scholarly journals Equivalent stabilizing force of members parabolically compressed by longitudinally variable axial force

2019 ◽  
Vol 262 ◽  
pp. 09004
Author(s):  
Antoni Biegus ◽  
Dariusz Czepiżak
Keyword(s):  
Force Constant ◽  
Axial Force ◽  
Central Zone ◽  
Force Distribution ◽  
Support Zone ◽  
Axial Forces ◽  
Parametric Studies ◽  
Parametric Analyses

The EN 1993-1-1 model of equivalent stabilizing force qd and Rd of bracings conservatively assumes that the braced member is compressed with a force constant along its length. This assumption is incorrect since the axial force distribution varies along the length of the braced member. As a result, the braced member generates equivalent stabilizing forces different from equivalent force qd and Rd acc. to EN 1993-1-1. This paper presents parametric studies of the equivalent stabilizing forces of the braced, compression top chord of roof trusses. The girder’s top chord is compressed parabolically by a variable axial force. The values of the axial compressive forces is: Nsupp in the support zone of truss and Nspan in the central zone of truss. Parametric analyses of the equivalent stabilizing force and the stress of the purlins and the bracings depending on axial forces Nsupp and Nspan in the braced member were carried out. The investigated problem is illustrated with exemplary calculations of the equivalent force in trusses.

scholarly journals Analytical and numerical research of equivalent stabilizing force of stiffened truss chords

2019 ◽  
Vol 262 ◽  
pp. 09003
Author(s):  
Antoni Biegus ◽  
Dariusz Czepiżak
Keyword(s):  
Axial Force ◽  
Geometric Nonlinearity ◽  
Central Zone ◽  
3D Models ◽  
Numerical Analyses ◽  
Support Zone ◽  
Is Research ◽  
Axial Forces ◽  
Numerical Research ◽  
Parametric Analyses

The aim of this paper is research of the equivalent stabilizing forces of the braced top flange of the truss. The study takes into account the initial bow imperfection e0 of the braced top flange and the im-perfection consisting in a twist of the roof girder’s principal plane by angle ϕ0(x). Moreover, axial force N3(x) in the top flange of the truss is assumed to be longitudinally parabolically variable. The values of the axial forces is: Nsupp in the support zone of the truss and Nspan in the central zone of truss. As part of this study parametric analyses of the equivalent stabilizing forces and the stress of the bracings depending on axial forces Nsupp and Nspan in the braced member were carried out. The results are compared with the results of numerical analyses of 3D models taking the geometric nonlinearity of the structure into account.

Advances In The Modeling And Dynamic Simulation of Reeving Systems Using The Arbitrary Lagrangian-Eulerian Modal Method

2021 ◽  
Author(s):  
José L. Escalona ◽  
Narges Mohammadi
Keyword(s):  
Finite Elements ◽  
Axial Force ◽  
Axial Direction ◽  
Rotary Inertia ◽  
Arbitrary Lagrangian Eulerian ◽  
Original Formulation ◽  
Absolute Position ◽  
Axial Forces ◽  
Modal Coordinates ◽  
Modal Method

Abstract This paper presents new advances in the arbitrary Lagrangian-Eulerian modal method (ALEM) recently developed for the systematic simulation of the dynamics of general reeving systems. These advances are related to a more convenient model of the sheaves dynamics and the use of axial deformation modes to account for non-constant axial forces within the finite elements. Regarding the sheaves dynamics, the original formulation uses kinematic constraints to account for the torque transmission at the sheaves by neglecting the rotary inertia. One of the advances described in this paper is the use of the rotation angles of the sheaves as generalized coordinates together with the rope-to-sheave no-slip assumption as linear constraint equations. This modeling option guarantees the exact torque balance the sheave without including any non-linear kinematic constraint. Numerical results show the influence in the system dynamics of the sheave rotary inertia. Regarding the axial forces within the finite elements, the original formulation uses a combination of absolute position coordinates and transverse local modal coordinates to account for the rope absolute position and deformation shape. The axial force, which only depends on the absolute position coordinates, is constant along the element because linear shape functions are assumed to describe the axial displacements. For reeving systems with very long rope spans, as the elevators of high buildings, the constant axial force is inaccurate because the weight of the ropes becomes important and the axial force varies approximately linearly within the rope free span. To account for space-varying axial forces, this paper also introduces modal coordinates in the axial direction. Numerical results show that a set of three modal coordinates in the axial direction is enough to simulate linearly varying axial forces.

scholarly journals Pullout Behavior of GFRP Anti-Floating Anchor Based on the FBG Sensor Technology

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Ming-yi Zhang ◽  
Zheng Kuang ◽  
Xiao-yu Bai ◽  
Xiao-yu Chen
Keyword(s):  
Axial Force ◽  
Shear Failure ◽  
Distribution Functions ◽  
Sensor Technology ◽  
Force Distribution ◽  
Test Results ◽  
Glass Fiber Reinforcement ◽  
Promising Solution ◽  
Service Conditions ◽  
Fbg Sensors

Building anti-floating anchors have been increasingly used in recent years, but conventional steel anchors under service conditions are easily subjected to chemical erosion. Glass fiber reinforcement polymer (GFRP) is a promising solution to this problem. In this study, field pullout tests were conducted on three full instrumented GFRP anti-floating anchors in weathered granite. Specifically, the GFRP anchors during pultrusion were innovatively embedded with bare fiber Bragg grating (FBG) sensors to monitor the axial force distribution along depth. It was found that the embedded FBG could reliably monitor the axial force distribution of GFRP anchors. The ultimate pullout force of a GFRP anchor with diameter of 28 mm and anchorage length of 5 m was up to 400 kN. The GFRP anchor yielded at 0.8 m underground. Force distribution and field photos at failure indicated shear failure occurred at the anchor/bolt interface at the end of the tests. The feasibility of the GFRP anti-floating anchor was also verified in civil engineering. Finally, an elastic mechanical model and Mindlin’s displacement solution are used to get distribution functions of axial force and shear stress along the depth, and the results accord with the test results.

Measurement of axial forces during emptying from the human stomach

1992 ◽  
Vol 263 (2) ◽  
pp. G230-G239 ◽  
Author(s):  
M. J. Vassallo ◽  
M. Camilleri ◽  
C. M. Prather ◽  
R. B. Hanson ◽  
G. M. Thomforde
Keyword(s):  
Axial Force ◽  
Longitudinal Axis ◽  
Force Transducer ◽  
Human Stomach ◽  
In Vitro Studies ◽  
In Vivo Studies ◽  
Dependent Manner ◽  
Axial Forces

Our aim was to measure axial forces in the stomach and to evaluate their relation to circumferential contractions of the gastric walls and the emptying of gastric content. We used a combination of simultaneous radioscintigraphy, gastroduodenal manometry, and an axial force transducer with an inflatable 2-ml balloon fluoroscopically placed in the antrum. In vitro studies demonstrated that the axial force transducer records only antegrade forces along the longitudinal axis of this probe in an intensity-dependent manner. In vivo studies were performed in five healthy subjects for at least 3 h after ingestion of radiolabeled meals. When administered separately, the emptying of liquids or solids from the stomach is associated with generation of antral axial forces and coincident phasic pressure activity; however, almost 20% (average) of gastric axial forces during emptying of liquids or solids are unassociated with proximal or distal antral pressure activity ("isolated" forces). High amplitude antral axial forces and pressures occur during both lag and postlag emptying phases. During emptying of liquids, there is a trend for axial forces to be coincident more often with proximal than with distal antral pressure activity and vice versa for the emptying of solids (P = 0.015). These data suggest that when placed in the antrum, the transducer can semiquantitatively record axial forces during gastric emptying. By combining these observations with the data from in vitro studies, it appears that axial forces predominantly result from traction on the balloon by the longitudinal vector resulting from circumferential gastric contractions. The combination of radioscintigraphy and measurement of antral axial forces is a promising method to evaluate mechanical forces involved in the emptying of the human stomach.

Analytical Computational Models for Relationship between Ultimate Bending Moment of Concrete Segments and Axial Force

2020 ◽  
Vol 853 ◽  
pp. 177-181
Author(s):  
Zhi Yun Wang ◽  
Shou Ju Li
Keyword(s):  
Numerical Simulation ◽  
Computational Model ◽  
Axial Force ◽  
Computational Models ◽  
Plane Deformation ◽  
Bending Moment ◽  
Analytical Models ◽  
Bending Moments ◽  
Axial Forces ◽  
Practical Engineering

Concrete segments are widely used to support soil and water loadings in shield-excavated tunnels. Concrete segments burden simultaneously to the loadings of bending moments and axial forces. Based on plane deformation assumption of material mechanics, in which plane section before bending remains plane after bending, ultimate bending moment model is proposed to compute ultimate bearing capacity of concrete segments. Ultimate bending moments of concrete segments computed by analytical models agree well with numerical simulation results by FEM. The accuracy of proposed analytical computational model for ultimate bending moment of concrete segments is numerically verified. The analytical computational model and numerical simulation for a practical engineering case indicate that the ultimate bending moment of concrete segments increases with increase of axial force on concrete segment in the case of large eccentricity compressive state.

Evaluation of foundation tie requirements in seismic design

1993 ◽  
Vol 20 (1) ◽  
pp. 73-81
Author(s):  
A. C. Heidebrecht ◽  
A. Rutenberg
Keyword(s):  
Axial Force ◽  
Seismic Design ◽  
Structural Model ◽  
Travelling Waves ◽  
Travelling Wave ◽  
Shear Forces ◽  
Seismic Codes ◽  
Axial Forces ◽  
Pile Caps ◽  
Spread Footings

A simple structural model is proposed to evaluate the axial force acting on tie beams interconnecting spread footings or pile caps due to differential ground motion estimated on the basis of the travelling wave assumption. The approach is intended to supplement the "ten percent rule" or similar multipliers specified by seismic codes as design axial forces on tie beams. It is shown that the axial force demand is rather modest. However, shear forces between footing and soil may be quite large depending on maximum column displacements and superstructure rigidity. Key words: foundations, tie beams, earthquake, travelling waves, seismic codes.

Study on Isolated Layer Mechanics Character of Combined Base Isolated Structure Based on Axial Forces Redistribute

2012 ◽  
Vol 166-169 ◽  
pp. 627-631 ◽  
Author(s):  
Fu You Zhang ◽  
Ming Gu ◽  
Yun Song ◽  
Song Xu
Keyword(s):  
Axial Force ◽  
Horizontal Displacement ◽  
Vertical Force ◽  
Isolation System ◽  
Isolation Layer ◽  
Calculating Method ◽  
Axial Forces ◽  
Rubber Bearings

Abstract：Combined isolation system is combined with rubber bearings which provide resilience forces and sliding isolated bearings which provide damp. According to the rule of axial forces redistributing between two kinds of bearings under earthquake, a calculating method considering the vertical force redistribute of isolation layer was given. With this method, the results of an example show that axial force will transfer from rubber bearings to sliding isolated bearings along with the horizontal displacement of isolation layer. The bigger the displacement is the more axial force transfers. So the axial-forces redistribution is a self-adjustable performance of the system, and also is an advantage for the system.

Parametric Studies on Bending of Twisted Timoshenko Beams Under Complex Loadings

2012 ◽  
Vol 28 (1) ◽  
pp. N1-N6 ◽  
Author(s):  
W.-R. Chen
Keyword(s):  
Twist Angle ◽  
Width Ratio ◽  
Algebraic Equations ◽  
Equilibrium Equations ◽  
Static Loads ◽  
Parametric Studies ◽  
Element Approach ◽  
Minimum Potential ◽  
Parametric Analyses ◽  
Twisted Beam

ABSTRACTStatic bending of a twisted Timoshenko beam subjected to combined transverse and axial loadings is studied. The equilibrium equations are established in the twist coordinates by applying the principle of minimum potential energy. The governing equations are then reduced into solvable algebraic equations using a finite element approach. The effects of the twist angle, thickness-to-width ratio, length-to-thickness ratio, loading and boundary conditions on the static bending characteristics of the twisted beams are investigated. The present parametric analyses will provide engineers a good insight into the influence of various structural aspects of the twisted beam on its response to different static loads.

scholarly journals ANALISIS PENGARUH PEMODELAN SAMBUNGAN TITIK BUHUL PADA STRUKTUR KUBAH GEODESIK

2021 ◽  
Vol 4 (2) ◽  
pp. 503
Author(s):  
Rivven Meilvin ◽  
Leo S. Tedianto
Keyword(s):  
Axial Force ◽  
Joint Modeling ◽  
Internal Force ◽  
Cross Sectional ◽  
Axial Forces ◽  
Translational Displacement ◽  
Single Structure ◽  
Dome Structure ◽  
Internal Forces ◽  
Geodesic Dome

The geodesic dome consists of steel rod elements joined together to form a single structure. Generally, these geodesic domes are analyzed by assuming the joints of the gusset points are joints and only receive axial forces on the rods. However, in reality, it is not easy to apply gusset joints as pure joints in construction. This research will analyze the geodesic dome by modeling the joints of the gusset points as joints where there is only axial force arising on the rods and modeling the rigid gusset points where there will also be moments and shear on the rods. The analysis will only be carried out by comparing the value of the displacement at each gusset joint modeling and checking the cross-sectional dimensions of the internal forces that arise with the help of the MIDAS GEN program in modeling the geodesic dome structure which has a diameter of 20000 mm and a height of 10000 mm with the type of steel profile. used is a pipe profile using two types of geodesic dome, namely type 2V and 3V. For loads that are calculated, namely dead load, live load, and wind load. The results showed a relatively small difference in translational displacement and the axial force was relatively the same in the internal force analysis, so it is better if the analysis by modeling the gusset connection as rigid.ABSTRAKKubah geodesik terdiri dari elemen batang baja yang disambung menjadi satu kesatuan struktur. Umumnya kubah geodesik ini dianalisis dengan menganggap sambungan titik buhulnya berupa sendi dan hanya menerima gaya aksial saja pada batang - batangnya. Namun pada kenyataannya untuk mengaplikasikan sambungan titik buhul sebagai sendi murni pada konstruksi tidaklah mudah. Penelitian ini akan menganalisis kubah geodesik   dengan memodelkan sambungan titik buhulnya sebagai sendi dimana hanya ada gaya aksial saja yang timbul pada batang - batangnya dan memodelkan titik buhulnya rigid dimana akan terjadi juga momen dan geser pada batang tersebut. Analisis hanya akan dilakukan dengan membandingkan nilai dari perpindahan pada setiap pemodelan sambungan titik buhul dan pengecekan dimensi penampang terhadap gaya – gaya dalam yang timbul dengan bantuan program MIDAS GEN dalam memodelkan struktur kubah geodesik yang mempunyai diameter 20000 mm dan tinggi 10000 mm dengan jenis profil baja yang digunakan adalah profil pipa dengan menggunakan dua tipe kubah geodesik yaitu tipe 2V dan 3V. Untuk beban yang diperhitungkan yaitu beban mati, beban hidup, dan beban angin. Hasil penelitian menunjukkan nilai perbedaan yang relatif kecil pada perpindahan translasi dan diperoleh gaya aksial yang relatif sama pada analisis gaya dalam yang timbul, sehingga sebaiknya analisis dengan pemodelan sambungan titik buhul sebagai rigid.

scholarly journals Axial force effect on the buckling of a constrained cylindrical shell

2019 ◽  
Author(s):  
A.V. Egorov ◽  
V.N. Egorov
Keyword(s):  
High Pressure ◽  
Cylindrical Shell ◽  
Axial Force ◽  
Composite Shell ◽  
Local Buckling ◽  
Front Surface ◽  
Cylindrical Part ◽  
Pressure Vessels ◽  
Metal Composite ◽  
Axial Forces

The article considers a constrained cylindrical shell structure. It is a two-ply cylinder in which the inner metal shell (liner) contacts on the outer front surface with a composite shell formed by wound carbon-fibre tape. The design model of this structure is used, among other things, for metal composite cylindrical high pressure vessels. When such vessels are in use, there is a danger of liner delamination from a rigid composite shell, which refers to prohibitive defects. The deformation of the liner in the central part of the vessel occurs under the influence of internal pressure applied to both the cylindrical part and to the bottoms from which axial forces appear. The present work is aimed at studying the effect of these axial forces on the local buckling of the liner in the cylindrical zone of the vessel. The model of the structure deformation includes technological deviations characteristic of real products and a 3D stress-strain state, changing in real time. The calculation was carried out in the LS-DYNA software package in a dynamic formulation using 3D solid elements. For the target level of pressure, the moments of delamination of the vessel and the buckling of the liner are determined. A comparison of two design schemes (i) with and (ii) without axial force taken into consideration is carried out. The necessity of taking into account axial forces when designing metal composite high pressure vessels is shown.

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