Academic literature on the topic 'Portal frame method'
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Journal articles on the topic "Portal frame method"
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R., H. Mohankar*, Imran Alam Md., Gaurav Gopesh, and Choudhary Shubham. "A STUDY OF PORTAL FRAME USING ANALYTICAL METHODS AND ETABS SOFTWARE." INTERNATIONAL JOURNAL OF ENGINEERING SCIENCES & RESEARCH TECHNOLOGY 5, no. 3 (2016): 835–40. https://doi.org/10.5281/zenodo.48372.
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Analysis of portal frames involves lot of complications and tedious calculations by conventional methods. To carry out such analysis is a time consuming task. The Moment Distribution Method & Slope Deflection Method for analysis of portal frames can be handy in approximate and quick analysis so as to get the detailed estimates ready. In this work, these two methods have been applied only for vertical loading conditions. This paper mainly deals with the comparative analysis of the results obtained from the analysis of single bay portal frame when analyzed manually and using ETABS Software separately. The result obtained from manually is mostly matched with the results obtained from ETABS software.
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Chen, Xu, and Hui Min Li. "The Alculation Method of Stable Bearing Capacity of Portal Frame." Applied Mechanics and Materials 351-352 (August 2013): 329–36. http://dx.doi.org/10.4028/www.scientific.net/amm.351-352.329.
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In recent years, the portal frame structure in the actual project has been widely used, but using the finite element method calculation of stable bearing capacity of portal frame is more complex, and very difficult to the design and construction personnel. With the known stability of the cantilever column carrying capacity and the vertex of the lateral displacement under concentrated force, the establishment of the ratio of the portal frame stability capacity and the stability of the cantilever column carrying capacity both in the same concentrated force vertex lateral displacement than the relationship between the structural mechanics solver to seek out frame to the lateral displacement of the vertex under concentrated force, obtained by computing the stability capacity of the portal frame, and with the exact solution comparison and found that the methods of theoretical calculation results coincide with the exact solution, and then get an easy way of solving the portal frame stable bearing capacity. After numerical example, this method is simple, easy to master, and it has important reference value.
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Faridmehr, Iman, Mahmood Md Tahir, Tom Lahmer, and Mohd Hanim Osman. "Seismic Performance of Steel Frames with Semirigid Connections." Journal of Engineering 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/5284247.
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The nonlinear stiffness matrix method was incorporated to investigate the structural performance of steel portal frames with semirigid connections. A portal frame with unstiffened extended end-plate connection was designed to demonstrate the adequacy of the proposed method. Besides, the seismic performance of steel portal frames with semirigid connections was investigated through time history analysis where kinematic hysteresis model was assigned to semirigid connections to account for energy dissipation and unloading stiffness. Based on the results of the study, it was found that generally semirigid connections influenced the force distribution which resulted in the decrease in base shear and lighter frame compared to the rigid one. The results also indicated that there was no direct relationship between maximum displacement at the top and connection stiffness in high-rise frames.
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BASAGA, H. B., M. E. KARTAL, and A. BAYRAKTAR. "RELIABILITY ANALYSIS OF STEEL BRACED REINFORCED CONCRETE FRAMES WITH SEMI-RIGID CONNECTIONS." International Journal of Structural Stability and Dynamics 12, no. 05 (2012): 1250037. http://dx.doi.org/10.1142/s021945541250037x.
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This paper presents the reliability analysis of the frame structures with semi-rigid connections. For this purpose, the SEMIFEM finite element program that is capable of dealing with the semi-rigid connections is coded in FORTRAN. Then, this program is connected to the reliability algorithm. The direct coupling method, which is a combination of the reliability method and finite element method, is utilized to determine the reliability indexes and probabilities of failure for the structure. The first order reliability method (FORM) is the one favored in the present reliability analysis. Two sets of steel framed structures are analyzed; each of four and eight stories, consisting of a portal frame and three types of concentrically braced frames. Concrete compression strength limit state in reinforced concrete (RC) columns, steel strength limit state in steel braces and inter-story drift limit state are considered in reliability evaluation. According to the limit states, X braced frames are determined as the safest structures, while the portal frames are regarded as the most unsafe structures. As the connection percentage increases, the safety of the structure increases in terms of inter-story drift and steel strength limit states, but decreases for concrete compression strength limit states.
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Far, Harry, and Claire Far. "Timber Portal Frames vs Timber Truss-Based Systems for Residential Buildings." Advances in Civil Engineering 2019 (July 28, 2019): 1–7. http://dx.doi.org/10.1155/2019/9047679.
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A large number of structures have been built during or after the construction of a house or residential-zoned building, which are not built at the same time and/or integrally with the structural integrity of the residential dwelling. These include carports, pergolas, sheds, and barns. The typical method of constructing these structures is a general timber truss and column system. The aim of this study is to look at the feasibility and economic incentive that may be gained from using a timber portal frame system, similar to the steel or timber portal frames used for larger industrial constructions, over the traditional timber truss and column arrangement. In this study, designs for three cases of timber truss and timber portals were carried out using industry appropriate methods and standards. Using the design information and data gathered through talks with industry professionals, both methods of construction were compared on cost and overall time duration. From the comparison of the truss and portal designs, the use of timber portal frames over timber truss systems proved to have advantage in relation to overall cost and man power involved. This could certainly affect the current attitude towards the construction of small residential buildings in the future.
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Liu, Feng, and Xiao Yan Wang. "Overall Reliability Assessment of Portal Frame Structure with Roof Beam Outward Offset." Applied Mechanics and Materials 501-504 (January 2014): 628–33. http://dx.doi.org/10.4028/www.scientific.net/amm.501-504.628.
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This article deals with the condition that the roof beams of portal frame are outward offset beyond the standard limit, determines the most unfavorable position of the portal frame structure under the load and establishes the criterion standard of structural failure based on the space overall finite element analysis. It adopts Monte-Carlo method in reliability analysis methods to realize the overall reliability analysis of the portal frame structure with the roof beam outward offset. Analysis shows that the actual structure is at safe state under the design load and the reliability conforms to the standard requirement.
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Xie, Ming, Fangbo Xu, Zhangdong Wang, et al. "Investigating Fire Collapse Early Warning Systems for Portal Frames." Buildings 15, no. 2 (2025): 296. https://doi.org/10.3390/buildings15020296.
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In recent years, firefighter accidents and people injured by the collapse of steel structures during a fire have occurred frequently, which has attracted the attention of the National Emergency Management Department and the Fire and Rescue Bureau. It is urgent to carry out research on early warning systems for building collapse during a fire. Existing early warning methods mainly use characteristic parameters such as temperature, vibration, and structural deformation. Due to the complexity of an actual fire, it is difficult to accurately predict the critical temperature of fire−induced instability in columns and the failure mode after the instability, and there are deviations in the collapse warnings. In this study, changes in ultrasonic transverse and longitudinal wave velocities at high temperatures are used to monitor the stiffness degradation of columns in fire in real time and improve the accuracy of early warning systems. In this study, four common collapse modes of portal frames are obtained by using the results of parametric numerical analysis. According to key displacements and the displacement rates of simple key measuring points, the elastic modulus threshold of a three−level early warning for portal frame collapse with different collapse modes is obtained. Combined with an ultrasonic experiment, the theoretical relationships between the transverse and longitudinal wave velocities and the elastic modulus of steel at high temperatures are verified, and the relationship between the transverse and longitudinal wave velocities and the overall damage of the portal frame is further constructed; then, a new early warning method for portal frame stability during a fire is proposed. Based on the change in wave velocity, a three-level early warning index for predicting portal frame stability during a fire is determined. When the collapse mode of a portal frame is an overall inward collapse, transverse and longitudinal wave velocities are reduced to 2635 m/s and 5308 m/s, respectively. At a second-level warning, they are reduced to 2035 m/s and 4176 m/s, respectively. At 1504 m/s and 3030 m/s, respectively, third-level warnings are issued. This research shows that the real−time monitoring of wave velocities provides an effective way for early warning systems to identify structural collapse. The proposed early warning method can be used as a quick and efficient early warning system for the collapse of portal frames during a fire, and its accuracy and applicability are verified by experiments.
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Jia, Wen Wen, and Deng Feng Wang. "Internal Force Evaluation of Non-Uniform Beam in Portal Frame." Applied Mechanics and Materials 423-426 (September 2013): 1454–58. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.1454.
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To simplify the internal force evaluation of portal frame being composed of non-uniform members, the force method was used to solve internal force of every key section of the non-uniform beam in portal frame with single-span. Gauss numerical integration method was used to simplify the complex integration when the deformation energy was calculated. Under the precondition of satisfied accuracy, the direct expressions of bending momentshear force and axial force of every key section of beam were obtained. The research work can be used as reference for the evaluation and design of portal frame members.
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Sabbagh-Yazdi, Saeed-Reza, and Ainullah Mirzazadah. "Comparing Numerical Results for Seismic Performance of Portal Steel Frames Braced with Steel: HSS Brace, Glulam Timber Brace, and Timber-Steel-BRB." Advances in Civil Engineering 2022 (July 20, 2022): 1–17. http://dx.doi.org/10.1155/2022/2705691.
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This study involves the application of timber-based bracings elements. For this purpose, seismic analyses are performed on special portal steel frames without the brace and diagonally braced with Glued Laminated Timber (glulam) and Timber-Steel Buckling Restrained Brace (TS-BRB), and the results are compared with the same configuration using steel Hollow Structural Sections (HSS) bracing, using OpenSees structural analyzer. First, to verify the accuracy of the modeling, the numerical results are compared with experimental measurements on several types of elements: (a) diagonally braced frame with steel Hollow Structural Sections with a concentrically steel braced frame which was tested by the quasi-static method under cyclic loading protocol by previous researchers, (b) diagonally glulam braced frame with results of shake table tests on single-story timber braced frames, and (c) Timber-Steel Buckling Restrained Brace (TS-BRB) frame with experimental results of Heavy Timber Buckling-Restrained Braced Frame (HT-BRB). In the second step, the aforementioned timber base bracing alternatives (glulam, TS-BRB) are applied in the special portal steel frame, then the seismic performance of the frame is investigated under pushover, cyclic, time history, and incremental dynamic analysis (IDA), and then the results are compared with the behavior of similar portal frame in two conditions without the brace and diagonally braced with the steel-HSS brace. Results showed that steel-HSS, glulam, and timber-steel buckling restrained braces have significant roles in energy dissipation, increasing shear capacity, decreasing interstory drift, and decreasing weight and cost of estimation of the structure.
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S. J. Modak, S. J. Modak. "Determination of Influence Lines of a Portal Frame Adopting Matrix Method of Structural Analysis." Indian Journal of Applied Research 3, no. 7 (2011): 224–26. http://dx.doi.org/10.15373/2249555x/july2013/70.
Full textDissertations / Theses on the topic "Portal frame method"
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Park, Ashley Yuuki. "Semi-rigid joints to tubular columns and their use in semi-continuous frame design." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/semirigid-joints-to-tubular-columns-and-their-use-in-semicontinuous-frame-design(5214b6d8-7df6-4197-bbcd-d4d92b8330df).html.
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Traditionally, joints are assumed to be either pinned or fully rigid, but in reality, many behave between these two extremes giving them a semi-rigid classification. By acknowledging the semi-rigidity of nominal pin joints, steel frames can be designed as semi-continuous in which the beam bending moments are partially transmitted to the column members and the need for lateral bracing is eliminated, thus reducing material and construction costs. This thesis presents the results of numerical and theoretical studies of the behaviour of bolted endplate connections to Rectangular Hollow Section (RHS) columns using flowdrill bolts and their applications in semi-continuous frame design. Such connections exhibit significant levels of initial stiffness, strength, and deformation capacity while being more cost-effective than fully welded connections. Despite this, there is limited theoretical work carried out that allows such connections to be designed using analytical methods. In addition, there are no standardised connection design tables like that for open section columns (SCI, 1995), thereby inhibiting their adoption in practice. In this thesis, newly derived equations for initial stiffness that have a greatly improved range of validity and accuracy over existing equations are presented. Equations for bending strength of a newly derived elliptical mechanism based on yield line theory and for membrane action based on internal work principles are given. Equations for flowdrill thread stripping due to gross deformation of the RHS face are also presented thus allowing prediction of all common RHS face failure mechanisms. Equations for deformation capacity are derived thus making it possible to predict the full load-deflection behaviour of the RHS face in tension component. When combined with existing equations for bolt and endplate components, it is possible to predict the full moment-rotation behaviour of bolted endplate connections to RHS columns. Extensive parametric studies using finite element analysis (FEA) as well as validation against existing tests show that the newly derived equations can accurately predict the component-level and whole joint behaviour for a wide range of configurations. Taking advantage of the initial stiffness properties that these connections offer, a parametric study is conducted to show that connections with relatively simple detailing can offer sufficient initial stiffness and strength to enable unbraced semi-continuous design of low-rise steel frames. A hand calculation method for SLS sway in semi-continuous frames is also presented thus allowing the designer to readily carry out scheme designs without advanced software knowledge. A systematic method for the detailing of these connections for use in unbraced frame design is presented to facilitate adoption in practice.
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Chen, Lu. "Robustness in fire of steel framed structures with realistic connections." Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/robustness-in-fire-of-steel-framed-structures-with-realistic-connections(fcf4d94b-56f4-42bc-b20a-e2e497d4c14a).html.
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Joints are the most critical elements in a steel framed structure. In most design guides or codes, the joints are assumed to a have higher fire resistance than the connected structural members because of the lower temperatures in the joints. However, in severe fire conditions, a connected beam's temperature may be higher than its limiting temperature and the beam may develop catenary action when the beam’s axial shortening from large deflections becomes greater than the beam’s thermal expansion. This beam catenary action force could fracture the joints, increasing the risk of progressive collapse. This research focuses on the interaction between joints and the connected steel beams and columns in steel framed structures in fire, including how the behaviour of a joint-beam assembly may be efficiently analyzed and how the joints may be constructed to achieve high degrees of catenary action. Three methods of simulating the joint behaviour in fire have been developed and implemented in the commercial finite element software ABAQUS. In the first modelling method, all structural members, including the connections, were simulated using detailed solid elements to enable detailed behaviour of the structure to be faithfully represented. In the second method, the columns were represented by conventional line (beam) elements, the joints were represented using springs (Connector Elements) based on the component based method, and the beam was modelled using solid elements. In the third method, the joints were modelled using springs as in the second method and the beam and columns were simulated using line (beam) elements. As expected, the detailed simulation method was extremely time-consuming, but was able to produce detailed and accurate results. The simulation results from the second and third methods contained some inaccuracies, but depending on the simulation objective, their simulation results may be acceptable. In particular, the third simulation method was very efficient, suitable for simulating complete frame structures under very large deflections in fire. The first method (detailed finite element method) was then used to investigate how to change the joint details to increase the survivability of restrained steel beams and beam-column assemblies at high temperatures since it enables detailed behaviour of the structure to be faithfully represented. It is found that by improving joint deformation capacity, in particular, using extended endplate connection with fire resistant bolts, very high temperatures can be resisted. The frame robustness in fire was investigated using the third simulation method to save computation time. The simulation structure was three-bay by three-floor and different scenarios of fire location, fire spread and initial structural damage were considered. The simulation results show that once failure of a column occurs, progressive collapse of the structure could be easily triggered and it would be rather futile to only enhance the joint capacity. Therefore, in addition to the measures of improving joint capacities (both rotation and strength), design of the affected columns should include consideration of the additional catenary forces from the connected beams and the increased effective lengths. Furthermore, the lateral bracing system should be ensured to provide the structure with lateral restraint.
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Nguyen, Hoai Cuong. "Strength and Behaviour of Cold-Rolled Aluminium Portal Frames." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25465.
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This doctoral thesis presents a comprehensive study on cold-rolled aluminium portal frames composed of back-to-back lipped channel sections. The research included an extensive experimental program on full-scale portal frames and components, a numerical simulation part on finite element modelling, and finally a proposal development of the design for the cold-rolled aluminium frame systems. The primary aim is to explore the structural behaviour and ultimate strength through experiments and numerical analyses, leading to the development of proposed provisions for the design of cold-rolled aluminium portal frames using Advanced Analysis. The study also evaluates the applicability of the current standards to the design of cold-rolled aluminium portal frames.
Towards observing the structural behaviour and determining the ultimate strength, a series of seven full-scale tests on two-bay single-span cold-rolled aluminium portal frame systems, having a size of 14 m long by 6.7 m high, were carried out. Various frame configurations were tested for both gravity loading and combined horizontal and gravity loading conditions. Separate tests were performed on the column base connection to quantify the flexural stiffnesses of the base connections about the column-major and -minor axes so that the semi-rigidity of the base connection used in the full-scale frame test was evaluated, and the effects of different base brackets on the column base stiffness were also examined. Other laboratory experiments, including coupon and point fastener connection tests, were also conducted to obtain the necessary information on material properties, connection characteristics. Further, initial geometric imperfections of both members and systems were thoroughly measured for use in further numerical investigations.
Nonlinear finite element simulations using shell elements and advanced analysis of the full-scale frames and the base connections were developed and calibrated against experimental results. All sources of major nonlinear actions, notably geometric, material, connector and contact nonlinearities, were included in the numerical finite element models. In details, the individual bolts used for the connections were simulated by deformable point-based fasteners. The force-deformation characteristics of the deformable fasteners, which were obtained from the point fastener connection tests, were incorporated and successfully implemented in the Advanced Analysis. Parametric studies were subsequently carried out on the basis of the calibrated modelling technique to determine the effect of the column base stiffness, as well as various configurations of the lateral bracing for columns, on the frame ultimate strength for both gravity load and a combination of horizontal load and gravity load. A larger span finite element model was also created to study the suitability of the frame design for larger spans.
The strengths of cold-rolled aluminium portal frames were determined by the conventional methods available in the current international aluminium design standards/specifications and by the Direct Design Method using Advanced Analysis. A comparison of predicted strengths from the various design approaches was then performed. To account for inherent uncertainties in the strength of the cold-rolled aluminium portal frames, a system reliability analysis was conducted to derive system resistance factors. It was highlighted that the Direct Design Method using Advanced Analysis as proposed in this study is the robust and realistic method for the design of cold-rolled aluminium portal frames and is likely the future design method for all types of structures including those comprised of cold-rolled aluminium sections.
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Rinchen. "Long-span cold-formed steel single C-section portal frames." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/18882.
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This thesis presents a comprehensive study of long-span cold-formed steel single C-section portal frames. The study includes the formulation of a nonlinear beam finite element for thin-walled sections, a series of full-scale frame tests and component tests, finite element modelling and advanced analysis followed by the formulation of design guidelines. The study was aimed at exploring the structural behaviour through experiment and numerical analysis towards developing provisions for the design of cold-formed steel portal frames using Advanced Analysis. A nonlinear thin-walled beam element for general open cross-sections was formulated, incorporating warping effect and non-coincident location of the shear centre and the centroid. It was successfully implemented in the geometric nonlinear analysis framework of the OpenSees finite element software. Towards investigating the behaviour and determining the ultimate strength, six full-scale tests on cold-formed steel single C-section portal frames were conducted. Separate tests were performed on frame connections, point-fastener connections and coupons to obtain the material parameters required for numerical modelling. Advanced shell finite element models of the full-scale frames and frame connections were created and validated against experimental results. The bolts and screws used for the connections between components were represented by point-based deformable fasteners. The force-deformation characteristics of the deformable fasteners were incorporated and successfully implemented in the Advanced Analysis. The strength of cold-formed steel single C-section portal frames determined by the Direct Strength Method and the Direct Design Method were compared. To account for inherent uncertainties in the strength of CFS portal frames, system resistance factors were derived. It was concluded that the Direct Design Method using Advanced Analysis is the likely future method for the design of cold-formed steel portal frames.
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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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Lee, Seungjea. "Robustness of reinforced concrete framed building at elevated temperatures." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/robustness-of-reinforced-concrete-framed-building-at-elevated-temperatures(db90ad82-86b5-4ba3-9ef1-42e7004b4b34).html.
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This thesis presents the results of a research programme to investigate the behaviour and robustness of reinforced concrete (RC) frames in fire. The research was carried out through numerical simulations using the commercial finite element analysis package TNO DIANA. The main focus of the project is the large deflection behaviour of restrained reinforced concrete beams, in particular the development of catenary action, because this behaviour is the most important factor that influences the frame response under accidental loading. This research includes four main parts as follows: (1) validation of the simulation model; (2) behaviour of axially and rotationally restrained RC beams at elevated temperatures; (3) derivation of an analytical method to estimate the key quantities of restrained RC beam behaviour at elevated temperatures; (4) response and robustness of RC frame structures with different extents of damage at elevated temperatures. The analytical method has been developed to estimate the following three quantities: when the axial compression force in the restrained beam reaches the maximum; when the RC beams reach bending limits (axial force = 0) and when the beams finally fail. To estimate the time to failure, which is initiated by the fracture of reinforcement steel at the catenary action stage, a regression equation is proposed to calculate the maximum deflections of RC beams, based on an analysis of the reinforcement steel strain distributions at failure for a large number of parametric study results. A comparison between the analytical and simulation results indicates that the analytical method gives reasonably good approximations to the numerical simulation results. Based on the frame simulation results, it has been found that if a member is completely removed from the structure, the structure is unlikely to be able to develop an alternative load carrying mechanism to ensure robustness of the structure. This problem is particularly severe when a corner column is removed. However, it is possible for frames with partially damaged columns to achieve the required robustness in fire, provided the columns still have sufficient resistance to allow the beams to develop some catenary action. This may be possible if the columns are designed as simply supported columns, but have some reserves of strength in the frame due to continuity. Merely increasing the reinforcement steel area or ductility (which is difficult to do) would not be sufficient. However, increasing the cover thickness of the reinforcement steel to slow down the temperature increase is necessary.
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Athanasios, Dimitriou. "Surface pre-treatment methods for improving adhesion ability in wood plymer composite for frame and furniture construction applications." Thesis, Bangor University, 2015. https://research.bangor.ac.uk/portal/en/theses/surface-pretreatment-methods-for-improving-adhesion-ability-in-wood-plymer-composite-for-frame-and-furniture-construction-applications(0e7da265-4f1a-4506-aad1-f3e84105aff1).html.
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Kulkarni, Raghavendra B. "Inverse problems solution using spectral finite element methods." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5471.
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Inverse problems are very challenging as these problems involve, finding the cause by analyzing the effects. In structural dynamics problems, the effects are normally measured in terms of dynamic responses in structures. These responses which are used to find the cause generally have partial data, embedded with measurement noise, and are truncated. Due to these problems, inverse problems are generally ill-posed in most cases as against forward problems.
In this dissertation, we solve five different types of inverse problems involving high-frequency transient loads. All these problems are solved using the time-domain spectral element method (TSFEM) along with experimental or numerically simulated responses.
The dissertation starts with the formulation of the forward problem, which is obtaining the responses from known input forces. The general formulation of TSFEM of composite Timoshenko beam is derived. The isotropic beam formulation is shown as a special case in this formulation.
Five different inverse problems solved in the thesis are:
1. Force identification problem: A new algorithm is developed using a 1-D waveguide, involving an eight noded spectral finite element. The force identification is carried out, using a few measured responses on the structure, and using TSFEM we reconstruct the input force. This is followed by a portal frame example to demonstrate the wave reflection complexities. New procedures are developed to use various types of response data like displacement, velocity, acceleration, and strain to identify the force.
2. Material identification problem: A new procedure making use of the developed TSFEM, few responses, and nonlinear least square techniques are used to determine the material properties. Also, we show the case, in which we derive the material properties without force input consideration.
3. Crack location detection problem: A new procedure is developed using TSFEM and mechanics of crack. Three methods are described, in which the first method uses only responses and wave speeds to determine the location of the crack. In the second method, force reconstruction using the measured responses is carried out and this, in turn, is used to determine the location of the crack. The third method uses the residues of the actual force and the reconstructed forces using the healthy beam matrices and cracked beam responses. A new procedure to identify the crack location using a general force input pulse having many frequency components is also developed.
4. Material defect identification: Material defects like voids or density changes are identified using TSFEM. Location and magnitude of defect are identified using response computation and using the method of residues.
5. Porous location and identification in a composite material: TSFEM is used to construct a porous element and this is used along with a healthy beam to generate the responses. A force reconstruction algorithm is used to identify the location of the porous element. The Force residue method to identify the location of the defect is also demonstrated. Further, we make use of the material identification algorithm with a few modifications to evaluate all the parameters for the porous element.
Books on the topic "Portal frame method"
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Wan, Chi-Wah. Optimum design of a simple portal frame using risk analysis method. 1985.
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Park, Simon. Poets, Patronage, and Print in Sixteenth-Century Portugal. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780192896384.001.0001.
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Portugal was not always the best place for poets in the sixteenth century. Against the backdrop of an expanding empire, poets struggled to articulate their worth to rulers and patrons. Many of their works considered what poetry could do and what its value was. The answers that poets like Luís de Camões, Francisco de Sá de Miranda, António Ferreira, and Diogo Bernardes offered to these questions ranged from lofty ideals to more practical concerns of making ends meet. This book articulates a ‘pragmatics of poetry’ that combines literary analysis and book history with methods from sociology to explore how poets thought about themselves and negotiated the value of their verse. Poets compared their work to that of lawyers and doctors and tried to set themselves apart as a special group of professionals. They threatened their patrons as well as flattered them and tried to turn their poetry from a gift into something like a commodity or service that had to be paid for. While poets set out to write in the most ambitious genres, they sometimes refused to spend months composing an epic without the prospect of reward. Their books of verse, when printed, were framed as linguistic propaganda as well as objects of material and aesthetic worth at a time when many said that non-devotional poetry was a sinful waste of time. This is therefore a book about how poets, metaphorically and more literally, tried to turn poetry and the paper it was written on into gold.
Book chapters on the topic "Portal frame method"
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Dong, Pool Ip. "13. Children’s Emerging Play and Experience in the Covid-19 Era." In Play in a Covid Frame. Open Book Publishers, 2023. http://dx.doi.org/10.11647/obp.0326.13.
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This chapter examines diverse distance education strategies used in Korean early childhood education and care (ECEC). Focused on the Covid-19 situation in the South Korean educational context, it introduces how Korean teachers and parents made an effort to promote and provide opportunities for children’s play. Examples of this include teachers sending ‘A Package for Play’, using education portals and providing distance education through media (e.g. real-time interactive learning via Zoom and content-based learning via TV programmes). This chapter also analyzes how young children, teachers, parents and educational cultures were changed as they faced the challenges of Covid-19 in South Korea. Lockdowns and school closures offered young children an opportunity to realize the importance of their friends in their play. Some Korean parents’ perception of distance education changed from one of anxiety and pressure to a chance to better understand their children and ECEC. For Korean teachers, it was an opportunity to try creative new teaching methods and support for play in ECEC settings. The Korean cases in this chapter will give an insightful perspective into diverse educational resilience, educational possibilities and implications in the Covid-19 era.
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Klötzer, Christian, Martin-Christoph Wanner, Wilko Flügge, and Lars Greitsch. "Implementation of Innovative Manufacturing Technologies in Foundries for Large-Volume Components." In Annals of Scientific Society for Assembly, Handling and Industrial Robotics 2021. Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-74032-0_19.
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AbstractThe development of new manufacturing technologies opens up new perspectives for the production of propellers (diameter < 5 m), especially since the use of the established sand casting process as a technology is only partially competitive in today’s market. Therefore, different applications of generative manufacturing methods for the implementation into the production process were investigated. One approach is the mould production using additive manufacturing processes. Investigations showed that especially for large components with high wall thicknesses available systems and processes for sand casting mould production are cost-intensive and conditionally suitable. With our development of a large-format FDM printer, however, the direct production of large-format positive moulds for, for example, yacht propellers up to 4 m in diameter is possible. Due to the comparatively low accuracy requirements for the mould, the focus is on the durability of the drive system and the rigidity of this FDM printer. Equipped with simple linear technology in portal design and cubic design of the frame structure with rigid heated print bed, the aim is to achieve maximum material extrusion via the print head. The production of plastic models not only facilitates handling during the moulding process, but also allows considerable time and cost savings to be made during the running process. A further step in our development is the direct production of the components using WAAM. A possible concept for robot-supported build-up welding for the production of new innovative propeller geometries is presented using the example of a hollow turbine blade for a tidal power plant.
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Lin, Huhu, Qian Liu, and Siwen Liu. "Toward Moire-Free Video: A Multi-Scale Feature Alignment and Removal Network." In Advances in Transdisciplinary Engineering. IOS Press, 2024. http://dx.doi.org/10.3233/atde240468.
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The widespread adoption of portable photography devices, such as smartphones, has led to an increased occurrence of moire patterns on camera screens, which significantly degrades the quality of visual perception. While most research has focused on the removal of moire patterns in images, video moire removal has not been well investigated. This paper focus on the removal of moire patterns in videos and propose a two-stage video moire removal network. The first stage aligns the information between adjacent frames through a multi-scale frame alignment network, accomplishing the temporal aggregation of information. The second stage is the moire removal net-work, which restores the contaminated areas from both texture and color perspectives. A novel dataset construction method is introduced, allowing for precise alignment between moire-affected images and reference images by capturing pure white background images to extract moire patterns. Extensive experiments on the TCL-V1 dataset and the new dataset demonstrate the effectiveness of the proposed scheme compared with state-of-the-art results in video moire removal.
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Marti-Puig Pere, Masferrer Gerard, and Serra Moises. "Low-complex Real-Time Breathing Monitoring System for Smartphones." In Frontiers in Artificial Intelligence and Applications. IOS Press, 2014. https://doi.org/10.3233/978-1-61499-452-7-257.
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Monitoring breathing is required in many applications of medical and health fields but it can also be used also in a new set of applications that involve fields as diverse as entertainment games or some new applications oriented to develop skills such as focused attention. As smartphones are widespread around the world it is assumed that an important number of such applications must run on such platforms. In this work, an automatic, low-complex real-time system for monitoring breathing is presented. The system uses the acoustic signal recorded by a standard microphone placed in the area of the nostrils. The method is based on the Sequencial Walsh Hadamard (SWH) transform coefficients computed on non-overlapped frames to finally provide a reduced set of real parameters. These parameters feed a linear classifier that labels the frames in three different groups: inspiration, transition and expiration, in real time. The system runs in a smartphone or any portable device, only requiring as auxiliary equipment, a standard microphone from a conventional Bluetooth Headset.
Conference papers on the topic "Portal frame method"
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Gottsäter, Erik, Oskar Larsson, Mario Plos, Miklós Molnár, and Roberto Crocetti. "Simulation of Thermal Load Distribution in Portal Frame Bridges." In IABSE Congress, Stockholm 2016: Challenges in Design and Construction of an Innovative and Sustainable Built Environment. International Association for Bridge and Structural Engineering (IABSE), 2016. http://dx.doi.org/10.2749/stockholm.2016.0009.
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Uneven exposure to e.g. solar radiation can cause temperature differences between various structural parts of a bridge, which leads to tensile stresses if the parts cannot move freely. In this study, thermal simulations and stress calculations on a model of a portal frame bridge are performed with the aim of evaluating the temperature difference between the bridge parts. It is shown that the temperature difference between parts which is proposed by Eurocode 1 is overestimated, thus the resulting stress distribution being unrealistic. Using the design method proposed by Eurocode 1 is therefore likely to exaggerate the required reinforcement in crack width limit design, which in turn would lead to unnecessary costs and environmental impacts. Further studies are needed in order to determine proper thermal load values and temperature distributions.
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Yin, T., L. Yu, and H. P. Zhu. "Structural Damage Identification Based on Model Updating." In 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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Leamy, Michael J. "Wave Based Analysis of Buckling in Columns and Frames." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12926.
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This paper reports a wave-based analysis approach for predicting static buckling instabilities in axially-loaded columns and frames. It builds upon recent work on the wave-based vibration analysis of frame-like structures modeled by Timoshenko beams. To predict buckling, axial preload modeling is included in the equations of motion and the wave-based analysis approach is reformulated accordingly. This reformulation includes development of reflection and transmission matrices for a general, four-member angled joint. An eigenvalue problem (EVP) is then solved for example systems by setting the frequency of the wave solutions arbitrarily close to zero while seeking the axial preload which zeroes the EVP determinant. Numerical conditioning of the EVP problem is discussed as an essential step for ensuring successful application of the method. Notably, the method allows exact solutions to parameterized systems to be computed quickly and easily without the need for special discretization or mesh generation. This is exploited, for example, to find the optimal cross-brace location for an H-frame by varying a single parameter in the EVP determinant, avoiding the need to regenerate geometry and/or discretization (e.g., mesh topology). For a conservatively-loaded column, and for example portal and H-frames, results from the introduced approach show excellent agreement with known solutions.
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Chornay, Morn, and Xin Zhao. "Multilevel Decomposition Model for Optimal Design of Multi-Story Structures." In IABSE Congress, Nanjing 2022: Bridges and Structures: Connection, Integration and Harmonisation. International Association for Bridge and Structural Engineering (IABSE), 2022. http://dx.doi.org/10.2749/nanjing.2022.0216.
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<p>Multilevel decomposition optimization method decomposes a large problem into small subproblems to be solved separately and maintain effects between subproblems effectively by sensitivity derivatives, and it serves as a useful tool for design engineer team to work on a large structural optimization problem simultaneously and effectively. The present paper illustrates the application of this method on the optimization of a portal frame of a multi-story steel structure, and three level of substructure is chosen to solve the optimization problem. The 1st level is the entire structural system constrained to total lateral displacement, the 2nd level is each story frame constrained to story drift, and the 3rd level is related element sizing based on local constrains due to strength, serviceability, and member stability.</p>
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KAMAL, MAYANK, and SAUVIK BANERJEE. "VIBRATION BASED DAMAGE IDENTIFICATION IN WELDED ASYMMETRICAL STEEL FRAMES USING REGULARIZATION TECHNIQUES." In Structural Health Monitoring 2023. Destech Publications, Inc., 2023. http://dx.doi.org/10.12783/shm2023/36811.
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The damage identification problem for a frame structure can be formulated in a linear equation in the form Aθ = b. In this formulation, matrix A represents the FE model parameters, vector θ represents the change in state variables or the mathematical parameters which are to be determined, and vector b represents the response to an external excitation. In the real test case, the matrix A can be rectangular, and the linear relation is an over-determined and ill-posed problem. The results of these ill-posed problems are non-continuous and thus require special solution techniques like regularization techniques for getting a solution. This study is aimed at damage identification based on the vibration analysis of asymmetrical multistory plane frame structures with welded joints. Time-domain response analysis assisted by various regularization techniques is used to identify the damage in the portal frame structures, which is caused due to loss of stiffness. Initially, the effectiveness of the regularization method is examined by considering a one-story steel frame with welded connection, which is then analyzed analytically with FE formulation by simulating single damage cases. The analysis has been extended for an instrumented multistory asymmetrical plane frame structures for single damage cases with static analysis. Various regularization techniques like Lð regularization or Least absolute shrinkage and selection operator (LASSO), Lï regularization, elastic net regularization, and linear regression are used to study their effectiveness in the damage identification without doing model updating of the numerical model. In the study, the Lð regularization gives better results than other methods for a single damage case. The damage identification in asymmetrical steel frames needs to be better studied, and this study can be replicated for more complex steel structures for real-life damage scenarios. This can be developed as a real-time standalone early warning system for important steel frame structures, thus ensuring their timely maintenance and continuous sustainable use.
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Srirengan, Kanthi, Partha Chakrabarti, and Rupak Ghosh. "Modal Superposition Technique to Predict the Seismic-Pushover Load for Jacket-Type Structures." In ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2002. http://dx.doi.org/10.1115/omae2002-28258.
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Two novel methods namely the Dominant Modes method and the All Modes method to predict the seismic-pushover load for the jacket-type structures are presented. Both of these methods are based on the linear superposition of the modal reactions. As a preliminary evaluation, the linear elastic response of a jacket structure subjected to seismic-pushover loads is compared with that obtained from the response spectrum analysis. Furthermore, the nonlinear inelastic behavior obtained from the seismic-pushover analysis is compared with that obtained from the nonlinear time-history analysis, for a portal frame subjected to El Centro earthquake motion. When more than one mode is dominant in an excitation direction, both the linear elastic and the nonlinear inelastic responses obtained using the loads generated from the All Modes method are representative of the reference solutions.
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Rocha, Rodrigo T., Jose M. Balthazar, Angelo M. Tusset, Vinicius Piccirillo, Frederic C. Janzen, and Jorge L. P. Felix. "On Mode Coupling Analysis and Stability Regions to Energy Harvesting in a Two-Degrees-of-Freedom Portal Frame Platform." In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67532.
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This work aims to study the modal coupling of a nonlinear two-degrees-of-freedom portal frame platform and a numerical analysis of the system with a nonlinear piezoelectric (PZT) material coupled to one of its columns, both externally base-excited. The nonlinear platform possesses two-to-one internal resonance between its two vibration modes and presenting the saturation phenomenon. The nonlinearities of the piezoelectric material are considered by a nonlinear mathematical relation. Here, it is considered an electro-dynamical shaker with harmonic output. The employed methodology to carry out the analysis of this work was: the application of the method of multiple scales to find the best configuration of the parameters, and to find some kind of phenomena due to the two-to-one internal resonance; several numerical simulations were carried out to optimize the energy harvesting through parametrical variations, bifurcation diagrams, stability diagrams. It will be analyzed: the influence of the nonlinearity of the piezoelectric material and of the electro-dynamical shaker on the energy harvesting. Results showed great influence of the nonlinearity of the material and using the electro-dynamical device. It was possible to gain considerably in energy harvesting and stability of the system.
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Yu, L., T. Yin, and H. P. Zhu. "Statistics-Based Noise Analysis for Vibration-Based Damage Identification." In 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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Gottsäter, Erik, Oskar Larsson Ivanov, and Mario Plos. "Crack widths in portal frame bridges subjected to restraint effects." In IABSE Congress, New York, New York 2019: The Evolving Metropolis. International Association for Bridge and Structural Engineering (IABSE), 2019. http://dx.doi.org/10.2749/newyork.2019.1100.
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<p>Restraint stresses appear in structural parts which are prevented from adjusting their shape when subjected to e.g. shrinkage or thermal actions. If the restrained stresses are large, cracking might occur, which can affect the durability of the structure. In the case of restraint effects, the reinforcement required in a bridge to limit the crack widths can be difficult to determine, as the magnitude of the restraint stresses depend on the stiffness of the structure. If cracking occurs, the stiffness is reduced and thereby also the stresses. For this reason, in structural parts affected by restraint effects, it can be hard to estimate both the number of cracks that will appear and the resulting restraint stress that governs the crack widths.</p><p>In this study, crack widths in a portal frame bridge subjected to thermal actions and shrinkage were investigated using non-linear FE analysis. A bond-slip relation was used for concrete-reinforcement interaction, as the resulting crack spacing was unknown. Corresponding analysis was performed using linear elastic material models and hand calculations of crack widths, for two different thermal load cases, and relations between the results from the different methods are presented. The result can lead to the development of a more accurate design model, which would lead to more efficient use of reinforcement.</p>
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Shooter, Steven B., and Charles F. Reinholtz. "Extrinsic Calibration of Portable Manipulators." In ASME 1992 Design Technical Conferences. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/detc1992-0251.
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Abstract Portable manipulators are installed for operation and then removed upon completion of their task. Typical applications of portable manipulators include the inspection of nuclear reactors, inspection and repair of nuclear steam generators and asbestos removal in buildings. In such operations, it is difficult to precisely position the manipulator at a fixed location within its workplace, yet this is critical for accurate tool positioning. It can be possible, however, to position the tool tip at several points in the environment using video feedback and manual operator control of the manipulator. This provides sufficient information to determine the position and orientation of the manipulator base frame with respect to the environment, hereafter referred to as extrinsic calibration. Following extrinsic calibration, subsequent moves of the manipulator can be automated. This paper describes a closed-form method for performing extrinsic calibration by contacting the tool to a total of six places on three orthogonal plane surfaces of reference.
Reports on the topic "Portal frame method"
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Mazzoni, Silvia, Nicholas Gregor, Linda Al Atik, Yousef Bozorgnia, David Welch, and Gregory Deierlein. Probabilistic Seismic Hazard Analysis and Selecting and Scaling of Ground-Motion Records (PEER-CEA Project). Pacific Earthquake Engineering Research Center, University of California, Berkeley, CA, 2020. http://dx.doi.org/10.55461/zjdn7385.
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This report is one of a series of reports documenting the methods and findings of a multi-year, multi-disciplinary project coordinated by the Pacific Earthquake Engineering Research Center (PEER) and funded by the California Earthquake Authority (CEA). The overall project is titled “Quantifying the Performance of Retrofit of Cripple Walls and Sill Anchorage in Single-Family Wood-Frame Buildings,” henceforth referred to as the “PEER–CEA Project.” The overall objective of the PEER–CEA Project is to provide scientifically based information (e.g., testing, analysis, and resulting loss models) that measure and assess the effectiveness of seismic retrofit to reduce the risk of damage and associated losses (repair costs) of wood-frame houses with cripple wall and sill anchorage deficiencies as well as retrofitted conditions that address those deficiencies. Tasks that support and inform the loss-modeling effort are: (1) collecting and summarizing existing information and results of previous research on the performance of wood-frame houses; (2) identifying construction features to characterize alternative variants of wood-frame houses; (3) characterizing earthquake hazard and ground motions at representative sites in California; (4) developing cyclic loading protocols and conducting laboratory tests of cripple wall panels, wood-frame wall subassemblies, and sill anchorages to measure and document their response (strength and stiffness) under cyclic loading; and (5) the computer modeling, simulations, and the development of loss models as informed by a workshop with claims adjustors. This report is a product of Working Group 3 (WG3), Task 3.1: Selecting and Scaling Ground-motion records. The objective of Task 3.1 is to provide suites of ground motions to be used by other working groups (WGs), especially Working Group 5: Analytical Modeling (WG5) for Simulation Studies. The ground motions used in the numerical simulations are intended to represent seismic hazard at the building site. The seismic hazard is dependent on the location of the site relative to seismic sources, the characteristics of the seismic sources in the region and the local soil conditions at the site. To achieve a proper representation of hazard across the State of California, ten sites were selected, and a site-specific probabilistic seismic hazard analysis (PSHA) was performed at each of these sites for both a soft soil (Vs30 = 270 m/sec) and a stiff soil (Vs30=760 m/sec). The PSHA used the UCERF3 seismic source model, which represents the latest seismic source model adopted by the USGS [2013] and NGA-West2 ground-motion models. The PSHA was carried out for structural periods ranging from 0.01 to 10 sec. At each site and soil class, the results from the PSHA—hazard curves, hazard deaggregation, and uniform-hazard spectra (UHS)—were extracted for a series of ten return periods, prescribed by WG5 and WG6, ranging from 15.5–2500 years. For each case (site, soil class, and return period), the UHS was used as the target spectrum for selection and modification of a suite of ground motions. Additionally, another set of target spectra based on “Conditional Spectra” (CS), which are more realistic than UHS, was developed [Baker and Lee 2018]. The Conditional Spectra are defined by the median (Conditional Mean Spectrum) and a period-dependent variance. A suite of at least 40 record pairs (horizontal) were selected and modified for each return period and target-spectrum type. Thus, for each ground-motion suite, 40 or more record pairs were selected using the deaggregation of the hazard, resulting in more than 200 record pairs per target-spectrum type at each site. The suites contained more than 40 records in case some were rejected by the modelers due to secondary characteristics; however, none were rejected, and the complete set was used. For the case of UHS as the target spectrum, the selected motions were modified (scaled) such that the average of the median spectrum (RotD50) [Boore 2010] of the ground-motion pairs follow the target spectrum closely within the period range of interest to the analysts. In communications with WG5 researchers, for ground-motion (time histories, or time series) selection and modification, a period range between 0.01–2.0 sec was selected for this specific application for the project. The duration metrics and pulse characteristics of the records were also used in the final selection of ground motions. The damping ratio for the PSHA and ground-motion target spectra was set to 5%, which is standard practice in engineering applications. For the cases where the CS was used as the target spectrum, the ground-motion suites were selected and scaled using a modified version of the conditional spectrum ground-motion selection tool (CS-GMS tool) developed by Baker and Lee [2018]. This tool selects and scales a suite of ground motions to meet both the median and the user-defined variability. This variability is defined by the relationship developed by Baker and Jayaram [2008]. The computation of CS requires a structural period for the conditional model. In collaboration with WG5 researchers, a conditioning period of 0.25 sec was selected as a representative of the fundamental mode of vibration of the buildings of interest in this study. Working Group 5 carried out a sensitivity analysis of using other conditioning periods, and the results and discussion of selection of conditioning period are reported in Section 4 of the WG5 PEER report entitled Technical Background Report for Structural Analysis and Performance Assessment. The WG3.1 report presents a summary of the selected sites, the seismic-source characterization model, and the ground-motion characterization model used in the PSHA, followed by selection and modification of suites of ground motions. The Record Sequence Number (RSN) and the associated scale factors are tabulated in the Appendices of this report, and the actual time-series files can be downloaded from the PEER Ground-motion database Portal (https://ngawest2.berkeley.edu/)(link is external).
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TESTS, MODELLING AND DESIGN OF UNSYMMETRICAL BACK-TO-BACK COLD-FORMED STEEL ANGLES UNDER COMPRESSION. The Hong Kong Institute of Steel Construction, 2024. http://dx.doi.org/10.18057/ijasc.2024.20.2.11.
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Built-up cold-formed steel (CFS) unsymmetrical angles are increasingly used in structures such as portal frames, roof trusses, and transmission towers. However, there are limited studies on CFS unequal back-to-back angle columns (BBUAC) with stiffeners. This paper presents the results of six experimental tests on intermediate BBUAC with intermittent screw fasteners. The findings include the deformed shapes at failure and the load-axial shortening behavior. Additionally, a nonlinear finite element (FE) model that accounts for both material and geometric nonlinearity was developed. The experimental results were used to validate this FE model. The paper presents a total of 166 new data points, which include six concentric compressive tests and 160 finite element analysis (FEA) results on the compressive strength of BBUAC. The effectiveness of the current design rules, based on the Direct Strength Method (DSM), was also evaluated. The evaluation revealed that the current DSM is unconservative. As a result, a modified DSM approach is proposed.