scholarly journals Preliminary Numerical Analysis of a Novel Retaining System in Dry Sandy Soil and Its First Application to a Deep Excavation in Wuhan (China)

2020 ◽  
Vol 10 (6) ◽  
pp. 2006
Author(s):  
Yapeng Zhang ◽  
Congxin Chen ◽  
Meiqing Lei ◽  
Yun Zheng ◽  
Haina Zhang ◽  
...  
Keyword(s):  
Numerical Study ◽  
Bending Moment ◽  
Bending Moments ◽  
Deep Excavation ◽  
Retaining Structure ◽  
Real World Application ◽  
New Form ◽  
Batter Piles ◽  
Levels Of Support ◽  
New System

A new form of retaining system for use in deep excavations in crowded cities is proposed in this paper. The new system, which we have coined the herringbone retaining system (HRS) involves the use of vertical and batter piles, capping beams, and wales. A numerical study was conducted (using the finite difference tool FLAC3D) to investigate various aspects of the behavior of the new system and reveal the mechanisms responsible for it. The HRS method was compared subsequently to two other commonly-used systems: the cantilever retaining structure (CRS) and horizontal-strutted retaining structure (HSRS). The results show that using the HRS method significantly reduces the deformation of the vertical piles and bending moments acting on them. More specifically, the maximum values of the deformation and bending moment were calculated to be 4.5% and 23.1% of the corresponding CRS values, respectively (the corresponding figures calculated for the HSRS method are 5.3% and 19.7%, respectively), so the HRS and HSRS methods provide similar levels of support. Finally, a real-world application of the system was presented to provide a valuable reference for the future use of HRS.

Analysis of Internal Force and Deformation for Pit Retaining Structure by Considering the Interaction of Pile Stiffness

2013 ◽  
Vol 838-841 ◽  
pp. 397-401
Author(s):  
Ming Li ◽  
Ren Wang Liang
Keyword(s):  
Finite Difference ◽  
Engineering Design ◽  
Axial Force ◽  
Influence Factors ◽  
Bending Moment ◽  
Internal Force ◽  
Equivalent Stiffness ◽  
Deep Excavation ◽  
Retaining Structure ◽  
Design Software

In this paper, taking one deep excavation engineering as an example, modeling by the FLAC3D finite difference software, combining with the Lizheng deep excavation supporting design software, taking the equivalent stiffness of combination pile as 2.300-4.789(10-2m3), and analyzing the pile body bending moment, anchor axial force and pit deformation by considering interaction of pile stiffness. In addition, in this paper the influence factors of pile stiffness has been discussed, and provides a reference for the engineering design.

scholarly journals Effect of Turbine Weight on the Seismic Response of a Wind Turbine-Monopile System Located in Liquefied Multilayer Soil

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Mehran Tirandazian ◽  
Gholamreza Nouri
Keyword(s):  
Wind Turbine ◽  
Seismic Response ◽  
Wind Turbines ◽  
Numerical Study ◽  
Lateral Displacement ◽  
Bending Moment ◽  
Transverse Motion ◽  
Bending Moments ◽  
Significant Difference ◽  
Pile Column

The core objectives of sustainable development are to develop access to renewable, sustainable, reliable, and cost-effective resources. Wind is an essential source of renewable energy, and monopile wind turbines are one method proposed for harnessing wind power. Offshore wind turbines can be vulnerable to earthquakes and liquefaction. This numerical study defined the effects of wind turbine weight on the seismic response of a wind turbine-monopile system located in liquefied multilayered soil with layer thicknesses of 5, 10, 15, and 20 m using four far-field records. OpenSees PL analysis indicated that if the liquefied sand had a lower density or a thickness of more than 10 m, then an increase in the earthquake acceleration beyond 0.4 g caused the pile to float like liquefied soil and to lose its vertical bearing capacity. Moreover, increasing the wind turbine power from 2 to 5 kW had no significant effect on the soil-structure interaction response. As the earthquake acceleration increased, the bending moment of the pile-column also increased as long as liquefaction did not occur and the pile-column deformation remained rotational-spatial in shape. As the acceleration and liquefaction increased and the pile began to float in response to its transverse motion, there was no significant difference in the pile-column displacement along the length, but there was a decrease in the pile-column bending moments. As this phenomenon increased and the pile continued to float, transformation of the pile increased the difference between the displacement of the pile-column along its length and further increased the bending moments. These results were derived from multiple correlation analysis, the bending moment relations, and lateral displacement of the pile-column of the wind turbine.

Effect of Torsion on Collapse Bending Moment for 24-Inch Diameter Schedule 80 Pipes With Wall Thinning

2012 ◽  
Author(s):  
Kunio Hasegawa ◽  
Yinsheng Li ◽  
Bostjan Bezensek ◽  
Phuong Hoang
Keyword(s):  
Power Plants ◽  
Bending Moment ◽  
Combined Loading ◽  
Bending Moments ◽  
Compressive Stresses ◽  
Wall Thinning ◽  
Nominal Thickness ◽  
Calculation Results ◽  
Loading Modes ◽  
Local Wall Thinning

Piping items in power plants may experience combined bending and torsion moments during operation. Currently, there is a lack of guidance in the ASME B&PV Code Section XI for combined loading modes including pressure, torsion and bending. Finite element analyses were conducted for 24-inch diameter Schedule 80 pipes with local wall thinning subjected to tensile and compressive stresses. Plastic collapse bending moments were calculated under constant torsion moments. From the calculation results, it can be seen that collapse bending moment for pipes with local thinning subjected to tensile stress is smaller than that subjected to compressive stress. In addition, equivalent moment is defined as the root the sum of the squares of the torsion and bending moments. It is found that the equivalent moments can be approximated with the pure bending moments, when the wall thinning length is equal or less than 7.73R·t for the wall thinning depth of 75% of the nominal thickness, where R is the mean radius and t is the wall thickness of the pipe.

scholarly journals 3-D Numerical Study of Mechanical Behaviors of Pile-Anchor System

2014 ◽  
Vol 580-583 ◽  
pp. 238-242
Author(s):  
Ri Cheng Liu ◽  
Bang Shu Xu ◽  
Bo Li ◽  
Yu Jing Jiang
Keyword(s):  
Simulation Analysis ◽  
Numerical Study ◽  
Bending Moments ◽  
Mechanical Behaviors ◽  
Foundation Pit ◽  
Anchor System ◽  
Anchor Cable ◽  
Axial Forces ◽  
Toppling Failure ◽  
Potential Failure

Mechanical behaviors of pile-soil effect and anchor-soil effect are significantly important in supporting engineering activities of foundation pit. In this paper, finite difference method (FDM) was utilized to perform the numerical simulation of pile-anchor system, composed of supporting piles and pre-stressed anchor cables. Numerical simulations were on the basis of the foundation pit of Jinan’s West Railway Station, and 3D simulation analysis of foundation pit has been prepared during the whole processes of excavation, supporting and construction. The paper also analyzed the changes of bending moments of piles and axial forces of cables, and discussed mechanical behaviors of pile-anchor system, through comparisons with field monitoring. The results show that the parameters concluding vertical gridding’s number, cohesion of pile and soil, and pile stiffness have robust influences on supporting elements’ behaviors. Mechanical behaviors of supporting pile and axial forces of anchor cable changed dramatically, indicating that the potential failure form was converted from toppling failure to sliding failure.

scholarly journals Comparison of Induced Deflection and Forces in Piles Adjacent to Tunnelling and Deep Excavation in 2D and 3D Problems

2018 ◽  
Vol 203 ◽  
pp. 04011
Author(s):  
Ong Yin Hoe ◽  
Hisham Mohamad
Keyword(s):  
Bending Moment ◽  
Pile Group ◽  
3D Models ◽  
Deep Excavation ◽  
Pile Groups ◽  
Out Of Plane ◽  
National University ◽  
Plane Direction ◽  
2D And 3D ◽  
2D Model

There is a trend in Malaysia and Singapore, engineers tend to model the effect of TBM tunneling or deep excavation to the adjacent piles in 2D model. In the 2D model, the pile is modelled using embedded row pile element which is a 1-D element. The user is allowed to input the pile spacing in out-of-plane direction. This gives an impression to engineers the embedded pile row element is able to model the pile which virtually is a 3D problem. It is reported by Sluis (2014) that the application of embedded pile row element is limited to 8D of pile length. It is also reported that the 2D model overestimates the axial load in pile and the shear force and bending moment at pile top and it is not realistic in comparison to 3D model. In this paper, the centrifuge results of single pile and 6-pile group - tunneling problem carried out in NUS (National University of Singapore) are back-analysed with Midas GTS 3D and a 2D program. In a separate case study, pile groups adjacent to a deep excavation is modelled by 3D and 2D program. This paper compares the deflection and forces in piles in 2D and 3D models.

Investigation of Smooth Pipe Bends Under the Effect of In-Plane Bending

2017 ◽  
Author(s):  
Diana Abdulhameed ◽  
Michael Martens ◽  
J. J. Roger Cheng ◽  
Samer Adeeb
Keyword(s):  
High Stress ◽  
Circular Cross Section ◽  
Bending Moment ◽  
Bend Angle ◽  
Bending Moments ◽  
Bend Radius ◽  
Pipe Bend ◽  
Cross Sectional ◽  
Smooth Pipe ◽  
Plane Bending

Pipe bends are frequently used to change the direction in pipeline systems and they are considered one of the critical components as well. Bending moments acting on the pipe bends result from the surrounding environment, such as thermal expansions, soil deformations, and external loads. As a result of these bending moments, the initially circular cross-section of the pipe bend deforms into an oval shape. This consequently changes the pipe bend’s flexibility leading to higher stresses compared to straight pipes. Past studies considered the case of a closing in-plane bending moment on 90-degree pipe bends and proposed factors that account for the increased flexibility and high-stress levels. These factors are currently presented in the design codes and known as the flexibility and stress intensification factors (SIF). This paper covers the behaviour of an initially circular cross-sectional smooth pipe bend of uniform thickness subjected to in-plane opening/closing bending moment. ABAQUS FEA software is used in this study to model pipe bends with different nominal pipe sizes, bend angles, and various bend radius to cross-sectional pipe radius ratios. A comparison between the CSA-Z662 code and the FEA results is conducted to investigate the applicability of the currently used SIF factor presented in the design code for different loading cases. The study showed that the in-plane bending moment direction acting on the pipe has a significant effect on the stress distribution and the flexibility of the pipe bend. The variation of bend angle and bend radius showed that it affects the maximum stress drastically and should be considered as a parameter in the flexibility and SIF factors. Moreover, the CSA results are found to be un-conservative in some cases depending on the bend angle and direction of the applied bending moment.

Structural Reliability of Oil Tanker in the Adriatic Sea Damaged in Collision and Exposed to Combined Bending Moments

2018 ◽  
Author(s):  
Maro Ćorak ◽  
Joško Parunov
Keyword(s):  
Structural Reliability ◽  
Adriatic Sea ◽  
Bending Moment ◽  
State Function ◽  
Regression Equations ◽  
Bending Moments ◽  
Damage Stability ◽  
Safety Indices ◽  
Oil Tanker ◽  
Damaged Ship

The aim of the paper is the assessment of structural reliability of oil tanker which may be damaged in collision accident in the Adriatic Sea and exposed to combined, horizontal and vertical bending moments. Damage size is assumed based on the direct numerical simulation of the ship-ship collision. This is justified for some specific sea environments, as the Adriatic Sea, where ship sailing routes and representative ship types involved in accidents are known, so possible collision scenarios may be reasonably predicted. Residual bending moment capacity under combined bending moment is calculated using regression equations developed based on non-linear finite element analysis. Still water vertical bending moments are obtained by damage stability analysis. Vertical and horizontal wave bending moments are determined by short-term response analysis of damaged ship in the Adriatic Sea, using transfer functions obtained by 3D panel hydrodynamic method. Limit state function is defined using interaction equation for damaged ship exposed to combined bending moments. Safety indices are calculated by FORM for different collision scenarios that are generated by MC simulations. Such approach enables to determine the safety indices for the most frequent damages and also to reveal the most critical situations resulting in the lowest safety indices.

Design Charts for Symmetrical Ring Girders

1957 ◽  
Vol 24 (1) ◽  
pp. 144-147
Author(s):  
G. P. Fisher
Keyword(s):  
Energy Analysis ◽  
Bending Moment ◽  
Bending Moments ◽  
Bending Energy ◽  
Normal Loading ◽  
Critical Design ◽  
Design Charts ◽  
Ring Location

Abstract Charts, based on classical bending-energy analysis, are presented for the determination of critical design moments in symmetrical ring girders varying in shape from circular through round to sharp-cornered rings. The girders are subjected to uniform normal loading in the plane of the ring. Location and magnitude of all critical bending moments are given, from which the maximum bending moment is easily selected.

Ship Operational and Safety Aspects of Ballast Water Exchange at Sea

1994 ◽  
Vol 31 (04) ◽  
pp. 315-326
Author(s):  
John B. Woodward ◽  
Michael G. Parsons ◽  
Armin W. Troesch
Keyword(s):  
Bending Moment ◽  
Bending Moments ◽  
University Of Michigan ◽  
Bulk Carrier ◽  
Rough Water ◽  
Design Values ◽  
Wave Heights ◽  
Ballast Tanks ◽  
The University ◽  
Wave Induced

A dry bulk carrier, a tanker, and a containership—taken as typical of ships trading to U.S. ports—are analyzed for possible hazards caused by emptying and refilling ballast tanks at sea. Using hydrostatic data furnished by the shipowners, hull bending moments and stabilities are investigated to find the tank-emptying operations that produce the greatest changes in those parameters. As should be expected, bending moment changes do not exceed allowable stillwater values. Changes in GM are insignificant. The worst hydrostatic cases serve as a guide to conditions that should be analyzed in rough water. The University of Michigan SHIPMO program shows that in waves of 10-ft significant height wave-induced bending moments and shears are far below the design values published by the American Bureau of Shipping. On the other hand, in waves of 20-ft significant height, the maximum wave heights that occur occasionally can cause moments or shears that exceed design values. For the 20-ft case, both linear and nonlinear versions of SHIPMO are used.

Bending Moments and Shear Forces in Ships Sailing in Irregular Waves

1981 ◽  
Vol 25 (04) ◽  
pp. 243-251
Author(s):  
J. Juncher Jensen ◽  
P. Terndrup Pedersen
Keyword(s):  
Linear Part ◽  
Vertical Motion ◽  
Bending Moment ◽  
Irregular Waves ◽  
Bending Moments ◽  
Shear Forces ◽  
Strip Theory ◽  
Wave Heights ◽  
Exciting Forces ◽  
Wave Induced

This paper presents some results concerning the vertical response of two different ships sailing in regular and irregular waves. One ship is a containership with a relatively small block coefficient and with some bow flare while the other ship is a tanker with a large block coefficient. The wave-induced loads are calculated using a second-order strip theory, derived by a perturbational procedure in which the linear part is identical to the usual strip theory. The additional quadratic terms are determined by taking into account the nonlinearities of the exiting waves, the nonvertical sides of the ship, and, finally, the variations of the hydrodynamic forces during the vertical motion of the ship. The flexibility of the hull is also taken into account. The numerical results show that for the containership a substantial increase in bending moments and shear forces is caused by the quadratic terms. The results also show that for both ships the effect of the hull flexibility (springing) is a fair increase of the variance of the wave-induced midship bending moment. For the tanker the springing is due mainly to exciting forces which are linear with respect to wave heights whereas for the containership the nonlinear exciting forces are of importance.

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