5” x 10” (14cm x 25.4cm), were 8’ long (2.44m), and were reinforced with either #3 or #4 mild steel rebar. 13 PSC girders having cross-section dimensions representing a half-scaled AASHTO type II shape, were 20’ long (6.1m), and were prestressed with five 7/16” (11.1mm) diameter low-lax 7-wire strands. Ten of the PSC girders were statically loaded until failure under a 4-point testing setup, but 3 PSC girders were dynamically tested under fatigue loading using a 3-point arrangement. Different configurations of CFRP laminates, number and spacing of CFRP transverse U-wraps, and amount of longitudinal CFRP layers are studied. The results present the flexural behavior of all specimen including load-deflection characteristics, strain characteristics, and modes of failure. Ultimately, results are used to recommend important considerations, needed criteria, and proper design procedures for a safe and optimized CFRP repair configuration.
41
El-Gharib, Georges. "Evaluation of the Empirical Deck Design for Vehicular Bridges." UNF Digital Commons, 2014. http://digitalcommons.unf.edu/etd/489.
Full textAbstract:
This research evaluated the feasibility of the empirical design method for reinforced concrete bridge decks for the Florida Department of Transportation [FDOT]. There are currently three methods used for deck design: empirical method, traditional method and finite element method. This research investigated and compared the steel reinforcement ratios and the stress developed in the reinforcing steel for the three different methods of deck design. This study included analysis of 15 bridge models that met the FDOT standards. The main beams were designed and load rated using commercial software to obtain live load deflections. The bridges were checked to verify that they met the empirical method conditions based on the FDOT Structures Design Guidelines – January 2009. The reinforced concrete decks were designed using the traditional design method. Then the bridges were analyzed using three-dimensional linear finite element models with moving live loads. The reinforced concrete decks were designed using dead load moment, live load moment, and future wearing surface moment obtained from the finite element models. The required reinforcing steel ratio obtained from the finite element method was compared to the required reinforcing steel ratio obtained from traditional design method and the empirical design method. Based on the type of beams, deck thicknesses, method of analysis, and other assumptions used in this study, in most cases the required reinforcing steel obtained from the finite element design is closer to that obtained from the empirical design method than that obtained from the traditional design method. It is recommended that the reinforcing steel ratio obtained from the empirical design method be used with increased deck thicknesses to control cracking in the bridge decks interior bays.
42
Bernard, Lukáš. "Stavební průzkum a diagnostika železobetonové konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409951.
Full textAbstract:
This diploma thesis deals with construction and technological survey of the reinforced concrete structure. The first part of the diploma thesis deals with the properties of the reinforced concrete and with the building survey methods applied in the second part of the thesis. The second part of the diploma thesis focuses on diagnostics of existing structure. More specifically, the hardness of the concrete is tested using a Schmidt hammer and then it is further specified by testing the cores. The reinforcement in the reinforced concrete is also tested using electromagnetic indicator, ground-penetrating radar, and chopped probes. Lastly, a static assessment of the selected girder and column is conducted.
43
Al-Soudani, Maha. "Diagnosis of reinforced concrete structures in civil engineering by GPR technology : development of alternate methods for precise geometric recognition." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30090.
Full textAbstract:
La méconnaissance de la géométrie réelle d'une structure mène à une évaluation incorrecte de son état. Par conséquent, une estimation imprécise de sa capacité portante, sa durabilité, sa stabilité et la nécessité de mettre en place une réparation ou un renforcement. En outre, l'optimisation du temps requis pour le processus de réparation a besoin de bien connaître les différentes parties de la structure à évaluer et également pour éviter les zones critiques telles que les aciers, les câbles, etc., lors de la réparation. Par conséquent, il est nécessaire d'utiliser des techniques d'évaluation non destructive (END) afin de connaître la géométrie réelle de la structure, notamment l'emplacement des armatures dans les structures en béton armé. Le GPR est considéré comme une technique non-destructive idéale pour détecter et localiser les renforts. Cependant, sa précision de localisation est limitée. Le but de ce projet de recherche a donc été d'accroître la précision du GPR en matière de reconnaissance géométrique interne de structures en béton armé. L'objectif principal de cette étude est de localiser précisément le positionnement des armatures dans le plan ausculté ainsi qu'en profondeur. Pour atteindre cet objectif, une nouvelle méthodologie de mesures et du traitement des signaux GPR a été proposée dans cette étude. Plusieurs configurations d'acquisition de données en utilisant des signaux simulés sont testées pour proposer et développer un algorithme d'imagerie du milieu de propagation afin de définir sa géométrie interne et de localiser précisément les barres de renforcement. Des traitements supplémentaires sont appliqués pour améliorer la précision de la détection et pour identifier les différentes interfaces dans le milieu testé. L'algorithme et le traitement sont appliqués aux signaux simulés. Des validations expérimentales ont ensuite été appliquées aux signaux réels acquis sur différentes dalles en béton armé. L'objectif est de tester la capacité de l'algorithme d'imagerie proposé pour localiser différents objets enfouis. Les résultats encourageants montrent que cet algorithme est capable d'estimer la position de différents objets enfouis et pas uniquement les armatures avec une erreur d'estimation de (0-1) mm. Les performances de l'algorithme ont été comparées à celles d'une méthode de migration et aux résultats de mesure obtenus avec un pachomètre. Ces comparaisons ont systématiquement révélé une meilleure précision de la localisation avec l'algorithme développé.Une autre étude a été proposée dans ce travail en testant l'algorithme avec des signaux réels modifiés. Ces signaux sont produits en réduisant le gain le moins possible. La conclusion la plus évidente de cette étude est que l'algorithme proposé est capable de localiser les différents objets même si les signaux réfléchis par eux sont de faible amplitudeLack of acquaintance in the real geometry of a structure leads to incorrect evaluation of its state. Consequently, this will lead to inaccurate estimation of bearing capacity, durability, stability and moreover, the need for repair or strengthening. Furthermore, optimization of the required time for repair process needs to well recognize the parts of structure to be assessed and also to avoid the critical zones such as reinforcing bars, cables, etc., during repairing. Therefore; it becomes necessary to use a non-destructive testing (NDT) method in order to know the real geometry of structure in particular, the location of reinforcements in reinforced concrete structures. GPR is considered as an ideal non-invasive technique in detecting and locating these reinforcements. However, its accuracy in localization is limited. The aim of this research project has therefore been to increase the accuracy of GPR in recognizing the internal geometry of reinforced concrete structures. The main objective of this study is to locate accurately the position of reinforcements into three dimensions. To achieve this purpose, a new methodology for GPR measurement and processing is proposed in this study.Several configurations of data acquisition using simulated signals are tested to propose and develop an appropriate imaging algorithm for the propagation medium to imagine its internal geometry and to locate accurately the reinforcing bars. Further processing are applied to improve the accuracy of detection and to identify the different interfaces in the tested medium. Both algorithm and processing are applied on simulated signals. Subsequent experimental validations have been applied using real signals acquired from different real reinforced concrete slabs. The goal is to test the ability of proposed imaging algorithm for the localization of different targets. The encouraging results indicate that this algorithm is able to estimate the position of different buried targets and not only the reinforcing bars with an estimation error of (0-1)mm.The performance of proposed algorithm has compared to those of migration method and to the results obtained from pachometer. These comparisons have systematically revealed a better localization accuracy using the developed algorithm.Another study has been proposed in this work by testing the algorithm using modified real signals. These signals are produced by reducing the gain as less as possible. The most obvious finding to emerge from this study is that the proposed algorithm is able to localize the different goals even if the signals reflected by them are of low amplitude
44
Thölken, Denise. "Efeito da rigidez de pilar parede no comportamento sísmico de edifício de concreto armado." Universidade Tecnológica Federal do Paraná, 2013. http://repositorio.utfpr.edu.br/jspui/handle/1/962.
Full textAbstract:
Este trabalho tem como objeto o estudo do efeito da rigidez de pilar parede no comportamento estrutural de edifícios de concreto armado submetidos a sismos. Foram consideradas as premissas da norma brasileira ABNT NBR15421:2006, que apresenta os critérios para projeto de estruturas resistentes a sismo. A análise linear com emprego dos métodos da norma - método das forças horizontais equivalentes, método espectral e histórico de aceleração no tempo - foi aplicada em edifícios com dois tipos de sistemas estruturais, sendo eles pórtico de concreto e sistema dual pórtico de concreto e pilar parede. Os resultados foram analisados nos pórticos de extremidade das estruturas nos sentidos longitudinal (x) e transversal (y), comparando-se os deslocamentos de cada pavimento e esforços cortantes, momento fletor e normal nas bases dos pilares. A comparação foi realizada entre os três métodos aplicados e os sistemas estruturais analisados.The aim of this work is to study the stiffness effect of wall columns on structural behavior of reinforced concrete buildings subjected to seismic action. The premises of the Brazilian standard ABNT NBR14521:2006 were considered, which presents criteria for earthquake resistant design of structures. The linear analysis employed the methods of the Brazilian standard - equivalent static load method, response spectrum analysis and time history method - were applied to buildings with two types of structural systems, namely concrete frame and dual system concrete frame and wall columns. The results were analyzed in edge frames structures in the longitudinal and transverse directions, comparing the displacement of each floor and shear, bending moment and axial forces on the bases of the columns. A comparison was made between the three methods applied and the structural systems analyzed.
45
Mai, Tien chinh. "Evaluation non destructive des matériaux de construction par technique électromagnétique aux fréquences radar : modélisation et expérimentation en laboratoire." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0384/document.
Full textAbstract:
Les structures en béton armé ou en bois se dégradent sous des actions mécaniques et climatiques. Les propriétés physiques et mécaniques de ces matériaux sont liées aux conditions d'exposition et à leurs variations. L’évaluation non destructive de ces propriétés en amont des dégradations est une nécessité pour les maîtres d'ouvrages afin de prédire la durée de vie des structures dans un contexte de gestion durable du patrimoine bâti. La présence d’eau dans les pores du béton est un facteur qui facilite la pénétration des agents agressifs (dioxyde de carbone, chlorures, etc. responsables de l’initiation de pathologies comme la corrosion des aciers). Pour le cas du matériau bois, les causes les plus fréquentes des détériorations sont souvent d’origine biologiques (champignons et insectes). L’humidité est également reconnue comme une des conditions les plus importantes pour le développement de ces attaques. Il est donc nécessaire d’évaluer et de quantifier la variation spatiale de l’humidité dans ces matériaux de construction pour limiter les actions de réparation. Le système radar (Ground Penetrating Radar, « GPR ») est un outil d’auscultation des matériaux totalement non destructif, rapide, compact et sans contact. Cette technique est basée sur la propagation des ondes électromagnétiques. Cette propagation est fortement liée à la permittivité et la conductivité du matériau qui sont très sensibles aux variations de l’humidité. L’objectif de cette thèse est double : d’une part, modéliser l’effet des variations de l’humidité dans un matériau homogène, multi-couches ou avec gradient, et d’autre part, de quantifier expérimentalement l’effet d’un gradient d’humidité sur le béton et celui de l’anisotropie sur le bois. Pour cela, un modèle analytique a été développé en se basant sur la notion des lois de mélange (ajustées sur des mesures expérimentales de la permittivité en prenant en compte l’effet de la dispersion fréquentielle) et sur la propagation d’une onde plane. Une simulation numérique a permis d’apprécier l’effet d’un gradient et d’un milieu anisotropique sur la vitesse de propagation des ondes radar. La phase expérimentale a été effectuée sur un matériau modèle homogène et isotrope comme le sable pour comparer les différentes méthodes de mesure de la vitesse de l’onde directe. Une analyse fréquentielle de l’atténuation a été également étudiée pour évaluer la dispersion de l’atténuation dans un milieu considéré comme homogène. La deuxième partie de l’expérimentation a consisté à suivre par mesures radar le séchage d’une dalle en béton instrumentée par capteurs d’humidité. Enfin, une campagne expérimentale sur des échantillons en bois de deux essences (Pin et Epicéa) soumis à des humidités variables entre 0 et 50% a été menée. La phase de modélisation et de simulation a montré que la dispersion fréquentielle est significative seulement dans le cas d’un béton humide à forte salinité et que l’anisotropie et le gradient ont un effet significatif sur la propagation. La phase expérimentale a montré que dans le cas d’un matériau homogène, la vitesse est indépendante de la distance émetteur-récepteur, et qu’elle est variable dans le cas d’un béton soumis à un gradient d’humidité. Enfin, les essais sur le bois montrent que la partie réelle de sa permittivité est croissante en fonction de l’humidité. Le contraste de permittivité entre direction longitudinale et transversale (tangentielle ou radiale) est négligeable à l’état sec du matériau et commence à être significatif à partir de la saturation des fibres. Cela permet de privilégier la direction longitudinale à la direction transversale pour évaluer l’humidité des structures en boisThe reinforced concrete or the timber structures are degraded under mechanical and climatic actions. Physical and mechanical properties of these materials are linked to outdoor exposure conditions and their variations. The early non-destructive evaluation of these properties before the initiation of degradations is a need for masters of structures in order to predict the service life of the structures in a context of sustainable management of the built heritage. The presence of water in the pores of the concrete is a factor which facilitates the penetration of aggressive agents (carbon dioxide, chlorides, etc. responsible of the initiation of pathologies such as steel corrosion). In the case of wood material, the most common causes of damage are often of biological origin (fungi and insects). Moisture is also recognized as one of the most important conditions for the development of these attacks. It is therefore necessary to evaluate and quantify the spatial variation of the humidity in the building materials to limit repair actions. The GPR system (Ground Penetrating Radar) is an auscultation tool of materials which is completely non-destructive, fast, compact, and contactless. This technique is based on the propagation of electromagnetic waves. This propagation is strongly linked to the permittivity and the conductivity of the material that are highly sensitive to changes in humidity. The objective of this thesis is twofold: first, modelling the effect of moisture variation in a homogeneous material, multi-layers or with gradient, and secondly, to experimentally quantify the effect of a moisture gradient on the concrete and the effect of the anisotropy (case of wood material). An analytical model has been developed based on the concept of mixing laws (Fitted on experimental measurements of the permittivity by taking into account the effect of the frequency dispersion) and the propagation of a plane wave. A numerical simulation was used to assess the effects of a gradient and the effect of an anisotropic medium on the propagation velocity of the radar waves. The experimental phase was performed on a homogeneous and isotropic model material such as sand to compare different measurement methods of the velocity of the direct wave. A frequency analysis of the attenuation was also examined to evaluate the dispersion of the attenuation in a considered homogeneous medium. The second part of the experiment was to monitor, by radar measurements, the drying of a concrete slab instrumented by humidity sensors. Finally, an experimental campaign on samples of two species of wood (Pine and Spruce) with different moisture content between 0 and 50% was conducted. The modelling and simulations phase has shown that the frequency dispersion is significant only in the case of wet concrete with a high salinity content. The anisotropy and the gradient have a significant effect on the spread. The experimental phase showed that in the case of a homogeneous material, the speed is independent of the offset (distance between transmitter and receiver), and it varies in the case of concrete with a moisture gradient. Finally, tests on the timber indicate that the real part of its permittivity increases as a function of moisture. The contrast between longitudinal and transverse direction (tangential or radial) is negligible in the dry state of the material and begins to be very significant from the fiber saturation point. It indicates that the longitudinal direction, instead of the transverse direction, is more convenient to measure the moisture of wood structures
46
Drbohlav, Martin. "Realizace rekonstrukce mostu u obce Planá." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392224.
Full textAbstract:
The part of the construction project "Reconstruction of the realization of the bridge at Planá" is elaborated. These are in particular the following: technical report for the construction tech-nological project, object time schedule of the construction, study of the implementation of the main technological stages of construction, project of the building site and implementation of the reinforced concrete structures.
47
Resl, Jaroslav. "Stavební průzkum a diagnostika konstrukce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240360.
Full textAbstract:
The thesis is focused on the overview of the diagnostic methods for engineering surveys reinforced concrete constructions. The practical part explains engineering surveys of industrial building, evaluation of concrete strength on existing building and results from search reinforcements on individual elements. Next part is focused on load testing precast floor slab removed from construction and evaluation load capacity. The last part include structural design of elected parts (precast floor slab and beam).
48
Vojtek, Ondřej. "Stavebně technologický projekt bytového domu v Brně - Slatině." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-372271.
Full textAbstract:
This diploma thesis deals with construction and technological project of apartment building in Brno – Slatina, Kigginsova street. Thesis focus on technological phase of monolithic rough superstructure and masonry work. For this phases were processed technogical specifications and controlling ad testing schedules. Within this thesis was also compiled technical report, solution of transport roads, technical report and drawings of site equipmet. For main object was compiled itemized budget, which was foundation for completing time schedule. In diploma thesis are further processed safety requirements and chosen construction details.
49
Těžký, Filip. "Příprava realizace bytového domu v Brně - Slatině." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-391973.
Full textAbstract:
The diploma thesis deals with the building - technological project of the apartment house in Brno - Slatina, Lučiny. The purpose will be an optimal design of construction progress with regard to finance and time. For this phase were processed the site equipment with the design of the lifting strap, the transport routes and the machine assembly. In addition, an item budget, which was followed by a detailed schedule. Based on these documents was created a balance of machines and workers. For monolithic constructions were developed a technological regulation and a control and test plan. Furthermore, the calculation of the decanting time and the design of the formwork turnover, supplemented by its drawing. In the diploma thesis is elaborated a plan for safety and health protection in the workplace and selected design details.
50
Ashrafi, Karzan, and Ahmed Ibrahim Ali. "Testning av betongskivor för inredningsändamål." Thesis, Linnéuniversitetet, Institutionen för byggteknik (BY), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-104763.
Full textAbstract:
Detta examensarbete syftar till att utveckla ett nytt sätt att använda betong för inredningsändamål. Betong har alltid använts i större byggnader, infrastruktur och andra kategorier. Nyligen började den moderna inredningen använda betong inomhus, till exempel som bänkskiva eller som en hylla. Arbetet fokuserar på en huvudfråga: Är betong ett bra materialval för inredning? För att besvara denna fråga bestämdes några punkter för att komma till huvudfrågan. Följande punkter behövde testat och analyserad för att komma till svaren: - Beräkna och testa betongens hållfasthet - Testa slagtålighet - Analysera hur betong reagerar med kemikalier med olika pH-värde - Förhållandet mellan miljö och betong - Studera produktionen av betong Laborationstest, litteraturskällor och fältstudier användes som metoder för att få ett resultat av ovan nämnda punkter. Resultaten visar att betong kan användas som inredningsändamål och kan användas i större utsträckning än vad som är fallet idag. Sammanfattningsvis är betong ett bra material som används för inredningsändamål och den framtida tekniken kommer att minska koldioxidutsläppen som följer med produktionen av betongen. Det kommer att göra betong ännu bättre som material att använda i framtiden.The following thesis aims to develop a new way to use concrete as interior material. Concrete has always been used in larger scale buildings, infrastructure and in other categories. Recently the modern interior design started to use concrete indoors for example as countertop or as a shelf. This thesis focuses on one main question: is concrete a good material choice for interior use. To answer that question, we decided to have sub questions to help to get to the main question. The following questions needed test and analysis methods to get to the answers: - Calculate and test the strength of concrete - Test impact resistance - Analyze how concrete reacts with chemicals with different PH-values - Study the production of concrete - Relation between environment and concrete Lab tests, literature sources, and field studies was used as methods to answer those questions. The results shows that concrete can be utilized as interior material and can be used to a greater extent than is the case today. In conclusion concrete is a good material as used for interior purposes and the future technology will decrease carbon dioxide emissions that comes with production of the concrete. That will make concrete even better as material to use in the future.