The Overall Stability Calculation Method for Sway Frame

2012 ◽  
Vol 594-597 ◽  
pp. 686-690
Author(s):  
Wei Feng Tian ◽  
Ji Ping Hao ◽  
Chun Lei Fan
Keyword(s):  
Calculation Method ◽  
Theoretical Calculations ◽  
Simple Calculation ◽  
Elastic Stability ◽  
Negative Stiffness ◽  
Effective Length ◽  
Good Precision ◽  
Stiffness Ratio ◽  
Stability Calculation ◽  
Effective Length Method

There are three levels in stability calculating for sway frame. The first level is the traditional effective length method. The second level is the effective length method considering interaction of columns in one story and the third level is the effective length method considering inter-story interaction. The traditional effective length method may lead to unsafe design. Using the concept of equivalent negative stiffness, story stiffness to negative stiffness ratio factor and story support factor were proposed. Through the story stiffness to negative stiffness ratio factor, the weak-story and the inter-story support relationship can be found. Then, a formula for calculating the elastic stability capacity of sway frame is proposed, by which the inter-column interaction and inter-story interaction can be considered, and the finite element buckling analysis for stability capacity can be avoided. Through the stability capacity, the column effective length can be calculated. The results show that this simple calculation method has good precision and accuracy, can be used for engineering design and theoretical calculations.

A Simple Calculation Method of Flashover Characteristics for Long Air Gaps under Various Discharge Conditions

1993 ◽  
Vol 113 (3) ◽  
pp. 252-258
Author(s):  
Kiyoto Nishijima ◽  
Itaru Tsuneyasu ◽  
Hiraku Nakahodo ◽  
Masaharu Minakami
Keyword(s):  
Calculation Method ◽  
Simple Calculation ◽  
Air Gaps

Comparison Between the Effects of Zero and Non-Zero Flow Acceleration on the Entropy Wave Decay: An Experimental Study

2021 ◽  
Vol 143 (11) ◽  
Author(s):  
S. M. Hosseinalipour ◽  
E. Rahmani ◽  
A. Fattahi
Keyword(s):  
Hot Spot ◽  
Theoretical Models ◽  
Fast Response ◽  
Effective Length ◽  
Combustion Instabilities ◽  
Convergent Nozzle ◽  
Flow Acceleration ◽  
Wave Decay ◽  
Accelerated Flow ◽  
Effective Length Method

Abstract Entropy wave, as the convecting hot spot, is one of the sources of combustion instabilities, which is less explored through the literature. Convecting in a highly turbulent flow of a combustor, entropy waves may experience some levels of dissipation and deformation. In spite of some earlier investigations in the zero acceleration flow, the extent of the wave decay has not been clear yet. Further, there exist no results upon the wave decay in non-zero accelerated flows. This is of crucial importance, as the wave passes through the end nozzle of the combustor or gas turbine stages. The current experiment, therefore, compares the wave decay in both flow of constant and variable bulk velocity, meaning, respectively, a uniform pipe and a convergent nozzle. The comparison will aid the theoretical models to reduce complexity by simplifying the relations of non-zero acceleration flow to those of no acceleration, as followed by the earlier effective-length method. Reynolds number and inlet turbulence intensity are considered as the governing hydrodynamic parameters for both investigated flows. The entropy wave is generated by an electrical heater module and detected using fast-response thermocouples. The results show that the entropy wave variation is point-wise and frequency-dependent. The accelerated flow of the nozzle is generally found to be more dissipative in comparison with the zero acceleration flow.

A simple calculation method for estimating the flow velocity on the roof of a train running through a tunnel using an unsteady incompressible flow model

2019 ◽  
Vol 234 (7) ◽  
pp. 734-748
Author(s):  
Katsuhiro Kikuchi ◽  
Satoru Ozawa ◽  
Yuhei Noguchi ◽  
Shinya Mashimo ◽  
Takanobu Igawa
Keyword(s):  
Boundary Layer ◽  
Flow Velocity ◽  
Calculation Method ◽  
Model Experiment ◽  
Flow Model ◽  
Simple Calculation ◽  
Dimensional Model ◽  
One Dimensional ◽  
Calculation Results ◽  
Tunnel System

Predicting the aerodynamic phenomena in a train-tunnel system is important for increasing the speed of railway trains. Among these phenomena, many studies have focused on the effects of pressure; however, only a few studies have examined the effects of flow velocity. When designing train roof equipment such as a pantograph and an aerodynamic braking unit, it is necessary to estimate the flow velocity while considering the influence of the boundary layer developed on the train roof. Until now, numerical simulations using a one-dimensional model have been utilized to predict the flow velocity around a train traveling through a tunnel; however, the influence of the boundary layer cannot be taken into consideration in these simulations. For this purpose, the authors have previously proposed a simple calculation method based on a steady incompressible tunnel flow model that can take into account the influence of the boundary layer, but this method could not incorporate the unsteadiness of the flow velocity. Therefore, in this study, the authors extend the previous simple calculation method such that it can be used for an unsteady incompressible tunnel flow. The authors compare the calculation results obtained from the extended method with the results of a model experiment and a field test to confirm its effectiveness.

scholarly journals Analytical method comparison on critical force of the stepped column model of telescopic crane

2018 ◽  
Vol 10 (10) ◽  
pp. 168781401880869 ◽  
Author(s):  
Fenglin Yao ◽  
Wenjun Meng ◽  
Jie Zhao ◽  
Zhanjiao She ◽  
Guoshan Shi
Keyword(s):  
Ritz Method ◽  
Method Comparison ◽  
Recursive Formula ◽  
Transcendental Equation ◽  
Critical Force ◽  
Effective Length ◽  
Deflection Curve ◽  
Stability Calculation ◽  
Column Model ◽  
The Ideal

The calculation of the critical force of the stepped column model of telescopic boom crane is the key to stability calculation of all-terrain crane. In slightly bending theory, differential equation can be built up, and then the deflection curve of ideal column can be obtained. Using this curve and the Rayleigh–Ritz method, the Euler force of the ideal column can be obtained. For n-stepped columns, Euler forces and the effective length coefficients can be acquired using the deflection curve of the ideal column and parabolic curve, respectively, combined with the Rayleigh–Ritz method. Differential equations of the n-stepped telescopic boom are established based on the vertical and horizontal buckling theory. The recursive formula of the stability of the n-stepped telescopic boom is deduced by the mathematical induction method. For the transcendental equation in the recursive formula, combined with the structural force characteristics and supplementary formulas, the Levenberg–Marquardt numerical optimization algorithm is used to solve the equations with n unknowns. Length coefficients obtained by the three methods are compared using GB3811-2008 and ANSYS 17.0. The results show that the accuracy of the numerical algorithm is the highest, and the first two algorithms will produce large errors when the stepped columns have more steps.

Study on Drifting Drilling Assembly and Casing String’s Stiffness Ratio

2011 ◽  
Vol 339 ◽  
pp. 583-589
Author(s):  
Xiao Dong Zhang ◽  
Ru Yi Gou ◽  
Hong Jun Liang ◽  
Yan Gong ◽  
Ping Xiao
Keyword(s):  
Computer Program ◽  
Calculation Method ◽  
Focal Point ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Stiffness Ratio ◽  
Conservation Of Energy ◽  
Assembly Design ◽  
Ratio Calculation ◽  
Deep Well

Drilling technology of ultra-deep well is still the focal point of drilling research, there are many difficulties in ultra-deep well drilling, such as bottom hole with high temperature and high pressure, complex geology, borehole with sharp dogleg, etc. These technical difficulties put forward higher request in casing running, well quality must be controlled strictly in order to run larger diameter combination casing string successfully. Well quality is closely linked with the drifting drilling assembly design. The accurate stiffness ratio calculation is the key prerequisite of drifting drilling assembly design. In this paper, a new mechanical model is applied to simulate deflection of the drifting drilling assembly. The solution of variable cross-section beam’s equivalent stiffness is applied to solve the stiffness of the drifting drilling assembly. Modified stiffness ratio calculation method for drifting drilling assembly and casing string is proposed. In the process of calculation formula derivation, the conservation of energy law has been used multiple times. At last, the VB computer program is compiled, which contains the modified calculation method. The computer program calculation value is larger than the conventional method’s calculation value. Modified calculation method is more reasonable, which has important significance for drifting drilling assembly optimal design.

The Study about Flexural Performance of GFRP Bar Reinforced Concrete Beams Based on Numerical Calculation Method

2010 ◽  
Vol 29-32 ◽  
pp. 1350-1356
Author(s):  
Qing Guo Yang ◽  
Yu Wei Zhang ◽  
Zhi Zhong Tu
Keyword(s):  
Reinforced Concrete ◽  
Numerical Calculation ◽  
Bearing Capacity ◽  
Calculation Method ◽  
Concrete Beams ◽  
Simple Calculation ◽  
Reinforced Concrete Beams ◽  
Displacement Curve ◽  
Gfrp Bar ◽  
Numerical Calculation Method

Replacing the steel bar with GFRP (Glass Fiber Reinforced Plastics) bar can improve the durability of concrete structure in the corrosive environment. Different ratios of GFRP bar lead huge difference performance of GFRP reinforced concrete beams; therefore, to reduce the workload, it is very necessary to study GFRP reinforced concrete beams’ performance with suitable numerical calculation method. In the study, first, GFRP reinforced concrete beams’ mechanical behavior and failure characteristics were researched through the flexural experiments of GFRP reinforced concrete beams with different ratio of GFRP bar; Second, the numerical calculation model of GFRP reinforced concrete beams was built according to experimental results which contain the load-displacement curve and the phenomenon that concrete in compression zone are crushed, then the calculation criterion of obtaining the beam’s bearing capacity was proposed. Lastly, the bending bearing capacity of GFRP bar reinforced concrete beams with different ratio of GFRP is obtained through the finite element calculation, and the practical and simple calculation formula is acquired.

scholarly journals Plastic limit bearing calculation of blasting-roof in deep hole mining and its applications

2019 ◽  
Vol 6 (7) ◽  
pp. 190074
Author(s):  
Wei Wang ◽  
Zhouquan Luo ◽  
Yaguang Qin ◽  
Jun Xiang
Keyword(s):  
Boundary Conditions ◽  
Calculation Method ◽  
Virtual Work ◽  
Theoretical Calculations ◽  
Limit State ◽  
Mechanical Analysis ◽  
Deep Hole ◽  
Plastic Limit ◽  
Analysis Model ◽  
Various Boundary Conditions

A plastic bearing calculation method for a blasting-roof is proposed to solve the problem of determining the blasting-roof thickness in deep hole mining. A mechanical analysis model for the plastic bearing was built for the typical boundary conditions of blasting-roofs. The external and internal work of the blasting-roof are equal under the plastic limit state through calculation. The limit bearing formulae of blasting-roofs under various boundary conditions were derived based on the principle of virtual work. A Vertical Crater Retreat stope was taken as the object, and the safe blasting-roof thickness was determined to be 6 m using the derived formula (considering the safety coefficient). A numerical model of stope was constructed using the Surpac-Flac3D technique, while the blasting-roof stability was simulated under different thicknesses. Variations in the simulated indexes (stress and plastic zone volume) prove that the theoretical calculations are reliable. The plastic bearing calculation method can provide a new method to determine the blasting-roof thickness in deep hole mining.

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