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Artykuły w czasopismach na temat "Portal frame experiment"
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Li, Qi Cai, Zhen Shan Wang, Ming Zhou Su, Xue Chao Shao i Lin Shen. "Experiment on the Hysteretic Behaviors of Light-Weight Steel Portal Frame with Tapered Members". Advanced Materials Research 368-373 (październik 2011): 206–10. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.206.
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In order to study the seismic behavior of steel portal frame structures, Cyclic loading test on a 1:3-scaled model of single-story single-bay steel portal frame with tapered members has been carried out. Based on test results, hysteretic curve, skeleton curve, stiffness degradation and transverse displacement of the structure are obtained. Meanwhile, the seismic performances of the structure are analyzed from aspects of ductility, energy consumption, stiffness degradation, bearing capacity, etc. It is concluded that ductility and energy consumption capacity of this structure are poor; because of its light weight, the structure attracts little seismic load; when portal frame structure designed according to current Chinese design codes suffers from small seismic action, it has enough seismic bearing capacity.
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Mottershead, J. E., T. K. Tee, C. D. Foster i R. Stanway. "An Experiment to Identify the Structural Dynamics of a Portal Frame". Journal of Vibration and Acoustics 112, nr 1 (1.01.1990): 78–83. http://dx.doi.org/10.1115/1.2930102.
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This paper describes the application of sequential frequency domain techniques to the estimation of mass, stiffness, and damping parameters using measured frequency response functions from a portal frame rig. The theory of the method has been described in the authors’ previous publications. A portal frame is representative of many engineering structures. It is lightly damped and may be thought of as an element of several larger structures such as bridges, transmission towers, and the steel foundations of modern power generating plant. The results offered in this paper are thus of interest to a broad range of engineering problems where it is required to obtain mathematical models in terms of physical parameters.
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van de Lindt, John W., i R. Karthik Rechan. "Seismic Performance Comparison of a High-Content SDA Frame and Standard RC Frame". Advances in Civil Engineering 2011 (2011): 1–12. http://dx.doi.org/10.1155/2011/478475.
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This study presents the method and results of an experiment to study the seismic behavior of a concrete portal frame with fifty percent of its cement content replaced with a spray dryer ash (SDA). Based on multiple-shake-table tests, the high content SDA frame was found to perform as well as the standard concrete frame for two earthquakes exceeding design-level intensity earthquakes. Hence, from a purely seismic/structural standpoint, it may be possible to replace approximately fifty percent of cement in a concrete mix with SDA for the construction of structural members in high seismic zones. This would help significantly redirect spray dryer ash away from landfills, thus, providing a sustainable greener alternative to concrete that uses only Portland cement, or only a small percentage of SDA or fly ash.
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Wang, Zhen Shan, Ming Zhou Su, An Liang Song, Zhen Pang i Lin Shen. "Aseismic Test and Finite Element Analysis of Light-Weight Steel Portal Frame with Tapered Members". Advanced Materials Research 368-373 (październik 2011): 211–14. http://dx.doi.org/10.4028/www.scientific.net/amr.368-373.211.
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To study on the failure model, ductility, energy dissipation capacity, structural displacement, and stiffness of the portal frame structures on the effect of earthquake force, a pseudo-static experiment with a 1/3 scaled model has been completed. Based on the test result, though the ductility and the energy consumption capacity of the structure are poor, the requirement on aseismatic bearing capacity is satisfied, because the structure suffers the smaller seismic force as the deadweight of structure is light. Built up a finite element model according to the test specimen, then performed finite element analysis, the results showed that the finite element model can be used for seismic analysis of the portal frame.
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Su, Yi Sheng, Shu Fang Zheng, Qi Liang Li i Jin Yun Quan. "Experimental Study on the Static Performance of Joints in the Castellated Portal Frame of Light-Weight Steel". Applied Mechanics and Materials 166-169 (maj 2012): 563–68. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.563.
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In order to study the mechanical behavior of joints in the castellated portal frame of light-weight steel under static loads, a static loads experiment has been performed for these new joints in this paper. The experiment members include four castellated joints and one solid-web joint of original steel, considering three vary parameters which are connection form of joints, joint region with setting stiffener and the distance from the center of hole to joint region. Experiment shows: the stiffness of castellated joints is higher than the one of solid-web joint. The parameters have a great influence on the mechanical behavior of joints, except the connection form of joints.
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Nishiyama, M., H. Mugurama i F. Watanabe. "Hysteretic restoring force characteristics of unbounded prestressed concrete framed structure under earthquake load". Bulletin of the New Zealand Society for Earthquake Engineering 22, nr 2 (30.06.1989): 112–21. http://dx.doi.org/10.5459/bnzsee.22.2.112-121.
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An analytical method, by which hysteretic restoring force characteristics of unbonded prestressed concrete framed structure can be statically pursued on the basis of material properties, is presented. The bond-slip relationship between concrete and prestressing tendon is taken into account, and thus the method covers unbonded members and bonded members. For verifying the propriety of the analytical method, the experiment is carried out on a portal frame with an unbonded prestressed concrete beam of 4.2 m in length and reinforced concrete columns of 1 m in height. High intensity reversed cyclic lateral loading is applied. The experimental results show a good agreement with the analytical ones in terms of load-deflection relation and the fluctuation of the tendon stress at anchorage end.
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., M. Muthulakshmi, i M. Vinod Kumar . "Experimental Studies on Fibre Integrated Lightweight Concrete Frames Under Lateral Forces: A Review". Asian Journal of Engineering and Applied Technology 7, nr 1 (5.03.2018): 88–91. http://dx.doi.org/10.51983/ajeat-2018.7.1.874.
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Reinforced Concrete (RC) framed structure with masonry infill is the most common type of building in which, RC frames participate in resisting lateral forces. The poor performance of RC frame buildings under lateral forces is due to its heavy mass and rigid construction. Use of Lightweight concrete (LWC) is preferred since the dead load of concrete is enormous. A low density of the LWC, decreases the weight of the building thus reducing the effect of lateral forces. However, LWC having a lower modulus of elasticity, has a faster rate of crack development in RC members. So, fibres are employed as an additive to increase the energy absorption capacity and to control the crack development. Pumice is a natural material of volcanic origin, has low density, which makes it ideal for production of LWC. Based on these ideas, Pumice aggregate is used as a partial replacement of coarse aggregate to its volume with addition of steel fibres to the volume of concrete. This paper summarizes the collected literatures related to RC frames, LWC, Fibre Reinforced Concrete (FRC) and thereby attempts to predict the lateral load response of RC portal frame with the use of LWC and Steel fibres.
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Dheyaa Jaafar Witwit, Jaafar, i Nameer Abed Al-Ameer Alwash. "Experimental and Numerical Investigation for R/C Portal Frames Tested Under Uniform Load". International Journal of Engineering & Technology 7, nr 4.19 (27.11.2018): 763. http://dx.doi.org/10.14419/ijet.v7i4.19.27995.
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This paper presents an experimental and numerical investigations for three reinforced self-compacting concrete portal frames tested under uniform load. Control frame was tested without any types of strengthening, while second frame was strengthened with CFRP-sheet with dimensions (75 * 1000) mm at the bottom of beam and with dimensions (75 *700) mm at both joints, (350 mm) extending to the upper surface of the beam and (350 mm) on the outer face of the column. The last frame was cast in two pours tested without strengthening. The experimental tests showed that strengthened frame had stiffness more than control frame and its ultimate load was more than control frame by (19.45 %), while frame with two pours has an ultimate load less than a control frame with (11.26 %), however stiffness seem approximately to the control frame. Deflection for strengthened frame was less than control frame by (4.76%), on the other hand frame with two pours deflection was more than control frame by (4.55 %). A numerical finite element program ultimate load was more than experimental by about (4.28 %).
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Ozola, Lilita, i Janis Fabriciuss. "Numerical and Experimental Analysis of Timber Portal Frame with Semi-Rigid Knee Joints". IOP Conference Series: Materials Science and Engineering 1203, nr 3 (1.11.2021): 032008. http://dx.doi.org/10.1088/1757-899x/1203/3/032008.
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Abstract The problems related to development of rotational deformations of a knee joints and crack propagation in rafter elements of timber portal frames were discussed in this article. The rotational displacement, which develops between the rafter and column members due to the bending deformations of the bolts in the knee joint with a simultaneous embedment into the wood, increases the global deformations of the portal frame. Additionally, to axial force and bending moment the rafter elements are heavily loaded with shear force at the sections near knee joint especially. All effects together create very complicated complex of affecting factors. In the current study the design methodology of timber portal frames has been revised with the purpose to develop a more comprehensive set of design conditions for timber portal frames with dowel type fasteners in the knee joints. It is suggested to use the Hoffman failure criterion taking into account the difference of strength in tension and compression to manage the effects of plastic yielding combined with the crack development in wood assumed it as an orthotropic material. It has been proved by case studies of timber portal frames under service loads, as well as by tests and theoretical considerations. The set of design conditions must be supplement by additional clauses comprising Hoffman failure criterion regarding timber sections heavily loaded in shear and cross grain tension. Also, it is recommended that the design capacity of dowel type fastener should be decreased when shear force transferred by the bolt acts perpendicular to the grain direction inducing tension cross grain direction. Other measure may be application of some surface strengthening method.
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BAO, YUEQUAN, YONG XIA, HUI LI, YOU-LIN XU i PENG ZHANG. "DATA FUSION-BASED STRUCTURAL DAMAGE DETECTION UNDER VARYING TEMPERATURE CONDITIONS". International Journal of Structural Stability and Dynamics 12, nr 06 (grudzień 2012): 1250052. http://dx.doi.org/10.1142/s0219455412500526.
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A huge number of data can be obtained continuously from a number of sensors in long-term structural health monitoring (SHM). Different sets of data measured at different times may lead to inconsistent monitoring results. In addition, structural responses vary with the changing environmental conditions, particularly temperature. The variation in structural responses caused by temperature changes may mask the variation caused by structural damages. Integration and interpretation of various types of data are critical to the effective use of SHM systems for structural condition assessment and damage detection. A data fusion-based damage detection approach under varying temperature conditions is presented. The Bayesian-based damage detection technique, in which both temperature and structural parameters are the variables of the modal properties (frequencies and mode shapes), is developed. Accordingly, the probability density functions of the modal data are derived for damage detection. The damage detection results from each set of modal data and temperature data may be inconsistent because of uncertainties. The Dempster–Shafer (D–S) evidence theory is then employed to integrate the individual damage detection results from the different data sets at different times to obtain a consistent decision. An experiment on a two-story portal frame is conducted to demonstrate the effectiveness of the proposed method, with consideration on model uncertainty, measurement noise, and temperature effect. The damage detection results obtained by combining the damage basic probability assignments from each set of test data are more accurate than those obtained from each test data separately. Eliminating the temperature effect on the vibration properties can improve the damage detection accuracy. In particular, the proposed technique can detect even the slightest damage that is not detected by common damage detection methods in which the temperature effect is not eliminated.
Rozprawy doktorskie na temat "Portal frame experiment"
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Blum, Hannah Beth. "Long-Span Cold-Formed Steel Double Channel Portal Frames". Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/16290.
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A comprehensive study on long-span cold-formed steel portal frames composed of back-to-back channel sections is presented. The aim of the study is to determine appropriate design guidelines in order for engineers to safely and efficiently build larger frames. The system analyzed herein is a haunched portal frame with a knee brace connected between the column and rafter. The objectives of the research were achieved through an extensive experimental study as well as numerical investigations. A comprehensive experimental program was completed to determine the strength and behavior of the frames. A total of nine full scale portal frame systems were tested, eight of which had unbraced columns. Variations to the frame layout, including modifications to the knee connection and the addition of sleeve stiffeners, were tested for both vertical and combined wind and vertical loading conditions. Column base rotational stiffness was quantified in the full scale experiments and in separate component tests. An advanced shell finite element model was created and calibrated with measured material and sections properties and column base stiffness, and was validated with the experimental results. A parametric study was completed to determine the effects of various configurations of the knee brace connection, as well as column base stiffness, on frame ultimate load. A larger span model was created to determine the suitability of the frame design for larger spans. A design procedure was developed to determine frame design loads. An energy method approach was employed to calculate the elastic buckling capacity of the column, which considers the elastic torsional restraint provided by the knee connection. A calibrated beam element model was used to determine the internal actions of the frame. A reliability check was completed and it was determined that the developed design method is suitable to design cold-formed steel portal frames.
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Garzeri, Flavio José. "Dinâmica não linear de um pórtico plano sob carregamento não ideal: análise numérica e experimental". Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-28032017-080049/.
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Nesta tese, apresenta-se a análise numérica e experimental do comportamento dinâmico não linear de um pórtico excitado por uma fonte não ideal - um motor elétrico de corrente contínua desbalanceado - como exemplo dessa classe de problemas. Elabora-se um modelo matemático com quatro graus de liberdade: dois relacionados com o deslocamento horizontal e vertical do ponto de apoio da máquina e dois com os parâmetros de funcionamento do motor elétrico. Adota-se a formulação Lagrangeana para gerar as equações de movimento contendo termos não lineares até ordem cúbica. A solução numérica é obtida através do método de Runge-Kutta com passo adaptativo. Ensaios dinâmicos e estáticos foram realizados com o motor e com o sistema completo, com vistas a validar o modelo matemático. Um sistema de medição digital armazenou todos os dados obtidos em arquivos de fácil leitura pelos programas atualmente disponíveis. Filmagens de alta velocidade e fotografia estroboscópica registraram movimentos típicos relacionados com comportamentos não lineares. Os resultados numéricos e experimentais mostram boa correlação entre si, além de apresentarem alguns dos fenômenos associados ao se forçar uma estrutura a passar por uma de suas ressonâncias excitando-a com um dispositivo com potência limitada, como o efeito Sommerfeld. Outros fenômenos, devido ao comportamento geometricamente não linear da estrutura, são também detectados, tais como saturação modal e transferência de energia.Numerical and experimental analysis of the nonlinear dynamics of a portal frame excited by a non-ideal source - an unbalanced direct current motor - is presented in this thesis as an example of this class of problems. A four degree of freedom model is elaborated: two of them related to the horizontal and vertical structural displacements and two others to the functioning parameters of the motor. A Lagrangian approach for deducing the equations of motion, up to cubic non-linear terms is followed. The numerical solution is obtained through Runge-Kutta algorithm with adaptive step. Static and dynamic tests were performed with the motor and with the complete system, in order to validate the mathematical model. A digital acquisition system recorded all data in computer files, ready to be read by available commercial programs. High speed filming and stroboscopic photography were used to register typical movements related to nonlinear behavior. Numerical and mathematical results show good correlation, as well as present some phenomena related to passage through resonance with limited power excitation such as the Sommerfeld effect. Some other phenomena, related to the nonlinear behavior of the structure are also detected, as modal saturation and energy transference.
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Susila, Gede Adi. "Experimental and numerical studies of masonry wall panels and timber frames of low-rise structures under seismic loadings in Indonesia". Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/experimental-and-numerical-studies-of-masonry-wall-panels-and-timber-frames-of-lowrise-structures-under-seismic-loadings-in-indonesia(3ceb094b-4e6e-432a-b3de-3d4c306b0551).html.
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Indonesia is a developing country that suffers from earthquakes and windstorms and where at least 60% of houses are non-engineered structures, built by unskilled workers using masonry and timber. The non-engineered housing units developed in urban region are also vulnerable to seismic hazard due to the use of low quality of material and constructions method. Those structures are not resistant to extreme lateral loads or ground movement and their failure during an earthquake or storm can lead to significant loss of life. This thesis is concerned with the structural performance of Indonesian low-rise buildings made of masonry and timber under lateral seismic load. The research presented includes a survey of forms of building structure and experimental, analytical and numerical work to predict the behaviour of masonry wall and traditional timber frame buildings. Experimental testing of both masonry and timber have been carried out in Indonesia to establish the quality of materials and to provide material properties for numerical simulations. The experimental study found that the strength of Indonesia-Bali clay brick masonry are below the minimum standard required for masonry structures built in seismic regions, being at least 50% lower than the requirement specified in British Standard and Eurocode-6 (BS EN 1996-1-1:2005). In contrast, Indonesian timber materials meet the strength classes specified in British Standard/Eurocode- 5 (BS EN 338:2009) in the range of strength grade D35-40 and C35).Structural tests under monotonic and cyclic loading have been conducted on building components in Indonesia, to determine the load-displacement capacity of local hand-made masonry wall panels and timber frames in order to: (1) evaluate the performance of masonry and timber frame structure, (2) investigate the dynamic behaviour of both structures, (3) observe the effect of in-plane stiffness and ductility level, and (4) examine the anchoring joint at the base of timber frame that resists the overturning moment. From these tests, the structural ductility was found to be less than two which is below the requirement of the relevant guidelines from the Federal Emergency Management Agency, USA (FEMA-306). It was also observed that the lateral stiffness of masonry wall is much higher than the equivalent timber frame of the same height and length. The experimental value of stiffness of the masonry wall panel was found to be one-twelfth of the recommended values given in FEMA-356 and the Canadian Building code. The masonry wall provides relatively low displacement compared to the large displacement of the timber frame at the full capacity level of lateral load, with structural framing members of the latter remaining intact. The weak point of the timber frame is the mechanical joint and the capacity of slip joint governs the lateral load capacity of the whole frame. Detailed numerical models of the experimental specimens were setup in Abaqus using three-dimensional solid elements. Cohesive elements were used to simulate the mortar behaviour, exhibiting cracking and the associated physical separation of the elements. Appropriate contact definitions were used where relevant, especially for the timber frame joints. A range of available material plasticity models were reviewed: Drucker-Prager, Crystalline Plasticity, and Cohesive Damage model. It was found that the combination of Crystalline Plasticity model for the brick unit and timber, and the Cohesive Damage model for the mortar is capable of simulating the experimental load-displacement behaviour fairly accurately. The validated numerical models have been used to (1) predict the lateral load capacity, (2) determine the cracking load and patterns, (3) carry out a detailed parametric study by changing the geometric and material properties different to the experimental specimens. The numerical models were used to assess different strengthening measures such as using bamboo as reinforcement in the masonry walls for a complete single storey, and a two-storey houses including openings for doors and windows. The traditional footing of the timber structures was analysed using Abaqus and was found to be an excellent base isolation system which partly explains the survival of those structures in the past earthquakes. The experimental and numerical results have finally been used to develop a design guideline for new construction as well as recommendations for retrofitting of existing structures for improved performance under seismic lateral load.
Części książek na temat "Portal frame experiment"
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Cantero, Daniel, i Raid Karoumi. "Total Load Effects of Portal Frame Bridges in High-Speed Railway Lines". W Conference Proceedings of the Society for Experimental Mechanics Series, 107–16. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-15248-6_12.
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Walker, James, i Robert Xiao. "Experimental Testing of a Portal Frame Connection Using Glued-In Steel Rods". W Materials and Joints in Timber Structures, 555–66. Dordrecht: Springer Netherlands, 2014. http://dx.doi.org/10.1007/978-94-007-7811-5_51.
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Rocha, Rodrigo Tumolin, Jose Manoel Balthazar, Angelo Marcelo Tusset, Vinicius Piccirillo i Jorge Luis Palacios Felix. "Using Saturation Phenomenon to Improve Energy Harvesting in a Portal Frame Platform with Passive Control by a Pendulum". W Dynamical Systems: Theoretical and Experimental Analysis, 319–29. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-42408-8_25.
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Bennett, Peggy D. "Taking your best self to school". W Teaching with Vitality. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780190673987.003.0070.
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So many expectations feel like they are consuming us. Lesson planning, committee work, test preparation, learning new material . . . and on and on. The stress caused by living in constant anxiety can interfere with sleep, mood, digestion, resilience, and, of course, good teaching Too easily and too frequently, we can find ourselves in perpetual fight- or- flight mode, readying ourselves for battle or to run and hide. When we consciously choose the intention to be our best, all sorts of interactions, big and small, shift our focus and recast our feelings. Manifesting our intent each morning can powerfully frame the way we want to behave, react, comment, and care. • Breathe in the attitude and behaviors you want to feel and portray. • Exhale the tension, doubt, and fear that subdue your joy. • Set a tone for relationships by warmly greeting those in school. • Show your concern by listening to those who are troubled. • Spread goodwill by words and deeds that support others. • Acknowledge and affirm if you cannot support. • Grasp every opportunity to be the best teacher you can be. The simple yet powerful attitudes and behaviors described here will not take away the hard, sometimes tedious work that is required of all educators. The challenges are givens. We know the work is difficult, and we do it anyway. Regaining the life in our teaching may require us to take baby steps as we experiment with what works for us. Our mental, physical, and social health is worth every step.
Streszczenia konferencji na temat "Portal frame experiment"
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Brasil, Reyolando M., Flávio J. Garzeri i José M. Balthazar. "An Experimental Study of the Nonlinear Dynamics of a Portal Frame Foundation for a Non Ideal Motor". W ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/vib-21548.
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Abstract An experimental approach to the study of forced nonlinear vibrations of portal frames excited by nonideal motors is presented. The interaction of the structure with the excitation source may lead to the occurrence of interesting phenomena during the forward and reverse passage through the several resonance states of the systems. As an application, a rotating unbalanced motor with limited power is considered mounted on the horizontal beam of a simple portal frame. As a starting point the problem is reduced to a three-degree-of-freedom model, and its equations of motion, derived elsewhere via a Lagrangian approach, are presented. Next, experimental work on a prototype is described. The results show the expected phenomena associated with the passage through resonance with limited power. Further, for a two-to-one relationship between the frequencies associated with the first symmetric mode and the sway mode, modal saturation and energy transference due to internal coupling and external resonance are observed at certain levels of excitation.
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Mendonça, Tiago, Vítor Brito i Manuel Almeida. "Portal and cantilever sign/signal gantries – Inspection and retrofitting". W IABSE Symposium, Guimarães 2019: Towards a Resilient Built Environment Risk and Asset Management. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/guimaraes.2019.1243.
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<p>This paper presents an experimental work about the condition and maintenance ratings of portal and cantilever sign gantries in Portugal, in which an extensive inspection campaign (about 1500 structures) was carried out. According to the results obtained, approximately 35% of the sign structures present insufficient condition rating, requiring priority repair works. The critical anomalies registered were lack of tightening/absence of connection elements, incorrect geometry of connection system and structural collapse of steel plates and profiles. Additionally, an inventory campaign was carried out, allowing to perform a structural design verification of approximately 80% of the inspected structures. Based on the structural analysis performed, a significant part of the existing portal and cantilever frames present structural strengthening or replacement needs and, consequently, these of structures require monitoring actions.</p>
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Kawaguchi, Jun, Shosuke Morino, Toshikazu Sugimoto i Junya Shirai. "Experimental Study on Structural Characteristics of Portal Frames Consisting of Square CFT Columns". W Composite Construction in Steel and Concrete IV Conference 2000. Reston, VA: American Society of Civil Engineers, 2002. http://dx.doi.org/10.1061/40616(281)63.
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Fabriciuss, Janis, i Lilita Ozola. "Duration of load effects on development of deformations in bolted moment connection". W Research for Rural Development 2020. Latvia University of Life Sciences and Technologies, 2020. http://dx.doi.org/10.22616/rrd.26.2020.034.
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Experience saved in the construction industry shows that the timber portal frames with semi-rigid connections at knee joint exhibit permanently increase displacements at the knee and apex point. Normally, timber portal frame with semi-rigid knee joint connection is made with mechanical fasteners located in double circles and cannot be designed without relevant rotation at connection during structures’ exploitation time. The only way to increase connection rigidity is to rise distance from fasteners location at connection, but at the same time, the tension and shear stress become significant at the external section of members. The previous experience is obtained by a model testing showing that deformations at semi-rigid connections are non-linear. These were tests under short-term load and did not disclose creep effects, which can be significant. This study is aimed at the examination of increasing deformations with time under constant static load (creep effects) in semi-rigid dowelled connection. Experimental test models were made and set under long-term load in controlled environmental conditions (heated laboratory room). Results show a significant creep influence to decrease connection stiffness. Corresponding numerical test of orthotropic 3d model by Dlubal RFEM software tools was performed analyzing the value of expected deformations. Results of the numerical test showed that friction between timber elements and extra nuts on bolts can increase connection stiffness. Research results in this stage show that the creep can affect connection stiffness more than expected. Also, experimental test results showed lower deformation values comparing with the ones obtained by the numerical test.
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Yin, T., L. Yu i H. P. Zhu. "Structural Damage Identification Based on Model Updating". W ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95691.
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This paper presents a new method for structural damage identification based on the finite element (FE) model updating techniques. First, an objective function is defined as minimizing the sum of differences between the experimental and analytical modal data (natural frequencies and mode shapes), which is set as a nonlinear least-squares problem with bound-constrains. The trust-region approach is then used to solve the minimization problem in order to make this optimization process more robust and reliable. In addition, the expansion and weighting of the original objective function are investigated so that the presented method can be well applied into the damage identification of more real structures. Finally, a numerical simulation model of two-story portal frame structure is adopted to evaluate the efficiency of the proposed technique when both the single and multiple damage cases are set up in the model. Some important issues are also discussed in this paper. The illustrated results show that the single and multiple damages on the two-story portal frame structure can be well identified by the proposed method.
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Aghakouchak, Ali Akbar, i Behrouz Asgarian. "Inelastic Analysis of Jacket Type Offshore Structures Using Fiber Elements". W ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28416.
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The fiber beam-column post-buckling element has been formulated and implemented in the non-linear program DRAIN-3DX to predict Buckling, Post-buckling and hysteresis behaviour of tubular Struts and Portals. In this element both material and geometric non-linearities are considered. The element is applied to simulate post buckling and hysteric response of tubular members subjected to cyclic loading. Also Psuedo-Static analysis of X-braced frame subjected to cyclic load has been perfomed. The predicted overall response matched well with the available experimental and other analytical results.
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Lepourry, Clemence, Hugues Somja, Pisey Keo, Piseth Heng i Franck Palas. "An innovative concrete-steel structural system allowing for a fast and simple erection". W 12th international conference on ‘Advances in Steel-Concrete Composite Structures’ - ASCCS 2018. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/asccs2018.2018.7014.
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In usual concrete buildings, medium to long span slabs can only be achieved by using prestressed beams. However, these elements are heavy, making their handling expensive; the cladding of these beams to vertical elements creates several difficulties, particularly in case of moment resisting frames; at last, their precamber implies a cautious management of the concreting and is a source of defects. Steel-concrete composite beams may offer an alternative, with similar performances. However they are not considered by concrete builders, because specific tools and skills are needed to erect them on site. Moreover usual composite members require a supplementary fire protection, which is costly and unsightly. This article presents an innovative steel-concrete moment resisting portal frame that overcomes these difficulties. It is based on composite tubular columns, and a composite beam made of a U-shaped steel profile used as permanent formwork to encase a concrete beam. This steel-concrete duality of beams allows an erection on site without any weld or bolt by a wise positioning of the construction joints. Moreover, as the resistance to fire is ensured by the concrete beam, the system does not require any additional fire protection. Finally, as only steel elements have to be handled on site, there is no need of heavy cranes. This system has been used to build a research center near Rennes, in France. As it is not covered in present norms, an experimental validation was required. After a detailed description of the structural system, the full-scale tests which have been performed are presented : - A series of asymmetrical push-out tests in order to determine the behaviour and resistance of shear connectors; - One 6-point bending test made to investigate the resistance of the USCHB under sagging bending moment; Two tests of the beam-column joint.
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Brasil, R. M. L. R. F., F. J. Garzeri i J. M. Balthazar. "Experimental Validation of a Non-Linear Model Under Non-Ideal Excitation". W ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/vib-48627.
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We present measurements of the non-linear oscillations of a portal frame foundation for a non ideal motor. We consider a three-time redundant structure with two columns, clamped in their bases and a horizontal beam. An electrical unbalanced motor is mounted at mid span of the beam. Two non linear phenomena are studied: a) mode saturation and energy transfer between modes; b) interaction between high amplitude motions of the structure and the rotation regime of a real limited power motor. The dynamic characteristics of the structure were chosen to have one-to-two internal resonance between the antisymmetrical mode (sway motions) and the first symmetrical mode natural frequencies. As the excitation frequency reaches near resonance conditions with the 2nd natural frequency, the amplitude of this mode grows up to a certain level and then it saturates. The surplus energy pumped into the system is transferred to the sway mode, which experiences a sudden increase in its amplitude. Energy is transformed from low amplitude high frequency motion into high amplitude low frequency motion. Such a transformation is potentially dangerous. We consider the fact that real motors, such as the one used in this study, have limited power output. In this case, this energy source is said to be non ideal, in contrast to the ideal source whose amplitude and frequency are independent of the motion of the structure. Our experimental research detected the Sommerfeld Effect: as the motor accelerates to reach near resonant conditions, a considerable part of its output energy is consumed to generate large amplitude motions of the structure and not to increase its own angular speed. For certain parameters of the system, the motor can get stuck at resonance not having enough power to reach higher rotation regimes. If some more power is available, jump phenomena may occur from near resonance to considerably higher motor speed regimes, no stable motions being possible between these two.
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Yu, L., T. Yin i H. P. Zhu. "Statistics-Based Noise Analysis for Vibration-Based Damage Identification". W ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95673.
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As the vibration-based structural damage detection methods are easily affected by the environmental noise, a novel noise analysis method is proposed based on the statistics in this paper together with the Monte Carlo technique for assessing the influence of experimental noise of modal data on sensitivity-based damage detection methods. Different from the commonly used random perturbation technique, the proposed technique is deduced directly by the Moore–Penrose generalized inverse of sensitivity matrix under the differential quotient rule of composite function. It can not only make the analysis process more effective but also analyze the noise influence on both frequencies and mode shapes in a similar way. Furthermore, an improved modal sensitivity based damage detection method is also proposed and compared with other two commonly used sensitivity-based methods in this paper. A one-story portal frame is adopted to evaluate the efficiency of both the proposed noise analysis technique and the improved modal sensitivity based method. The assessment results show that the proposed statistics-based noise analysis technique is effective and more suitable for the vibration-based damage identification. The improved modal sensitivity based method is more robust to noise than the other commonly used sensitivity-based methods.
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Ring, Brock P., Daniel K. Atkinson, Andrew W. Henderson i Evan C. Lemley. "Development of a Low Cost Particle Image Velocimetry System for Fluids Engineering Research and Education". W ASME 2013 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fedsm2013-16239.
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Particle image velocimetry (PIV) has transformed fluid mechanics research in recent years. PIV also holds the possibility to transform fluids engineering undergraduate education with the ability of students to get hands-on experience in visualization of real flow fields. One barrier to use of PIV is the cost of a system. Research grade systems are often over $100,000 and inaccessible to many undergraduate students. Recent availability of low-cost high-frame-rate digital cameras, lasers, and public domain software offer potential accessibility for PIV for many labs at academic institutions. In this paper we describe the development of a PIV system for under $1000 including specific components and their costs. In our lab this system is currently being used for several liquid flow experiments including obtaining the flow field in and near small bifurcations. Although we are using the system for liquid flows, it may be used for gas flows as well. One issue that is addressed is the cost of flow seeding — this has been solved by using pulverized green algae as seed particles with a strong reflection by a 532 nm green laser. The system is small and portable and is useful for observing flow in locations that are not of direct interest for experiments, but may have a bearing on flow conditions in experimental measurements; such as upstream of test sections. We describe some examples of how we have used the lost-cost PIV system in our lab and how it can be used for fluids engineering education and research. The current research application of this system is performing loss coefficient calculations in a test section using the energy dissipation.
Raporty organizacyjne na temat "Portal frame experiment"
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EXPERIMENTS ON BOLTED CONNECTIONS IN COLD-ROLLED ALUMINIUM PORTAL FRAMES. The Hong Kong Institute of Steel Construction, sierpień 2022. http://dx.doi.org/10.18057/icass2020.p.241.
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The use of portal frame systems composed of cold-rolled aluminium profiles is likely to be a new structural solution in corrosive environments. In such structural systems, stainless steel bolts are commonly used as connectors to fasten various aluminium components in the full-scale systems. In these connections, the point fasteners may experience either shear force, torque and/or a combination of both, leading to complex behaviours of the connections. While the failure may occur at a bolt, the other structural components are still in the elastic state. Hence, investigation into the load-deformation responses of bolt connectors is essential to further understand the complexity of bolted connections in the portal frame systems. In this study, experiments on different configurations of bolted connections subjected to shear force and/or torque were carried out at the University of Sydney to investigate the behaviour and to provide the load-deformation characteristics of the bolted connections
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EXPERIMENTAL STUDY ON BEHAVIOR OF THE GUSSET-PLATE JOINT OF ALUMINUM ALLOY PORTAL FRAME. The Hong Kong Institute of Steel Construction, sierpień 2022. http://dx.doi.org/10.18057/icass2020.p.257.
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"The aluminum alloy portal frames are increasingly being used for lightweight building construction. This paper investigated the flexural behavior of the bolted gusset-plate joint applied in the beam-beam connection of aluminum alloy portal frames. Bending tests were conducted on 3 aluminum alloy bolted gusset-plate joints. The failure phenomenon indicated that the thin plate joint failed by the buckling of gusset plates, while the thick plate joint failed by the buckling of sleeves. The momentrotation curves showed that thickening the gusset plate can effectively prevent the buckling of gusset plates and increase the flexural capacity and bending stiffness of joints. In addition, the longitudinal spacing of bolts has a significant influence on the joint stiffness but has no obvious influence on the bearing capacity of the joint. The stress on the two gusset plates of the joint was uneven, which led to the decline of bearing performance of thin plate joints."