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William Mcguire - One of the best experts on this subject based on the ideXlab platform.
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spread of plasticity quasi plastic Hinge Approach
Journal of Structural Engineering-asce, 1994Co-Authors: Mourad R. Attalla, Gregory G. Deierlein, William McguireAbstract:The paper describes a method of inelastic analysis for steel frames that provides the accuracy of distributed plasticity methods with the computational efficiency of elastic‐plastic‐Hinge methods. It accounts for spread‐of‐plasticity effects without the need for through‐section and lengthwise discretization of a beam‐column element. This is accomplished through nonlinear equations for the force‐strain relationships of the cross section that are calibrated to data from inelastic analyses and numerical integration of the cross‐section model along the element length to obtain inelastic flexibility coefficients for the member. The flexibility coefficients are employed in generating an inelastic stiffness matrix in which geometric nonlinearity is also accounted for. The proposed model has been implemented and tested using several example problems known to be sensitive to spreading‐plasticity effects.
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Spread of Plasticity—Quasi-Plastic-Hinge Approach
Journal of Structural Engineering, 1994Co-Authors: Mourad R. Attalla, Gregory G. Deierlein, William McguireAbstract:The paper describes a method of inelastic analysis for steel frames that provides the accuracy of distributed plasticity methods with the computational efficiency of elastic‐plastic‐Hinge methods. It accounts for spread‐of‐plasticity effects without the need for through‐section and lengthwise discretization of a beam‐column element. This is accomplished through nonlinear equations for the force‐strain relationships of the cross section that are calibrated to data from inelastic analyses and numerical integration of the cross‐section model along the element length to obtain inelastic flexibility coefficients for the member. The flexibility coefficients are employed in generating an inelastic stiffness matrix in which geometric nonlinearity is also accounted for. The proposed model has been implemented and tested using several example problems known to be sensitive to spreading‐plasticity effects.
W.f. Chen - One of the best experts on this subject based on the ideXlab platform.
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Second-order inelastic analysis of composite framed structures based on the refined plastic Hinge method
Engineering Structures, 2009Co-Authors: Mark A. Bradford, W.f. ChenAbstract:Abstract Composite steel-concrete structures experience non-linear effects which arise from both instability-related geometric non-linearity and from material non-linearity in all of their component members. This paper therefore presents a numerical procedure capable of addressing geometric and material non-linearities at the strength limit state based on the refined plastic Hinge method. The refined plastic Hinge Approach models the elasto-gradual-plastic material non-linearity with strain-hardening under the interaction of bending and axial actions. This produces a benign method for a beam–column composite element under general loading cases. Another main feature of this paper is that, for members containing a point of contraflexure, its location is determined and a node is then located at this position to reproduce the real flexural behaviour and associated material non-linearity of the member. The formulation with the refined plastic Hinge Approach is efficacious and robust, and so a full frame analysis incorporating geometric and material non-linearity is tractable. Following development of the theory, its application is illustrated with a number of varied examples.
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Second-order inelastic analysis of composite framed structures based on the refined plastic Hinge method
Science & Engineering Faculty, 2009Co-Authors: Bardford, W.f. ChenAbstract:Composite steel-concrete structures experience non-linear effects which arise from both instability-related geometric non-linearity and from material non-linearity in all of their component members. Because of this, conventional design procedures cannot capture the true behaviour of a composite frame throughout its full loading range, and so a procedure to account for those non-linearities is much needed. This paper therefore presents a numerical procedure capable of addressing geometric and material non-linearities at the strength limit state based on the refined plastic Hinge method. Different material non-linearity for different composite structural components such as T-beams, concrete-filled tubular (CFT) and steel-encased reinforced concrete (SRC) sections can be treated using a routine numerical procedure for their section properties in this plastic Hinge Approach. Simple and conservative initial and full yield surfaces for general composite sections are proposed in this paper. The refined plastic Hinge Approach models springs at the ends of the element which are activated when the surface defining the interaction of bending and axial force at first yield is reached; a transition from the first yield interaction surface to the fully plastic interaction surface is postulated based on a proposed refined spring stiffness, which formulates the load-displacement relation for material non-linearity under the interaction of bending and axial actions. This produces a benign method for a beam-column composite element under general loading cases. Another main feature of this paper is that, for members containing a point of contraflexure, its location is determined with a simple application of the method herein and a node is then located at this position to reproduce the real flexural behaviour and associated material non-linearity of the member. Recourse is made to an updated Lagrangian formulation to consider geometric non-linear behaviour and to develop a non-linear solution strategy. The formulation with the refined plastic Hinge Approach is efficacious and robust, and so a full frame analysis incorporating geometric and material non-linearity is tractable. By way of contrast, the plastic zone Approach possesses the drawback of strain-based procedures which rely on determining plastic zones within a cross-section and which require lengthwise integration. Following development of the theory, its application is illustrated with a number of varied examples.
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Improved nonlinear plastic Hinge analysis of space frame structures
Engineering Structures, 2000Co-Authors: J.y. Richard Liew, Hong Chen, N.e. Shanmugam, W.f. ChenAbstract:Abstract This paper is concerned with second-order plastic Hinge analysis of three-dimensional frame structures. The beam–column formulation is based on the use of stability interpolation functions for the transverse displacements, and considers the elastic coupling effects between axial, flexural and torsional displacements. The developed computer program can be used to predict accurately the elastic flexural buckling load of columns and frames by modelling each physical member as one element. It can also be used to predict the elastic buckling loads associated with axial-torsional and lateral-torsional instabilities, which are essential for predicting the nonlinear behaviour of space frame structures. The member bowing effect and initial out-of-straightness are also considered so that the nonlinear spatial behaviour of structures can be captured with fewer elements per member. Material nonlinearity is modelled by using the concentrated plastic Hinge Approach. Plastic Hinge between the member ends is allowed to occur. Numerical examples including both geometric and material nonlinearities are used to demonstrate the robustness, accuracy and efficiency of the proposed analytical method and computer program.
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Analysis and Design of Steel Frames Considering Panel Joint Deformations
Journal of Structural Engineering, 1995Co-Authors: J.y. Richard Liew, W.f. ChenAbstract:This paper provides insight to the background of the development and requirements for panel–zone design in the 1986 AISC LRFD specifications. In particular, two criteria for the design of beam–column panel zones are discussed; the first method is based on the von Mises first–yield criterion for the panel–zone web, and the other utilizes the post–yield shear resistance of the panel derived from the flexural resistance of boundary elements surrounding the panel–zone joint. The nonlinear behavior of a moment–resisting frame with panel–zone joints designed according to these two requirements is studied. Lui’s 1985 rigorous second–order elastic– plastic Hinge analysis is used to assess the performance of a frame considering panel–zone deformations. An advanced analysis technique based on a notional–load plastic–Hinge Approach is introduced. This advanced analysis technique is used to evaluate the proper design criteria for panel–zone joints in moment–resisting frames, and to study the influence of panel–zone deformations on the frame’s limit of resistance. From these studies, the effects of the panel–zone deformations on the overall frame resistance can then be summarized and discussed.
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Second‐Order Inelastic Analysis Methods for Steel‐Frame Design
Journal of Structural Engineering, 1992Co-Authors: W. S. King, Donald W. White, W.f. ChenAbstract:Two simplified methods for second‐order inelastic analysis of steel frames, termed the modified plastic‐Hinge and the beam‐column strength Approaches, are presented. These analysis models are comparable to elastic‐plastic‐Hinge analysis in efficiency, and yet, they alleviate the problems associated with overprediction of stiffness and strength by the usual elastic‐plastic‐Hinge analysis methods. The modified plastic‐Hinge method is based on simple modifications to the elastic‐plastic‐Hinge model, which account for the degradation in stiffness as the cross‐section strength is Approached at critical locations along the member length. The beam‐column strength method is similar to the modified plastic‐Hinge Approach, except that in this model, equations for the strength of the overall member are employed rather than expressions for the cross‐section strength. The performance of these analysis models is contrasted with results from elastie‐plastic‐Hinge and refined plastic‐zone analysis solutions as well as re...
Ronda Landers - One of the best experts on this subject based on the ideXlab platform.
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reducing surgical errors implementing a three Hinge Approach to success
AORN Journal, 2015Co-Authors: Ronda LandersAbstract:Abstract Surgical errors can have serious consequences including patient deaths, and recent reports suggest that surgical errors continue to occur at unacceptable rates. Studies indicate that causative factors for surgical error include human factors, OR interruptions, staffing issues, and error-reporting trends. A “three-Hinge” Approach can be used to implement a safety program that emphasizes use of a safe surgery checklist and the Centers for Medicare & Medicaid Services reporting requirements for ambulatory surgery centers. The three Hinges are the assignment of a change agent, ideally an RN with a doctorate in nursing practice; team cohesiveness; and continuous quality monitoring.
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Reducing Surgical Errors: Implementing a Three‐Hinge Approach to Success
AORN Journal, 2015Co-Authors: Ronda LandersAbstract:Abstract Surgical errors can have serious consequences including patient deaths, and recent reports suggest that surgical errors continue to occur at unacceptable rates. Studies indicate that causative factors for surgical error include human factors, OR interruptions, staffing issues, and error-reporting trends. A “three-Hinge” Approach can be used to implement a safety program that emphasizes use of a safe surgery checklist and the Centers for Medicare & Medicaid Services reporting requirements for ambulatory surgery centers. The three Hinges are the assignment of a change agent, ideally an RN with a doctorate in nursing practice; team cohesiveness; and continuous quality monitoring.
Siu-lai Chan - One of the best experts on this subject based on the ideXlab platform.
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Advanced analysis of hybrid steel and concrete frames: Part 2: Refined plastic Hinge and advanced analysis
Journal of Constructional Steel Research, 2012Co-Authors: Si-wei Liu, Yao-peng Liu, Siu-lai ChanAbstract:Abstract Robust geometric and material nonlinear analysis of buildings under ultimate loads is a key to success of advanced analysis, performance-based seismic design and progressive collapse analysis. This is the second part of two companion papers about the advanced analysis of hybrid steel and concrete frames allowing for various effects such as initial imperfections, gradual cracking effect and geometrical and material nonlinearities. Besides the use of Pointwise–Equilibrium–Polynomial (PEP) element allowing for initial imperfections and the P–Δ–δ effects by one element per member, the plastic Hinge Approach is refined for modelling of material yielding. In order to assess the sectional strength, the cross-section analysis technique described in the companion paper is utilized in this paper for analysis of steel reinforced concrete (RC) and steel-concrete composite (SCC) sections. Cracking in concrete component, which has significant influence on structural deformation and internal force distribution, is considered by using the Branson's model combined with the concrete cracking fracture surface. The distinct feature of the proposed method is that it integrates the accurate cross-sectional analysis technique to the refined lumped plasticity Approach such that a feasible and reliable solution can be obtained. Members with previous experimental results and a portal frame are studied and compared for validation of the proposed method.
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Material yielding by both axial and bending spring stiffness at elevated temperature
Journal of Constructional Steel Research, 2007Co-Authors: Siu-lai Chan, Xiao Xiong ZhaAbstract:Material yielding is typically modeled either by plastic zone or plastic Hinge methods under the context of geometric and material nonlinear finite element methods. In fire analysis of steel structures, the plastic zone method is widely used, but it requires extensively more computational efforts. The objective of this paper is to develop the nonlinear material model allowing for interaction of both axial force and bending moment, which relies on the plastic Hinge method to achieve numerical efficiency and reduce computational effort. The biggest advantage of the plastic-Hinge Approach is its computational efficiency and easy verification by the design code formulae of the axial force–moment interaction yield criterion for beam–column members. Further, the method is reliable and robust when used in analysis of practical and large structures. In order to allow for the effect of catenary action, axial thermal expansion is considered in the axial restraint equations. The yield function for material yielding incorporated in the stiffness formulation, which allows for both axial force and bending moment effects, is more accurate and rational to predict the behaviour of the frames under fire. In the present fire analysis, the mechanical properties at elevated temperatures follow mainly the Eurocode 3 [Design of steel structures, Part 1.2: Structural fire design. European Committee for Standisation; 2003]. Example of a tension member at a steady state heating condition is modeled to verify the proposed spring formulation and to compare with results by others. The behaviour of a heated member in a highly redundant structure is also studied by the present Approach.
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Elastoplastic and Large Deflection Analysis of Steel Frames by One Element per Member. I: One Hinge along Member
Journal of Structural Engineering-asce, 2004Co-Authors: Zhi-hua Zhou, Siu-lai ChanAbstract:The ultimate load of a typical steel frame is dependent on the geometrically nonlinear and material yielding effects. The complexity for considering material yielding by the plastic Hinge Approach is the unknown location of the plastic Hinge, which can occur at the ends or any position along the element length. For the latter case, a member is divided into many elements in order to approximate the location of a plastic Hinge. This process is tedious, inconvenient to use, and involves extensive computer time. Further, the strength check for sectional capacity using the LRFD code requires an assumption of the \iK factor or the effective length ratio, which further complicates a computer analysis for the ultimate load of a steel frame. To describe the formation of a plastic Hinge along an element in a member at the ultimate limit state, a single element capable of modeling the P–δ. effect as well as the formation of the plastic Hinge is needed. This paper adopts a simple concept of superimposition of triangular deflected shapes due to the formation of plastic Hinge to the fifth order deflection shape for elastic deflection to yield the final deflection of the element, the plastic pointwise equilibrium polynomial (PPEP) element. Equilibrium of moment and shear at midspan of an element is maintained for accurate modeling of the P–δ effect in the tangent and secant stiffness. The robustness, accuracy and reliability of the developed element are demonstrated in a number of worked examples.
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A simulation-based large deflection and inelastic analysis of steel frames under fire
Journal of Constructional Steel Research, 2004Co-Authors: Siu-lai ChanAbstract:Abstract This paper presents an accurate and robust geometric and material nonlinear formulation to predict structural behaviour of unprotected steel members at elevated temperatures. A fire analysis including large displacement effects for frame structures is presented. This finite element formulation of beam–column elements is based on the plastic Hinge Approach to model the elasto-plastic strain-hardening material behaviour. The Newton–Raphson method allowing for the thermal-time dependent effect was employed for the solution of the nonlinear governing equations for large deflection in thermal history. A combined incremental and total formulation for determining member resistance is employed in this nonlinear solution procedure for the efficient modeling of nonlinear effects. Degradation of material strength with increasing temperature is simulated by a set of temperature–stress–strain curves according to both ECCS and BS 5950 Part 8, which implicitly allows for creep deformation. The effects of uniform or non-uniform temperature distribution over the section of the structural steel member are also considered. Several numerical and experimental verifications are presented.
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Elastoplastic and Large Deflection Analysis of Steel Frames by One Element per Member. I: One Hinge along Member
Journal of Structural Engineering, 2004Co-Authors: Zhi-hua Zhou, Siu-lai ChanAbstract:The ultimate load of a typical steel frame is dependent on the geometrically nonlinear and material yielding effects. The complexity for considering material yielding by the plastic Hinge Approach is the unknown location of the plastic Hinge, which can occur at the ends or any position along the element length. For the latter case, a member is divided into many elements in order to approximate the location of a plastic Hinge. This process is tedious, inconvenient to use, and involves extensive computer time. Further, the strength check for sectional capacity using the LRFD code requires an assumption of the K factor or the effective length ratio, which further complicates a computer analysis for the ultimate load of a steel frame. To describe the formation of a plastic Hinge along an element in a member at the ultimate limit state, a single element capable of modeling the P - δ effect as well as the formation of the plastic Hinge is needed. This paper adopts a simple concept of superimposition of triangular deflected shapes due to the formation of plastic Hinge to the fifth order deflection shape for elastic deflection to yield the final deflection of the element, the plastic pointwise equilibrium polynomial (PPEP) element. Equilibrium of moment and shear at midspan of an element is maintained for accurate modeling of the P - δ effect in the tangent and secant stiffness. The robustness, accuracy and reliability of the developed element are demonstrated in a number of worked examples.Department of Civil and Environmental Engineerin
Mourad R. Attalla - One of the best experts on this subject based on the ideXlab platform.
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spread of plasticity quasi plastic Hinge Approach
Journal of Structural Engineering-asce, 1994Co-Authors: Mourad R. Attalla, Gregory G. Deierlein, William McguireAbstract:The paper describes a method of inelastic analysis for steel frames that provides the accuracy of distributed plasticity methods with the computational efficiency of elastic‐plastic‐Hinge methods. It accounts for spread‐of‐plasticity effects without the need for through‐section and lengthwise discretization of a beam‐column element. This is accomplished through nonlinear equations for the force‐strain relationships of the cross section that are calibrated to data from inelastic analyses and numerical integration of the cross‐section model along the element length to obtain inelastic flexibility coefficients for the member. The flexibility coefficients are employed in generating an inelastic stiffness matrix in which geometric nonlinearity is also accounted for. The proposed model has been implemented and tested using several example problems known to be sensitive to spreading‐plasticity effects.
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Spread of Plasticity—Quasi-Plastic-Hinge Approach
Journal of Structural Engineering, 1994Co-Authors: Mourad R. Attalla, Gregory G. Deierlein, William McguireAbstract:The paper describes a method of inelastic analysis for steel frames that provides the accuracy of distributed plasticity methods with the computational efficiency of elastic‐plastic‐Hinge methods. It accounts for spread‐of‐plasticity effects without the need for through‐section and lengthwise discretization of a beam‐column element. This is accomplished through nonlinear equations for the force‐strain relationships of the cross section that are calibrated to data from inelastic analyses and numerical integration of the cross‐section model along the element length to obtain inelastic flexibility coefficients for the member. The flexibility coefficients are employed in generating an inelastic stiffness matrix in which geometric nonlinearity is also accounted for. The proposed model has been implemented and tested using several example problems known to be sensitive to spreading‐plasticity effects.