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Highway and Urban Environment - Proceedings of the 8th Highway and Urban Environment

Posted by: shadabg - 10-22-2012, 06:20 AM - Forum: Traffic Engineering - No Replies

Highway and Urban Environment - Proceedings of the 8th Highway and Urban Environment Symposium

The 8th Highway and Urban Environment Symposium (8HUES) was held on 12–14 June 2006 in Nicosia, Cyprus. 8HUES was hosted in Cyprus by the Cyprus Institute. HUES is run by Chalmers University of Technology within the Alliance for Global Sustainability (AGS).

The following facts provide a background for 8HUES:
• 150 abstracts for posters and papers were accepted
• 80 delegates (24 female) attended the symposium
• 23 countries were represented, including all continents
• 71 oral presentations at the symposium
• 20 poster presentations
• 50 written manuscripts for these proceedings

HUES was initiated by Professor Ron Hamilton at Middlesex Polytechnic (now University) in the early 1980s. The initial aim was to measure and assess challenges in highway pollution. These challenges particularly included urban photochemical smog, with an emphasis on ozone formation and particle release. The first symposium was titled “Highway Pollution” and had a clear aim to make a difference. The proceedings were published in an interdisciplinary journal.

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Numerical Analysis and Design Criteria of Embankments on Floating Piles

Posted by: hapsea - 10-21-2012, 08:50 AM - Forum: Civil Engineering MSc and PhD thesis - No Replies

Numerical Analysis and Design Criteria of Embankments on Floating Piles

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Small-Strain Stiffness of Soils and its Numerical Consequences

Posted by: hapsea - 10-21-2012, 08:37 AM - Forum: Civil Engineering MSc and PhD thesis - No Replies

Small-Strain Stiffness of Soils and its Numerical Consequences

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Numerical Modeling of Expansive Soil Behavior

Posted by: hapsea - 10-21-2012, 08:08 AM - Forum: Civil Engineering MSc and PhD thesis - Replies (1)

Numerical Modeling of Expansive Soil Behavior

Expansive soils contain clay minerals named montmorillonites or smectites. In this type
of soils, significant deformations are associated with changes in suction and degree of
saturation. As expansive soils are widespread in nature, they constitute an important
challenge for geotechnical engineering. In the unsaturated zone well above the phreatic
groundwater level the soil moisture content varies significantly over the seasons and the
study of expansive soil behaviour is thus based on unsaturated soil mechanics and unsaturated
groundwater flow. At present unsaturated flow is getting increasing attention
in literature and so is the mechanical behaviour of unsaturated soils. Although the title
of this study refers to expansive soils, most of the developments reported are applicable
to unsaturated soils in general.
Being from Syria, a land with large areas of expansive soils, Ayman Abed came to
Stuttgart to study the mechanical behaviour of such soils. Being not a specialist in this
field, I was very pleased to havemy colleague Professor Antonio Gens from Barcelona as
a co-advisor. No doubt, the Barcelona BasicModel represented the state-of-the-art in the
elastoplastic modelling of unsaturated soils in the year 2004 when Ayman Abed came to
Stuttgart, and a detailed description of this model is contained in the present study.
The main original contribution of this thesis to geomechanics is the extension or generalisation
of the Barcelona Basic Model from isotropic to anisotropic soil. Indeed unsaturated
clays are mostly anisotropic and should thus be modelled within the framework
of anisotropic plasticity as presently also done for saturated clays.
This study represents a significant contribution to the subject of unsaturated soil mechanics
that can be used as a spring board for further research in this challenging field
of geomechanics. To me it has been a great pleasure to work with Ayman Abed and I am
very happy to congratulate him with this achievement of the doctoral thesis.

Contents
1 Introduction 1
1.1 Unsaturated expansive soil . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 Surface tension and suction . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.4 Objectives and scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.5 Layout of Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Fundamental Principles 7
2.1 Sign convention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Stresses and equilibrium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Displacements and strains . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.4 Stresses in unsaturated soil . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.5 Stress-strain relationship for unsaturated elastic soil . . . . . . . . . . . . . 16
2.6 Experimental determination of elastic soil parameters . . . . . . . . . . . . 19
2.6.1 Typical stress paths as used in triaxial tests on unsaturated soil . . 20
3 Elastoplastic Modeling of Soil 27
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.2 Plastic behavior modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
3.2.1 Yield function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.2.2 Flow rule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3.2.3 Hardening law . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
3.2.4 The consistency condition . . . . . . . . . . . . . . . . . . . . . . . . 33
3.3 The stress-strain formulation in case of elastoplastic model . . . . . . . . . 34
3.4 Cam Clay model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.4.1 Isotropic loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
3.4.2 Yield surface and flow rule . . . . . . . . . . . . . . . . . . . . . . . 38
3.4.3 Modified Cam Clay hardening rule . . . . . . . . . . . . . . . . . . 40
3.4.4 Elastoplastic matrix for Cam Clay model . . . . . . . . . . . . . . . 40
3.4.5 On the failure criterion as used in Cam Clay . . . . . . . . . . . . . 41
3.5 On Modified Cam Clay parameters . . . . . . . . . . . . . . . . . . . . . . . 44
3.5.1 Stiffness parameters as used in Cam Clay model . . . . . . . . . . . 44
3.5.2 Strength parameter as used in Cam Clay model . . . . . . . . . . . 45
4 Elastoplastic Modeling of Unsaturated Soil 47
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.2 Experimental evidences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.2.1 Effect of suction on soil stiffness . . . . . . . . . . . . . . . . . . . . 47
4.2.1.1 Loading-unloading under constant suction . . . . . . . . 48
4.2.1.2 Wetting under constant net stress . . . . . . . . . . . . . . 49
4.2.1.3 Drying under constant net stress . . . . . . . . . . . . . . . 51
4.2.1.4 Yielding of unsaturated soil . . . . . . . . . . . . . . . . . 52
4.2.2 Effect of suction on soil strength . . . . . . . . . . . . . . . . . . . . 52
4.2.3 Summary on the experimental observations . . . . . . . . . . . . . 54
4.3 Early attempts to model unsaturated soil behavior . . . . . . . . . . . . . . 55
4.3.1 Volumetric and shear strains . . . . . . . . . . . . . . . . . . . . . . 55
4.3.2 Shear strength . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.4 Barcelona Basic Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.4.1 Isotropic loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
4.4.1.1 Net stress primary loading-unloading . . . . . . . . . . . 61
4.4.1.2 Suction primary loading-unloading . . . . . . . . . . . . . 62
4.4.1.3 General expression for isotropic stress state . . . . . . . . 63
4.4.1.4 Isotropic plastic compression upon wetting . . . . . . . . 64
4.4.2 More general states of stress . . . . . . . . . . . . . . . . . . . . . . . 66
4.4.2.1 Elastic behavior . . . . . . . . . . . . . . . . . . . . . . . . 66
4.4.2.2 Plastic behavior . . . . . . . . . . . . . . . . . . . . . . . . 67
4.4.2.3 LC and SI coupling . . . . . . . . . . . . . . . . . . . . . . 69
4.4.3 Elastoplastic matrix for Barcelona Basic Model . . . . . . . . . . . . 69
4.5 On the parameters of Barcelona Basic Model . . . . . . . . . . . . . . . . . 73
4.5.1 Parameters , 1 and pc . . . . . . . . . . . . . . . . . . . . . . . . . 73
4.5.2 Suction stiffness parameters . . . . . . . . . . . . . . . . . . . . . . . 75
4.5.3 Capillary cohesion parameter . . . . . . . . . . . . . . . . . . . . . . 75
5 Finite Element Implementation 77
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.2 Balance and kinematic equations . . . . . . . . . . . . . . . . . . . . . . . . 78
5.3 Virtual work principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
5.4 Finite element discretization in case of unsaturated soil . . . . . . . . . . . 80
5.5 Local integration of constitutive equation . . . . . . . . . . . . . . . . . . . 83
5.5.1 Explicit integration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
5.5.2 Implicit integration . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
5.5.2.1 Elastic predictor . . . . . . . . . . . . . . . . . . . . . . . . 84
5.5.2.2 Plastic corrector with return mapping . . . . . . . . . . . . 84
5.5.3 Stress integration with LC is active . . . . . . . . . . . . . . . . . . . 87
5.5.4 Stress integration with SI is active . . . . . . . . . . . . . . . . . . . 87
5.5.5 Stress integration when both LC and SI are active . . . . . . . . . . 89
5.6 The global iterative procedure . . . . . . . . . . . . . . . . . . . . . . . . . . 91
5.6.1 Global and element stiffness matrices . . . . . . . . . . . . . . . . . 91
5.6.2 Global Newton-Raphson iterations . . . . . . . . . . . . . . . . . . . 92
5.7 Validation of the BB-model implementation . . . . . . . . . . . . . . . . . . 94
5.7.1 Test Number 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5.7.2 Test Number 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
5.7.3 Test Number 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
5.7.4 Test Number 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
5.7.5 Test Number 5 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
5.7.6 Test Number 6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
6 Unsaturated ground water flow 105
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
6.2 Governing partial differential equation . . . . . . . . . . . . . . . . . . . . . 105
6.2.1 Steady-state water flow . . . . . . . . . . . . . . . . . . . . . . . . . 105
6.2.2 Transient saturated water flow . . . . . . . . . . . . . . . . . . . . . 106
6.2.3 Transient unsaturated water flow . . . . . . . . . . . . . . . . . . . . 109
6.2.4 Multiphase flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
6.2.5 Fitting functions for soil degree of saturation . . . . . . . . . . . . . 112
6.2.6 Fitting functions for soil water permeability . . . . . . . . . . . . . 114
6.3 Finite element discretization in space . . . . . . . . . . . . . . . . . . . . . . 116
6.4 Finite differences discretization in time . . . . . . . . . . . . . . . . . . . . . 117
6.5 Picard iteration method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
6.6 Validation of the finite element code being used . . . . . . . . . . . . . . . 119
6.6.1 Validation in case of unsaturated stationary ground water flow . . 119
6.6.2 Validation in case of unsaturated transient ground water flow . . . 121
7 Anisotropic model for unsaturated soil 123
7.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
7.2 Origin of anisotropy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
7.3 Empirical observations and constitutive modeling of anisotropy . . . . . . 124
7.4 Models based on Cam Clay model . . . . . . . . . . . . . . . . . . . . . . . 125
7.4.1 SANICLAY model . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125
7.4.2 S-Clay1 model for anisotropic soil . . . . . . . . . . . . . . . . . . . 128
7.4.2.1 The initial value of . . . . . . . . . . . . . . . . . . . . . 129
7.4.2.2 The constant . . . . . . . . . . . . . . . . . . . . . . . . . 129
7.4.2.3 The constant μ . . . . . . . . . . . . . . . . . . . . . . . . . 130
7.4.2.4 S-Clay1 in the general state of stress . . . . . . . . . . . . . 130
7.5 Anisotropy in unsaturated soil . . . . . . . . . . . . . . . . . . . . . . . . . 131
7.5.1 Anisotropic model for unsaturated soil . . . . . . . . . . . . . . . . 133
7.5.1.1 Flow and hardening rules . . . . . . . . . . . . . . . . . . 135
7.5.1.2 General states of stress . . . . . . . . . . . . . . . . . . . . 136
7.5.1.3 Numerical implementation of the new anisotropic model 137
7.6 Numerical validation of the implemented model . . . . . . . . . . . . . . . 138
7.6.1 Case 1: Isotropic fully saturated soil . . . . . . . . . . . . . . . . . . 140
7.6.2 Case 2: Isotropic unsaturated soil . . . . . . . . . . . . . . . . . . . . 142
7.6.3 Case 3: Anisotropic fully saturated soil . . . . . . . . . . . . . . . . 144
8 Boundary value problems 147
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147
8.2 Problem 1: Shallow foundation exposed to a ground water table increase . 147
8.2.1 Geometry, boundary conditions and initial conditions . . . . . . . . 147
8.2.2 The interaction between the ground water flow finite element code
and the deformation code . . . . . . . . . . . . . . . . . . . . . . . . 148
8.2.3 Results of numerical analyses with isotropic BB-model . . . . . . . 149
8.2.4 Calculation with an anisotropic model . . . . . . . . . . . . . . . . . 152
8.3 Problem 2: Bearing capacity of unsaturated soil . . . . . . . . . . . . . . . . 153
8.4 Problem 3: Shallow foundation exposed to a rainfall event . . . . . . . . . 158
8.4.1 Phase 1: Deformation due to foundation loading . . . . . . . . . . . 159
8.4.2 Phase 2: Deformation due to infiltration . . . . . . . . . . . . . . . . 160
8.5 Problem 4: Trial wall on expansive soil in Sudan . . . . . . . . . . . . . . . 162
8.5.1 Soil properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162
8.5.2 The test procedure and measurements . . . . . . . . . . . . . . . . . 165
8.5.3 Numerical simulation . . . . . . . . . . . . . . . . . . . . . . . . . . 166
8.5.3.1 Geometry and boundary conditions . . . . . . . . . . . . 166
8.5.3.2 Parametric study . . . . . . . . . . . . . . . . . . . . . . . 167
8.5.3.3 Model predictions versus field data . . . . . . . . . . . . 170
9 Conclusions and recommendations 175
9.1 Conclusions on modeling and numerical implementation . . . . . . . . . . 175
9.2 Conclusions on the response of shallow foundation on unsaturated soil . . 176
9.2.1 Isotropic behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
9.2.2 Anisotropic behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
9.3 Recommendation for further research . . . . . . . . . . . . . . . . . . . . . 177
Bibliography 177

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SCI P358 - Joints in Steel Construction - Simple Joints to Eurocode 3

Posted by: justsagar - 10-21-2012, 01:37 AM - Forum: Eurocode (EC) - Replies (3)

P-358_ Joints in Steel Construction - Simple Joints to Eurocode 3

This publication is one of a series of “Green Books” that cover a range of steelwork connections. This publication provides guidance for nominally pinned joints (the most common joint type in steel building structures) that primarily carry vertical shear and, as an accidental limit state, tying forces. The connections are designed in accordance with Eurocode 3 and its UK National Annexes.

Resistance tables are provided for the commonly used connection types, including partial depth end plates, fin plates, splices and column bases. A new full depth end plate (i.e. welded to both flanges) has been introduced, which offers a significantly increased tying resistance compared to a partial depth end plate. Detailed design checks are included to cover non-standard joints and facilitate the development of design software.

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hollo - bolt

Posted by: mowafi3m - 10-20-2012, 07:02 PM - Forum: Journals, Papers and Presentations - Replies (1)

hollo bolt

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Introduction to Marine Engineering

Posted by: shadabg - 10-20-2012, 07:33 AM - Forum: Water & Hydraulic Engineering - No Replies

Introduction to Marine Engineering

Progress has been made in many areas of marine engineering since the first edition of this book was published. A greater emphasis is now being placed on the cost-effective operation of ships. This has meant more fuel-efficient engines, less time in port and the need for greater equipment reliability, fewer engineers and more use of automatically operated machinery.

The marine engineer is still, however, required to understand the working principles, construction and operation of all the machinery items in a ship. The need for correct and safe operating procedures is as great as ever. There is considerably more legislation which must be understood and complied with, for example in relation to the discharging of oil, sewage and even black smoke from the funnel. Engineers must now be more environmentally aware of the results of their activities and new material is included in this revised edition dealing with exhaust emissions, environmentally friendly refrigerants and fire extinguishants.

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Structural Engineering Reference Manual

Posted by: amadoo02 - 10-20-2012, 06:49 AM - Forum: Analysis & Design - Replies (9)

Structural Engineering Reference Manual - 4th Edition

The Structural Engineering Reference Manual is the most comprehensive reference and study guide available for engineers preparing for the NCEES Structural I and Structural II exams and the California state structural exam. The structural PE exams require a thorough familiarity with relevant codes, and the 4th edition of the Structural Engineering Reference Manual has been updated to the latest exam code specifications.

The most trusted reference for the Structural I and II exams
Updated to the new structural design standards 2005 edition of AISC 2005 edition of NDS 2005 editions of ACI 318 and ACI 530/ASCE 5/TMS 402 2004 editions of AASHTO 2005 edition of ASCE 7 2006 edition of IBC A complete introduction to the exam format and content Nearly 40 practice problems with solutions Numberous tables, charts, and figures at your fingertips An easy-to-use index for quick reference

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[REQUEST]MULTIPLE HTML FILES TO SINGLE PDF CONVERTER

Posted by: aslam - 10-20-2012, 02:42 AM - Forum: Free Discussion - Replies (1)

	MULTIPLE HTML FILES TO SINGLE PDF CONVERTER: I need a free/patched converter (software) which can convert multiple html files stored on my pc to single PDF file.

Papers

Posted by: Songoku - 10-19-2012, 10:36 PM - Forum: Archive - Replies (1)

	Dear colleagues, Can someone help me getting the following papers: Buckling of stepped crane columns D.J. Fraser, R.Q. Bridge Buckling length of non-uniform members under stepped axial loads John Ch. Ermopoulos Stability criteria for Timoshenko columns with intermediate and end concentrated axial loads C.M. Wanga, , K.H. Nga, S. Kitipornchai Thanks in advance

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