Gas Turbine Engineering Handbook

Gas Turbine Engineering Handbook

Gas Turbine Engineering Handbook

Preference :

Gas Turbine Engineering Handbook discusses the design, fabrication, installation, operation, and maintenance of gas turbines. The third edition is not only an updating of the technology in gas turbines, which has seen a great leap forward in the 2000s, but also a rewriting of various sections to better answer today's problems in the design, fabrication, installation, operation, and maintenance of gas turbines. The third edition has added a new chapter that examines the case histories of gas turbines from deterioration of the performance of gas turbines to failures encountered in all the major components of the gas turbine. The chapter on Maintenance Techniques has been completely rewritten and updated. The revised chapter deals with Long Term Service Agreements (LTSAs), and special maintenance tables have been added so that you can troubleshoot problems on gas turbines that you may encounter. The new advanced gas turbines have firing temperatures of 2600 ~ (1427 ~ and pressure ratios exceeding 40:1 in aircraft gas turbines, and over 30:1 in industrial turbines. This has led to the rewriting of Chapter 7, to fully understand the operating mechanics of these high pressure ratio axial-flow compressors. The chapter covers in detail the advent of surge, and describes in great detail the different mechanisms of surge, rotating stall, and choke flow conditions in the compressor of the gas turbine. Advances in materials and coatings have spurred this technology, and the new edition has treated this new area in great detail. The emphasis on low NOx emissions from gas turbines has led to the development of a new breed of Dry Low NOx combustors, and their problems are dealt with in depth in this new edition. The third edition deals with an upgrade in the design and maintenance of advanced gas turbines and deals with most of the applicable codes both in the area of performance and mechanical standards. The new edition has been written with the experienced engineer in mind who is working in power plants, and in petrochemical and offshore installations. This edition should help him or her understand more clearly problems encountered in the field, and how to prevent them.

The use of gas turbines in the petrochemical, power generation, and offshore industries has mushroomed in the past few years. The power industry in the past ten years has embraced the combined cycle power plants, and the new high efficiency gas turbines are at the center of this growth segment of the industry. However, due to the spiraling costs of natural gas, many of these plants designed for base load service have been cycled on a daily basis from part loads of 50% to full load, and in many cases have had to be shutdown on weekends. The new maintenance chapters, with their case histories, should be of great assistance to the engineers in the field who have to operate their plant at other than design conditions of base loaded operation. Investigation of operating these plants on other fuels is also handled in this edition 

Gas Turbine Engineering Handbook

Content :

• An Overview of Gas Turbines
• Theoretical and Actual Cycle Analysis
• Compressor and Turbine Performance Characteristics
• Performance and Mechanical Standards
• Rotor Dynamics
• Centrifugal Compressors
• Axial-Flow Compressors
• Radial-Inflow Turbines
• Axial-Flow Turbines
• Combustors
• Materials
• Fuels
• Bearings and Seals
• Gears

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Shigley’s Mechanical Engineering Design

Shigley’s Mechanical Engineering Design

Richard G. Budynas,  J. Keith Nisbett

Preference :

This text is intended for students beginning the study of mechanical engineering
design. The focus is on blending fundamental development of concepts with practical
specification of components. Students of this text should find that it inherently
directs them into familiarity with both the basis for decisions and the standards of
industrial components. For this reason, as students transition to practicing engineers,
they will find that this text is indispensable as a reference text. The objectives of the
text are to:

• Cover the basics of machine design, including the design process, engineering
mechanics and materials, failure prevention under static and variable loading, and
characteristics of the principal types of mechanical elements
• Offer a practical approach to the subject through a wide range of real-world applica-
tions and examples
• Encourage readers to link design and analysis
• Encourage readers to link fundamental concepts with practical component specification.

New and revised end-of-chapter problems. This edition includes 1017 end-of-
chapter problems, a 43 percent increase from the previous edition. Of these prob-
lems, 671 are new or revised, providing a fresh slate of problems that do not have
years of previous circulation. Particular attention has been given to adding
problems that provide more practice with the fundamental concepts. With an eye
toward both the instructor and the students, the problems assist in the process of
acquiring knowledge and practice. Multiple problems with variations are available
for the basic concepts, allowing for extra practice and for a rotation of similar
problems between semesters.

Shigley’s Mechanical Engineering Design

Content :

• Introduction to Mechanical Engineering Design
• Materials
• Load and Stress Analysis
• Deflection and Stiffness
• Failure Prevention
• Failures Resulting from Static Loading 
• Fatigue Failure Resulting from Variable Loading
• Design of Mechanical Elements
• Shafts and Shaft Components
• Screws, Fasteners, and the Design of Nonpermanent Joints
• Welding, Bonding, and the Design of Permanent Joints 
• Mechanical Springs
• Rolling-Contact Bearings
• Lubrication and Journal Bearings
• Gears—General 
• Spur and Helical Gears
• Bevel and Worm Gears
• Clutches, Brakes, Couplings, and Flywheels
• Flexible Mechanical Elements
• Power Transmission Case Study
• Finite-Element Analysis
• Statistical Considerations

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Handbook of Diesel Engines

Handbook of Diesel Engines

Klaus Mollenhauer,  Helmut Tschoeke

Preference :

This machine is destined to completely revolutionize engine engineering and replace everything that exists.(From Rudolf Diesel’s letter of October 2, 1892 to the publisher Julius Springer.)

Although Diesel’s stated goal has never been fully achievable of course, the diesel engine indeed revolutionized drive systems. This handbook documents the

current state of diesel engine engineering and technology. The impetus to publish a Handbook of Diesel Engines grew out of ruminations on Rudolf Diesel’s transformation of his idea for a rational heat engine into reality more than 100 years ago. Once the patent was filed in 1892 and work on his engine commenced the following year, Rudolf Diesel waited another 4 years until the Association of German Engineers provided him a platform to present his engine to the public at its convention in Kassel on June 16, 1897. The engine came to bear the name of its ingenious inventor soon thereafter.

The editors and publisher intend this English edition of the handbook to furnish readers outside 

German-speaking regions a scholarly and practical presentation of the current state of the diesel engine and its large range of applications. The handbook has not only been conceived for diesel experts but also ‘‘diesel laypersons’’ with prior knowledge of engineering or at least an interest in technology. Furthermore, it is intended to benefit students desiring a firsthand comprehensive and sound overview of diesel engine engineering and technology and its state of development.

Handbook of Diesel Engines

Content :

• History and Fundamental Principles of the Diesel Engine 
• Gas Exchange and Supercharging
• Diesel Engine Combustion
• Fuels
• Fuel Injection Systems
• Fuel Injection System Control Systems
• Engine Component Loading
• Crankshaft Assembly Design, Mechanics and Loading
• Engine Cooling
• Materials and Their Selection
• Lubricants and the Lubrication System
• Start and Ignition Assist Systems
• Intake and Exhaust Systems
• Exhaust Heat Recovery
• Diesel Engine Exhaust Emissions
• Vehicle Diesel Engines
• Industrial and Marine Engines
• Standards and Guidelines for Internal Combustion Engines

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Sheet Piling Handbook 3rd Edition

Sheet Piling Handbook 3rd Edition 

The history of sheet piling goes back to the beginning of the last century. The book Ein Produkt
erobert die Welt – 100 Jahre Stahlspundwand aus Dortmund (A product conquers the world –
100 years of sheet pile walls from Dortmund) describes the success story of sheet piling. The
story is closely linked with Tryggve Larssen, government building surveyor in Bremen, who
invented the sheet pile wall made from rolled sections with a channel-shaped cross-section. In
1902 the so-called LARSSEN sheet piles – known as such from this date onwards – were used
as a waterfront structure at Hohentorshafen in Bremen – and are still doing their job to this day!
Since then, LARSSEN sheet piles have been manufactured in the rolling mill of HOESCH
Spundwand und Profil GmbH.
Over the years, ongoing developments in steel grades, section shapes and driving techniques

have led to a wide range of applications for sheet piling. The applications include securing ex-
cavations, waterfront structures, foundations, bridge abutments, noise abatement walls, highway

structures, cuttings, landfill and contaminated ground enclosures, and flood protection schemes.
The main engineering advantages of sheet pile walls over other types of wall are:
• the extremely favourable ratio of steel cross-section to moment of resistance,
• their suitability for almost all soil types,
• their suitability for use in water,
• the fast progress on site,
• the ability to carry loads immediately,
• the option of extracting and reusing the sections,
• their easy combination with other rolled sections,
• the option of staggered embedment depths,
• the low water permeability, if necessary using sealed interlocks, and
• there is no need for excavations.

The driving work calls for a certain amount of play in the interlocks and so these joints be-
tween the sheet piles are not watertight. Owing to their convoluted form, however, water seep-
ing through the joint does have to negotiate a relatively long path. Ultra-fine particles in the

soil accumulate in the interlocks over time, which results in a “self-sealing” effect, which is
augmented by corrosion. According to EAU 2004 section 8.1.20.3 (R 117), in walls standing
in water this natural sealing process can be assisted by installing environmentally compatible
synthetic seals. If a sheet pile wall is required to be especially watertight, the interlocks can be
filled with a permanently plastic compound or fitted with a preformed polyurethane interlock
seal. The materials used exhibit high ageing and weathering resistance plus good resistance to

water, seawater and, if necessary, acids and alkalis. Polyurethane interlock seals are factory-
fitted to the interlocks of multiple piles and the joints threaded on site are sealed with further

preformed polyurethane seals.

Interlocks can be sealed with bituminous materials to achieve a watertight joint. Such mater-
ials can be applied in the works or on site. The watertightness is achieved according to the

displacement principle: excess sealant is forced out of the interlock when threading the next
pile.

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Beam Column Design Spreadsheet to ACI-318 and ACI-350

Beam Column Design Spreadsheet to ACI-318 and ACI-350

Beam column design spreadsheet evaluates concrete members carrying both flexure and axial load using thrust-moment, or P-M, interaction diagrams generated per ACI 318 and ACI 350. Standard axial/flexural provisions, Ch 10, are considered.  ACI 350 durability factor is used to factor down the flexural and axial capacities instead of factoring up the factored loads. The end result is an "inner curve" that governs for ACI 350 capacity in the tension-controlled and transition zones.

Assumptions/Limitations:

- Only one layer of steel each for top face reinforcing and bottom face reinforcing

- Ties are provided for confinement (not spirals)

Validation:

-XLC formulae and peer review provide verification of intended functionality.

-Cross-check against software solution (SP Column)

References:

-ACI 318-11

-ACI 350-06

LINK

Excel Construction Management Templates

Excel Construction Management Templates

Excel Construction Management Templates are very important for managers as it's
very difficulit to manage construction projects. they Require alot of 
stakeholders, details and documentation. So we provide more
 than 15 free excel construction management templates to download and use them
the templates involve : 

• Construction Timeline
• Construction Budget
• Construction Estimator
• Bid Tabulation Template
• Abstract of Bids Template
• Subcontractor Documentation Tracker
• Construction Documentation Tracker
• Daily/Weekly Inspection Report
• Contractor Progress Payment Template
• Change Order Request Summary
• Change Order Log
• Request for Information Log
• Residential Remodel Project Timeline
• Certified Wage & Hour Payroll Form
• Time & Materials Invoice
• Project Punchlist
• Project Closeout Checklist
• Construction Management with Smartsheet

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Unsaturated Soil Mechanics

Unsaturated Soil Mechanics

The principal aim of this book is to provide a thorough grounding in unsat-
urated soil mechanics principles from three fundamental perspectives: ther-
modynamics, mechanics, and hydrology. The book is written to guide a first

course on the subject and is primarily intended for undergraduate seniors,
graduate students, and researchers with backgrounds in the more general fields
of geotechnical engineering, soil science, environmental engineering, and
groundwater hydrology.
In formulating this book, we have maintained the opinion that a first course
in any branch of mechanics should emphasize the fundamental principles that
govern the phenomena of interest. A principles-based approach to learning is
most beneficial to the general reader and is particularly appropriate for the
subject of unsaturated soil mechanics as it remains a young, dynamic, and

rapidly emerging field of research and practice. Our general viewpoint to-
wards the pursuit of understanding is reflected by Thomas Henry Huxley’s

(1825–1895) statement: ‘‘The known is finite, the unknown infinite; intellec-
tually we stand on an islet in the midst of an illimitable ocean of inexplica-
bility. Our business in every generation is to reclaim a little more land.’’ We

hope that this book will provide the necessary background and motivation for

those who desire to explore and reclaim the ocean of unsaturated soil me-
chanics problems that nature and society continue to present.

The history of unsaturated soil mechanics is embedded in the history of hydrology, 
soil mechanics, and soil physics. Engineering problems involving

unsaturated soil span numerous subdisciplines and practices within the general
field of civil engineering. Hydrologists, for example, have long recognized
that modeling of regional or local surface water and groundwater systems and
oc-
curring in the near-surface unsaturated soil zone. Quantitative evaluation of

moisture flux at the atmosphere-subsurface boundary requires not only knowl-
edge of the relevant soil and pore water properties but also the predominant

environmental conditions at the soil-atmosphere interface. Unsaturated soil
often comprises cover or barrier materials for landfills and hazardous waste

storage facilities of interest to the geo-environmental community. Contami-
nant transport and leaching processes are often strictly unsaturated fluid trans-
port phenomena, occurring in many cases as multiphase transport problems.

As national and international policy with regard to the health of the natural
environment is becoming increasingly more regulated, recognition of these

types of geo-enviromental issues and development of solutions from an un-
saturated soil mechanics framework is becoming more and more common.

Many of the more traditional geotechnical engineering problems also fall
wholly or partly into the category of unsaturated soil mechanics problems.
Compaction, for example, a classical application involving unsaturated soil,

has been routine practice for improving the mechanical and hydraulic prop-
erties of soil since far before the formation of civil engineering as a formal

discipline in the mid-nineteenth century. Compacted soil comprising the many
earthworks constructed all over the world is most appropriately considered

from an unsaturated soils framework. It has long been recognized that ex-
pansive soils pose a severe threat to civil engineering infrastructure such as

roads, housing, and transportation facilities nationally and internationally. Ex-
pansive soil formations in the United States alone are responsible for billions

of dollars in damage costs each year, an amount exceeding that of all other
natural hazards combined, including earthquakes, floods, fires, and tornados
(Jones and Holtz, 1973). 

LINK

Ribbed Slab Design Spreadsheets to Eurocode

Ribbed Slab Design Spreadsheets to Eurocode

• Ribbed slabs are widely used in many countries. This is attributed to the rapid shattering, ease of construction, and the reduction in the time of erection. This type of slabs or flooring system consists of series of small closed spaced reinforced concrete T-beams. These floors are suitable for building with light live loads.
The advantages of ribbed slab :

• Quick and simple to install
• Minimizes the need for skilled labor
•  Supplied on short lead times
•  Tailored to any type of site requirements
•  Saves aggregate, concrete and steel
•  Speeds construction
•  Lowering building costs
•  Reducing the cycle time of building
•  Maximum control of concrete curing
• Providing a higher quality floor surface;
• Achieving longer spans in pile/beam structural
• slabs and pile numbers may be optimized to limit additional costs
•  Monolithic poured concrete foundation slabs
•  Solution for Structural Weight Limits
• Contributing to GREEN or LEED certified building

In one-way ribbed slab, loads are transferred in one direction, and the main reinforcement is distributed in the same direction of the load. With accurate to temperature and shrinkage,

 minimum of Φ33 bars diameter will be used in both direction and 
crossing each other over the blocks ( practically).I

LINK

Civil Engineering Materials Fifth Edition

Civil Engineering Materials Fifth Edition

The importance of an understanding of the materials used in civil engineering and
building projects is widely recognised, and this is reflected by the increasing
emphasis being placed on the teaching of material properties at undergraduate
level. This introductory textbook on materials satisfies a need for a single book
covering the principal materials used in civil engineering and building works.
The aim has been to provide students with an authoritative text which will also
serve as a valuable source of reference in their subsequent careers. In this fifth edition,
with three new contributors, the Parts on Metals, Timber and Bituminous
Materials have been rewritten, and all other Parts have been extensively revised to
maintain an up-to-date coverage of all materials. The fundamental properties of
soils continue to be covered in greater depth than usual, in recognition of the
importance of soils as construction materials, and an additional chapter has been
included to assist the reader in the transition from the study of soils as a material
to the related topic of soil mechanics. Extensive references to all relevant British
and other Standards are made throughout the book.
The treatment of material properties here is suitable for students studying for a
degree or equivalent qualification in civil engineering, building technology, architecture
and other related disciplines. The particular point in a course at which the
study of civil engineering and building materials is introduced will depend on the
course structure of the individual educational institution but would generally be
during the first two years of a three or four year course. Similarly, the extent of
further formal study of materials depends on the emphasis and structure of the
course within a particular educational institution. However, it is not envisaged that
further formal study of the basic material properties of metals, timber, concrete,
polymer materials and bricks and blocks will be required, although the application
of these materials within the general context of analysis and design might well
continue throughout the remainder of a course. Further formal study of soils might
normally be expected to continue, for civil engineering students, within the context
of soil mechanics, with further formal study of bituminous materials only
where highway materials are studied in later years. In this context, readers should
recognise the need for continued study, whether this be of an informal or formal
nature, throughout their subsequent careers if they are to ma

An understanding of the properties of materials is essential in both the design and
construction phases of any civil engineering or building project if this is to prove
satisfactory for its intended purpose. For the student reader it is believed that a few
introductory remarks, in this context, might make the study of materials more
meaningful in itself, rather than merely being a part of a required course of study.
Civil engineering and building projects include roads, railways, bridges, tunnels,
dams, culverts, water and waste-water treatment plants, water distribution
and drainage systems, coastal protection works, harbours, power stations, airports,
industrial complexes and a wide range of building structures for residential, commercial,
sports and leisure purposes. During the initial planning and design stages
of a project the principal factors upon which any subsequent decision to proceed
will be based include its economic viability and sociological and environmental
impact.
During this initial or conceptual design stage, consideration is given to possible
alternative locations and/or layouts of the associated works and to a preliminary
assessment of suitable construction materials.
For building structures, alternative layouts and structural forms are studied
together with the suitability of different materials for use in the structural elements
for each of these. The decision as to which structural form and choice of materials
are the most appropriate depends on a number of factors including, but not limited
to, the cost, physical properties, durability and availability of materials and
the ease and speed of construction. All of these affect the first cost (of construction)
and/or the subsequent costs (of maintenance) during the design life of the
structure, both of these being important considerations when assessing the economic
viability of any project. It should be noted that the term choice of materials
is used here to mean the choice of not only the generic names of materials (steel,
concrete, aluminium, polymer, timber, brick, etc.) but also their specific type,
composition and/or performance acceptance criteria.

LINK

Two Way Slab Design Spreadsheets to Eurocode 2

Two Way Slab Design Spreadsheets to Eurocode 2 

Two-way spanning slabs For rectangular slabs with standard edge conditions and subject to uniformly distributed loads, normally the bending moments are obtained using tabulated coefficients. Such
coefficients are provided later in this section.
 Main reinforcement for two way slabs designs in both directions.
This situation happen when slab were supported at all four span sides and
ratio long per short span less or equivalent to two. Bending moment and shear
force for two way slab depends on ratio ly / lx and extension between his slab
and supporter whether easily supported or constrained.Two way simply supported slab
 have a panel and easily
supported in edge and panel can lift upward when moment acting on
it, slab is supported by beam steel or extension between slab and non

monolithic beam. Moment only exist in center part of span.

Two way slab constrained have more than one panel or in
section slab edge can be prevent from lifted. This situation happen
when slab connected by monolithic with the supporter or slab panel
connected by monolithic between one and another and moment acting
at slab edge. This type of slab has four moment value at one slab
panel namely two moment amid span and two moment at direction x and y.

LINK

Advances in Water Resources Engineering

Advanced Concrete Technology Processes

The past 35 + years have seen the emergence of a growing desire worldwide that
positive actions be taken to restore and protect the environment from the degrading
effects of all forms of pollution—air, water, soil, thermal, radioactive, and noise.
Since pollution is a direct or indirect consequence of waste, the seemingly idealistic
demand for “zero discharge” can be construed as an unrealistic demand for zero
waste. However, as long as waste continues to exist, we can only attempt to abate
the subsequent pollution by converting it into a less noxious form. Three major
questions usually arise when a particular type of pollution has been identified: (1)
How serious are the environmental pollution and water resources crisis? (2) Is the
technology to abate them available? And (3) do the costs of abatement justify the
degree of abatement achieved for environmental protection and water resources
conservation? This book is one of the volumes of the Handbook of Environmental
Engineering series. The principal intention of this series is to help readers formulate
answers to the above three questions.

The traditional approach of applying tried-and-true solutions to specific environmental
and water resources problems has been a major contributing factor to the
success of environmental engineering, and has accounted in large measure for the
establishment of a “methodology of pollution control.” However, the realization
of the ever-increasing complexity and interrelated nature of current environmental
problems renders it imperative that intelligent planning of pollution abatement
systems be undertaken. Prerequisite to such planning is an understanding of the
performance, potential, and limitations of the various methods of environmental
protection available for environmental scientists and engineers. In this series of
handbooks, we will review at a tutorial level a broad spectrum of engineering systems
(natural environment, processes, operations, and methods) currently being utilized,
or of potential utility, for pollution abatement and environmental protection.
We believe that the unified interdisciplinary approach presented in these handbooks
is a logical step in the evolution of environmental engineering.

Treatment of the various engineering systems presented will show how an engineering
formulation of the subject flows naturally from the fundamental principles
and theories of chemistry, microbiology, physics, and mathematics. This emphasis
on fundamental science recognizes that engineering practice has in recent years
become more firmly based on scientific principles rather than on its earlier dependency
on empirical accumulation of facts. It is not intended, though, to neglect
empiricism where such data lead quickly to the most economic design; certain engineering
systems are not readily amenable to fundamental scientific analysis, and in
these instances we have resorted to less science in favor of more art and empiricism.
Since an environmental water resources engineer must understand science within
the context of applications, we first present the development of the scientific
basis of a particular subject, followed by exposition of the pertinent design concepts
and operations, and detailed explanations of their applications to environmental
conservation or protection. Throughout the series, methods of mathematical modeling,
system analysis, practical design, and calculation are illustrated by numerical
examples. These examples clearly demonstrate how organized, analytical reasoning
leads to the most direct and clear solutions. Wherever possible, pertinent cost data
have been provided.

Our treatment of environmentalwater resources engineering is offered in the belief
that the trained engineer should more firmly understand fundamental principles,
be more aware of the similarities and/or differences among many of the engineering
systems, and exhibit greater flexibility and originality in the definition and innovative
solution of environmental system problems. In short, the environmental and
water resources engineers should by conviction and practice be more readily adaptable
to change and progress.

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An Introduction to Structural Optimization

An Introduction to Structural Optimization

This book has grown out of lectures and courses given at Linköping University,
Sweden, over a period of 15 years. It gives an introductory treatment of problems
and methods of structural optimization. The three basic classes of geometrical optimization
problems of mechanical structures, i.e., size, shape and topology optimization,
are treated. The focus is on concrete numerical solution methods for discrete
and (finite element) discretized linear elastic structures. The style is explicit
and practical: mathematical proofs are provided when arguments can be kept elementary
but are otherwise only cited, while implementation details are frequently
provided. Moreover, since the text has an emphasis on geometrical design problems,
where the design is represented by continuously varying—frequently very many—
variables, so-called first order methods are central to the treatment. These methods
are based on sensitivity analysis, i.e., on establishing first order derivatives for objectives
and constraints. The classical first order methods that we emphasize are
CONLIN and MMA, which are based on explicit, convex and separable approximations.
It should be remarked that the classical and frequently used so-called optimality
criteria method is also of this kind. It may also be noted in this context that
zero order methods such as response surface methods, surrogate models, neural networks,
genetic algorithms, etc., essentially apply to different types of problems than
the ones treated here and should be presented elsewhere. The numerical solutions
that are presented are all obtained using in-house programs, some of which can be
downloaded from the book’s homepage at www.mechanics.iei.liu.se/edu_ug/strop/.
These programs should also be used for solving some of the more extensive exercises
provided.
The text is written for students with a background in solid and structural mechanics
with a basic knowledge of the finite element method, although in our experience
such knowledge could be replaced by a certain mathematical maturity. Previous
exposure to basic optimization theory and convex programming is helpful but not
strictly necessary.
The first three chapters of the book represent an introductory and preparatory
part. In Chap. 1 we introduce the basic idea of mathematical design optimization
and indicate its place in the broader frame of product realization, as well as define
basic concepts and terminology. Chapter 2 is devoted to a series of small-scale problems
that, on the one hand, give familiarity with the type of problems encountered
in structural optimization and, on the other hand, are used as model problems in
upcoming chapters. Chapter 3 reviews basic concepts of convex analysis, and exemplifies
these by means of concepts from structural mechanics. Chapter 4 is, from an
algorithmic point of view, the core chapter of the book. It introduces the basic idea of
sequential explicit convex approximations, and CONLIN and MMA are presented.
In Chap. 5 the latter is applied to stiffness optimization of a truss.

A structure in mechanics is defined by J.E. Gordon [17] as “any assemblage of materials
which is intended to sustain loads.” Optimization means making things the
best. Thus, structural optimization is the subject of making an assemblage of materials
sustain loads in the best way. To fix ideas, think of a situation where a load is
to be transmitted from a region in space to a fixed support as in Fig. 1.1.We want to
find the structure that performs this task in the best possible way. However, to make
any sense out of that objective we need to specify the term “best.” The first such
specification that comes to mind may be to make the structure as light as possible,
i.e., to minimize weight. Another idea of “best” could be to make the structure as
stiff as possible, and yet another one could be to make it as insensitive to buckling or
instability as possible. Clearly such maximizations or minimizations cannot be performed
without any constraints. For instance, if there is no limitation on the amount
of material that can be used, the structure can be made stiff without limit and we
have an optimization problem without a well defined solution. Quantities that are
usually constrained in structural optimization problems are stresses, displacements
and/or the geometry. Note that most quantities that one can think of as constraints
could also be used as measures of “best,” i.e., as objective functions. Thus, one can
put down a number of measures on structural performance—weight, stiffness, critical
load, stress, displacement and geometry—and a structural optimization problem
is formulated by picking one of these as an objective function that should be maximized
or minimized and using some of the other measures as constraints. In Sect. 1.3
we will be specific about how such a formulation looks in mathematical terms. In
the next section, Sect. 1.2, we will temporarily move the perspective in the other
direction, and look at how structural optimization enters a broader picture.

LINK

Shear Strengthening of T-beam with FRP

Shear Strengthening of T-beam with FRP

The rehabilitation of existing reinforced concrete (RC) bridges and building becomes necessary due to ageing, corrosion of steel reinforcement, defects in construction/design, demand in the increased service loads, and damage in case of seismic events and improvement in the design guidelines. Fiber-reinforced polymers (FRP) have emerged as promising material for rehabilitation of existing reinforced concrete structures. The rehabilitation of structures can be in the form of strengthening, repairing or retrofitting for seismic deficiencies. RC T-section is the most common shape of beams and girders in buildings and bridges. Shear failure of RC T-beams is identified as the most disastrous failure mode as it does not give any advance warning before failure. The shear strengthening of RC T-beams using externally bonded (EB) FRP composites has become a popular structural strengthening technique, due to the well-known advantages of FRP composites such as their high strength-to-weight ratio and excellent corrosion resistance.

A few studies on shear strengthening of RC T-beams using externally bonded FRP sheets have been carried out but still the shear performance of FRP strengthened beams has not been fully understood. The present study therefore explores the prospect of strengthening structurally deficient T-beams by using an externally bonded fiber reinforced polymer (FRP).
This study assimilates the experimental works of glass fiber reinforced polymer (GFRP) retrofitted RC T-beams under symmetrical four-point static loading system. The thirteen number of beams were of the following configurations, (i) one number of beam was considered as the control beam, (ii) seven number of the beams were strengthened with different configurations and orientations of GFRP sheets, (iii) three number of the beams strengthened by GFRP with steel bolt-plate, and (iv) two number of beams with web openings strengthened by U-wrap in the shear zone of the beams.
The first beam, designated as control beam failed in shear. The failures of strengthened beams are initiated with the debonding failure of FRP sheets followed by brittle shear failure. However, the shear capacity of these beams has increased as compared to the control beam which can be further improved if the debonding failure is prevented. An innovative method of anchorage technique has been used to prevent these premature failures, which as a result ensure full utilization of the strength of FRP. A theoretical study has also been carried out to support few of the experimental findings.

LINK

Advances in Environmental Geotechnics

Advances in Environmental Geotechnics

Despite reductions in waste generation, landfills will
continue to be required for the safe disposal of municipal
solid waste (MSW) for the foreseeable future. These
landfills will generate both leachate and gas whose
escape from the facility must be controlled to
environmentally acceptable levels. The leachate is
predominantly water but typically contains dissolved
organic and inorganic chemicals and suspended solids
(e.g. microbes, particulate matter etc.) whose escape
from the landfill must be controlled to negligible levels.
Landfill gas is predominantly comprised of methane and
carbon dioxide which are of concern as greenhouse gases
(especially methane) but it also contains trace amounts
of volatile organic compounds. From an engineering
perspective, the long-term performance of the modern
MSW landfill will be governed by the performance of a
system comprised of three primary subsystems: the
barrier system below the waste, the landfill operations,
and the landfill cover and gas collection system. To
provide long-term environmental protection, this system
must contain contaminants for what is called the
contaminating lifespan of the landfill (i.e. the period of
time during which the landfill will produce contaminants
at levels that could have unacceptable impacts if they
were discharged into the surrounding environment). For
large modern landfills this could be hundreds of years
(Rowe et al. 2005).

The release of contaminants contained in landfill
leachate can be reduced to environmentally acceptable
levels with a suitable barrier system below the waste that
includes a leachate collection system and a liner system.
The leachate collection system minimizes the driving
force for leachate escape (i.e. the leachate head acting on
the underlying liner). The liner system provides
resistance to the migration of contaminants both by the
pressure driven movement of leachate containing
contaminants (often referred to as leakage or advection)
and the concentration driven movement of contaminants
by a process of diffusion (those not familiar with the
terminology and contaminant transport processes should
refer to Rowe et al. 2004 for details). The leachate
collection system typically involves a series of
perforated pipes in a granular drainage layer together
with a means of removing the leachate that is collected.
The barrier system may involve a single liner or a double
liner with a secondary leachate collection system (also
called a leak detection system) between the two liners.

Referring to the present state of the art, the
theoretical modeling approaches applied to
Environmental Geotechnics can be split in two main
domains: flow-transport phenomena in porous media and
mechanical behavior of particulate media. Only in few
cases the two domains are fully coupled in order to set
up more sophisticated models that theoretically should
be able to result in a better representation of some actual
problems.
Practical application aspects within the
Environmental Geotechnics field require to model mass
and energy flows in order to be able to cope with
situations such as: 1) subsoil pollutant migration and
control, 2) assessment of short and long term
performances of mineral and polymeric barriers and 3)
polluted sites contaminant treatment and extraction.
On the other hand, the theoretical prediction of
particulate material mechanical behavior is often applied
to Environmental Geotechnics problems involving: 1)
waste landfill stability, management, extension and
reclamation, 2) re-use of waste and by-products and 3)
assessment of pollutant barriers performances subjected
to large stress/strain variations.
Just a very basic treatment of the main general
aspects related with mass and energy transport and
mechanical behavior of porous and particulate media
would require more than a textbook. Therefore, in the
following, after a very short review of the basic
framework and equations concerning the two aforementioned
main domains, a number of practical applications will be
considered as illustrative examples including: (1)
prediction of short and long term behavior of
geosynthetic clay liners (GCLs) for pollutants control;
(2) modeling of multiphase mass and energy flows for
speeding up contaminant extraction by electrical currents
and; (3) high vacuum; and (4) assessment of mechanical
behavior of lining systems on old landfill for allowing
side and vertical extensions.

Geosynthetic clay liners (GCLs) are factory
manufactured liners that consist of a thin layer of
bentonite (∼5-10 mm thick) that is either sandwiched
between two geotextiles or attached to a polymer
membrane and held together by needle-punching,
stitching or gluing with an adhesive. GCLs are
increasingly used in covers and bottom liners for
landfills because of their low hydraulic conductivity to
water (i.e. k typically ≤ 3.0⋅10-11m/s). The main
advantages of GCLs are the limited thickness, the
material quality assurance, the ease of installation, the
good compliance with differential settlements of
underlying soil or waste and the low cost (Bouazza,2002).
On the other hand, the limited thickness of this
barrier can produce vulnerability to mechanical accidents,
limited sorption capacity, and an increase of pollutant
diffusive transport if an underlying attenuation mineral
layer is not provided. Moreover, when exposed to water
solutions containing high ion concentrations or di-valent
cations, bentonite can undergo a significant increase of
the hydraulic conductivity.
The evaluation of GCL performances as pollutant
barriers needs an adequate theoretical approach for
modeling the simultaneous migration of water and
solutes through bentonite. Bentonite is a clay soil
containing typically at least 70% of the three layered
(2:1) clay mineral montmorillonite, which is
characterized by a very high total specific surface (∼760m2/g)
 and a negative electric charge. The ultra-fine pore
size (< 100 Å) of this clay soil and the electric
interaction between montmorillonite particles and ions in
pore solution determine macroscopic phenomena that

cannot be modeled on the basis of the advective-diffusive

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