Improving the tie force method for progressive collapse design of RC frames

2018 ◽  
Vol 9 (4) ◽  
pp. 520-531 ◽  
Author(s):  
Arash Naji
Keyword(s):  
Design Methodology ◽  
Progressive Collapse ◽  
Limit State ◽  
Content Type ◽  
Catenary Action ◽  
Closed Form Solutions ◽  
Rc Frames ◽  
Orthogonal Beams ◽  
Similar Equation ◽  
Good Agreement

Purpose The purpose of this paper is to recover the deficiency of existing tie force (TF) methods by considering the decrease in section strength due to cracking and by selecting limit state of collapse according to section properties. Design/methodology/approach A substructure is selected by isolating the connected beams from the entire structure. For interior joints, the TFs in the orthogonal beams are obtained by catenary action. For corner joints, the TFs are assessed by beam action. For edge joints, however, the resistance is gained by greater of the resistance under catenary action for periphery beams and beam action for all the connecting beams in both directions. For catenary action, the TF capacities must satisfy Equation (20). On the other hand, for beam action, the TF must satisfy Equation (16), while R is calculated from Equation (17). In the case where the length of the connecting beams is similar, Equation (19) can be used. Findings Closed form solutions are available for TFs on both beam and catenary stages. Originality/value The proposed formulation makes designing more practical and convenient. However, the proposed formulation had good agreement with experimental results.

Thermohydraulics of the liquid films in rotating heat pipes

2019 ◽  
Vol 30 (6) ◽  
pp. 2861-2866 ◽  
Author(s):  
Kamel Hooman ◽  
Mohammad Reza Safaei ◽  
Hussein Togun ◽  
Mahidzal Dahari
Keyword(s):  
Film Thickness ◽  
Heat Pipe ◽  
Flow Rate ◽  
Design Methodology ◽  
Heat Pipes ◽  
Liquid Films ◽  
Practical Application ◽  
Content Type ◽  
Closed Form Solutions ◽  
Good Agreement

Purpose In this study, closed-form solutions are presented to investigate thermohydraulics of liquid films in a rotating heat pipe. The film thickness is expressed as a function of flow rate. Design/methodology/approach Further, sensitivity of both film thickness and flow rate to the length of the rotating heat pipe can now be investigated using the explicit expressions presented here. Findings To make it easier for practical application, an approximate solution is presented on top of the exact solution. Originality/value Both approximate and exact solutions are then applied to note that results are in good agreement when compared to those available in the literature.

The estimation of the length constant of a long cooling fin by variational iteration method

2015 ◽  
Vol 25 (4) ◽  
pp. 887-891 ◽  
Author(s):  
Yan Zhang ◽  
Qiaoling Chen ◽  
Fujuan Liu ◽  
Ping Wang
Keyword(s):  
Nonlinear Equation ◽  
Nonlinear Equations ◽  
Iteration Method ◽  
Design Methodology ◽  
Variational Iteration Method ◽  
Engineering Problem ◽  
Content Type ◽  
Variational Iteration ◽  
Length Constant ◽  
Good Agreement

Purpose – The purpose of this paper is to validate the variational iteration method (VIM) is suitable for various nonlinear equations. Design/methodology/approach – The He’s VIM is applied to solve nonlinear equation which is derived from actual engineering problem. The result was compared with other method. Findings – The result obtained from VIM shows good agreement with Xu’s result which provide a solid evidence that VIM is convenient and effective for solving nonlinear equation in the engineering. Originality/value – The VIM can be extended to many academic and engineering fields for nonlinear equations solving.

Executive options with inflated equity prices

2014 ◽  
Vol 10 (3) ◽  
pp. 266-292 ◽  
Author(s):  
Linus Wilson ◽  
Yan Wendy Wu
Keyword(s):  
Boards Of Directors ◽  
Stock Price ◽  
Design Methodology ◽  
Ceo Compensation ◽  
Managerial Compensation ◽  
Equity Prices ◽  
Content Type ◽  
Closed Form Solutions ◽  
Compensation Package ◽  
Applied Game Theory

Purpose – The purpose of this paper is to solve the optimal managerial compensation problem when shareholders are either naïvely optimistic or rational. Design/methodology/approach – The paper uses applied game theory to derive the optimal CEO compensation package with over optimistic shareholders. Findings – The results suggest that boards of directors should decrease option grants to CEOs when equity is likely to be irrationally overvalued at the date when the CEO's options vest. Research limitations/implications – The implications of the model are consistent with the available empirical evidence. In addition, the model generates new testable predictions about managerial stock price manipulation, the number of options granted, and the magnitude of the options’ strike prices that have not yet been formally tested. Originality/value – This is the only paper to derive closed-form solutions to optimal CEO compensation when shareholders are naïvely optimistic.

General inverse solution of six-degrees-of-freedom serial robots based on the product of exponentials model

2018 ◽  
Vol 38 (3) ◽  
pp. 361-367 ◽  
Author(s):  
Haixia Wang ◽  
Xiao Lu ◽  
Wei Cui ◽  
Zhiguo Zhang ◽  
Yuxia Li ◽  
...  
Keyword(s):  
Design Methodology ◽  
Degrees Of Freedom ◽  
Screw Theory ◽  
Complex Problem ◽  
Content Type ◽  
Geometrical Properties ◽  
Closed Form Solutions ◽  
Six Degrees Of Freedom ◽  
Serial Robots ◽  
Six Dof

Purpose Developing general closed-form solutions for six-degrees-of-freedom (DOF) serial robots is a significant challenge. This paper thus aims to present a general solution for six-DOF robots based on the product of exponentials model, which adapts to a class of robots satisfying the Pieper criterion with two parallel or intersecting axes among its first three axes. Design/methodology/approach The proposed solution can be represented as uniform expressions by using geometrical properties and a modified Paden–Kahan sub-problem, which mainly adopts the screw theory. Findings A simulation and experiments validated the correctness and effectiveness of the proposed method (general resolution for six-DOF robots based on the product of exponentials model). Originality/value The Rodrigues rotation formula is additionally used to turn the complex problem into a solvable trigonometric function and uniformly express six solutions using two formulas.

A modified elliptic model of anisotropy in nonlinear magnetic materials

2010 ◽  
Vol 29 (6) ◽  
pp. 1482-1492 ◽  
Author(s):  
Oszkár Bíró ◽  
Stefan Außerhofer ◽  
Kurt Preis ◽  
Yu Chen
Keyword(s):  
Design Methodology ◽  
Magnetic Field Intensity ◽  
Nonlinear Behaviour ◽  
Content Type ◽  
Steel Material ◽  
Elliptic Model ◽  
Typical Behaviour ◽  
Magnetisation Curve ◽  
Principal Directions ◽  
Good Agreement

PurposeGrain‐oriented steel has a distinctly anisotropic and nonlinear behaviour. Only in rare cases is the magnetisation curve known for directions other than the principal ones. The paper aims at providing a model to obtain these curves for any direction if those in the easy and hard directions are only given.Design/methodology/approachThe well‐known elliptic model is modified in order to correctly mimic the typical behaviour of grain‐oriented steel which is not described correctly by the original elliptic model. An additional condition is introduced to fix the angle between the flux density and magnetic field intensity.FindingsThe model is found to yield good agreement with measurements in case of a special material for which measured curves for intermediate angles are available.Research limitations/implicationsFurther research is necessary to establish whether the model is applicable to other materials.Originality/valueThe new model can be used in numerical analyses of devices comprising saturated grain‐oriented steel material if the magnetisation curves are given in the principal directions.

Modelling dynamic characteristics of the IGBT with thermal phenomena taken into account

2017 ◽  
Vol 34 (3) ◽  
pp. 160-164 ◽  
Author(s):  
Krzysztof Górecki ◽  
Paweł Górecki
Keyword(s):  
Design Methodology ◽  
Thermal Characteristics ◽  
Thermal Inertia ◽  
Bipolar Transistors ◽  
Insulated Gate Bipolar Transistors ◽  
Switching Circuit ◽  
Content Type ◽  
Different Types ◽  
Thermal Phenomena ◽  
Good Agreement

Purpose This paper aims to propose the electrothermal dynamic model of the insulated gate bipolar transistors (IGBT) for SPICE. Design/methodology/approach The electrothermal model of this device (IGBT), which takes into account both electrical and thermal phenomena, is described. Particularly, the sub-threshold operation of this device is considered and electrical, and thermal inertia of this device is taken into account. Attention was focused on the influence of electrical and thermal inertia on waveforms of terminal voltages of the considered transistor operating in the switching circuit and on waveforms of the internal temperature of this device. Findings The correctness of the presented model is verified experimentally and a good agreement of the calculated and measured electrical and thermal characteristics of the considered device is obtained. Research limitations/implications The presented model can be used for different types of IGBT, but it is dedicated for SPICE software only. Originality/value The form of the worked out model is presented and the results of experimental verification of this model are shown.

scholarly journals Effects of Corrosion on Compressive Arch Action and Catenary Action of RC Frames to Resist Progressive Collapse Based on Numerical Analysis

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2662
Author(s):  
Lu Zhang ◽  
Tingyu Wei ◽  
Hongyu Li ◽  
Jian Zeng ◽  
Xiaofang Deng
Keyword(s):  
Numerical Model ◽  
Mechanical Performance ◽  
Progressive Collapse ◽  
Significant Loss ◽  
Catenary Action ◽  
Rc Frames ◽  
Collapse Resistance ◽  
Arch Action ◽  
Rebar Corrosion ◽  
Modeling Strategy

Many negative factors can influence the progressive collapse resistance of reinforced concrete (RC) frame structures. One of the most important factors is the corrosion of rebar within the structure. With increasing severity of corrosion, the duration, robustness, and mechanical performance can be greatly impaired. One specific side effect of rebar corrosion is the significant loss of protection against progressive collapse. In order to quantify the effects of rebar corrosion on load-resisting mechanisms (compressive arch action (CAA) and tensile catenary action (TCA)) of RC frames, a series of numerical investigations were carried out in this paper. The previous experimental results reported in the literature provide a benchmark for progressive collapse behavior as a sound condition and validate the proposed numerical model. Furthermore, based on the verified numerical model, the CAA and TCA with increasing corrosion and an elapsed time from 0 to 70 years are investigated. Comparing with the conventional empirical model, the proposed numerical model has shown the ability and feasibility in predicting the collapse resistance capacity in structures with corroded rebar. Therefore, this numerical modeling strategy provides comprehensive insights into the change of load-resisting mechanisms in these structures, which can be beneficial for optimizing the design.

A new effective viscosity model for nanofluids

2018 ◽  
Vol 28 (3) ◽  
pp. 571-583 ◽  
Author(s):  
Saleh Etaig ◽  
Reaz Hasan ◽  
Noel Perera
Keyword(s):  
Nusselt Number ◽  
Regression Analysis ◽  
Effective Viscosity ◽  
Design Methodology ◽  
Viscosity Model ◽  
Horizontal Pipe ◽  
Content Type ◽  
Proposed Model ◽  
Novel Model ◽  
Good Agreement

Purpose The purpose of this paper is to present a novel model for predicting the effective viscosity of nanofluids. At present, no unified model exists for the same. Design/methodology/approach The present effective viscosity model draws upon the regression analysis of carefully selected published papers covering experimental, numerical and theoretical findings. Findings Unlike some other models, this one is reliable and has a good level of accuracy. This model has been assessed in a numerical investigation using a 3D horizontal pipe, and the results are presented. Originality/value This is a new model for predicting the effective viscosity of nanofluids. The proposed model has been tested in a 3D horizontal pipe, and the predicted results for viscosity and Nusselt number show good agreement with the available data.

A semi-analytical analysis on beam-column ultimate strength with different initial deflections

2016 ◽  
Vol 13 (6) ◽  
pp. 487-493
Author(s):  
Zhongwei Li ◽  
Xiaochuan Yu
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Ultimate Strength ◽  
Design Methodology ◽  
Computer Code ◽  
Element Analysis ◽  
Content Type ◽  
Beam Columns ◽  
Different Shapes ◽  
Good Agreement

Purpose A new beam-column ultimate strength calculation method has been developed and compared with nonlinear finite element analysis by ANSYS and ABAQUS. Design/methodology/approach A computer code ULTBEAM2 based on this method has been used for one and three span beam-columns with I-shaped cross-section under axial compression. Findings This paper studies the ultimate strength of beam-columns with various initial deflections of different shapes and magnitudes. Originality/value The comparison of ULTBEAM2 and finite element analysis shows good agreement for all cases with different initial deflections.

scholarly journals Strengthening of Precast RC Frame to Mitigate Progressive Collapse by Externally Anchored Carbon Fiber Ropes

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1306
Author(s):  
Jianwu Pan ◽  
Xian Wang ◽  
Hao Dong
Keyword(s):  
Carbon Fiber ◽  
Load Capacity ◽  
Progressive Collapse ◽  
Analytical Models ◽  
Deformation Condition ◽  
Strengthening Effect ◽  
Rc Frame ◽  
Catenary Action ◽  
Rc Frames ◽  
Collapse Failure

The robustness of precast reinforced concrete (RC) frames is relatively poor, while the precast RC frames are strengthened to mitigate progressive collapse, avoiding “strong beams and weak columns” and the anchorage failure of strengthening materials under large deformation condition are the key problems. Aiming to discuss these problems, this paper carried out an experimental research of strengthening on three half-scale assembled monolithic frame subassemblages to mitigate progressive collapse. One specimen was strengthened by implanting carbon fiber rope (CFR) with polymer into concrete, one specimen was strengthened by binding CFR with special knot, and the last one was not strengthened. The failure mode, collapse failure mechanism and strengthening effect of subassemblages were discussed. Analytical models of load capacity increment contributed by CFR and construction suggestions of precast RC frame to mitigate progressive collapse were proposed. The results indicated that none of the strengthened specimens had anchorage failure. The two strengthening methods significantly increased the load capacity of the subassemblages in the catenary action (CA) stage with little effect on the flexural action (FA) stage and compressive arch action (CAA) stage.

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