Improvement of the load-carrying capacity of offshore skirted foundations by electrokinetics

2003 ◽  
Vol 40 (5) ◽  
pp. 949-963 ◽  
Author(s):  
S Micic ◽  
J Q Shang ◽  
K Y Lo
Keyword(s):  
Shear Strength ◽  
Carrying Capacity ◽  
Undrained Shear Strength ◽  
Engineering Practice ◽  
Foundation Engineering ◽  
Load Carrying Capacity ◽  
Steel Cylinder ◽  
Load Carrying ◽  
Adjacent Soil ◽  
Undrained Shear

Originating from the problem facing offshore foundation engineering, the present study is focused on using electrokinetics to enhance the load-carrying capacity of skirted foundations embedded in soft marine deposits. An experimental study was carried out in a model tank having dimensions of 150 cm × 75 cm × 70 cm. The experiments were conducted on the Welland River sediment mixed with a high salinity solution that simulates the composition of seawater. A steel cylinder of 320 mm in diameter was embedded in the sediment to represent a skirted foundation. Electrodes were installed around the steel cylinder, and a voltage of 5.2 V was applied over 28 days with polarity reversal. The load-carrying capacity of the steel cylinder and the undrained shear strength of the adjacent soil were measured after the electrokinetic treatment. The effect of electrokinetics is evaluated by comparing a series of test results performed on the untreated and treated soil. The load-carrying capacity of the steel cylinder and the undrained shear strength of the adjacent soil increased up to three times after treatment. The study also shows that electrokinetics can regain and further enhance the load carrying capacity of the embedded skirted foundation model after failure. With further development, the technology has the potential to be applied in offshore engineering practice to increase the load-carrying capacity of skirted foundations installed in soft clayey sediments.Key words: electrokinetics, skirted foundations, soft marine clay, load-carrying capacity, soil improvement.

scholarly journals The use of dilatometer test for the determination of undrained shear strength in organic soils

2008 ◽  
Vol 40 (1) ◽  
pp. 97-105
Author(s):  
Simon Rabarijoely
Keyword(s):  
Shear Strength ◽  
Undrained Shear Strength ◽  
Organic Soils ◽  
Engineering Practice ◽  
Empirical Correlations ◽  
Empirical Formulas ◽  
Geotechnical Design ◽  
Design Calculations ◽  
Undrained Shear

The use of dilatometer test for the determination of undrained shear strength in organic soils The use of dilatometer test for the determination of undrained shear strength in organic soils. In engineering practice the empirical correlations or charts are often use to determine soil properties for design calculations. The DMT tests results are analysed on the basis of the empirical formulas proposed by Marchetti (1980). In this paper the new chart to determine the τfu of organic mud was proposed. The chart presents the relationships between dilatometer readings (p0 - u0), (p1 - u0), σ'v0 and τfu. The chart will be helpful in geotechnical design of embankments constructed on organic subsoil.

Force Transfer Mechanism in Embedded Steel Column Bases

2006 ◽  
Vol 326-328 ◽  
pp. 1805-1810 ◽  
Author(s):  
Young Ho Kim ◽  
Seung Sik Lee ◽  
Jae Ho Jung ◽  
Soon Jong Yoon
Keyword(s):  
Shear Strength ◽  
Bond Strength ◽  
Carrying Capacity ◽  
Experimental Results ◽  
Load Carrying Capacity ◽  
Force Transfer ◽  
Load Carrying ◽  
Steel Column ◽  
Force Transfer Mechanism ◽  
Column Base

This paper presents the results of an investigation on the force transfer mechanism in an embedded column base of a composite structure. In the experimental program, eighteen push-out specimens were tested. The factors influencing the mechanism of force transfer were the amount of confining reinforcement, compressive strength of concrete, and diameter of stud connectors. The results of experiment indicated that force transfer could be characterized into two stages, and the factors governing each stage were identified. The first stage was governed by the bond strength between the steel column base and the concrete. The second stage begun after chemical debonding and was governed by the shear strength of stud connectors as well as the frictional strength between the steel and the concrete. Based on the experimental results, the equations to estimate the bond strength, the friction strength, and the shear strength of stud connectors were proposed. The load carrying capacity of an embedded steel column base could be predicted by taking the sum of the shear strength of stud connectors and the friction strength. The predicted load carrying capacity was found to agree well with the experimental results over various range of concrete stress.

scholarly journals Theoretical Equations for the Ratio of Undrained Shear Strength to Vertical Effective Stress for Normally Consolidated Saturated Cohesive Soils

2022 ◽  
Vol 28 (3) ◽  
pp. 241-252
Author(s):  
Sugeng Krisnanto
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Effective Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Undrained Shear Strength ◽  
Engineering Practice ◽  
Cohesive Soils ◽  
Vertical Effective Stress ◽  
Undrained Shear

Abstract Two theoretical equations are developed to calculate the ratio of undrained shear strength to the vertical effective stress (the ratio of (su/sv’)) for normally consolidated saturated cohesive soils. The effective stress approach is used as the basis in the development of the theoretical equations. The theoretical equations are developed by relating the total and the effective stress paths. The development of the excess pore-water pressure is quantified using Skempton A and B pore-water pressure parameters. The theoretical equations are developed for two initial stress conditions: (i) an initially hydrostatic condition and (ii) an initially Ko (non-hydrostatic) condition. The performance of the theoretical equations of this study is compared with field and laboratory measurement data obtained from the literature. The close results between the theoretical equations and the measurements show that the theoretical equations of this study can compute the ratio of (su/sv’) well. Using the theoretical equations, the values of the ratio of (su/sv’) commonly used in engineering practice can be explained from the soil mechanics framework. Keywords: Saturated cohesive soils, c/p ratio, normally consolidated soil, undrained shear strength, effective shear strength, theoretical equation. Abstrak Dua persamaan teoritis dikembangkan untuk menghitung rasio kuat geser tak teralirkan dengan tegangan efektif vertikal (rasio (su/sv’)) untuk tanah kohesif jenuh terkonsolidasi normal. Pendekatan tegangan efektif dijadikan dasar dalam pengembangan kedua persamaan teoretis ini. Persamaan teoretis tersebut dikembangkan menghubungkan lintasan tegangan total dan lintasan tegangan efektif. Kenaikan tekanan air pori ekses dikuantifikasi menggunakan parameter tekanan air pori A dan B dari Skempton. Persamaan teoretis dikembangkan untuk dua kondisi tegangan awal: (i) tegangan awal hidrostatik dan (ii) teganan awal Ko (non hidrostatik). Kinerja kedua persamaan teoretis tersebut dibandingkan terhadap data pengukuran lapangan dan pengujian laboratorium yang diperoleh dari literatur. Persamaan teoretis dari studi ini memiliki kinerja yang baik dalam memperhitungan rasio (su/sv’) yang ditunjukkan dengan dekatnya hasil perhitungan menggunakan persamaan teoretis dan hasil pengukuran lapangan maupun pengujan laboratorium. Dengan persamaan teoretis tersebut, nilai rasio (su/sv’) yang biasa digunakan dalam rekayasa praktis bisa dijelaskan secara mekanika tanah. Kata-kata Kunci: Tanah kohesif jenuh, rasio c/p, tanah terkonsolidasi normal, kuat geser tak teralirkan, kuat geser efektif, persamaan teoretis.  

scholarly journals Double Shear Load Carrying Capacity of Kempas and GFRP Dowelled Connections

2020 ◽  
Vol 9 (3) ◽  
pp. 2820-2824
Keyword(s):  
Shear Strength ◽  
Carrying Capacity ◽  
Timber Species ◽  
Fibre Reinforcement ◽  
Shear Load ◽  
Load Carrying Capacity ◽  
Ultimate Shear Strength ◽  
Design Data ◽  
Double Shear ◽  
Load Carrying

Glass fibre reinforcement polymers (GFRP) application for reinforcement of wood, concrete and steel member is relatively becoming more variety in construction applications. Although it is possible to build large monolithic structures with composite materials, there are still several reasons for the structure to fail. One of the main reasons that contribute to this failure is the connection performance due to its function in carrying load across the structure. Thus having the right fundamental data for connection design purposes according to the specific and technological upgraded materials is very important. One of the basic methodologies in gaining the design data is through experimental double shear test which can be verified by European Yield Model (EYM) theory. Therefore, the objective of this research is to determine the load carrying capacity of double shear strength behaviour connections made of Kempas timber species as the main member and dowelled by the GFRP or the Kempas rod. The specimens were tested under the shear load with 2mm/min rate and tested until failure. From the experiment, it was found that the average ultimate shear strength of member dowelled with GFRP rod is 21.36% higher compared to one doweled with Kempas rod. According to mode of failure between two types of bolt, GFRP dowelled performs well (Mode I& IV) rather than Kempas dowelled (Mode IV).

Shear strengthening of reinforced concrete beams with high-strength steel wire and engineered cementitious composites

2021 ◽  
pp. 136943322110463
Author(s):  
Fang Yuan ◽  
Wangren Wei ◽  
Ren Hu
Keyword(s):  
Shear Strength ◽  
Carrying Capacity ◽  
Steel Wire ◽  
High Strength ◽  
Shear Resistance ◽  
Shear Capacity ◽  
Load Carrying Capacity ◽  
Cementitious Composite ◽  
Shear Strengthening ◽  
Load Carrying

Engineered cementitious composite (ECC) is a type of high-performance fibre-reinforced cementitious composite with good ductility and excellent crack control ability. It has attracted increasing attention as a structural repair material in severely corrosive environments. However, the strength improvement is limited when ECC is used alone for shear strengthening of existing reinforced concrete (RC) members, although its shear capacity is much higher than that of other brittle cementitious materials such as cement mortar. This study proposes a novel shear strengthening method for RC beams with both high load-carrying capacity and good durability through the combination of high-strength steel wire and an ECC layer. The shear behaviours of the beams were tested under static loading. The test results showed that the shear strength and the ultimate displacement were significantly improved through shear strengthening. A large number of fine cracks appeared on the ECC layer before the failure of the beams. The load-carrying capacity was reduced by pre-damage owing to the important role of the shear resistance of the concrete with respect to the total shear capacity. The shear strength of the strengthened beams cannot be accurately predicted by the current design code owing to the ignorance of the shear resistance of ECC.

scholarly journals Undrained shear strength of the heavily consolidated clay

2013 ◽  
Vol 45 (2) ◽  
pp. 207-216 ◽  
Author(s):  
Joanna Stróżyk ◽  
Matylda Tankiewicz
Keyword(s):  
Shear Strength ◽  
Compression Test ◽  
Clayey Soil ◽  
Triaxial Compression ◽  
Undrained Shear Strength ◽  
Engineering Practice ◽  
Compression Tests ◽  
Unconfined Compression ◽  
Unconfined Compression Test ◽  
Undrained Shear

Abstract Undrained shear strength of the heavily consolidated clay. The undrained shear strength (cu) is considered one of the most basic parameter characterizing soils in engineering practice. The particular importance of cu is in the case of clayey soil. This parameter also is the basis for the classification of soil according to the ISO standard. The undrained shear strength usually is determined from unconfined compression test or from triaxial compression test. In the simple way it can be estimated from the fall cone penetrometer test as index parameter. In the presented work the results of unconfined compression tests for very stiff, heavily consolidated clay were shown. All analysed clay specimens were taken from the large depth, up to 303 m below terrain level. The tests results: undrained shear strength (cu) and unconfined compression strength (qu) were discussed in the relation on in situ consolidation stress, Atterberg’s limits and the indicatory test - fall cone test results

scholarly journals Undrained Shear Strength cu and Undrained Elastic Modulus Eu of Anthropogenic Soils from Laboratory Tests

2021 ◽  
Vol 906 (1) ◽  
pp. 012118
Author(s):  
Matylda Tankiewicz ◽  
Joanna Strózyk ◽  
Zofia Zieba
Keyword(s):  
Shear Strength ◽  
Laboratory Tests ◽  
Triaxial Compression ◽  
Clay Fraction ◽  
Strain Curve ◽  
Undrained Shear Strength ◽  
Engineering Practice ◽  
Compression Tests ◽  
Materials Used ◽  
Undrained Shear

Abstract Undrained shear strength cu and undrained elasticity modulus Eu are one of the basic mechanical parameters describing soil properties in engineering practice. In a simple way cu can be established by fall cone test or, similar as the Eu modulus, can be determined from the stress-strain curve obtained from the uniaxial or triaxial compression tests. The paper presents the results of laboratory tests od cu and Eu parameters carried out on anthropogenic soil in uniaxial compression tests and fall cone tests. The soil used in the study represented different types of materials used in earthworks - containing different share of clay fraction. Tests were provided on the soil in different bulk density and water contents. The paper proposes a method of estimating Eu50 on the basis of cone penetrometer tests. Such test does not require any additional preparation and can be performed directly on the soil compacted in the cylinder of the Proctor’s apparatus, which allows for a quick assessment of the soil elasticity parameters.

Using piezocone dissipation test to estimate the undrained shear strength in cohesive soil

2015 ◽  
Vol 52 (3) ◽  
pp. 318-325 ◽  
Author(s):  
F.M. Mantaras ◽  
E. Odebrecht ◽  
F. Schnaid
Keyword(s):  
Shear Strength ◽  
Pore Pressure ◽  
Error Detection ◽  
Water Pressure ◽  
Undrained Shear Strength ◽  
Excess Pore Pressure ◽  
Engineering Practice ◽  
Stress History ◽  
Undrained Shear ◽  
Excess Pore

This paper describes a method developed to link the measured piezocone dissipation excess pore-water pressure (Δu) to the soil undrained shear strength (su). In cohesive soils, both Δu and su are dependent on the same variables (compressibility, stress state, stress history), which allows them to be related by the theoretical cavity expansion – critical state framework. A mathematical derivation is presented to demonstrate that the ratio of normalized maximum excess pore pressure and the normalized undrained shear strength fluctuates around a mean value, being affected by soil strength and compressibility and independent of stress history. The predicted su values obtained from the proposed approach are calibrated against field vane shear strength in both normally consolidated (monotonic dissipation tests) and overconsolidated soils (dilatory dissipation tests). Reported results are consistent and encourage the use of the method in engineering practice. On a routine basis, su estimated from pore pressure can be compared with values predicted from penetration resistance, adding desired redundancy for purposes of error detection when interpreting cone penetration testing with pore pressure measurement (CPTU) data.

Influence of Yield Strength Variability over Cross-Section to Steel Beam Load-Carrying Capacity

2005 ◽  
Vol 10 (2) ◽  
pp. 151-160 ◽  
Author(s):  
J. Kala ◽  
Z. Kala
Keyword(s):  
Yield Strength ◽  
Cross Section ◽  
Carrying Capacity ◽  
Bending Moment ◽  
Statistical Characteristics ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Strength Variability ◽  
Hot Rolled ◽  
Hot Rolled Steel

Authors of article analysed influence of variability of yield strength over cross-section of hot rolled steel member to its load-carrying capacity. In calculation models, the yield strength is usually taken as constant. But yield strength of a steel hot-rolled beam is generally a random quantity. Not only the whole beam but also its parts have slightly different material characteristics. According to the results of more accurate measurements, the statistical characteristics of the material taken from various cross-section points (e.g. from a web and a flange) are, however, more or less different. This variation is described by one dimensional random field. The load-carrying capacity of the beam IPE300 under bending moment at its ends with the lateral buckling influence included is analysed, nondimensional slenderness according to EC3 is λ¯ = 0.6. For this relatively low slender beam the influence of the yield strength on the load-carrying capacity is large. Also the influence of all the other imperfections as accurately as possible, the load-carrying capacity was determined by geometrically and materially nonlinear solution of very accurate FEM model by the ANSYS programme.

Fuzzy Sets Theory in Comparison with Stochastic Methods to Analyse Nonlinear Behaviour of a Steel Member under Compression

2005 ◽  
Vol 10 (1) ◽  
pp. 65-75 ◽  
Author(s):  
Z. Kala
Keyword(s):  
Fuzzy Sets ◽  
Carrying Capacity ◽  
Stochastic Methods ◽  
Nonlinear Behaviour ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Input Parameters ◽  
Stochastic Solution ◽  
Fuzzy Solution ◽  
Sets Theory

The load-carrying capacity of the member with imperfections under axial compression is analysed in the present paper. The study is divided into two parts: (i) in the first one, the input parameters are considered to be random numbers (with distribution of probability functions obtained from experimental results and/or tolerance standard), while (ii) in the other one, the input parameters are considered to be fuzzy numbers (with membership functions). The load-carrying capacity was calculated by geometrical nonlinear solution of a beam by means of the finite element method. In the case (ii), the membership function was determined by applying the fuzzy sets, whereas in the case (i), the distribution probability function of load-carrying capacity was determined. For (i) stochastic solution, the numerical simulation Monte Carlo method was applied, whereas for (ii) fuzzy solution, the method of the so-called α cuts was applied. The design load-carrying capacity was determined according to the EC3 and EN1990 standards. The results of the fuzzy, stochastic and deterministic analyses are compared in the concluding part of the paper.

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