Effect of Superstructure Stiffness on Liquefaction-Induced Failure Mechanisms

2012 ◽  
pp. 85-99
Author(s):  
S.P.G. Madabhushi ◽  
S.K. Haigh
Keyword(s):  
Failure Mechanisms ◽  
Soil Liquefaction ◽  
Field Observations ◽  
Finite Element Analyses ◽  
Bhuj Earthquake ◽  
Engineering Structures ◽  
Strong Earthquakes ◽  
Dynamic Centrifuge Test ◽  
Recent Earthquakes ◽  
Extensive Damage

Soil liquefaction following strong earthquakes causes extensive damage to civil engineering structures. Foundations of buildings, bridges etc can suffer excessive rotation/settlement due to liquefaction. Many of the recent earthquakes bear testimony for such damage. In this article a hypothesis that “Superstructure stiffness can determine the type of liquefaction-induced failure mechanism suffered by the foundations” is proposed. As a rider to this hypothesis, it will be argued that liquefaction will cause failure of a foundation system in a mode of failure that offers least resistance. Evidence will be offered in terms of field observations during the 921 Ji-Ji earthquake in 1999 in Taiwan and Bhuj earthquake of 2001 in India. Dynamic centrifuge test data and finite element analyses results are presented to illustrate the traditional failure mechanisms.

Effect of Superstructure Stiffness on Liquefaction-Induced Failure Mechanisms

2010 ◽  
Vol 1 (1) ◽  
pp. 70-87 ◽  
Author(s):  
S.P.G. Madabhushi ◽  
S.K. Haigh
Keyword(s):  
Failure Mechanisms ◽  
Soil Liquefaction ◽  
Field Observations ◽  
Finite Element Analyses ◽  
Bhuj Earthquake ◽  
Engineering Structures ◽  
Strong Earthquakes ◽  
Mode Of Failure ◽  
Dynamic Centrifuge Test ◽  
Recent Earthquakes

Soil liquefaction following strong earthquakes causes extensive damage to civil engineering structures. Foundations of buildings, bridges etc can suffer excessive rotation/settlement due to liquefaction. Many of the recent earthquakes bear testimony for such damage. In this article a hypothesis that “Superstructure stiffness can determine the type of liquefaction-induced failure mechanism suffered by the foundations” is proposed. As a rider to this hypothesis, it will be argued that liquefaction will cause failure of a foundation system in a mode of failure that offers least resistance. Evidence will be offered in terms of field observations during the 921 Ji-Ji earthquake in 1999 in Taiwan and Bhuj earthquake of 2001 in India. Dynamic centrifuge test data and finite element analyses results are presented to illustrate the traditional failure mechanisms.

scholarly journals Sustainable Measures for Protection of Structures Against Earthquake Induced Liquefaction

2021 ◽  
Author(s):  
Gopal S. P. Madabhushi ◽  
Samy Garcia-Torres
Keyword(s):  
Soil Liquefaction ◽  
Excess Pore Pressure ◽  
Economic Losses ◽  
Element Analysis ◽  
Centrifuge Testing ◽  
Centrifuge Tests ◽  
Liquefiable Soil ◽  
Recent Earthquakes ◽  
Excess Pore Pressures ◽  
Excess Pore

AbstractSoil liquefaction can cause excessive damage to structures as witnessed in many recent earthquakes. The damage to small/medium-sized buildings can lead to excessive death toll and economic losses due to the sheer number of such buildings. Economic and sustainable methods to mitigate liquefaction damage to such buildings are therefore required. In this paper, the use of rubble brick as a material to construct earthquake drains is proposed. The efficacy of these drains to mitigate liquefaction effects was investigated, for the first time to include the effects of the foundations of a structure by using dynamic centrifuge testing. It will be shown that performance of the foundation in terms of its settlement was improved by the rubble brick drains by directly comparing them to the foundation on unimproved, liquefiable ground. The dynamic response in terms of horizontal accelerations and rotations will be compared. The dynamic centrifuge tests also yielded valuable information with regard to the excess pore pressure variation below the foundations both spatially and temporally. Differences of excess pore pressures between the improved and unimproved ground will be compared. Finally, a simplified 3D finite element analysis will be introduced that will be shown to satisfactorily capture the settlement characteristics of the foundation located on liquefiable soil with earthquake drains.

Numerical Study of the Combined Loading Envelope of a Skirted Spudcan Foundation

2014 ◽  
Author(s):  
Ning Cheng ◽  
Mark J. Cassidy ◽  
Yinghui Tian
Keyword(s):  
Clay Soil ◽  
Numerical Study ◽  
Failure Mechanisms ◽  
Small Strain ◽  
Offshore Structures ◽  
Combined Loading ◽  
Finite Element Analyses ◽  
Failure Envelope ◽  
Foundation Type ◽  
Jack Up

Foundations for offshore structures, such as mobile jack-up units, are subjected to large horizontal (H) and moment (M) loads in addition to changing vertical (V) loads. The use of a combined vertical, horizontal and moment (V-H-M) loading envelope to define foundation capacities has become increasingly applied in recent years. However, there is no study on the skirted spudcan, a new alternative foundation type to the conventional spudcan footing for jack-ups. In this study, the combined V-H-M yield envelope of a skirted spudcan foundation in clay soil is investigated with small strain finite element analyses using 3D modeling. The footing’s uniaxial bearing capacities and failure mechanisms are described. The failure envelope for the combined V-H-M loadings is presented. A comparison of the bearing capacities between the spudcan and skirted spudcan of various dimensions is also presented.

scholarly journals Pull-Out Capacity and Failure Mechanisms of Strip Anchors in Clay

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3853
Author(s):  
Fernando Cañizal ◽  
Jorge Castro ◽  
Jorge Cañizal ◽  
César Sagaseta
Keyword(s):  
Failure Mechanisms ◽  
Cohesive Soils ◽  
Finite Element Analyses ◽  
Bottom Part ◽  
Pull Out ◽  
Shallow Failure ◽  
Plate Anchors ◽  
Floating Platforms ◽  
First Time ◽  
Analytical Limit

Plate anchors are a well-established solution for supporting the efforts of floating platforms for wind and marine renewable energies. The behavior of ultrathin rigid plate anchors buried in purely cohesive soils under undrained and plane-strain conditions is analyzed. As already known, a dimensional analysis shows that the pull-out capacity of the anchor may be expressed using a weightless break-out factor (Nc0) that only depends on the ratio between the depth and the anchor width (H/B). Using finite element analyses, tabulated values of the weightless break-out factor are provided in this paper and three different failure mechanisms are identified, namely very shallow (quasi-vertical), shallow or intermediate (semi-vertical), and deep (rotational). For very shallow failure mechanisms, the studied problem is completely equivalent to the trapdoor problem because immediate breakaway at the bottom part of the anchor is considered (vented conditions). The existing analytical solutions for the very shallow (Nc0 = 1.956 H/B) and deep cases (Nc = 3π + 2) using the slip-line method are reviewed and an analytical limit is proposed for the first time for the very shallow mechanism (H/B = 1.314). For shallow (intermediate) cases, the failure mechanism is identified and the angle of the main slip lines is numerically evaluated.

Seismic Damage Analyses of Staircases in RC Frame Structures

2012 ◽  
Vol 446-449 ◽  
pp. 2326-2330 ◽  
Author(s):  
Huan Jun Jiang ◽  
Hai Yan Gao ◽  
Bin Wang
Keyword(s):  
Internal Force ◽  
Frame Structure ◽  
Frame Structures ◽  
Rc Frame ◽  
Structural Members ◽  
First Line ◽  
Strong Earthquakes ◽  
Rc Frame Structure ◽  
Rc Frame Structures ◽  
Recent Earthquakes

Staircases in Reinforced Concrete (RC) frame structures suffered severe damages in recent earthquakes although they are regarded as critically important passages during emergencies. Staircases act as the first line of defense in earthquakes, and therefore they first yield and fail. Then they lose the action of safe passages so that the anticipated seismic performance objectives cannot be satisfied. To make sure that staircases work as safe passages in strong earthquakes, the current Chinese code for seismic design of buildings claims special requirements on the design of staircases. At first, the influence of staircases on the structural behavior of a typical RC frame structure is studied by the comparison of internal force in the structural members considering and neglecting the effect of staircases under frequent earthquakes. Besides, the effect of staircases on the yielding and failing mechanism of the frame structure is investigated through static elasto-plastic analyses. From this study the reason of the damages suffered by cast-in-site staircases in RC frame structures under earthquakes can be understood.

scholarly journals Geotechnical aspects of the 2007 Niigataken Chuetsu-Oki, Japan earthquake

2008 ◽  
Vol 41 (2) ◽  
pp. 83-89 ◽  
Author(s):  
Rolando P. Orense ◽  
Masayuki Hyodo ◽  
Hiroaki Kanda ◽  
Junya Ohashi
Keyword(s):  
Built Environment ◽  
West Coast ◽  
Civil Engineering ◽  
Soil Liquefaction ◽  
Earthquake Damage ◽  
The West ◽  
Engineering Structures ◽  
Ground Shaking ◽  
Preliminary Results ◽  
Damage Investigation

On 16 July 2007, an earthquake of magnitude 6.8 occurred with an epicentre off the west coast of Niigata Prefecture (Japan), causing widespread damage to buildings and other types of civil engineering structures due to ground shaking and earthquake-induced ground failures. Landsliding and soil liquefaction occurred extensively in various parts of the affected region. This paper presents the preliminary results of the post-earthquake damage investigation conducted at the affected areas after the earthquake, with emphasis on the seismic-induced ground failures and their effects on the built environment.

scholarly journals Liquefaction hazard assessment and ground failure probability analysis in the Kathmandu Valley of Nepal

2022 ◽  
Vol 9 (1) ◽  
Author(s):  
Mandip Subedi ◽  
Indra Prasad Acharya
Keyword(s):  
Soil Liquefaction ◽  
Kathmandu Valley ◽  
Borehole Data ◽  
Gorkha Earthquake ◽  
Engineering Structures ◽  
Liquefaction Potential ◽  
Ground Failure ◽  
2015 Gorkha Earthquake ◽  
Scenario Earthquakes ◽  
Liquefaction Hazard

AbstractDuring the 2015 Gorkha Earthquake (Mw7.8), extensive soil liquefaction was observed across the Kathmandu Valley. As a densely populated urban settlement, the assessment of liquefaction potential of the valley is crucial especially for ensuring the safety of engineering structures. In this study, we use borehole data including SPT-N values of 410 locations in the valley to assess the susceptibility, hazard, and risk of liquefaction of the valley soil considering three likely-to-recur scenario earthquakes. Some of the existing and frequently used analysis and computation methods are employed for the assessments, and the obtained results are presented in the form of liquefaction hazard maps indicating factor of safety, liquefaction potential index, and probability of ground failure (PG). The assessment results reveal that most of the areas have medium to very high liquefaction susceptibility, and that the central and southern parts of the valley are more susceptible to liquefaction and are at greater risk of liquefaction damage than the northern parts. The assessment outcomes are validated with the field manifestations during the 2015 Gorkha Earthquake. The target SPT-N values (Nimproved) at potentially liquefiable areas are determined using back analysis to ascertain no liquefaction during the aforesaid three scenario earthquakes.

scholarly journals EVALUATION OF THE SEISMIC INERTIA FORCES ON THE ACTUAL DAMAGE OF BRIDGES

2020 ◽  
pp. 28-33
Author(s):  
T. Kalachuk ◽  
I. Kolmykova ◽  
E. Shin
Keyword(s):  
Working Conditions ◽  
Dynamic Theory ◽  
Practical Interest ◽  
Seismic Resistance ◽  
Engineering Structures ◽  
Strong Earthquakes ◽  
Spectral Curves ◽  
Actual Damage ◽  
Seismic Forces ◽  
Inertia Forces

because of the constant threat of earthquakes in seismic hazardous areas, it is necessary to study the issues of seismic resistance of structures and development of methods of their design, taking into account the seismic factor. A significant share in the total volume of engineering structures permanent and built on canals and roads is occupied by artificial structures, such as aqueducts, small and medium bridges (overpasses). In this regard, the provision of seismic resistance of these structures is of practical interest. Buildings and structures located in seismic areas are affected by factors that cause the occurrence of seismic forces and changes in the working conditions of structures during earthquakes The article presents the results of comparison of calculations in the dynamic theory (by the method of spectral curves) and static seismic coefficient determination with the actual data on damage to structures in strong earthquakes. A formula for calculating the coefficient of seismicity is proposed.

scholarly journals Failure mechanisms and bending strength of Fuchsia magellanica var. gracilis stems

2021 ◽  
Vol 18 (175) ◽  
pp. 20201023
Author(s):  
Timothy Hone ◽  
Max Mylo ◽  
Olga Speck ◽  
Thomas Speck ◽  
David Taylor
Keyword(s):  
Bending Strength ◽  
Imaging Techniques ◽  
Plastic Hinge ◽  
Failure Mechanisms ◽  
Biological Evolution ◽  
Internal Crack ◽  
Damage Development ◽  
Engineering Structures ◽  
Three Point Bending ◽  
Bending Resistance

In the course of biological evolution, plant stems have evolved mechanical properties and an internal structure that makes them resistant to various types of failure. The mechanisms involved during damage development and failure in bending are complex and incompletely understood. The work presented builds on a theoretical framework outlined by Ennos and van Casteren, who applied engineering mechanics theory to explain why different woody stems fail in different ways. Our work has extended this approach, applying it to a detailed analysis of one particular species: Fuchsia magellanica var. gracilis . When subjected to three-point bending, stems of this species exhibited one of two failure mechanisms: a plastic hinge or a greenstick fracture. We developed a predictive model using a computer simulation and a mathematical analysis using the theory of plastic bending. Required material properties were obtained from tests, the literature and imaging techniques. We found that greenstick fractures are more likely to occur in more lignified stems with a higher density. We discovered a new failure mode: an internal crack caused by tensile transverse stress. This work helps in understanding how plants have evolved their bending resistance and may assist in the creation of novel engineering structures inspired by these principles.

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