scholarly journals Design and analysis of plate anchors in sand

2021 ◽  
Author(s):  
Muhammad Waseem
Keyword(s):  
Failure Modes ◽  
Design Procedure ◽  
Embedment Depth ◽  
Offshore Platforms ◽  
Failure Plane ◽  
Transmission Towers ◽  
Plate Anchor ◽  
Plate Anchors ◽  
Anchor Design ◽  
Uplift Forces

Plate anchors, as an efficient and reliable anchorage system, have been widely used to resist uplift forces produced by structures, such as transmission towers, offshore platforms, submerged pipelines, and tunnels. In order to design a plate anchor it is important to know the factors which influence the design and uplift behavior of anchors embedded in sand. In this report a number of model uplift tests and numerical investigations made by different authors are described and based on these readings the uplift behavior of anchors in sand is explored and anchor's design procedure is described. In addition, basic anchor types, failure modes in anchors, and design codes are mentioned. Based on this study, it is found that the failure plane and uplift capacity is significantly influenced by the soil density and embedment depth. Therefore, it is concluded that the influence of sand density and embedment depth should be considered in anchor design.

scholarly journals Design and analysis of plate anchors in sand

2021 ◽  
Author(s):  
Muhammad Waseem
Keyword(s):  
Failure Modes ◽  
Design Procedure ◽  
Embedment Depth ◽  
Offshore Platforms ◽  
Failure Plane ◽  
Transmission Towers ◽  
Plate Anchor ◽  
Plate Anchors ◽  
Anchor Design ◽  
Uplift Forces

Plate anchors, as an efficient and reliable anchorage system, have been widely used to resist uplift forces produced by structures, such as transmission towers, offshore platforms, submerged pipelines, and tunnels. In order to design a plate anchor it is important to know the factors which influence the design and uplift behavior of anchors embedded in sand. In this report a number of model uplift tests and numerical investigations made by different authors are described and based on these readings the uplift behavior of anchors in sand is explored and anchor's design procedure is described. In addition, basic anchor types, failure modes in anchors, and design codes are mentioned. Based on this study, it is found that the failure plane and uplift capacity is significantly influenced by the soil density and embedment depth. Therefore, it is concluded that the influence of sand density and embedment depth should be considered in anchor design.

scholarly journals Ultimate Pullout Capacity of a Square Plate Anchor in Clay with an Interbedded Stiff Layer

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Tugen Feng ◽  
Jingyao Zong ◽  
Wei Jiang ◽  
Jian Zhang ◽  
Jian Song
Keyword(s):  
Finite Element ◽  
Empirical Formula ◽  
Soil Layer ◽  
Embedment Depth ◽  
Layered Soils ◽  
Pullout Capacity ◽  
Plate Anchor ◽  
Square Plate ◽  
Plate Anchors ◽  
Ultimate Pullout Capacity

Three-dimensional nonlinear numerical analysis is carried out to determine the ultimate pullout capacity of a square plate anchor in layered clay using the large finite element analysis software ABAQUS. An empirical formula for the pullout bearing capacity coefficient of a plate anchor in layered soils is proposed based on the bearing characteristics of plate anchors in single-layer soils. The results show that a circular flow (circulation field) is induced around the plate anchor during the uplift process and that the flow velocity and circulation field range are mainly affected by the properties of the soil around the plate anchor. The bearing characteristics of plate anchors in layered soils are influenced by factors such as the embedment depth of the plate anchor, the friction coefficient between the soil and the plate anchor, the thickness of the upper soil layer, and the thickness of the middle soil layer. The rationality of the finite element numerical calculation results and the empirical formula is verified by comparing the results from this study with results previously reported in the literature.

Deformation Mechanism of Plate Anchor in Sand

2011 ◽  
Vol 250-253 ◽  
pp. 1469-1473
Author(s):  
Xin Zhang ◽  
Jin Chao Yue
Keyword(s):  
Cross Correlation ◽  
Failure Modes ◽  
Cohesionless Soil ◽  
Loading Capacity ◽  
Reliable Prediction ◽  
Dense Sand ◽  
Model Study ◽  
Plate Anchor ◽  
Uplift Resistance ◽  
Plate Anchors

Plate anchor is one of the most popular types of anchors widely used in geotechnical engineering. Reliable prediction of the ultimate uplift resistance of plate anchors requires its failure modes well understood. In this paper, an image-based deformation technique, the digital image cross-correlation (DIC), is used to measure the sand deformations around a scaled semi-circular anchor during uplifting. A series of tests have been conducted to investigate the failure modes of plate anchors in both loose and dense sand. Two distinctively different failure modes are measured by using DIC in both loose and dense sand respectively. This model study improves the understanding of the failure and development of loading capacity of uplift anchor in cohesionless soil.

Numerical Investigation Into the Keying Process of a Plate Anchor Vertically Installed in Cohesionless Soil

2018 ◽  
Author(s):  
Nabil Al Hakeem ◽  
Charles Aubeny
Keyword(s):  
Peak Load ◽  
Offshore Structures ◽  
Cohesionless Soil ◽  
Soil Conditions ◽  
Embedment Depth ◽  
Pullout Capacity ◽  
Vertical Loading ◽  
Wide Range ◽  
Plate Anchor ◽  
Plate Anchors

Vertically driven plate anchors offer an attractive anchoring solution for floating offshore structures, as they are both highly efficient and suitable for a wide range of soil conditions. Since they are oriented vertically after installation, keying is required to orient the anchor into the direction of applied loading. Simulation of the keying process has not been extensively investigated by previous research, especially for cohesionless soil. Reliable prediction of irrecoverable embedment loss during keying is needed, since such loss can lead to significant reduction in the uplift capacity of the plate anchors. Large deformation finite element analyses LDFE method using RITSS (Remeshing and Interpolation Technique with Small Strain) were used to simulate the keying process of strip plate anchor embedded in uniform cohesionless soil. LDFE showed that the loss in embedment depth of plate anchor during rotation is inversely proportional to the loading eccentricity e/B. It was also found that the maximum pullout capacity occurs before the end of keying process at orientations between 60° to 85° degrees for vertical loading. Also, the LDFE study showed that reduced elastic soil stiffness leading to increased levels of displacement at which the peak load is approached.

Influence of Human Error on Structural Reliability

2017 ◽  
Author(s):  
Eric Brehm ◽  
Robert Hertle ◽  
Markus Wetzel
Keyword(s):  
Human Error ◽  
Structural Reliability ◽  
Failure Modes ◽  
Structural Model ◽  
Limit State ◽  
Design Procedure ◽  
Material Strength ◽  
Limit States ◽  
The Impact

In common structural design, random variables, such as material strength or loads, are represented by fixed numbers defined in design codes. This is also referred to as deterministic design. Addressing the random character of these variables directly, the probabilistic design procedure allows the determination of the probability of exceeding a defined limit state. This probability is referred to as failure probability. From there, the structural reliability, representing the survival probability, can be determined. Structural reliability thus is a property of a structure or structural member, depending on the relevant limit states, failure modes and basic variables. This is the basis for the determination of partial safety factors which are, for sake of a simpler design, applied within deterministic design procedures. In addition to the basic variables in terms of material and loads, further basic variables representing the structural model have to be considered. These depend strongly on the experience of the design engineer and the level of detailing of the model. However, in the clear majority of cases [1] failure does not occur due to unexpectedly high or low values of loads or material strength. The most common reasons for failure are human errors in design and execution. This paper will provide practical examples of original designs affected by human error and will assess the impact on structural reliability.

scholarly journals Failure Modes and Resistance of Perforated Steel Rib Shear Connectors under Uplift Forces

2019 ◽  
Vol 2019 ◽  
pp. 1-16 ◽  
Author(s):  
Xiaoqing Xu ◽  
Yuqing Liu
Keyword(s):  
Composite Structures ◽  
Failure Modes ◽  
Analytical Models ◽  
Shear Connectors ◽  
Steel Bar ◽  
Concrete Damage ◽  
Uplift Resistance ◽  
Transverse Steel ◽  
Uplift Forces

In recent years, there is a rapid increase in the application of perforated steel rib shear connectors in steel and concrete composite structures. The connectors must not only ensure shear transfer but also sufficient uplift resistance. The shear behavior of connectors has been extensively investigated. However, studies on uplift resistance are lacking so far. Therefore, three push-out test specimens were tested to investigate the shear and tension behavior of perforated L-shaped and plain steel rib shear connectors. The failure modes of connectors were analyzed, and analytical models for the determination of uplift resistance were derived based on test results. The results showed that the ductility of perforated steel rib shear connectors under uplift force was smaller than that under shear force, and more severe concrete damage surrounding the rib and larger bending deformation of transverse steel bar was observed. The rib flange of L-shaped perforated rib has a significant contribution to the uplift resistance. It was suggested to increase the rib height of L-shaped rib to avoid the horizontal crack at the height of the rib flange. The validity of the proposed analytical models was confirmed by comparing the failure modes and capacities of specimens.

Water Deluge System Design for Fire Fighting

2016 ◽  
Author(s):  
Jin Lee ◽  
Sang Hwan Kim ◽  
Jung Kwan Seo ◽  
Jeom Kee Paik
Keyword(s):  
Fluid Dynamic ◽  
Design Procedure ◽  
Offshore Structures ◽  
Offshore Platforms ◽  
Probabilistic Sampling ◽  
Spray System ◽  
Safety Design ◽  
Fire Scenarios ◽  
Fire And Explosion ◽  
The Cost

The ships and offshore structures are exposed to inherently the risk of fire and explosion. These fire and explosion, accident caused by grave consequences not only to the ships and offshore platforms on the sea but the environment all mankind. The aim of this paper is to focus on an optimization of water deluge and mist spray system locations subjected to jet on the ships and offshore platforms. A trustworthy set of fire scenarios is identified and classified using probabilistic sampling methods calling for Latin Hyper Sampling. These events of fire are numerically calculated for selected scenarios by the computational Fluid Dynamic (CFD) code using a KFX. The Water Deluge Location Index (WLI) is then calculated by using the frequency and consequence of fire scenarios. And then, WLI are utilized to prioritize the optimal locations of water deluge and mist spray systems. The recommended methodology believes that can increase to certainties in the design procedure of unreliability and can regard the cost-effectiveness of safety design.

A Numerical Study on the Pull-Out Strengths of Anchor Bolts Embedded in Concrete Using the Smoothed Particle Hydrodynamics Method

2016 ◽  
Vol 711 ◽  
pp. 1111-1117 ◽  
Author(s):  
Yoshimi Sonoda
Keyword(s):  
Smoothed Particle Hydrodynamics ◽  
Failure Modes ◽  
Numerical Study ◽  
Failure Process ◽  
Embedment Depth ◽  
Anchor Bolt ◽  
Pull Out ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Anchor Bolts

The strength of an anchor bolt in concrete structure under pull-out load is usually designed by three possible failure modes such as fracture of anchor bolt, cone failure of concrete and bond failure between anchor bolt and concrete. In general, the design load is considered the smallest load corresponding to the aforementioned failure mechanisms. However, unexpected failure often occurs in the anchorage zone due to the complex failure or the change of failure condition. Therefore, it is important to develop the accurate analysis method of ultimate load bearing capacity of the anchor bolt. In this study, we conducted an analytical study using Adaptive Smoothed Particle Hydrodynamics (ASPH) in order to simulate the failure process of anchorage zone and discussed the effect of embedment depth of anchor bolts on their ultimate strength.

Risk Analysis and Risk Management for Offshore Platforms: Lessons From the Piper Alpha Accident

1993 ◽  
Vol 115 (3) ◽  
pp. 179-190 ◽  
Author(s):  
M. E. Pate´-Cornell
Keyword(s):  
Risk Management ◽  
Risk Analysis ◽  
Failure Modes ◽  
Wide Spectrum ◽  
Management Strategies ◽  
Quantitative Information ◽  
Management Tool ◽  
Offshore Platforms ◽  
Safety Measures ◽  
Risk Management Strategies

A probabilistic risk analysis (PRA) framework is used to identify the accident sequence of the 1988 Piper Alpha accident. This framework is extended to include the human decisions and actions that have influenced the occurrences of these basic events, and their organizational roots. The results of this preliminary analysis allow identification of a wide spectrum of possible risk reduction measures, ranging from classical technical solutions such as addition of redundancies, to organizational improvements such as a change in the maintenance procedures. An explicit PRA model is then developed to assess the benefits of some of these safety measures based, first, on the original contribution to the overall risk of the failure modes that these measures are designed to avert, and second, on the degree to which they can reduce the probabilities of these failure modes. PRA can then be used as a management tool, allowing optimization of risk management strategies based both on the qualitative information about causalities provided by the accident, and on the quantitative information about failure probabilities updated in the light of new events. It is shown how PRA can be used to assess, for example, the cost-effectiveness of safety measures designed to decrease the probability of severe fire damage onboard platforms similar to Piper Alpha.

Installation of dynamically embedded plate anchors as assessed through field tests

2015 ◽  
Vol 52 (9) ◽  
pp. 1270-1282 ◽  
Author(s):  
A.P. Blake ◽  
C.D. O’Loughlin
Keyword(s):  
Field Tests ◽  
Free Fall ◽  
Measurement Unit ◽  
Resistance Force ◽  
Embedment Depth ◽  
Acceleration Data ◽  
Plate Anchor ◽  
Central Shaft ◽  
High Degree ◽  
Force Profiles

A dynamically embedded plate anchor (DEPLA) is a rocket-shaped anchor that comprises a removable central shaft and a set of four flukes. The DEPLA penetrates to a target depth in the seabed by the kinetic energy obtained through free-fall in water. After embedment the central shaft is retrieved leaving the anchor flukes vertically embedded in the seabed. The flukes constitute the load-bearing element as a plate anchor. This paper focuses on the dynamic installation of the DEPLA. Net resistance and velocity profiles are derived from acceleration data measured by an inertial measurement unit during DEPLA field tests, which are compared with corresponding theoretical profiles based on strain rate–enhanced shear resistance and fluid mechanics drag resistance. Comparison of the measured net resistance force profiles with the model predictions shows fair agreement at 1:12 scale and good agreement at 1:7.2 and 1:4.5 scales. For all scales the embedment model predicts the final anchor embedment depth to a high degree of accuracy.

Sign in / Sign up

Export Citation Format

Share Document