scholarly journals A New Simple Design Method for the Plate Foundation of a Transmission Tower in Subsidence Area

2016 ◽  
Vol 10 (1) ◽  
pp. 251-265 ◽  
Author(s):  
Qianjin Shu ◽  
Guanglin Yuan ◽  
Leiliang Jia ◽  
Yong-an Wang ◽  
Jing Zhou
Keyword(s):  
Pelvic Floor ◽  
Contact Pressure ◽  
Positive Curvature ◽  
Design Method ◽  
Bending Moment ◽  
Simple Design ◽  
Transmission Tower ◽  
Floor Area ◽  
Curvature Deformation ◽  
Moving Process

In this article, we present a simple design method for the plate foundation of a transmission tower in a mining area, which is based on the theory of beam rested on an elastic foundation. The corresponding theoretical model has been developed with the synergistic reaction of a composite protection plate by considering the mining subsidence of ground. On the basis of this model, the function of flexural deformation and the distribution function of bending moment of the protection plate and their corresponding base counterforce have been deduced. The analysis of selected example shows that the control bending moment of the protection plate is the maximum positive bending moment at the center of the cross section during the moving process of pelvic floor. The tilt deformation is minimum, when the tower is either at the bottom or at the verge of pelvic floor. The tilt deformation is maximum at one-fourth times of the length of pelvic floor and is away from the bottom and the verge of pelvic floor. The contact pressure between the plate foundation and the soil is similar to a U-shaped distribution, when the protection plate is in pelvic floor area of a positive (curvature) deformation, and it is a M-shaped distribution, when the protection plate is in pelvic floor area of a negative (curvature) deformation. We do not observe any change of the contact pressure at the midpoint of the protection plate during the moving process of the basin.

Structural Design and Analysis of FPSO Topside Module Supports

2008 ◽  
Author(s):  
Lars O. Henriksen ◽  
Boyden D. W ◽  
Xiaozhi Wang ◽  
Donald Liu
Keyword(s):  
Finite Element ◽  
Structural Design ◽  
Design Method ◽  
Bending Moment ◽  
Analysis Approach ◽  
Simple Design ◽  
Support Structures ◽  
Hull Girder ◽  
Tank Pressure ◽  
Vertical Bending Moment

This paper addresses the unique structural challenges associated with the design and analysis of topside module support structures for installation on FPSO decks. Specifically, this paper addresses the loading on the interface stool structures while subjected to loads originating from hull girder deformation, FPSO tank pressure loads, and topside inertial loads due to vessel motions. The results of an advanced finite element based analysis approach is presented and compared to the results of a simple design method. The effects of hull girder deformation due to vertical bending moment loading are compared to the effects of local deck deformation due to loading induced by the FPSO tank structures and topside modules.

Finite Element Modeling of Self-Loosening of Bolted Joints

2004 ◽  
Author(s):  
Ming Zhang ◽  
Yanyao Jiang ◽  
Chu-Hwa Lee
Keyword(s):  
Finite Element ◽  
Contact Pressure ◽  
Bending Moment ◽  
Shear Loading ◽  
Transverse Load ◽  
Fe Model ◽  
Bolted Joint ◽  
Cyclic Bending ◽  
Second Stage ◽  
Cyclic Bending Moment

A three-dimensional finite element (FE) model with the consideration of the helix angle of the threads was developed to simulate the second stage self-loosening of a bolted joint. The second stage self-loosening refers to the graduate reduction in clamping force due to the back-off of the nut. The simulations were conducted for two plates jointed by a bolt and a nut and the joint was subjected to transverse or shear loading. An M12×1.75 bolt was used. The application of the preload was simulated by using an orthogonal temperature expansion method. FE simulations were conducted for several loading conditions with different preloads and relative displacements between the two clamped plates. It was found that due to the application of the cyclic transverse load, micro-slip occurred between the contacting surfaces of the engaged threads of the bolt and the nut. In addition, a cyclic bending moment was introduced on the bolted joint. The cyclic bending moment resulted in an oscillation of the contact pressure on the contacting surfaces of the engaged threads. The micro-slip between the engaged threads and the variation of the contact pressure were identified to be the major mechanisms responsible for the self-loosening of a bolted joint. Simplified finite element models were developed that confirmed the mechanisms discovered. The major self-loosening behavior of a bolted joint can be properly reproduced with the FE model developed. The results obtained agree quantitatively with the experimental observations.

Three-Dimensional Finite Element Analysis of Pipe Flange Connections: The Case of Using Compressed Asbestos Sheet Gasket

2002 ◽  
Author(s):  
Tomohiro Takaki ◽  
Toshimichi Fukuoka
Keyword(s):  
Contact Pressure ◽  
Three Dimensional ◽  
Numerical Procedure ◽  
Bending Moment ◽  
Elastic Interaction ◽  
Bearing Surface ◽  
Element Analysis ◽  
Bolt Stress ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

The most important factor for the leakage problem of pipe flange connections is considered to be contact pressure distribution at the gasket bearing surface in service. In this study, the mechanical behaviors of the pipe flange connection are evaluated using FEM as a three-dimensional contact problem, in which a gasket is modeled as a nonlinear one-dimensional gasket element. Here, the contact pressure distributions at the gasket bearing surface and the variations of the bolt stress are estimated under uniform bolt preloads or nonuniform ones due to the elastic interaction during bolting up. The numerical procedure proposed here can successively deal with the processes of bolt-up, applying inner pressure and applying bending moment. The analytical objects are pipe flanges specified in JIS B 2238 with compressed asbestos sheet gaskets being inserted. The validity of the numerical method is ascertained by experiment.

Leakage Analysis of a High Pressure Flange Connection Under Bending Moments: An Analytic Procedure

2014 ◽  
Author(s):  
Matthias Bortz ◽  
Rolf Wink
Keyword(s):  
High Pressure ◽  
Contact Pressure ◽  
Fluid Pressure ◽  
Safety Margin ◽  
Bending Moment ◽  
Operating Conditions ◽  
Bending Moments ◽  
Spherical Lens ◽  
Flange Connection ◽  
Bolt Stress

High pressure flange connections for LDPE plants are designed using lens ring gaskets and bolted flange connections. The sealing principle is to achieve a high contact pressure between the spherical lens shape and the conical tube end. This contact pressure must exceed the fluid pressure by a safety margin under all operating conditions. Bending moments acting on the flange connection will create an uneven distribution of contact pressure over the lens ring surface. In this paper a procedure is shown to analyse the influence of the bending moment under consideration of internal pressure on a flange connection using 3-dimensional finite element models. The variations in bolt stress and distribution of contact pressures due to the bending moment are of specific interest. A first approach will be provided to derive some simplified design rules regarding leakage assessment of such flange connections.

scholarly journals Shear Performance of Optimized-Section Precast Slab with Tapered Cross Section

2018 ◽  
Vol 11 (1) ◽  
pp. 163 ◽  
Author(s):  
Hyunjin Ju ◽  
Sun-Jin Han ◽  
Hyo-Eun Joo ◽  
Hae-Chang Cho ◽  
Kang Kim ◽  
...  
Keyword(s):  
Cross Section ◽  
Design Method ◽  
Precast Concrete ◽  
Bending Moment ◽  
Shear Behaviour ◽  
Element Analysis ◽  
Cross Sectional ◽  
Shear Design ◽  
Shear Performance ◽  
And Performance

The optimized-section precast slab (OPS) is a half precast concrete (PC) slab that highlights structural aesthetics while reducing the quantity of materials by means of an efficient cross-sectional configuration considering the distribution of a bending moment. However, since a tapered cross section where the locations of the top and bottom flanges change is formed at the end of the member, stress concentration occurs near the tapered cross section because of the shear force and thus the surrounding region of the tapered cross section may become unintentionally vulnerable. Therefore, in this study, experimental and numerical research was carried out to examine the shear behaviour characteristics and performance of the OPS with a tapered cross section. Shear tests were conducted on a total of eight OPS specimens, with the inclination angle of the tapered cross section, the presence of topping concrete and the amount of shear reinforcement as the main test variables and a reasonable shear-design method for the OPS members was proposed by means of a detailed analysis based on design code and finite-element analysis.

Numerical Analysis on Interaction of Superstructure-Piled Raft Foundation-Foundation Soil

2011 ◽  
Vol 261-263 ◽  
pp. 1578-1583
Author(s):  
Yong Le Li ◽  
Jiang Feng Wang ◽  
Qian Wang ◽  
Kun Yang
Keyword(s):  
Design Method ◽  
Bending Moment ◽  
Load Sharing ◽  
Differential Settlement ◽  
Pile Head ◽  
Secondary Stress ◽  
Foundation Soil ◽  
Piled Raft Foundation ◽  
Raft Foundation ◽  
Soil Load

based on the finite element method of superstructure-the pile raft foundation-the foundation soil action and interaction are studied. Research shows that the common function is considered, fundamental overall settlement and differential settlement with the increase of floor of a nonlinear trend. The influence of superstructure form is bigger for raft stress, the upper structure existing in secondary stress, and the bending moment and axial force than conventional design method slants big; With the increase of the floors, pile load sharing ratio is reduced gradually,but soil load sharing ratio is increased. Along with the increase of the upper structure stiffness, the load focused on corner and side pile; Increasing thickness of raft, can reduce the certain differential settlement and foundation average settlement, thus reducing the upper structure of secondary stress and improving of foundation soil load sharing ratio, at the same time the distribution of counterforce on the pile head is more uneven under raft, thus requiring more uneven from raft stress, considering the piles under raft and the stress of soils to comprehensive determines a reasonable raft thickness, which makes the design safety economy. As the foundation soil modulus of deformation of foundation soil improvement, sharing the upper loads increases, counterforce on the pile head incline to average, raft maximum bending moment decrease gradually.

Study on the Design Method of Deepwater Steel Lazy Wave Riser

2019 ◽  
Author(s):  
Zhao Wang ◽  
Wei Qin ◽  
Xiaojie Zhang ◽  
Jiannan Zhao ◽  
Yong Bai
Keyword(s):  
Oil And Gas ◽  
Design Method ◽  
Bending Moment ◽  
Design Criterion ◽  
Design Flow ◽  
Distribution Law ◽  
Gas Field ◽  
Field Development ◽  
Moment Distribution ◽  
Oil And Gas Field

Abstract The steel lazy wave riser has been used in deep-water oil and gas field development because it has good adaption to the movement of the upper platform and economic efficiency. The typical design criterion and design flow of steel lazy wave riser are introduced in this paper. The design method and the equivalence principle of distributed buoyancy modules are given. The formulas of equivalent hydrodynamic parameters are derived in this paper. The influences of distributed buoyancy modules (DBM) and the buoyancy factor on the configuration of the riser, the top tension, and the bending moment distribution are discussed and summarized. The distribution law of effective stress response along the pipe can be analyzed by dynamic analysis, and it provides reference for the global design of steel lazy wave riser.

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