Variation Of Bending Moment Research Articles

Crack-tip constraint analysis of bending specimens for considering higher order terms in asymptotic solution

In this research, a higher-order asymptotic J-A2-A4 solution was introduced for studying the effect of the bending moment on the crack-tip constraint of a specimen. The solution was applied to TPB and SENB specimens with varying bending moment loads, and compared to other methods such as FEA, HRR solution, J-A2 solution and J-A2-M solution. The results were analyzed and compared with the FEA, J-A2 theory and J-A2-M theory solutions obtained from references. The impact of global bending on the calculation of crack-tip opening stress was also investigated. The findings showed that the J-A2-A4 solution closely matched the FEA numerical results, and better accounted for the influence of global bending compared to the J-A2 method. Therefore, there is no need to modify the J-A2 method by adding a bending moment term, as suggested in the J-A2-M theory.

About effect of dynamic loading caused by concrete pump on bending moments, anchor forces and deformations in single level anchored retaining wall

This paper explore effect of dynamic loading caused by concrete pump on bending moments, anchor forces and deformations in single level anchored retaining wall. Dynamic loading is obtained by using a special developed dynamic mathematical model of truck-mounted concrete pump, by means of which are calculated the maximal dynamic loadings (acceleration and forces), which are transferred from concrete pump to the soil, and from there accordingly – from soil to the retaining wall under consideration. After that is performed a detailed finite element analysis of the retaining wall, by using software product Plaxis 3D, during which are analyzed the variation of bending moments, anchor forces and deformations in single level anchored retaining wall and after dynamic loading applying. There is also a numerical example considered, for which are calculated the maximal dynamic loadings, which are transferred from concrete pump to the soil, and from ground supports to the retaining wall. An amplification factor (dynamic factor) due to dynamic effects is calculated, by which is necessary to be multiplied the static loadings caused by concrete pump on soil. In the conclusion is made a qualitative assessment of the dynamic influence of concrete pump on the soil and the retaining wall section and ground anchor.

Action Path and Mechanism of Segment Joints in the Failure History of Shield Tunnel Lining

Focusing on the failure history of single-ring segmental lining structure, the action path and mechanism of segment joint on the segment bending moment was investigated in this study. The explicit equations of segment bending moment increment difference and segment bending moment diffusion coefficient were derived, and the causes of segment bending moment state variation in high load level were studied. In the failure history of segmental tunnel lining, the bending moment variation was mainly controlled by the bending moment increment difference per unit time (IND). IND was mainly controlled by the relative stiffness ratio of segment joints and their derivative. The action path of segment joints on segment internal force can be divided into: 1) the opening and yielding of segment joints, 2) the attenuation of rotational stiffness of segment joints, 3) the change of relative stiffness ratio and its derivative, 4) the IND value of non-zero, and 5) the drastic change of segment bending moment state. Furthermore, the rotation stiffness of the segment joint attenuated, and then the acceleration variation of segment bending moment was caused by segment joint effects because IND was not equal to 0, i.e., the segment bending moment increased or decreased sharply.

Mechanical model and characteristics of deep-water drilling riser-wellhead system under internal solitary waves

Internal solitary waves with a huge amount of energy easily trigger the large dynamic responses of riser-wellhead system and threaten its structural safety. However, previous studies have only focused on the dynamic response of the riser under internal solitary waves. The riser may experience excessive traction from the platform, especially from the mooring platform, in response to the arrival of internal solitary waves. The bottom of the riser connects to the wellhead system, which in turn exerts a reaction force on the riser. To address this problem, a coupled dynamic model of deep-water drilling mooring platform-riser-wellhead system under internal solitary waves is developed in this paper. A dynamic response analysis method based on the fourth-order Runge-Kutta method and finite element method is also proposed for the mooring platform-riser-wellhead system. A dynamical solver for the coupled system is then developed using MATLAB. The dynamic response characteristics of the riser-wellhead system under internal solitary waves are calculated. Results show that the displacement and bending moment of the system initially increases and then decreases along with the propagation of internal solitary waves, and finally reach equilibrium position. The displacement and bending moment reach their peak before the trough of internal solitary waves passes through the riser-wellhead system. The dynamic responses of the riser-wellhead system under the influence of internal solitary wave loads are much larger than those without the effect of internal solitary wave loads. The riser system experiences shearing loads at the interface of internal solitary waves, which trigger a step-like bending moment variation. The bending moment of the conductor under the mudline is greatly increased by the internal solitary waves.

Reduction of wave load on monopile-supported offshore wind turbine by a gear-type plate

This study investigates the wave diffraction problem of a vertical cylinder with a gear-type plate by using the linear wave theory and the method of eigenfunction expansion. The present model is demonstrated to be accurate, through a comparison with the numerical results of the boundary element method. The horizontal wave force acting on the cylinder can be reduced considerably by the gear-type plate. Meanwhile, the variation in bending moment at the bottom of the cylinder depends on the wave conditions and geometry parameters. A low value of the ratio between water depth and cylinder radius (d/r0) can result in an increase in the bending moment on the cylinder, rather than a decrease, due to the additional loads exerted by the gear-type plate. The bending moment on the cylinder can be reduced significantly by the gear-type plate as d/r0 increases. Within d/r0∈[4,10] of the present monopile-supported wind turbines, the wave loads on the monopile foundation can be reduced significantly by the proposed gear-type plate. Compared with a ring-type plate, a gear-type plate exhibits superior reduction effects over an equal plate area. The loads on the structures are insensitive to the wave exposure angle when the teeth number increases beyond three.

Thermo-mechanical characteristics of laterally loaded energy piles under multiple heating-cooling cycles in mountain area

In this paper, model tests of energy piles used in mountain area under asymmetry filed condition with and without an external lateral load under multiple heating-cooling cycles were conducted. The asymmetry of the soil will produce asymmetric temperature field and stress field in mountain area. The variation of pile top displacement, horizontal soil pressure, and pile bending moment due to cyclic temperature load were measured and analyzed. The results showed that the pile top horizontal displacement with an external lateral load decreased when the energy pile was heated and increased when it was cooled. However, the variation trends of pile top horizontal displacement with and without an external lateral load showed a significant difference. When the pile subjected to an external load was heated, the soil pressure at the upper part behind the pile would increase and that at the lower part would decrease, and the change was opposite during cooling. The bending moment would be changed by the thermal load, and it increased during heating with an external lateral load, while the variation of bending moment was not obvious during cooling.

Dynamic Behavior of Helical Piles in Dry and Liquefiable Soils using Scaled Shake Table Tests

The dynamic behavior of helical piles with different numbers of helices as well as a single slender shaft was examined through a series of scaled shake table tests. Multiple shakings were applied during each test series to evaluate the seismic behavior of the helical piles and the slender shaft considering different response parameters. A considerable ground settlement was observed during the first shaking in each test series, whereas negligible helical pile and slender shaft settlements were measured during all tests. The dynamic response of the helical piles was evaluated based on their bending moment variation along the depth and various measured response parameters at the model superstructure level. The bending moment variation indicated a similar trend along the depth for the helical piles and the slender shaft: the maximum moment was consistently observed at the boundary between dense and liquefiable layers. The observed bending moments along the depth increased with increases in input motion amplitude and superstructure weight. Densification of the liquefiable layer during different test series reduced the maximum bending moment along the depth for each pile due to increased relative density. Increasing the number of helices enhanced the dynamic performance of the helical piles compared to the slender shaft in terms of maximum bending moment, maximum horizontal displacement, residual horizontal displacement, and superstructure acceleration in different ground conditions.

Soil-structure interaction of integral abutments

Integral abutment bridges (IABs) are pioneering structures that offer certain advantages over conventional bridges. The main difference is the ability of IABs to eliminate the necessity of utilizing bearings and expansion joints. This results in more economical construction and enhanced structural performance. However, the intricate soil-structure interactions of IABs under the influence of seasonal changes are not yet fully understood. This paper aims to improve the understanding of these innovative structures by utilizing comprehensive numerical models to investigate their geostructural performance under various conditions. The case study selected for this research was the Middlesex bridge in Vermont, USA. A full-scale monitoring program at this bridge measured and recorded the bridge acting pressures, deformations, and internal forces, making it possible to gain insight into the thermal response of such structures. For the numerical research, a comprehensive two-dimensional numerical model, developed by using the PLAXIS software, was verified against the available field measurements. Subsequently, parametric studies were conducted to investigate earth pressure and pile bending moment variations influenced by different model conditions. Key model parameters were varied, including the constitutive soil model, thermal loading, backfill stiffness, pile size and orientation, and span length. It was found that utilizing a linear constitutive soil model could lead to significant inaccuracies in the results. Increasing the backfill stiffness was seen to increase passive earth pressures and decrease pile bending moments. With smaller pile sections, oriented for weak-axis bending, pile bending moments decreased substantially and lateral earth pressures increased. Because dead load magnitudes were closely linked to span lengths, pile bending moments and backfill pressures increased when fewer and longer bridge spans were used.

Influence of grouting on rehabilitation of an over-deformed shield tunnel lining in spatially variable soil

This study investigates the effect of grouting on an over-deformed operating shield tunnel considering soil spatial variability using the random finite difference method (RFDM). The compression modulus of soil is highlighted and simulated with a horizontally stratified anisotropic random field discretized by the Karhunen-Loeve expansion. The random finite difference model is firstly verified using an actual grouting case. Then, Monte Carlo simulations are executed to quantitatively evaluate the influence of soil spatial variability on the rehabilitation of the shield tunnel. On this basis, deformation rehabilitation of the tunnel by grouting under random pressure is explored initially. Results demonstrate that the spatial variability of the soil is the dominant factor affecting the rehabilitation of the shield tunnel under presumed constant grouting pressure. Meanwhile, the variability of the grouted area is mainly derived from the spatial variability of the soil. The correlation between the convergence reduction and maximum bending moment variation is more sensitive, affected by the variability of the soil and the grouted area. When the grouting pressure is further regarded to be randomly distributed, the effect of the variability of the grouted area will be significant on the amplification of the uncertainty of the tunnel performance.

STUDY ON BEHAVIOUR OF DIAGRID STRUCTURE FOR DIFFERENT DIAGRID ANGLES WITH CONSTRUCTION SEQUENCE ANALYSIS

It is frame work of diagonally intersecting metal, concrete, or wooden beams i.e. used in the construction of building and roofs and its diagonal components can carry both gravity and lateral loads due to their trigulated design and axial actions. Construction sequence analysis is a non linear analysis approach in which the structures in analyzed at various stages corresponding to the construction sequence and partially required loads are applied sequentially at every stage. A plan of 20 m × 20m size was considered. ETABS 2016 was used in modeling and analysis of structural members and subjected to seismic loads for zone V as per IS1893-2016. In total 6 models with different diagrid angles (520 620 & 680 ) and column removal scenario at different floor levels. To study bending moment and shear force variation in transfer girder beams for with and without construction sequence and study axial force variation in columns for with and without construction sequence analysis & also study seismic response of diagrid structure with different diagrid angles i.e., storey displacement and storey drift. For response spectrum analysis when compared different diagrid models (620 and 680), diagrid model 680 is less displacement as compared to other degrees implying that we take above 680 diagrid angle is best for tall buildings. A more realistic design than the standard design is produced by including sequential load case in the study of multistory RCC structure. Key Words: Diagrid angle, construction sequence analysis,

Constructive interference effects for tidal turbine arrays

The performance benefits of deploying tidal turbines in close side-by-side proximity to exploit constructive interference effects are demonstrated experimentally using two 1.2 m diameter turbines. The turbines are arrayed side-by-side at 1/4 diameter tip-to-tip spacing, and their performance compared with that of a single rotor. Tests were completed in the 25 m diameter, 2 m deep wave and current FloWave Ocean Energy Research facility. A detailed assessment of inflow conditions at different control points is used to understand the impact that rotors, designed for high blockage conditions, have on the approach flow. After accounting for global blockage, a 10.8 % uplift in the twin-turbine-averaged power coefficient, relative to that for a single turbine, is found for the turbine design speed, at the expense of a 5.2 % increase in thrust coefficient and 3.1 % increase in tip-speed-ratio. Flowfield mapping demonstrated flow effects at array and device scale including array bypass flows and jetting between turbines. Azimuthal variation of blade root flapwise and edgewise bending moments show that the turbines interact in a beneficial manner, with additional and sustained loading peaks as the blades pass in close proximity to the neighbouring rotor. Peak performance for the twin turbines occurred at a higher tip-speed-ratio than for the single turbine, which is consistent with the twin turbines exerting a higher thrust on the flow to achieve maximum power. The twin turbine performance variation with tip-speed-ratio is found to be more gradual than for the single turbine. Using differential rotor speed control we observe that array performance is robust to small differences in neighbouring rotor operating point. Through these experiments we demonstrate that there is a substantial, achievable performance benefit from closely arraying turbines for side-by-side operation and designing them for constructive interference.

Curved bridges live load bending moment distribution using straight and curved girders

abstract: The present study focuses on comparative parametric analysis of curved precast concrete bridges using straight and curved I-girders. The live load bending moment distribution for girders was studied using the bridge curvature and its relationship with the results obtained for a straight bridge. FEM 3D models were developed with restrictions on the transverse live load positions and with two different load models types: HL-93 (AASHTO) and TB-450 (NBR 7188, 2013). The parametric analysis results were calculated using the Modification Factor (MF) and the Bending Moment Distribution Factor (BMDF), calculated from the structural analysis of each model at the midspan. Globally, an increase was found in the total bending moment for the curved bridge models in relation to the straight bridge. In the examples herein studied, the larger the bending radius, the larger the maximal bending moment in the bridge center. For the external girders, the MF increases with the increase of the L/R. For the internal ones, the MF decreases with the increase of the L/R. In addition, the occurrence of “Load Shift” was different from the rigid body behavior, for there was demonstrated a different bending moment variation between external girder (G1) in relation to its adjacent (G2). Therefore, the structural behavior of straight (SG) and curved girders (CG) was analyzed, revealing that, in the SG, a significant gap occurred in the BMDF between G1 and G2 girders for all curvatures. For L/R = 0.6, it caused a difference of 17.8% in the BMDF between the G1 and G2 girders, while on the curved girders, a difference of only 6.6% was found.

Effect of Skew Angles on Longitudinal Girder and Deck Slab of Prestressed Concrete T Beam Girder Bridges

Abstract: The present paper shows the effects of varying skew angles on pre-stressed concrete (PSC) bridges using finite elemental method. Studies are carried out on PSC bridge decks to understand the influence of skew angle and loading on behaviour of bridges. The results of skewed bridges are compared with straight bridges for IRC Class AA Tracked loading. Also, a comparative analysis of the response of skewed PSC Slab Bridge decks with that of equivalent straight bridge decks is made. The variation of maximum longitudinal bending moment (BM), maximum transverse moment, maximum torsional moment, and maximum longitudinal stresses deflection at obtuse corner, acute corner with skew angles are studied for bridge deck. It is found that Live load longitudinal bending moments decreases with an increase in skew angle, whereas a maximum transverse moment and maximum torsional moment increases with an increase in skew angle. The benefit of pre-stressing is reflected in considerable decrease in the longitudinal bending moment, transverse moment and longitudinal stresses. The models are analysed with the help of software CSI-Bridge V 20 Version. Keywords: Skew angle effect, Longitudinal moment, Transverse moment, CSI- Bridge software, Deck slab, Finite element method.

Structural Responses of Statically Indeterminate Beams Induced by Soil Spatial Variability

The effect of the soil spatial variability on the structural assessment is explored in a context of statically indeterminate beams. The differential settlement among the four footings of a continuous beam is probabilistically determined considering various levels of soil spatial variability using the random finite element method. The settlement-induced beam internal forces, in terms of the transverse shear force and bending moment, are solved by using the force method. The variation of shear force and bending moment within a statically indeterminate beam, which is induced by the soil spatial variability, is systematically quantified using this probabilistic framework. This study points to the importance of properly addressing the effect of spatially varied soil conditions on structural design and promotes the integrated geotechnical and structural design.

Scientific investigation on the stress minimization of the RC thin roof structures using Finite element method of analysis

In cultivation of the fashionable and classy buildings, the gable and shell roof structures are found to be appealing owing to its trendy and auspicious features. This paper is presented to facilitate the designer to elect the finest slope for constructing the roofs by providing an analytical and finite element study for both the gable and shell roofs for the five distinct angles and apex height. Moreover, the bending moment variation with respect to the span and the stress factors like bending, axial and shear stresses are analyzed to suggest the cost effective angle with efficient material requirement. The economic suitability of the gable roof structures are optimized at the pitch angle range of 9° to 36° and 36° to 108° central angle regarding the shell roof structures.

Regularities of deformation of the bending of elastic elements and the parameters of vibrations of a dynamic tillage operating part

Revealing the regularities of bending deformation of elastic elements and vibration parameters of dynamic tillage operating parts is an urgent task, as it ensures the development of new innovative energy-efficient operating parts The aim of the study is to identify the patterns of deformation of elastic elements and oscillations of the wing of a dynamic tillage part of the operating part. The object of research is a dynamic arrow-shaped tillage operating part with a working width of 330 mm for surface tillage to a depth of 14 cm. The subject of research is the regularities of the bending deformation of elastic elements and the vibration parameters of dynamic tillage operating parts. The research was carried out using methods of mathematical modeling based on the study of physical laws that occur during soil cultivation; experimental studies on energy assessment of tillage operating part, analysis and generalization of experimental data. The scientific novelty of the work is represented by empirical dependencies for determining the value of the deflection of an elastic element, displacement of the extreme point of the wing and the amplitude of oscillations of the extreme point of the wing of a dynamic tillage operating part. The graphical and empirical dependences of the deflection value of the elastic element, the movement of the extreme point of the wing and the amplitude of its oscillations from the bending moment, the speed of movement and the load of the dynamic tillage operating part are given. It was found that within the range of bending moment variation from 36.2 to 95.35 N⋅m, the deflection of the elastic element ranges from 5.5 to 15.8 mm. At the same time, within the limits of the change in the speed of movement of the dynamic tillage worker from 1.94 to 3.61 m/s, the average value of the movement of the wing extreme point increases from 11.55 mm to 14.75 mm. The relationship of the parameters considered above on the bending moment, load and speed of movement of a dynamic tillage operating part is described by empirical dependencies with the coefficient of determination R 2 = 0.67 – 0.85. The error of the sample mean Sy of the investigated parameters of the dynamic operating part varied within 0.039 – 0.136.

Effect of Segmental Joint on Internal Forces in Tunnel Lining under Seismic Loading by Numerical Method

Although segmental tunnel linings are often used for seismic areas, the influence of segment joints on the segmental lining behavior under seismic loading has not been thoroughly considered in the literature. This paper presents the results of a numerical study investigating the effects of the rotational, axial, and radial joint stiffness of the longitudinal joints on the structural forces in segmental tunnel lining under seismic loading. A 3D finite element method is adapted to establish elaborate numerical models of the segments. The validity of the numerical model was tested by comparing the results obtained with the well-known analytical methods presented by Wang and Penzien. The results demonstrate that by increasing the rotational stiffness of the segmental joint, the bending moment increases. When the rotational stiffness ratio is less than 0.5, the positive and negative bending moment variations are more. The numerical modeling results show the variations in the bending moment and the difference between the positive and negative bending moment values increased by increasing the acceleration of seismic loading. Moreover, it is significant for the values. By increasing the rotational stiffness ratio of the segmental joint, the axial force ratio decreases. By increasing the axial and shear stiffness ratio of segmental joint, the variations in the bending moment and axial force in segmental lining is not significant and is ignorable in designing segmental lining.

Effects of Soil Simulation on the Interaction Analyses of Framed Structures Under 2-D and 3-D Conditions

The effects of some important factors on the development of differential settlements and flexural moments were investigated in the context of interaction analyses for two hypothetical building structures founded on a grid of strip footings. Geometrical simulations included 2-D and 3-D building models in order to identify possible differences when applying the simple 2-D simulation as against the more difficult 3-D one. Furthermore, in order to investigate the applicability of the simple linearly elastic soil model, comparisons were attempted between results obtained on the basis of linearly elastic and elastoplastic according to Mohr–Coulomb’s failure criterion interactive analyses. The variation of differential settlements (or rotations), bending moments and axial loads of the superstructure and foundation were studied versus the elastic modulus E or versus the global safety factor. Detailed conclusions were deduced based on representative diagrams. The comparisons between corresponding results obtained by 2-D and 3-D simulations indicated significant differences especially in cases of high relative rigidity, influenced by the thickness of the compressible soil layer. The comparisons between linearly elastic and elastoplastic soil simulation showed the important role of the relative rigidity in the interaction problem, especially for low values of the global safety factor.

Pogressive Collapse Analysis of Multi Storey (G+10) Building by Staad Pro. using Column Removal

This project presents an attempt to do progressive collapse analysis of multistory (G+10) residential building by STAAD Pro (Structural Analysis and Design Software Application). STAAD Pro is software that helps to analysis and design of low and high-rise buildings and portal frame structures. In this project G+10 RC frame building is analysis statically (linear method) along with Progressive Collapse analysis. In progressive collapse the weight of the building transfers to the neighbour columns in the structure causes to the failure of adjoining members and finally to the failure of partial or whole structure. All the members of the project are analyzed as per Indian codes IS 456:2000, IS 800:2007, and IS 1893:2002 (part1) code using this software. Here the result for is compared between the shear force, bending moment variations value of corner column, Zone1, Zone2, Zone 3 by STAAD Pro. With medium soil type and for Progressive Collapse analysis GSA guidelines are followed. As per GSA guidelines three column removal cases for each case1, case2, case3 one at a time has studied, namely Corner column removal, Exterior column removal and interior column removal all at ground floor.

Analytical study on one-way reinforced concrete beam-slab sub-structures under compressive arch action and catenary action

In case of accidental loading, compressive arch action and catenary action in beams and slabs can be mobilised to resist progressive collapse of reinforced concrete structures. Analytical models have been proposed for reinforced concrete beam-column sub-assemblages under compressive arch action and catenary action. Nonetheless, the effects of the slab on load resistance and deformation capacity of one-way beam-slab sub-structures have not been fully investigated. This paper presents a study on the structural behaviour of one-way beam-slab sub-structures subjected to compressive arch action and subsequent catenary action. In the study, an analytical model is developed to predict the load-displacement relationship and the axial force-displacement relationship of sub-structures. The model is developed in accordance with rigid-plastic assumption. Compatibility, equilibrium and constitutive models for steel reinforcement and concrete are taken into account in the model. Hogging and sagging moments are calculated by taking moments about the plastic centres of beam-slab sub-structures. The model is validated against published test data and reasonably good accuracy is obtained in terms of the load resistances under compressive arch action and catenary action. The variation of bending moments, neutral axis depths and steel strains can also be obtained through the analytical model. The model is then used for parametric study of the effects of longitudinal reinforcement, slab width, and thickness on compressive arch action and catenary action. The parametric study shows that the cross-sectional area of longitudinal reinforcement in the slab affects the catenary action capacity and the width and thickness of the slab affects the deformation capacity of one-way beam-slab sub-structures. Finally, conclusions are drawn from the analytical study which can be used in the design of one-way beam-slab sub-structures against progressive collapse.