Дисертації з теми "Flexural members"
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1
Jiang, Yi Carleton University Dissertation Engineering Civil and Environmental. "Interactive design of continuous flexural steel members." Ottawa, 1995.
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2
Lau, Tak-bun Denvid. "Flexural ductility improvement of FRP-reinforced concrete members." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B38907756.
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El-Rimawi, J. A. "The Behaviour of Flexural Members under Fire Conditions." Thesis, University of Sheffield, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608342.
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Lau, Tak-bun Denvid, and 劉特斌. "Flexural ductility improvement of FRP-reinforced concrete members." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B38907756.
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Al-Sunna, Raed Akram Saliba. "Deflection behaviour of FRP reinforced concrete flexural members." Thesis, University of Sheffield, 2006. http://etheses.whiterose.ac.uk/3597/.
Повний текст джерелаАнотація:
The design of fibre reinforced polymer (FRP) reinforced concrete (RC) can often be governed by the serviceability limit state of deflection. Currently, the evaluation of short-term deflection of FRP RC is undertaken using radically different approaches, in both research and codes of practice. This study investigates the short-term deflection behaviour of FRP RC, both experimentally and analytically, and examines the merits of those different approaches. Experimentally, 28 RC beams and slabs with glass, carbon or steel rebars are tested under four-point loading. The main variables considered are the reinforcement ratio, modulus of elasticity and bond. In addition to measuring deflections, closely-spaced strain gauges are used to measure rebar strains between one forced crack at midspan and two naturally-occurring cracks on either side. This setup enables the investigation of rebar strains, tension stiffening and bond between flexural cracks. Furthermore, in connection with concrete strains at the extreme compressive concrete fibre, the flexural load-curvature relationship is evaluated experimentally and used to decompose the total deflection into flexural and shear-induced deflections. Analytically two numerical analysis methods are used to provide further insight into the experimental results. Finite element analysis with smeared modelling of cracks is used to predict and examine the stress-displacement response in detail. Cracked section analysis is used to provide upper-bound deflections and strains. This study also deals with the ACI and Eurocode 2 approaches for prediction of short- term deflection. The deflection prediction and tension stiffening expressions of these codes are evaluated against the experimental results of this and other studies. The main conclusion is that deflection of FRP RC is essentially due to flexural curvatures, and can be reasonably evaluated by the tension stiffening model of Eurocode 2. However, with reinforcement of relatively low axial stiffness, and depending on the reinforcement bond characteristics, shear-induced deformations become significant and may need to be evaluated.
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Shitindi, Rowland V. "IMPROVEMENT OF DUCTILITY IN FRP-CONCRETE FLEXURAL MEMBERS." Kyoto University, 1999. http://hdl.handle.net/2433/181308.
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Figueredo, Stacy L. (Stacy Lee) 1981. "Design of an endoscopic biopsy needle with flexural members." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38273.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 96-97).
As a minimally invasive means of extracting a tissue sample from a patient, current endoscopic biopsy needles generally do not preserve tissue histology and often require multiple attempts to obtain a tissue sample. This paper presents an endoscopic biopsy needle with internal flexures that enable tissue to enter the hollow needle and then be severed from surrounding tissue when the needle is withdrawn. Using force-deflection and sample weight data from 10x scaled prototypes, variations of a flexural design captured 1.1 grams of a tissue phantom on average, as compared to wedge-type designs that averaged of 0.7-0.8 grams. Peak entrance forces for the flexure design were lower than for both wedge and extended wedge designs, and resistance forces were higher upon needle extraction. A low-angle 15-degree feature produced lower entrance resistance and larger exit resistance compared with 30 degree, 45 degree, and 60 degree features, which is desirable when retaining tissue. Manufacturing of a 1x scale prototypes, using a grinding and laser cutting process, suggested that flexural features could be produced in current endoscopic biopsy needles, but changes to the beveled cutting tip would first have to be made before flexural elements could be tested on actual liver samples.
by Stacy L. Figueredo.
S.M.
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Groulx, Jean-Guy Joseph Carleton University Dissertation Engineering Civil and Environmental. "Investigation of wood flexural members reinforced with glass fibers." Ottawa, 1995.
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Lee, Jaeman. "Flexural and Shear Failure Mechanisms of Precast/Prestressed Concrete Members." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174917.
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Kong, Kok Loon. "Cracking and tension zone behaviour in reinforced concrete flexural members." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.427779.
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Adiyastuti, Sri Murti Civil & Environmental Engineering Faculty of Engineering UNSW. "Influence of cracks on chloride induced corrosion in reinforced concrete flexural members." Awarded by:University of New South Wales. School of Civil and Environmental Engineering, 2005. http://handle.unsw.edu.au/1959.4/31878.
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The penetration of chloride ions plays a crucial role in reinforcement corrosion and affects the durability and service life of marine structures. The problem is even more acute once cracking occurs in a concrete member. The presence of cracks is shown to have a significant impact on chloride penetration into concrete. It has been recognized, for concrete cracked in flexure, the chloride diffusion coefficient in the tension zone is higher than that in the compression zone. Even a single crack in the tensile zone could contribute to a higher diffusion coefficient compared to that of uncracked members. In this study, the influence of flexural cracks on chloride ion penetration into reinforced concrete beams has been investigated experimentally and a two-dimensional theoretical model is developed. The experimental study investigated the influence of multiple flexural cracks on the chloride diffusivity of reinforced concrete beams and on the corrosion rate of reinforcing bars. The size of the reinforced concrete beams tested is 200 x 250 x 2200 mm with 20mm concrete cover. The beams were pre-cracked using a compression testing machine and the crack widths induced were maintained between 0.1 mm to 0.2 mm. The chloride profile was determined after 1 month, 1 year and 2 years of immersion in 3.0% NaCl solution. The measured chloride profiles of the beams with multiple cracks are compared to those obtained from the uncracked (control) beam. An observation was also made on the effect of cracks on the corrosion development of steel bar after two years of immersion in salt solution. Chloride concentration varied linearly with the depth of crack (at crack planes). A twodimensional model using finite element analysis is developed to evaluate the chloride penetration into cracked concrete. This model was used to verify the chloride penetration data which is obtained from the experimental results. The prediction of chloride ingress, using the two dimensional model agrees well with the short-term and long-term chloride profiles.
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Fam, Amir Zakaria Yassa Hanna. "Concrete-filled fibre-reinforced polymer tubes for axial and flexural structural members." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0010/NQ53056.pdf.
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Dempsey, Dwight David. "Flexural strengthening of timber members with mechanically fastened fiber reinforced polymer strips." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/21265.
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Elgarf, Mahmoud Sabry Abdelwahhab. "The effect of reinforcement corrosion on the structural performance of concrete flexural members." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2004. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=59721.
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Goodfellow, Roderick Gerald Charles. "Ductility of reinforced concrete flexural members constructed from high performance steel and concrete." Thesis, Imperial College London, 1999. http://hdl.handle.net/10044/1/7645.
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Hirani, Aliasgar, George John, and Henry Mupeta. "Resistance of Members to Flexural Buckling According to Eurocode 3 : - Focus on Imperfections." Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-46636.
Повний текст джерелаАнотація:
This work focuses mainly on the resistance of members to flexural buckling according to Eurocode 3. The work provides the mathematical backgrounds to the equations and buckling curves presented in Eurocode 3. The work also, attempts to reveal how different imperfections influence the flexural buckling resistance which is demonstrated through Finite Element (FE) simulations. The work presents modeling and analysis on a steel column in ABAQUS 6.14. Linear and non-linear buckling analyses of the steel column, with the influence of imperfections, are implemented in this work. Specifically, the imperfections considered in this study are material plasticity, initial bow and residual stress. The influence of initial bow imperfection of 0.1% of the length of the column considering flexural buckling was found to be 45.28% of the Euler buckling load. The influence of residual stresses, with a magnitude of maximum about 13% in the flange and 35% in the web, of the yielding strength, on flexural buckling is about 31.9% of the design Euler buckling load. The combined effect of residual stress and initial bow imperfection on flexural buckling is about 45.34% of the design Euler buckling load.
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Chamberlain, James M. Jr. "Flexural Resistance Factors for Partially Prestressed Members Using ASTM A 1035 Reinforcing Steel." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1353154594.
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Wahalathantri, Buddhi Lankananda. "Damage assessment in reinforced concrete flexural members using modal strain energy based method." Thesis, Queensland University of Technology, 2012. https://eprints.qut.edu.au/59509/1/Buddhi_Wahalathantri_Thesis.pdf.
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Damage assessment (damage detection, localization and quantification) in structures and appropriate retrofitting will enable the safe and efficient function of the structures. In this context, many Vibration Based Damage Identification Techniques (VBDIT) have emerged with potential for accurate damage assessment. VBDITs have achieved significant research interest in recent years, mainly due to their non-destructive nature and ability to assess inaccessible and invisible damage locations. Damage Index (DI) methods are also vibration based, but they are not based on the structural model. DI methods are fast and inexpensive compared to the model-based methods and have the ability to automate the damage detection process. DI method analyses the change in vibration response of the structure between two states so that the damage can be identified. Extensive research has been carried out to apply the DI method to assess damage in steel structures. Comparatively, there has been very little research interest in the use of DI methods to assess damage in Reinforced Concrete (RC) structures due to the complexity of simulating the predominant damage type, the flexural crack. Flexural cracks in RC beams distribute non- linearly and propagate along all directions. Secondary cracks extend more rapidly along the longitudinal and transverse directions of a RC structure than propagation of existing cracks in the depth direction due to stress distribution caused by the tensile reinforcement. Simplified damage simulation techniques (such as reductions in the modulus or section depth or use of rotational spring elements) that have been extensively used with research on steel structures, cannot be applied to simulate flexural cracks in RC elements. This highlights a big gap in knowledge and as a consequence VBDITs have not been successfully applied to damage assessment in RC structures. This research will address the above gap in knowledge and will develop and apply a modal strain energy based DI method to assess damage in RC flexural members.
Firstly, this research evaluated different damage simulation techniques and recommended an appropriate technique to simulate the post cracking behaviour of RC structures. The ABAQUS finite element package was used throughout the study with properly validated material models. The damaged plasticity model was recommended as the method which can correctly simulate the post cracking behaviour of RC structures and was used in the rest of this study. Four different forms of Modal Strain Energy based Damage Indices (MSEDIs) were proposed to improve the damage assessment capability by minimising the numbers and intensities of false alarms. The developed MSEDIs were then used to automate the damage detection process by incorporating programmable algorithms. The developed algorithms have the ability to identify common issues associated with the vibration properties such as mode shifting and phase change. To minimise the effect of noise on the DI calculation process, this research proposed a sequential order of curve fitting technique. Finally, a statistical based damage assessment scheme was proposed to enhance the reliability of the damage assessment results. The proposed techniques were applied to locate damage in RC beams and slabs on girder bridge model to demonstrate their accuracy and efficiency.
The outcomes of this research will make a significant contribution to the technical knowledge of VBDIT and will enhance the accuracy of damage assessment in RC structures. The application of the research findings to RC flexural members will enable their safe and efficient performance.
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Sherry, Samuel Thomas. "Carbon Fiber Reinforced Polymer Retrofits to Increase the Flexural Capacity of Deteriorated Steel Members." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104986.
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The load-carrying capacity of aging bridge members may at times be found insufficient due to deterioration and a historical trend towards increased truck axle loads beyond their design capacity. Structurally deficient bridges are problematic for bridge owners and users because they restrict traffic usage and require bridges to be posted (operate at less than their ideal capacity). Structural deficiency is the primary motivation for bridge owners to retrofit bridges to meet a specified operating demand. It may be required to replace or retrofit a portion or all of a deficient bridge. The replacement of an entire bridge or even a part of the bridge is generally less desirable than a retrofit solution because retrofits are generally a cheaper alternative to the entire replacement of a structure and usually do not require the bridge's closure. Standard strengthening solutions for corroded members include bolting or welding steel cover plates, replacing sections of the girder, or adding external prestressed tendons. However, these methods also have several challenges, including required lane closures, high installation costs, increased dead weight, and continuing corrosion issues.
One alternative to conventional retrofits is the use of carbon fiber-reinforced polymer (CFRP) laminates, which can be adhered to increase both strength and stiffness. CFRPs are a highly tailorable material with an extremely high strength-to-weight ratio, ease of installation and can potentially mitigate further corrosion concerns. Fiber Reinforced Polymers (FRPs) have already been widely accepted as a means of retrofitting reinforced concrete structures (AASHTO 2012, 2018a; ACI 2002, 2017; National Academies of Sciences, Engineering 2010, 2019) but have not yet been widely adopted in the steel industry due to the retrofit's material limitations (lower elastic modulus [less than 29,000 ksi], unanswered questions related to debonding, and no unified design or installation guides). However, newly developed materials and manufacturing processes have allowed for the economic development of stiffer CFRP materials suitable for steel structures, such as the high modulus (HM) CFRP strand sheet.
This research analytically and experimentally investigates how newly developed HM strand sheets perform in small scale tensile testing and large scale flexural testing (laboratory and in situ testing). During the laboratory testing, these HM strand sheets were compared against normal modulus (NM) CFRP plates to draw conclusions on these different retrofitting materials (strength, stiffness, bond behavior, and applicability of the retrofit). Another central point in examing these different retrofit materials is how CFRPs perform when attached to structural steel with significant corrosion damage. Corrosion damage typically results in a variable surface profile, which may affect a CFRP retrofit's bond behavior. While limited laboratory testing has been conducted on CFRP attached to steel structures with simulated deterioration, the surface profile does not represent realistic conditions. The effects of a variable surface profile on the NM plate material and HM strand sheet were investigated using small scale tensile testing and large scale flexural testing. All the variable surface profiles tested for bond strength were fabricated based on "representative" simulated corrosion samples or on specimens with significant corrosion.
Once all the variables pertaining to the new materials and the effect of a variable surface profile on CFRP retrofits had been examined in a laboratory setting, these retrofitting techniques were implemented on deteriorated in-service steel bridge structures. This research was the first to retrofit deteriorated in-service bridge structures with HM CFRP strand sheets in the United States. This in situ testing was used to compare the laboratory test data of an individually retrofitted girder to the behavior of a single girder that had been retrofitted in a bridge structure. This information was used to verify results on the behaviors of strengthening, stiffening, effects on live load distributions, and modeling assumptions of retrofitted bridge structures.
The results from the laboratory testing and in situ testing of CFRP retrofits on corroded steel structures were synthesized to provide information on performance and design guidance for future retrofits. This dissertation provides additional information on CFRP retrofits applied to variable surface profiles and provides data on new CFRP materials (HM strand sheets). With this information, Departments of Transportation (DOT) can be confident as to where and when different types of CFRPs are a suitable retrofit material for corroded or uncorroded steel structures.Doctor of Philosophy
The capacity of aging bridges may at times be found insufficient due to deterioration and a trend towards increased loading. Structurally deficient bridges are problematic for bridge owners and users because they restrict traffic usage and require bridges to operate at less than their intended capacity. Inadequate capacity are the primary motivation for bridge owners to repair (retrofit) bridges to meet specified traffic demands. Repairs usually do not require the bridge's closure to traffic. Standard repairs for corroded steel members include bolting or welding steel cover plates, replacing sections of the girder, or adding external prestressed tendons. However, these methods also have several challenges, including required bridge closures, high installation costs, increased weight, and continuing corrosion issues. One alternative to conventional repairs is the use of carbon fiber-reinforced polymer (CFRP) laminates, which can be adhered to the deteriorated members to increase strength and stiffness. CFRPs are an extremely versatile material with high strength, high stiffness, ease of installation and can potentially mitigate concerns about further corrosion. Fiber Reinforced Polymers (FRPs) have already been widely accepted as a means of retrofitting reinforced concrete structures(AASHTO 2012, 2018a; ACI 2002, 2017; National Academies of Sciences, Engineering 2010, 2019) but have not yet been widely adopted in the steel industry due to the lack of literature and economical implementation of the CFRPs on steel. However, over the past 20 years, research has been completed on the application of CFRPs on steel, and newly developed materials were created for the economic implementation of CFRP materials suitable for steel structures. In particular, this material is a high modulus (HM) CFRP strand sheet, which has a higher stiffness than a conventional CFRP. This research investigated how newly developed HM strand sheets perform in small-scale laboratory testing and large-scale laboratory testing. Where material strengths, bondability, and the efficacy of different repairs were examined against conventional means on steel structures with and without corrosion deterioration. Once all the variables pertaining to the new materials and the effects corrosion had on CFRP retrofits had been examined in a laboratory setting, these retrofitting techniques were implemented on a deteriorated in-service steel bridge structure (field study) that required repair. This research was the first to repair deteriorated in-use bridge structures with HM CFRP strand sheets in the United States. This information was used to verify results on the material's behavior. The laboratory testing and field testing of CFRP retrofits on corroded steel structures were summarized to provide information on performance and design guidance for future retrofits. This dissertation provides additional information on CFRP repairs applied to corroded steel and provides data on new CFRP materials (HM strand sheets). With this information, Departments of Transportation (DOT) can be confident as to where and when different types of CFRPs are a suitable retrofit material for corroded or uncorroded steel structures.
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Neela, Subhashini. "Flexural Behavior of Basalt FRP Bar Reinforced Concrete Members With and Without Polypropylene Fiber." University of Akron / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1291084015.
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He, Yuxiang Carleton University Dissertation Engineering Civil. "Interactive design of flexural steel members subjected to bending, and combined bending and torsion." Ottawa, 1993.
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22
Mahenthirarasa, Rokilan. "Cold-formed steel compression members exposed to extreme temperature environments." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/226125/1/Rokilan_Mahenthirarasa_Thesis.pdf.
Повний текст джерелаАнотація:
This thesis investigated the behaviour of cold-formed steel compression members under extreme temperature environments using experimental and numerical studies. It proposed both new and improved design models for (1) the elevated and sub-zero temperature mechanical properties of cold-formed steels and (2) the compression capacities of cold-formed steel members exposed to uniform and non-uniform elevated temperatures and uniform sub-zero temperatures. The proposed design models are likely to be adopted by the Australian and American cold-formed steel structures standards, while the new knowledge will enable increased applications of cold-formed steel members in the building industry.
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Esposito, Alessandro. "Creep deflection of low-strength reinforced concrete flexural members strengthened with carbon fiber composite sheets." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/10340/.
Повний текст джерелаАнотація:
The low-strength concrete is defined as a concrete where the compressive cubic strength is less than 15 MPa. Since the beginning of the last century, many low-strength concrete buildings and bridges have been built all over the world. Being short of deeper study, composite sheets are prohibited in strengthening of low-strength reinforced concrete members (CECS 146; ACI 440). Moreover, there are few relevant information about the long-term behavior and durability of strengthened RC members.
This fact undoubtedly limits the use of the composite materials in the strengthening applications, therefore, it is necessary to study the behaviours of low-strength concrete elements strengthened with composite materials (FRP) for the preservation of historic constructions and innovation in the strengthening technology.
Deformability is one of criteria in the design of concrete structures, and this for functionality, durability and aesthetics reasons. Civil engineer possibly encounters more deflection problems in the structural design than any other type of problem. Many materials common in structural engineering such as wood, concrete and composite materials, suffer creep; if the creep phenomenon is taken into account, checks for serviceability limit state criteria can become onerous, because the creep deformation in these materials is in the same order of magnitude as the elastic deformation.
The thesis presents the results of an experimental study on the long-term behavior of low-strength reinforced concrete beams strengthened with carbon fiber composite sheets (CFRP). The work has investigated the accuracy of the long-term deflection predictions made by some analytical procedures existing in literature, as well as by the most widely used design codes (Eurocode 2, ACI-318, ACI-435).
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Miàs, Oller Cristina. "Analysis of time-dependent flexural behaviour of concrete members reinforced with fibre reinforced polymer bar." Doctoral thesis, Universitat de Girona, 2012. http://hdl.handle.net/10803/96914.
Повний текст джерелаАнотація:
In this work, long-term behaviour of FRP RC beams has been investigated both analytically and experimentally to further extend the knowledge in this particular research domain. In this respect, a new methodology to determine the long-term deflections due to creep and shrinkage is presented. Based on multiplicative coefficients, the methodology is straightforward and simple, and therefore suitable to be used in design. In addition, an experimental campaign on two series of GFRP RC beams subject to long-term loading has been performed. Different reinforcement ratios, concrete strengths and sustained load levels have been considered. For comparison purposes steel reinforcement has also been used. The experimental long-term results have been reported and discussed. Furthermore they have been compared to predictions using the most representative procedures, as well as, the proposed methodology presented in this work.En aquest treball, es presenta una nova metodologia per a la determinació de fletxes diferides degudes als efectes de la fluència i la retracció del formigó. La metodologia presentada es basa en coeficients multiplicadors, essent així un mètode directe i simple, apte per ser utilitzar en el disseny. Addicionalment, l’estudi presenta els resultats d’una campanya experimental realitzada en dues etapes, on bigues armades amb barres de material compost han estat sotmeses a càrregues a llarg termini. S’han considerat diferents quanties de reforç, resistències de formigó i nivells de càrrega. Per tal de comparar-ne els resultats, també s’han assajat bigues armades amb barres d’acer. Els resultats experimentals han estat analitzats i comparats amb els models de predicció més significatius, així com amb la metodologia desenvolupada i presentada en aquest estudi.
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Mujagic, Ubejd. "Design and Behavior of Composite Steel-Concrete Flexural Members with a Focus on Shear Connectors." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/26745.
Повний текст джерелаАнотація:
This study consists of three self-standing parts, each dealing with a different aspect of design of composite steel-concrete flexural members.
The first part deals with a new type of shear connection in composite joists. Composite steel-concrete flexural members have increasingly become popular in design and construction of floor systems, structural frames, and bridges. A particularly popular system features composite trusses (joists) that can span large lengths and provide empty web space for installation of typical utility conduits. One of the prominent problems with respect to composite joists has been the installation of welded shear connection due to demanding welding requirements and the need for significant welding equipment at the job site. This part of the study presents a new type of shear connection developed at Virginia Tech â standoff screws. Results of experimental and analytical research are presented, as well as the development of a recommended design methodology.
The second part deals with reliability of composite beams. Constant research advances in the field of composite steel-concrete beam design have resulted in numerous enhancements and changes to the American design practice, embodied in the composite construction provisions of the AISC Specification (AISC 1999). Results of a comprehensive reliability study of composite beams are presented. The study considers specification changes since the original reliability study by Galambos et al. (1976), considers a larger database of experimental data, and analyses recent proposals for changes in design of shear connection. Comparison of three different design methods is presented based on a study of 15,064 composite beam cases. A method to consider effect of degree of shear connection on strength reduction factor is proposed.
Finally, while basic analysis theories between the two are similar, requirements for determining the strength of composite beams in Eurocode 4 (CEN 1992) and 1999 AISC Specification (AISC 1999) differ in many respects. This is particularly true when considering the design of shear connections. This part of the dissertation explores those differences through a comparative step-by-step discussion of major design aspects, and accompanying numerical example. Several shortcomings of 1999 AISC Specification are identified and adjustments proposed.Ph. D.
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Eilers, Michael G. Thiagarajan Ganesh. "Ductility behavior of concrete flexural members reinforced with a hybrid combination of GFRP and mild steel." Diss., UMK access, 2006.
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Thesis (M.S.)--School of Computing and Engineering. University of Missouri--Kansas City, 2006."A thesis in civil engineering." Typescript. Advisor: Ganesh Thiagarajan. Vita. Title from "catalog record" of the print edition Description based on contents viewed Oct. 30, 2007. Includes bibliographical references (leaves 70-71). Online version of the print edition.
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Peng, Jun, and 彭軍. "Effects of strain gradient on maximun concrete stress and flexural capacity of normal-strength RC members." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B43085787.
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Trent, Justin David. "Transfer Length, Development Length, Flexural Strength, and Prestress Loss Evaluation in Pretensioned Self-Consolidating Concrete Members." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/33161.
Повний текст джерелаАнотація:
The first objective of this thesis was to determine the effect of using self-consolidating concrete versus normal concrete on transfer and development lengths, and flexural strengths of prestressed members. Three small rectangular members were made, two cast with SCC mixes and one cast with a conventional mix, to determine the transfer length of each mix. Transfer lengths of both ends of each member were determined by measuring the concrete surface strains. The change in the transfer length was monitored by determining the transfer length of each member at prestress release, 7 days after release, and 28 days after release. All concrete mixes had lower than code determined transfer lengths at prestress release. Each concrete mix showed between a 12 to 56 percent increase in transfer length after 28 days. One SCC mix exceeded the ACI code stipulated 50 strand diameters 7 days after prestress transfer. The other SCC mix was consistently below the transfer length of the conventional concrete.
Separate development length members were cast in a stay-in-place steel form used for creating structural double tees. Each development length member was a stub tee. Iterative load testing was performed to determine the development length of each SCC and conventional mix. Development lengths for both SCC mixes were approximately 20 percent shorter than ACI and AASHTO code predictions. A development length for the conventional concrete was not determined due to non-repeating test data. The flexural strength of each member was determined during load testing. All concrete mixes achieved higher than the ACI predicted strengths.
The second objective of this thesis was to experimentally measure prestress losses and compare these experimental values to theoretical models. Crack initiation and crack reopening tests were performed to experimentally determine the prestress losses in each member. Three theoretical models were evaluated, the sixth edition PCI Design Handbook suggested model, a 1975 PCI Committee on Prestress Losses model, and the AASHTO LRFD prestress loss model. The crack initiation experimental values tended to be between 10 and 15 percent lower than theoretical models. In general, the crack reopening prediction of the effective prestress had a good correlation with theoretical models. This suggests crack reopening tests can be used as predictors of effective prestress, and as such, predictors of prestress losses in future experimental research. Additionally, the concrete type was shown to affect the prestress losses determined in the development length members. The SCC members tended to have higher effective prestress forces than the conventional concrete members, and thus had less prestress losses due to creep and shrinkage than the conventional concrete members.
Master of Science
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Peng, Jun. "Effects of strain gradient on maximun concrete stress and flexural capacity of normal-strength RC members." Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B43085787.
Повний текст джерела
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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.
Повний текст джерелаАнотація:
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.
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Ručinskas, Artūras. "Comparative analysis of stress-strain calculation methods and algorithms for concrete members reinforced with FRP re-bars." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110620_141822-28189.
Повний текст джерелаАнотація:
The final thesis consists of three main parts, each covering a certain aspect of investigation.
First chapter presents an extensive literature review, covering such aspects as: application of
FRP (fiber reinforced polymer) materials in modern-day civil engineering, characteristics of
FRP reinforcement for reinforced concrete structures, advantages and drawbacks of FRP rebars
compared to traditional materials, peculiarities of flexural behavior of FRP reinforced
members, review of existing empirical stress-strain calculation algorithms and building codes
for concrete members reinforced with FRP.
Second part aims at presenting gathered experimental data consisting of 51 FRP reinforced
flexural members under 4 point bending scheme. Taking into account such parameters as
reinforcement ratio, load intensity and elasticity modulus of FRP reinforcement, statistical
analysis on a number of calculation algorithms and building codes is performed in order to
evaluate their credibility and reliability for use in real-world structures.
The final part of the work presents a Simplified Discrete Crack model developed in VGTU
Department of Bridges and Special Structures. The model is applied for a series of collected
beams. The results are compared with theoretical predictions made by different design codes
and experimental values.
The final thesis consists of: 90 pages of text (without appendixes), 46 pictures, 17 tables. 3
appendixes are included. Literature list consisting of 82... [to full text]Baigiamąjį magistro darbą sudaro trys pagrindinės dalys. Pirmajame skyriuje pateikiama literatūros apžvalga, kurioje nagrinėjamos temos susijusios su pluoštinės armatūros panaudojimu lenkiamiems betoniniams elementams. Apžvelgiamos tokių elementų panaudojimo galimybės, privalumai ir trūkumai, deformacijų skaičiavimo metodai bei matematiniai modeliai. Antrajame skyriuje nagrinėjama surinkta polimerine armatūra armuotų sijų eksperimentinių duomenų imtis. Siekiant įvertinti skirtingų skaičiavimo metodų patikimumą ir pritaikomumą ne plienine armatūra armuotiems elementams, atliekama lyginamoji statistinė analizė. Jos metu įvertinama armavimo procento, apkrovimo lygio bei pluoštinės armatūros tamprumo modulio įtaka. Trečiojoje darbo dalyje surinktai eksperimentinių duomenų imčiai pritaikytas VGTU Tiltų ir Specialiųjų Statinių Katedroje sukurtas Diskrečiųjų plyšių modelis. Gautos priklausomybės palygintos su kitų skaičiavimo normų rezultatais bei eksperimentiniais duomenimis. Gauti rezultatai parodė, kad pritaikius tikslesnius praslydimo bei armatūros ir betono sąveikos ruožuose tarp plyšių modelius, diskrečiųjų plyšių modelis gali būti sėkmingai taikomas polimerine armatūra armuotų elementų elgsenai prognozuoti.
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Anapayan, Tharmarajah. "Flexural behaviour and design of hollow flange steel beams." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/36210/1/Tharmarajah_Anapayan_Thesis.pdf.
Повний текст джерелаАнотація:
The LiteSteel Beam (LSB) is a new hollow flange channel section developed by OneSteel Australian Tube Mills using a patented Dual Electric Resistance Welding technique. The LSB has a unique geometry consisting of torsionally rigid rectangular hollow flanges and a relatively slender web. It is commonly used as rafters, floor joists and bearers and roof beams in residential, industrial and commercial buildings. It is on average 40% lighter than traditional hot-rolled steel beams of equivalent performance. The LSB flexural members are subjected to a relatively new Lateral Distortional Buckling mode, which reduces the member moment capacity. Unlike the commonly observed lateral torsional buckling of steel beams, lateral distortional buckling of LSBs is characterised by simultaneous lateral deflection, twist and web distortion. Current member moment capacity design rules for lateral distortional buckling in AS/NZS 4600 (SA, 2005) do not include the effect of section geometry of hollow flange beams although its effect is considered to be important. Therefore detailed experimental and finite element analyses (FEA) were carried out to investigate the lateral distortional buckling behaviour of LSBs including the effect of section geometry. The results showed that the current design rules in AS/NZS 4600 (SA, 2005) are over-conservative in the inelastic lateral buckling region. New improved design rules were therefore developed for LSBs based on both FEA and experimental results. A geometrical parameter (K) defined as the ratio of the flange torsional rigidity to the major axis flexural rigidity of the web (GJf/EIxweb) was identified as the critical parameter affecting the lateral distortional buckling of hollow flange beams. The effect of section geometry was then included in the new design rules using the new parameter (K). The new design rule developed by including this parameter was found to be accurate in calculating the member moment capacities of not only LSBs, but also other types of hollow flange steel beams such as Hollow Flange Beams (HFBs), Monosymmetric Hollow Flange Beams (MHFBs) and Rectangular Hollow Flange Beams (RHFBs). The inelastic reserve bending capacity of LSBs has not been investigated yet although the section moment capacity tests of LSBs in the past revealed that inelastic reserve bending capacity is present in LSBs. However, the Australian and American cold-formed steel design codes limit them to the first yield moment. Therefore both experimental and FEA were carried out to investigate the section moment capacity behaviour of LSBs. A comparison of the section moment capacity results from FEA, experiments and current cold-formed steel design codes showed that compact and non-compact LSB sections classified based on AS 4100 (SA, 1998) have some inelastic reserve capacity while slender LSBs do not have any inelastic reserve capacity beyond their first yield moment. It was found that Shifferaw and Schafer’s (2008) proposed equations and Eurocode 3 Part 1.3 (ECS, 2006) design equations can be used to include the inelastic bending capacities of compact and non-compact LSBs in design. As a simple design approach, the section moment capacity of compact LSB sections can be taken as 1.10 times their first yield moment while it is the first yield moment for non-compact sections. For slender LSB sections, current cold-formed steel codes can be used to predict their section moment capacities. It was believed that the use of transverse web stiffeners could improve the lateral distortional buckling moment capacities of LSBs. However, currently there are no design equations to predict the elastic lateral distortional buckling and member moment capacities of LSBs with web stiffeners under uniform moment conditions. Therefore, a detailed study was conducted using FEA to simulate both experimental and ideal conditions of LSB flexural members. It was shown that the use of 3 to 5 mm steel plate stiffeners welded or screwed to the inner faces of the top and bottom flanges of LSBs at third span points and supports provided an optimum web stiffener arrangement. Suitable design rules were developed to calculate the improved elastic buckling and ultimate moment capacities of LSBs with these optimum web stiffeners. A design rule using the geometrical parameter K was also developed to improve the accuracy of ultimate moment capacity predictions. This thesis presents the details and results of the experimental and numerical studies of the section and member moment capacities of LSBs conducted in this research. It includes the recommendations made regarding the accuracy of current design rules as well as the new design rules for lateral distortional buckling. The new design rules include the effects of section geometry of hollow flange steel beams. This thesis also developed a method of using web stiffeners to reduce the lateral distortional buckling effects, and associated design rules to calculate the improved moment capacities.
33
Momeni, Amir Farid. "Effect of concrete properties and prestressing steel indentation types on the development length and flexural capacity of pretensioned concrete members." Diss., Kansas State University, 2016. http://hdl.handle.net/2097/32682.
Повний текст джерелаАнотація:
Doctor of PhilosophyCivil Engineering
Robert J. Peterman
A study was conducted to determine the effect of different concrete properties and prestressing steel indentation types on development length and flexural capacity of pretensioned members. Wires and strands commonly used in the manufacturing of prestressed concrete railroad ties worldwide were selected for the study. Thirteen different 5.32-mm-diameter prestressing wire types and six different strands (four, seven-wire strands and two, three-wire strands) were used to cast prisms with a square cross section. The ratio of concrete to prestressed steel in the test prism’s cross section was representable of typical concrete railroad ties. Thus, geometrical and mechanical properties of test prisms were representative of actual ties in the railroad industry. To understand the effect of concrete-release strengths and slumps on development length, all parameters were kept constant in the prisms except concrete-release strength and slump. To manufacture prisms with different release strengths, all four wires/strands were pulled and detensioned gradually when the concrete compressive strength reached 3500 (24.13 MPa), 4500 (31.03 MPa), and 6000 (41.37 MPa) psi. To determine the effect of different slumps on development length, prisms with different slumps of 3 in. (7.6 cm), 6 in. (15.2 cm), and 9 in. (22.9 cm) were manufactured and all other parameters were kept constant in prisms. All prisms were tested in three-point bending at different spans to obtain estimations of development length based on type of reinforcement, concrete-release strength, and concrete slump. Lastly, a design equation was developed based on experimental data for prediction of development length. In the last phase of load tests, cyclic-loading tests were conducted on the prisms manufactured with wires to evaluate the bond performance of wires with different indentation types under cyclic loading. A total of 210 load tests, including 14 cyclic tests, were conducted. The monotonic-load tests revealed a large difference in the development length of pretensioned concrete members manufactured with different wire/strand types and different concrete-release strengths. Also, the cyclic-load tests revealed a significant difference in bond performance of different wire types under cyclic loading compared to monotonic loading.
34
Jeyaragan, Sivapathasunderam. "Flexural behaviour and design of the new built-up LiteSteel beams." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/36209/1/Sivapathasunderam_Jeyaragan_Thesis.pdf.
Повний текст джерелаАнотація:
LiteSteel Beam (LSB) is a new cold-formed steel beam produced by OneSteel Australian Tube Mills. The new beam is effectively a channel section with two rectangular hollow flanges and a slender web, and is manufactured using a combined cold-forming and electric resistance welding process. OneSteel Australian Tube Mills is promoting the use of LSBs as flexural members in a range of applications, such as floor bearers. When LSBs are used as back to back built-up sections, they are likely to improve their moment capacity and thus extend their applications further. However, the structural behaviour of built-up beams is not well understood. Many steel design codes include guidelines for connecting two channels to form a built-up I-section including the required longitudinal spacing of connections. But these rules were found to be inadequate in some applications. Currently the safe spans of builtup beams are determined based on twice the moment capacity of a single section. Research has shown that these guidelines are conservative. Therefore large scale lateral buckling tests and advanced numerical analyses were undertaken to investigate the flexural behaviour of back to back LSBs connected by fasteners (bolts) at various longitudinal spacings under uniform moment conditions. In this research an experimental investigation was first undertaken to study the flexural behaviour of back to back LSBs including its buckling characteristics. This experimental study included tensile coupon tests, initial geometric imperfection measurements and lateral buckling tests. The initial geometric imperfection measurements taken on several back to back LSB specimens showed that the back to back bolting process is not likely to alter the imperfections, and the measured imperfections are well below the fabrication tolerance limits. Twelve large scale lateral buckling tests were conducted to investigate the behaviour of back to back built-up LSBs with various longitudinal fastener spacings under uniform moment conditions. Tests also included two single LSB specimens. Test results showed that the back to back LSBs gave higher moment capacities in comparison with single LSBs, and the fastener spacing influenced the ultimate moment capacities. As the fastener spacing was reduced the ultimate moment capacities of back to back LSBs increased. Finite element models of back to back LSBs with varying fastener spacings were then developed to conduct a detailed parametric study on the flexural behaviour of back to back built-up LSBs. Two finite element models were developed, namely experimental and ideal finite element models. The models included the complex contact behaviour between LSB web elements and intermittently fastened bolted connections along the web elements. They were validated by comparing their results with experimental results and numerical results obtained from an established buckling analysis program called THIN-WALL. These comparisons showed that the developed models could accurately predict both the elastic lateral distortional buckling moments and the non-linear ultimate moment capacities of back to back LSBs. Therefore the ideal finite element models incorporating ideal simply supported boundary conditions and uniform moment conditions were used in a detailed parametric study on the flexural behaviour of back to back LSB members. In the detailed parametric study, both elastic buckling and nonlinear analyses of back to back LSBs were conducted for 13 LSB sections with varying spans and fastener spacings. Finite element analysis results confirmed that the current design rules in AS/NZS 4600 (SA, 2005) are very conservative while the new design rules developed by Anapayan and Mahendran (2009a) for single LSB members were also found to be conservative. Thus new member capacity design rules were developed for back to back LSB members as a function of non-dimensional member slenderness. New empirical equations were also developed to aid in the calculation of elastic lateral distortional buckling moments of intermittently fastened back to back LSBs. Design guidelines were developed for the maximum fastener spacing of back to back LSBs in order to optimise the use of fasteners. A closer fastener spacing of span/6 was recommended for intermediate spans and some long spans where the influence of fastener spacing was found to be high. In the last phase of this research, a detailed investigation was conducted to investigate the potential use of different types of connections and stiffeners in improving the flexural strength of back to back LSB members. It was found that using transverse web stiffeners was the most cost-effective and simple strengthening method. It is recommended that web stiffeners are used at the supports and every third points within the span, and their thickness is in the range of 3 to 5 mm depending on the size of LSB section. The use of web stiffeners eliminated most of the lateral distortional buckling effects and hence improved the ultimate moment capacities. A suitable design equation was developed to calculate the elastic lateral buckling moments of back to back LSBs with the above recommended web stiffener configuration while the same design rules developed for unstiffened back to back LSBs were recommended to calculate the ultimate moment capacities.
35
Heva, Yasintha Bandula. "Behaviour and design of cold-formed steel compression members at elevated termperatures." Queensland University of Technology, 2009. http://eprints.qut.edu.au/29310/.
Повний текст джерелаАнотація:
Cold-formed steel members have been widely used in residential, industrial and commercial buildings as primary load bearing structural elements and non-load bearing structural elements (partitions) due to their advantages such as higher strength to weight ratio over the other structural materials such as hot-rolled steel, timber and concrete. Cold-formed steel members are often made from thin steel sheets and hence they are more susceptible to various buckling modes. Generally short columns are susceptible to local or distortional buckling while long columns to flexural or flexural-torsional buckling. Fire safety design of building structures is an essential requirement as fire events can cause loss of property and lives. Therefore it is essential to understand the fire performance of light gauge cold-formed steel structures under fire conditions. The buckling behaviour of cold-formed steel compression members under fire conditions is not well investigated yet and hence there is a lack of knowledge on the fire performance of cold-formed steel compression members. Current cold-formed steel design standards do not provide adequate design guidelines for the fire design of cold-formed steel compression members. Therefore a research project based on extensive experimental and numerical studies was undertaken at the Queensland University of Technology to investigate the buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. As the first phase of this research, a detailed review was undertaken on the mechanical properties of light gauge cold-formed steels at elevated temperatures and the most reliable predictive models for mechanical properties and stress-strain models based on detailed experimental investigations were identified. Their accuracy was verified experimentally by carrying out a series of tensile coupon tests at ambient and elevated temperatures. As the second phase of this research, local buckling behaviour was investigated based on the experimental and numerical investigations at ambient and elevated temperatures. First a series of 91 local buckling tests was carried out at ambient and elevated temperatures on lipped and unlipped channels made of G250-0.95, G550-0.95, G250-1.95 and G450-1.90 cold-formed steels. Suitable finite element models were then developed to simulate the experimental conditions. These models were converted to ideal finite element models to undertake detailed parametric study. Finally all the ultimate load capacity results for local buckling were compared with the available design methods based on AS/NZS 4600, BS 5950 Part 5, Eurocode 3 Part 1.2 and the direct strength method (DSM), and suitable recommendations were made for the fire design of cold-formed steel compression members subject to local buckling. As the third phase of this research, flexural-torsional buckling behaviour was investigated experimentally and numerically. Two series of 39 flexural-torsional buckling tests were undertaken at ambient and elevated temperatures. The first series consisted 2800 mm long columns of G550-0.95, G250-1.95 and G450-1.90 cold-formed steel lipped channel columns while the second series contained 1800 mm long lipped channel columns of the same steel thickness and strength grades. All the experimental tests were simulated using a suitable finite element model, and the same model was used in a detailed parametric study following validation. Based on the comparison of results from the experimental and parametric studies with the available design methods, suitable design recommendations were made. This thesis presents a detailed description of the experimental and numerical studies undertaken on the mechanical properties and the local and flexural-torsional bucking behaviour of cold-formed steel compression member at ambient and elevated temperatures. It also describes the currently available ambient temperature design methods and their accuracy when used for fire design with appropriately reduced mechanical properties at elevated temperatures. Available fire design methods are also included and their accuracy in predicting the ultimate load capacity at elevated temperatures was investigated. This research has shown that the current ambient temperature design methods are capable of predicting the local and flexural-torsional buckling capacities of cold-formed steel compression members at elevated temperatures with the use of reduced mechanical properties. However, the elevated temperature design method in Eurocode 3 Part 1.2 is overly conservative and hence unsuitable, particularly in the case of flexural-torsional buckling at elevated temperatures.
36
Heva, Yasintha Bandula. "Behaviour and design of cold-formed steel compression members at elevated temperatures." Thesis, Queensland University of Technology, 2009. https://eprints.qut.edu.au/29310/1/Yasintha_Heva_Thesis.pdf.
Повний текст джерелаАнотація:
Cold-formed steel members have been widely used in residential, industrial and commercial buildings as primary load bearing structural elements and non-load bearing structural elements (partitions) due to their advantages such as higher strength to weight ratio over the other structural materials such as hot-rolled steel, timber and concrete. Cold-formed steel members are often made from thin steel sheets and hence they are more susceptible to various buckling modes. Generally short columns are susceptible to local or distortional buckling while long columns to flexural or flexural-torsional buckling. Fire safety design of building structures is an essential requirement as fire events can cause loss of property and lives. Therefore it is essential to understand the fire performance of light gauge cold-formed steel structures under fire conditions. The buckling behaviour of cold-formed steel compression members under fire conditions is not well investigated yet and hence there is a lack of knowledge on the fire performance of cold-formed steel compression members. Current cold-formed steel design standards do not provide adequate design guidelines for the fire design of cold-formed steel compression members. Therefore a research project based on extensive experimental and numerical studies was undertaken at the Queensland University of Technology to investigate the buckling behaviour of light gauge cold-formed steel compression members under simulated fire conditions. As the first phase of this research, a detailed review was undertaken on the mechanical properties of light gauge cold-formed steels at elevated temperatures and the most reliable predictive models for mechanical properties and stress-strain models based on detailed experimental investigations were identified. Their accuracy was verified experimentally by carrying out a series of tensile coupon tests at ambient and elevated temperatures. As the second phase of this research, local buckling behaviour was investigated based on the experimental and numerical investigations at ambient and elevated temperatures. First a series of 91 local buckling tests was carried out at ambient and elevated temperatures on lipped and unlipped channels made of G250-0.95, G550-0.95, G250-1.95 and G450-1.90 cold-formed steels. Suitable finite element models were then developed to simulate the experimental conditions. These models were converted to ideal finite element models to undertake detailed parametric study. Finally all the ultimate load capacity results for local buckling were compared with the available design methods based on AS/NZS 4600, BS 5950 Part 5, Eurocode 3 Part 1.2 and the direct strength method (DSM), and suitable recommendations were made for the fire design of cold-formed steel compression members subject to local buckling. As the third phase of this research, flexural-torsional buckling behaviour was investigated experimentally and numerically. Two series of 39 flexural-torsional buckling tests were undertaken at ambient and elevated temperatures. The first series consisted 2800 mm long columns of G550-0.95, G250-1.95 and G450-1.90 cold-formed steel lipped channel columns while the second series contained 1800 mm long lipped channel columns of the same steel thickness and strength grades. All the experimental tests were simulated using a suitable finite element model, and the same model was used in a detailed parametric study following validation. Based on the comparison of results from the experimental and parametric studies with the available design methods, suitable design recommendations were made. This thesis presents a detailed description of the experimental and numerical studies undertaken on the mechanical properties and the local and flexural-torsional bucking behaviour of cold-formed steel compression member at ambient and elevated temperatures. It also describes the currently available ambient temperature design methods and their accuracy when used for fire design with appropriately reduced mechanical properties at elevated temperatures. Available fire design methods are also included and their accuracy in predicting the ultimate load capacity at elevated temperatures was investigated. This research has shown that the current ambient temperature design methods are capable of predicting the local and flexural-torsional buckling capacities of cold-formed steel compression members at elevated temperatures with the use of reduced mechanical properties. However, the elevated temperature design method in Eurocode 3 Part 1.2 is overly conservative and hence unsuitable, particularly in the case of flexural-torsional buckling at elevated temperatures.
37
Dolamune, Kankanamge Nirosha. "Structural behaviour and design of cold-formed steel beams at elevated temperatures." Thesis, Queensland University of Technology, 2010. https://eprints.qut.edu.au/33221/1/Nirosha_Dolamune_Kankanamge_Thesis.pdf.
Повний текст джерелаАнотація:
Cold-formed steel members are extensively used in the building construction industry, especially in residential, commercial and industrial buildings. In recent times, fire safety has become important in structural design due to increased fire damage to properties and loss of lives. However, past research into the fire performance of cold-formed steel members has been limited, and was confined to compression members. Therefore a research project was undertaken to investigate the structural behaviour of compact cold-formed steel lipped channel beams subject to inelastic local buckling and yielding, and lateral-torsional buckling effects under simulated fire conditions and associated section and member moment capacities. In the first phase of this research, an experimental study based on tensile coupon tests was undertaken to obtain the mechanical properties of elastic modulus and yield strength and the stress-strain relationship of cold-formed steels at uniform ambient and elevated temperatures up to 700oC. The mechanical properties deteriorated with increasing temperature and are likely to reduce the strength of cold-formed beams under fire conditions. Predictive equations were developed for yield strength and elastic modulus reduction factors while a modification was proposed for the stressstrain model at elevated temperatures. These results were used in the numerical modelling phases investigating the section and member moment capacities. The second phase of this research involved the development and validation of two finite element models to simulate the behaviour of compact cold-formed steel lipped channel beams subject to local buckling and yielding, and lateral-torsional buckling effects. Both models were first validated for elastic buckling. Lateral-torsional buckling tests of compact lipped channel beams were conducted at ambient temperature in order to validate the finite element model in predicting the non-linear ultimate strength behaviour. The results from this experimental study did not agree well with those from the developed experimental finite element model due to some unavoidable problems with testing. However, it highlighted the importance of magnitude and direction of initial geometric imperfection as well as the failure direction, and thus led to further enhancement of the finite element model. The finite element model for lateral-torsional buckling was then validated using the available experimental and numerical ultimate moment capacity results from past research. The third phase based on the validated finite element models included detailed parametric studies of section and member moment capacities of compact lipped channel beams at ambient temperature, and provided the basis for similar studies at elevated temperatures. The results showed the existence of inelastic reserve capacity for compact cold-formed steel beams at ambient temperature. However, full plastic capacity was not achieved by the mono-symmetric cold-formed steel beams. Suitable recommendations were made in relation to the accuracy and suitability of current design rules for section moment capacity. Comparison of member capacity results from finite element analyses with current design rules showed that they do not give accurate predictions of lateral-torsional buckling capacities at ambient temperature and hence new design rules were developed. The fourth phase of this research investigated the section and member moment capacities of compact lipped channel beams at uniform elevated temperatures based on detailed parametric studies using the validated finite element models. The results showed the existence of inelastic reserve capacity at elevated temperatures. Suitable recommendations were made in relation to the accuracy and suitability of current design rules for section moment capacity in fire design codes, ambient temperature design codes as well as those proposed by other researchers. The results showed that lateral-torsional buckling capacities are dependent on the ratio of yield strength and elasticity modulus reduction factors and the level of non-linearity in the stress-strain curves at elevated temperatures in addition to the temperature. Current design rules do not include the effects of non-linear stress-strain relationship and therefore their predictions were found to be inaccurate. Therefore a new design rule that uses a nonlinearity factor, which is defined as the ratio of the limit of proportionality to the yield stress at a given temperature, was developed for cold-formed steel beams subject to lateral-torsional buckling at elevated temperatures. This thesis presents the details and results of the experimental and numerical studies conducted in this research including a comparison of results with predictions using available design rules. It also presents the recommendations made regarding the accuracy of current design rules as well as the new developed design rules for coldformed steel beams both at ambient and elevated temperatures.
38
Sahin, Serkan. "A Comparative Study Of Aisc-360 And Eurocode 3 Strength Limit States." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610894/index.pdf.
Повний текст джерелаАнотація:
Nowadaysdesign, fabrication and erection of steel structures can be taken place at different locations as a result of rapid globalization
owners may require the use of widely accepted steel design codes. Therefore, engineers are faced with the challenge of being competent with several design specifications for a particular material type. AISC-360 and EC3 are widely accepted steel structure design specifications that utilize limit state principles with some similarities and differences in application. Hereby a study has been undertaken to put together the nominal strength expressions presented in both AISC-360 and EC3 codes in a single document, to identify the similarities and the differences in calculated strengths and to facilitate rapid learning of either of the specifications with prior knowledge of the other. Because of the wide scope of specifications, only fundamental failure modes are considered in this thesis. Resistance equations are directly compared with each other wherever possible. For cases where the treatment of specifications is entirely different, representative members were considered for comparison purposes.
39
Weiland, Silvio, and Manfred Curbach. "Interaktion gemischter Bewehrungen bei der Verstärkung von Stahlbeton mit textilbewehrtem Beton." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2009. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1244051366655-25294.
Повний текст джерелаАнотація:
Textile Bewehrungen stellen eine hervorragende Alternative zu bisherigen Verstärkungsmethoden dar. Die Wirksamkeit von Textilbetonverstärkungen konnte bereits eindrucksvoll nachgewiesen werden. Um sowohl die vorhandene Bausubstanz, als auch die Verstärkung optimal auszulasten, ist es erforderlich, das Zusammenwirken beider Bewehrungsarten unter Berücksichtigung der unterschiedlichen Verbundeigenschaften zu beschreiben. In diesem Beitrag wird das gemeinsamen Tragverhalten von Betonstahl und textiler Bewehrung eingehend erläutert. Zur Veranschaulichung wird daher vor allem die Verbundtragwirkung und deren Einfluss auf gerissene Zugglieder genauer untersucht.
40
Siahaan, Ropalin. "Structural behaviour and design of rivet fastened rectangular hollow flange channel beams." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/106913/1/Ropalin_Siahaan_Thesis.pdf.
Повний текст джерелаАнотація:
This thesis presents a study into the structural behaviour and design of the innovative rivet fastened Rectangular Hollow Flange Channel Beams (RHFCB). The RHFCB utilizes the inexpensive self-pierce rivet fastening in its fabrication, providing cost effective structural solutions in floor systems. The first part of the thesis focuses on the section moment capacities of the beams subject to local buckling effects while the second part investigates the member moment capacities of intermediate span beams subject to the unique lateral distortional buckling effects. Each part involves experimental investigations, advanced finite element analyses, parametric studies and design recommendations.
41
Weiland, Silvio. "Interaktion von Betonstahl und textiler Bewehrung bei der Biegeverstärkung mit textilbewehrtem Beton." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-37944.
Повний текст джерелаАнотація:
Textilbewehrter Beton zur Verstärkung von Stahlbetonbauteilen ist neben den klassischen und etablierten Verfahren eine äußerst interessante Alternative, die die Vorteile der leichten Kohlenstofffaserklebeverstärkungen mit denen von Spritzbeton mit Bewehrung verbindet. Aus den theoretischen und experimentellen Untersuchungen in dieser Arbeit können wichtige Erkenntnisse zum gemeinsamen Tragverhalten von Betonstahl und textiler Bewehrung sowie zu den Auswirkungen der verbundbedingten Unterschiede abgeleitet werden. Mit den theoretischen Betrachtungen werden das gemeinsame Tragverhalten und der Einfluss des unterschiedlichen Verbundverhaltens auf die Zugkraftaufteilung gezeigt und qualifiziert. Die Behandlung der verbundbedingten Unterschiede bei gemischt mit Betonstahl und Textil bewehrten Zuggliedern ist analog dem Vorgehen bei gemischter Beton- und Spannstahlbewehrung bzw. Klebebewehrung mit Verbundbeiwerten darstellbar. Zur Ableitung entsprechender Kennwerte werden verschiedene Möglichkeiten diskutiert. Zudem wird eine vereinfachte Bemessung vorgeschlagen. Insgesamt sind die Ergebnisse ein wesentlicher Schritt auf dem Weg zur baupraktischen Anwendung von Textilbetonverstärkungen und ermutigen bereits zum umsichtigen Einsatz unter Beachtung der Sicherheitsaspekte. Noch offene Fragen und notwendiger Klärungsbedarf sollten die Wissbegier anregen und vertiefende Forschungsvorhaben und weitere experimentelle Untersuchungen ermöglichenTextile reinforcement represents an excellent alternative to existing techniques for strengthening of concrete structures, combining the benefits of lightweight fiber reinforced polymer strengthening with those of shotcrete with reinforcement. The theoretical and experimental studies in this thesis provide essential insights into the common load bearing behaviour of reinforcing steel and textile reinforcements as well as on the impact of the different bond characteristics of both types of rein-forcement. With the theoretical investigations, the combined load bearing behaviour and the influence of the different bond characteristics on distribution of the forces could be shown and qualified. The inter-action of both reinforcement types, taking into account the different bond characteristics, can be represented by bond coefficients analogous to the approach to mixed steel and pre-stressing-steel reinforcements. So as to derive the appropriate parameters, several options were discussed. Moreover, a simplified approach to design a TRC-strengthening-layer was proposed. Overall, the results are an essential step towards the practical application of textile reinforced con-crete for the strengthening of concrete structures and should already be encouraging the prudent use while considering the necessary safety aspects. Remaining issues and necessary clarifications should stimulate curiosity and in-depth research projects and allow further experimental studies
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Wu, Zhenhua. "Behavior of high-strength concrete members under pure flexure and axial-flexural loading." 2006. http://www.lib.ncsu.edu/theses/available/etd-12122006-101746/unrestricted/etd.pdf.
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Mota, Carlos P. "Flexural and shear behaviour of FRP-RC members." 2005. http://hdl.handle.net/1993/20192.
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Marques, Liliana Raquel Simões. "Tapered steel members : flexural and lateral-torsional buckling." Doctoral thesis, 2012. http://hdl.handle.net/10316/24318.
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Hasan, Noor Md Sadiqul. "Time dependent flexural analysis of reinforced concrete members." Thesis, 2016. http://hdl.handle.net/2440/103968.
Повний текст джерелаАнотація:
Concrete is one of the most widely used building materials in the construction industry in the world. Time dependent behaviour of concrete is the major concern for the structural engineers due to its significant effect in the long term serviceability and durability. Reinforced concrete (RC) members are prone to the effect of time dependent deformations that are known as shrinkage and creep, can produce substantial deformations and deflections to the structure. The mechanics of quantifying the serviceability deflection of RC beams is complex due to flexural cracking and the associated partial interaction (PI) behaviour of slip between the reinforcement and adjacent concrete. Add the additional complexity of time dependent concrete shrinkage to this partial-interaction (PI) behaviour and the problem becomes very complex. Current design and analysis techniques to quantify serviceability deflection of reinforced concrete (RC) members are generally built on two major principles which are full interaction (FI) through the use of moment curvature approaches; and a uniform longitudinal shrinkage strain εsh [sh subscript] within the member to simplify the analysis technique. Both of the premises are gross approximations and with regard to the first premise, RC beams are subject to flexural cracking and the associated partial interaction (PI) behaviour of slip between the reinforcement and adjacent concrete. Furthermore with regard to the second premise, numerous tests have shown that εsh [sh subscript] varies along both the depth and width of the beam and which is far from uniform. Hence there are two major sources of error in the quantification of serviceability deflections of RC beams for design and which are due to the PI mechanisms that occur in practice; and that due to the time dependent material properties of creep and shrinkage. This thesis deals with the development of PI numerical mechanics models with non-linear shrinkage strain variations achieved from a moisture diffusion model developed in this study and that is required to simulate the PI behaviour of RC beams in order to considerably reduce the source of error occurred due to the application of numerical mechanics model. Hence this new mechanics model will allow: the development of better design mechanics rules for serviceability deflection; and also assist in the better quantification of non-linear shrinkage and creep by removing or considerably reducing the existing mechanics source of error. Importantly, this research provides mechanics solutions for all the facets that control the serviceability time dependent behaviour of RC beams and it is envisaged that these numerical mechanics solutions can provide researchers with the tools to develop simple design procedures as they simulate the major mechanisms influencing cracking and tension stiffening in reinforced concrete beams. Current shrinkage test methodology is having some limitations that are all surfaces are exposed to the environment and they are small scaled which leads to a uniformity of shrinkage strain and which are not present in real size RC beams. Therefore in this thesis, a new form of experimental setup for shrinkage have been proposed to better quantify the shrinkage variations along both the width and depth of RC members with varying the sizes and surface boundary conditions.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2016.
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Chen, Chun-Wen, and 陳俊文. "Study on Provisions of Flexural Members– 2005 AISC Specification –." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/05574911077578124930.
Повний текст джерелаАнотація:
碩士國立中興大學
土木工程學系所
95
Many practical engineers use ASD to design different civil structures, more engineers switch from ASD to LRFD design. In fact, LRFD design has gradually become the major design criteria for steel structures in the United States. Similar steel design trend can be found in Taiwan. AISC (2005) has published both ASD and LRFD in the same design manual, which allows practical engineers to explore both design methods. AISC (2005) has published both ASD and LRFD in the same design manual, which allows practical engineers to explore both design methods. This research has incorporated with the 2005AISC investigated all equations and fundamental backgrounds regarding to the flexural design of a steel beam. The research results are presented and summarized using tables and charts.
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Ching, Lee Cha, and 李家慶. "The Application of Auto-Clave Concrete in Prestressed Flexural Members." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/09114722600366009201.
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Yeh, Shyr Wei, and 葉時偉. "On the Strengthening of RC Flexural Members - Attach Steel Plates Laterally." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/35928497306120423127.
Повний текст джерелаАнотація:
碩士國立中興大學
土木工程學系
86
RC樑因強度不足而採黏貼鋼鈑的補強方式，已逐漸被工程界廣泛應用 。然而，因學界研究成果一直無法配合工程界實際應用之需要，致使鋼鈑 補強設計至今仍無一完整之理論依據可作參考，間接造成鋼鈑補強方式無 法有效整合其設計理念。因此，本研究規劃對撓曲強度不足之全尺寸RC懸 臂樑試體，進行純裂縫灌注環氧樹脂、兩側未錨碇柱面鋼鈑補強及兩側錨 碇柱面鋼鈑補強試驗。以探討撓曲強度不足之試體，經上述補強方式後， 試體之各種補強效應。同時，並對側貼有、無錨碇柱面鋼鈑之補強方式作 一整體性評估，以探討實際應用於工程界之可能性。從最後試驗結果發現 ，原RC樑純裂縫灌注環氧樹脂補強後，試體之強度及勁度與原RC樑差異不 大。而在原RC樑側貼鋼鈑未錨碇柱面時，整體補強效應未如預期明顯。若 側貼鋼鈑並錨碇於柱面後，整體補強效應則明顯大有提昇。總體而言，對 撓曲強度不足之RC樑試體，採側貼鋼鈑補強時，若能將補強鋼鈑以適當方 式錨錠於柱面，對提昇整體補強效應會有實質助益，此點值得工程實務界 在進行鋼鈑補強設計時之參考。
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Green, Perry Stanton. "The inelastic behavior of flexural members fabricated from high performance steel /." Diss., 2000. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9995523.
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He-ShengLi and 李和昇. "Tension stiffening behavior and structural flexural behavior of steel reinforced UHPFRC members." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/90239151604279765299.
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