A Comprehensive Method of Determining Cable Force during Closure Condition for CFST Arch Bridge

2012 ◽  
Vol 204-208 ◽  
pp. 2004-2008
Author(s):  
Guo Fu Sun ◽  
Ji Hua Li
Keyword(s):  
Optimization Method ◽  
Initial State ◽  
Closure Condition ◽  
Stay Cables ◽  
Comprehensive Method ◽  
Cable Force ◽  
Cable Crane ◽  
Backward Analysis ◽  
Cable Forces ◽  
Iteration Analysis

The steel tubular arch is hoisted segment by segment through cable crane and the stayed cables are used to maintain stability and balance. The determination of the stayed-cable forces and construction camber value of the erected rib segments becomes the key issue to ensure construction quality and safety. The forward iteration analysis method, which combines finite element method with optimization method as provided in this paper, can easily and effectively determine the stayed-cable forces and construction camber value in the erection of the rib segments, and the stay cables can be tensioned to their target force values only at one time. Finally, the example is demonstrated to prove the correctness and affectivity of the present method. Numerical example indicates that the results based on the method may be used to the backward analysis of the initial state, and that the proposed CM has excellent features of quick convergence rate and best global performance.

Cable Force Optimization Method in Two Stages for Spatial Cables

2013 ◽  
Vol 405-408 ◽  
pp. 1695-1698
Author(s):  
Hai Xin Huang ◽  
Ying Zhang ◽  
Shou Shan Cheng ◽  
Fan Li
Keyword(s):  
Spatial Structure ◽  
Optimization Method ◽  
Subsequent Stage ◽  
Nonlinear Structure ◽  
Influence Matrix ◽  
Force Optimization ◽  
Initial Stage ◽  
Cable Force ◽  
Cable Forces ◽  
Two Stages

To get the ideal cable forces of the arch bridge with spatial oblique cables,Rigid Support Continuous Beam Method and Rigid Suspender Method are discussed.The results show that the former is unsuitable for the spatial structure with smaller horizontal stiffness,and the latter does not consider the elastic deformations of the cables.An improved cable force optimization method is provided,which takes Rigid Suspender Method as the initial stage to obtain initial cable forces and takes Influence Matrix Method as the subsequent stage for cable force increments.The method by test is proved to be effective to spatial structure and nonlinear structure with spatial cables.

scholarly journals Optimization of Cable Force Adjustment in Cable-Stayed Bridge considering the Number of Stay Cable Adjustment

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Han-Hao Zhang ◽  
Nan-Nan Sun ◽  
Pei-Zhi Wang ◽  
Man-Hui Liu ◽  
Yuan Li
Keyword(s):  
Sensitivity Analysis ◽  
Calculation Method ◽  
Maintenance Phase ◽  
Optimization Method ◽  
Stay Cable ◽  
Stay Cables ◽  
Design Variables ◽  
Optimization Calculation ◽  
Cable Force ◽  
Cable Stayed Bridges

Modern cable-stayed bridges are spatial, multicable systems. The cable force needs to be adjusted during the construction phase and maintenance phase. The existing calculation methods of cable force adjustment mainly considered the rationality of structural force, but only few research studies have been conducted on how to reduce the number of stay cables which need to be adjusted. This study aims to propose an optimization calculation method including the optimization module with the sensitivity analysis and updating design variable module (UDVM), which are used for cable force adjustment in cable-stayed bridges. Based on the finite difference method, the sensitivity analysis is adopted in the optimization module, which can capture the response of structures as design variables vary; the particle swarm optimization method is adopted for structural optimization. The proposed method can dramatically reduce the number of stay cables which need to be adjusted and ensure the main girder stresses remain in a reasonable state during stay cable adjustment progress by UDVM. Moreover, the proposed method can continuously update the objective function, constraint conditions, and design variables. Finally, this proposed optimization calculation method is applied to two different cable-stayed bridges to validate the reliability and feasibility of the method.

Calculation of Contact Forces of Large-Scale Heavy Forging Manipulator Grippers

2009 ◽  
Vol 419-420 ◽  
pp. 645-648 ◽  
Author(s):  
Qun Ming Li ◽  
Dan Gao ◽  
Hua Deng
Keyword(s):  
Large Scale ◽  
Optimization Method ◽  
Contact Forces ◽  
Robotic Hand ◽  
Closure Condition ◽  
Contact Points ◽  
Robot Hands ◽  
Calculation Results ◽  
Forging Manipulator ◽  
Gripping Force

Different from dexterous robotic hands, the gripper of heavy forging manipulator is an underconstrained mechanism whose tongs are free in a small wiggling range. However, for both a dexterous robotic hand and a heavy gripper, the force closure condition: the force and the torque equilibrium, must be satisfied without exception to maintain the grasping/gripping stability. This paper presents a gripping model for the heavy forging gripper with equivalent friction points, which is similar to a grasp model of multifingered robot hands including four contact points. A gripping force optimization method is proposed for the calculation of contact forces between gripper tongs and forged object. The comparison between the calculation results and the experimental results demonstrates the effectiveness of the proposed calculation method.

scholarly journals Motion-Based Design of Passive Damping Devices to Mitigate Wind-Induced Vibrations in Stay Cables

Vibration ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 269-289 ◽  
Author(s):  
Javier Naranjo-Pérez ◽  
Javier Jiménez-Manfredi ◽  
Javier Jiménez-Alonso ◽  
Andrés Sáez
Keyword(s):  
Objective Function ◽  
Design Method ◽  
Optimization Method ◽  
Design Criterion ◽  
Passive Damping ◽  
Characteristic Parameters ◽  
Additional Function ◽  
Wind Action ◽  
Multi Objective ◽  
Stay Cables

Wind action can induce large amplitude vibrations in the stay cables of bridges. To reduce the vibration level of these structural elements, different types of passive damping devices are usually installed. In this paper, a motion-based design method is proposed and implemented in order to achieve the optimum design of different passive damping devices for stay cables under wind action. According to this method, the design problem is transformed into an optimization problem. Thus, its main aim is to minimize the different terms of a multi-objective function, considering as design variables the characteristic parameters of each considered passive damping device. The multi-objective function is defined in terms of the scaled characteristic parameters, one single-function for each parameter, and an additional function that checks the compliance of the considered design criterion. Genetic algorithms are considered as a global optimization method. Three passive damping devices have been studied herein: viscous, elastomeric and friction dampers. As a benchmark structure, the Alamillo bridge (Seville, Spain), is considered in order to validate the performance of the proposed method. Finally, the parameters of the damping devices designed according to this proposal are successfully compared with the results provided by a conventional design method.

Application of Quadratic Programming Method to Cable Force Calculation of Cable Erection Arch Bridge

2014 ◽  
Vol 587-589 ◽  
pp. 1364-1369
Author(s):  
Cheng Wu ◽  
Jin Yu Liu ◽  
Shui Xing Zhou
Keyword(s):  
Quadratic Programming ◽  
High Precision ◽  
Steel Tube ◽  
Influence Matrix ◽  
Calculation Process ◽  
Cable Force ◽  
Quadratic Programming Method ◽  
Cable Forces ◽  
Force Calculation ◽  
Number Of Iterations

Taking the bare arch deformation under gravity as target alignment, the influence matrix that associates the cable forces with segment deformation is obtained via ANSYS program, and the cable force is quickly calculated by MATLAB quadratic programming toolbox. It is illustrated with an example of Guizhou Zong-xi River Bridge, which is a 360-meter concrete filled steel tube bridge in construction, and the calculation process is given. The results show that, this new method has the advantages of high precision and less number of iterations.

Calculation of Cable Force for Long-Span Rib Arch Bridge Construction under Seasonal Ambient Temperature

2011 ◽  
Vol 378-379 ◽  
pp. 341-344
Author(s):  
Wei Feng Tian ◽  
Shui Xing Zhou ◽  
Ayad Thabet Saeed Alghabsha
Keyword(s):  
Ambient Temperature ◽  
Control Method ◽  
Difficult Problem ◽  
State Control ◽  
Optimization Analysis ◽  
Arch Bridge ◽  
Long Span ◽  
Unstressed State ◽  
Cable Force ◽  
Cable Forces

Calculation of cable force under seasonal ambient temperature is the key and difficult problem in the construction of long-span rib arch bridge. It affects the final cable forces and deformations of arch rib after arch closure. Unstressed state control method is introduced in the construction of Daning River Bridge; unstressed qualities of ribs and unstressed length of cables can be obtained by optimization analysis of the maximum cantilever state in construction. According to unstressed state control method, the cable forces of each segment were calculated using the forward-iteration method. These results offer the basis for construction control, and guarantee the arch rib line and cable forces to meet the design requirements, and an arch closure with high precision.

scholarly journals Fatigue-free operation of most body-powered prostheses not feasible for majority of users with trans-radial deficiency

2017 ◽  
Vol 42 (1) ◽  
pp. 84-92 ◽  
Author(s):  
Mona Hichert ◽  
Alistair N Vardy ◽  
Dick Plettenburg
Keyword(s):  
Daily Basis ◽  
Maximum Force ◽  
Force Transmission ◽  
Anthropometric Measures ◽  
Physical Strength ◽  
Long Duration ◽  
Arm Circumference ◽  
Cable Force ◽  
Cable Forces ◽  
Force Range

Background: Body-powered prostheses require cable operation forces between 33 and 131 N. The accepted upper limit for fatigue-free long-duration operation is 20% of a users’ maximum cable operation force. However, no information is available on users’ maximum force. Objectives: To quantify users’ maximum cable operation force and to relate this to the fatigue-free force range for the use of body-powered prostheses. Study design: Experimental trial. Methods: In total, 23 subjects with trans-radial deficiencies used a bypass prosthesis to exert maximum cable force three times during 3 s and reported discomfort or pain on a body map. Additionally, subjects’ anthropometric measures were taken to relate to maximum force. Results: Subjects generated forces ranging from 87 to 538 N. Of the 23 subjects, 12 generated insufficient maximum cable force to operate 8 of the 10 body-powered prostheses fatigue free. Discomfort or pain did not correlate with the magnitude of maximum force achieved by the subjects. Nine subjects indicated discomfort or pain. No relationships between anthropometry and maximal forces were found except for maximum cable forces and the affected upper-arm circumference for females. Conclusion: For a majority of subjects, the maximal cable force was lower than acceptable for fatigue-free prosthesis use. Discomfort or pain occurred in ~40% of the subjects, suggesting a suboptimal force transmission mechanism. Clinical relevance The physical strength of users determines whether a body-powered prosthesis is suitable for comfortable, fatigue-free long-duration use on a daily basis. High cable operation forces can provoke discomfort and pain for some users, mainly in the armpit. Prediction of the users’ strength by anthropometric measures might assist the choice of a suitable prosthesis.

scholarly journals PC Cable-Stayed Bridge Main Girder Shear Lag Effects: Assessment of Single Cable Plane in Construction Stage

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Yan-feng Li ◽  
Xing-long Sun ◽  
Long-sheng Bao
Keyword(s):  
Bending Moment ◽  
Main Beam ◽  
Shear Lag ◽  
Distribution Law ◽  
Element Analysis ◽  
Cable Stayed Bridge ◽  
Action Point ◽  
Cable Force ◽  
Beam Section ◽  
Cable Forces

A model test and finite element analysis were conducted in this study to determine the distribution law of shear lag effect in the main beam section, a box girder, during the cable-stayed bridge construction process. The experimental and theoretical results were compared in an example of loading the control section. The stress value of the cable tension area of the main beam upper edge was found to markedly change when tensiling the cable force and was accompanied by prominent shear lag effect. After a hanging basket load was applied, the main beam of certain sections showed alternating positive and negative shear lag characteristics. The shear lag distribution law in the box girder of the single-cable-plane prestressed concrete cable-stayed bridge along the longitudinal direction was determined in order to observe the stress distribution of the girder. The results show that finite element analysis of the plane bar system should be conducted at different positions in the bridge under construction; the calculated shear lag coefficient of the cable force acting at the cable end of the cantilever reflects the actual force. In the beam segments between the cable forces, the shear lag coefficient determined by the ratio of the bending moment to the axial force reflects the actual stress at the cable force action point. In the midspan beam section between the action points of cable forces, the shear lag coefficient of the bending moment reflects the actual stress. The section shear lag coefficient can be obtained by linear interpolation of the beam section between the cable action point and the middle of the span.

scholarly journals A Comparative Study of 4-Cable Planar Manipulators Based on Cylindrical Algebraic Decomposition

2011 ◽  
Author(s):  
Damien Chablat ◽  
Erika Ottaviano ◽  
Guillaume Moroz
Keyword(s):  
Jacobian Matrix ◽  
Parallel Robots ◽  
Feasibility Problem ◽  
Closure Problem ◽  
Mobile Platforms ◽  
Implicit Representation ◽  
Closure Condition ◽  
Cylindrical Algebraic Decomposition ◽  
Force Closure ◽  
Cable Force

The aim of this paper is to present a systematic method for verifying the force-closure condition for general 3-DOF fully-constrained cable manipulators with four cables as based on the CAD (Cylindrical Algebraic Decomposition). A fundamental requirement for a cable manipulator to be fully controllable is that all its cables must be in tension at any working configurations. In other words, all the cable forces must be positive (assuming a positive cable force representing a tension and a negative cable force being a compression). Such a force feasibility problem is indeed referred to a force-closure problem (also called vector-closure problem assuming that the vectors of interest are the row vectors of the Jacobian matrix of the manipulator). The boundaries of the workspace can be obtained by the study of the Jacobian matrix of the manipulator. Therefore, this is equivalent to study the singularity conditions of four 3-RPR parallel robots. By using algebraic tools, it is possible to determine the singularity surfaces and their intersections yielding the workspace. Thus, it will be shown that the use of the CAD allows to get an implicit representation of the workspace as a set of cells. A comparative workspace analysis of three designs of mobile platforms, a line, a square and a triangle will be presented and discussed in this paper for a planar 4-cable fully-constrained robot.

Research on Cable Force Testing Method of Cable-Stayed Bridge Model Test

2013 ◽  
Vol 351-352 ◽  
pp. 1325-1330
Author(s):  
Yan Qiang Li ◽  
Yan Liang Du
Keyword(s):  
Model Test ◽  
Element Model ◽  
Test Model ◽  
Cable Stayed Bridge ◽  
Testing Method ◽  
Stay Cables ◽  
Bridge Model ◽  
Cable Force ◽  
Method Of Measurement ◽  
Main Component

A new method of measurement of the cable force in cable-stayed bridge model test is introduced. Pressure ring sensor is used as the main component in this method and the tension of the stay cables can be measured real-time and in time. It is vertified that this method is exact and credible by model test and can be used in actual cable-stayed bridge. The static measurements for the test model are conducted. The testing results are compared with the numerical results of finite element model developed for the test model. A platform is established for the future researchs.

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