There are various techniques to optimize either structural parameters, or structural controllers, but there are not many techniques that can simultaneously optimize the structural parameters and controller. The advantage of integrating the structural and controller optimization problems is that structure and controller interaction is taken into account in the design process and a more efficient overall design (lower control force/lighter weight) can be achieved, and also multidisciplinary design optimization can be performed. The down side is that the combined optimization problem is more difficult to formulate and solve, and computations are increased. This volume is a comprehensive treatment of dynamic analysis and control techniques in structural dynamic systems and the wide variety of issues and techniques that fall within this broad area, including the interactions between structural control systems and structural system parameters.

Soil-structure interaction is an area of major importance in geotechnical engineering and geomechanics Advanced Geotechnical Engineering: Soil-Structure Interaction using Computer and Material Models covers computer and analytical methods for a number of geotechnical problems. It introduces the main factors important to the application of computer methods and constitutive models with emphasis on the behavior of soils, rocks, interfaces, and joints, vital for reliable and accurate solutions. This book presents finite element (FE), finite difference (FD), and analytical methods and their applications by using computers, in conjunction with the use of appropriate constitutive models; they can provide realistic solutions for soil-structure problems. A part of this book is devoted to solving practical problems using hand calculations in addition to the use of computer methods. The book also introduces commercial computer codes as well as computer codes developed by the authors. Uses simplified constitutive models such as linear and nonlinear elastic for resistance-displacement response in 1-D problems Uses advanced constitutive models such as elasticplastic, continued yield plasticity and DSC for microstructural changes leading to microcracking, failure and liquefaction Delves into the FE and FD methods for problems that are idealized as two-dimensional (2-D) and three-dimensional (3-D) Covers the application for 3-D FE methods and an approximate procedure called multicomponent methods Includes the application to a number of problems such as dams , slopes, piles, retaining (reinforced earth) structures, tunnels, pavements, seepage, consolidation, involving field measurements, shake table, and centrifuge tests Discusses the effect of interface response on the behavior of geotechnical systems and liquefaction (considered as a microstructural instability) This text is useful to practitioners, students, teachers, and researchers who have backgrounds in geotechnical, structural engineering, and basic mechanics courses.

Over 140 experts, 14 countries, and 89 chapters are represented in the second edition of the Bridge Engineering Handbook. This extensive collection highlights bridge engineering specimens from around the world, contains detailed information on bridge engineering, and thoroughly explains the concepts and practical applications surrounding the subject. Published in five books: Fundamentals, Superstructure Design, Substructure Design, Seismic Design, and Construction and Maintenance, this new edition provides numerous worked-out examples that give readers step-by-step design procedures, includes contributions by leading experts from around the world in their respective areas of bridge engineering, contains 26 completely new chapters, and updates most other chapters. It offers design concepts, specifications, and practice, as well as the various types of bridges. The text includes over 2,500 tables, charts, illustrations, and photos. The book covers new, innovative and traditional methods and practices; explores rehabilitation, retrofit, and maintenance; and examines seismic design and building materials. The fourth book, Seismic Design contains 18 chapters, and covers seismic bridge analysis and design. What's New in the Second Edition: Includes seven new chapters: Seismic Random Response Analysis, Displacement-Based Seismic Design of Bridges, Seismic Design of Thin-Walled Steel and CFT Piers, Seismic Design of Cable-Supported Bridges, and three chapters covering Seismic Design Practice in California, China, and Italy Combines Seismic Retrofit Practice and Seismic Retrofit Technology into one chapter called Seismic Retrofit Technology Rewrites Earthquake Damage to Bridges and Seismic Design of Concrete Bridges chapters Rewrites Seismic Design Philosophies and Performance-Based Design Criteria chapter and retitles it as Seismic Bridge Design Specifications for the United States Revamps Seismic Isolation and Supplemental Energy Dissipation chapter and retitles it as Seismic Isolation Design for Bridges This text is an ideal reference for practicing bridge engineers and consultants (design, construction, maintenance), and can also be used as a reference for students in bridge engineering courses.

The finite element, an approximation method for solving differential equations of mathematical physics, is a highly effective technique in the analysis and design, or synthesis, of structural dynamic systems. Starting from the system differential equations and its boundary conditions, what is referred to as a weak form of the problem (elaborated in the text) is developed in a variational sense. This variational statement is used to define elemental properties that may be written as matrices and vectors as well as to identify primary and secondary boundaries and all possible boundary conditions. Specific equilibrium problems are also solved.
This book clearly reveals the effectiveness and great significance of the finite element method available and the essential role it will play in the future as further development occurs.

"Eco-efficient Construction and Building Materials" reviews ways of assessing the environmental impact of construction and building materials. Part one discusses the application of life cycle assessment (LCA) methodology to building materials as well as eco-labeling. Part two includes case studies showing the application of LCA methodology to different types of building material, from cement and concrete to wood and adhesives used in building. Part three includes case studies applying LCA methodology to particular structures and components.
Reviews ways of assessing the environmental impact of construction and building materialsProvides a thorough overview, including strengths and shortcomings, of the life cycle assessment (LCA) and eco-labeling of eco-efficient construction and building materialsIncludes case studies showing the application of LCA methodology to different types of building material, from cement and concrete to wood and adhesives used in building

"

The first of two books concentrating on the dynamics of slender bodies within or containing axial flow, "Fluid-Structure Interaction, Volume 1" covers the fundamentals and mechanisms giving rise to flow-induced vibration, with a particular focus on the challenges associated with pipes conveying fluid.

This volume has been thoroughly updated to reference the latest developments in the field, with a continued emphasis on the understanding of dynamical behaviour and analytical methods needed to provide long-term solutions and validate the latest computational methods and codes.

In this edition, Chapter 7 from Volume 2 has also been moved to Volume 1, meaning that Volume 1 now mainly treats the dynamics of systems subjected to internal flow, whereas in Volume 2 the axial flow is in most cases external to the flow or annular. "
Provides an in-depth review of an extensive range of fluid-structure interaction topics, with detailed real-world examples and thorough referencing throughout for additional detail. Organized by structure and problem type, allowing you to dip into the sections that are relevant to the particular problem you are facing, with numerous appendices containing the equations relevant to specific problems. Supports development of long-term solutions by focusing on the fundamentals and mechanisms needed to understand underlying causes and operating conditions under which apparent solutions might not prove effective.

"The author, George A. Martin, knows his subject, not only fence building but the farm and its requirements. He knows the stock: the unconfinable pig, the dexterous cow. He knows his materials, especially wood. I count twenty-one species of tree in the text, each especially suited for a particular application. He knows the value of work well done, done to last, and he aims to give value himself, in authorship as in the building of simple necessary structures."
from the Foreword by Castle Freeman

Project management lessons learned on the Big Dig, America's biggest megaproject, by a core member responsible for its daily operations

In "Megaproject Management," a central member of the Big Dig team reveals the numerous risks, challenges, and accomplishments of the most complex urban infrastructure project in the history of the United States. Drawing on personal experience and interviews with project engineers, executive oversight commission officials, and core managers, the author, a former deputy counsel and risk manager for the Big Dig, develops new insights as she describes the realities of day-to-day management of the project from a project manager's perspective.

The book incorporates both theory and practice and is therefore highly recommended to policymakers, academics, and project management practitioners. Focusing on lessons learned, this insightful coursebook presents the Big Dig as a massive case study in the management of risk, cost, and schedule, particularly the interrelation of technical, legal, political, and social factors. It provides an analysis of the difficulties in managing megaprojects during each phase and over the life span of the project, while delivering useful lessons on why projects go wrong and what can be done to prevent project failure. It also offers new ideas to enhance project management performance and innovation in our global society.

This unique guide: Defines megaproject characteristics and frameworksReviews the Big Dig's history, stakeholders, and governanceExamines the project's management scope, scheduling, and cost management--including project delays and cost overrunsAnalyzes the Big Dig's risk management and quality managementReveals how to build a sustainable project through integration and change introduction

The Finite Element Method: Its Basis and Fundamentals offers a complete introduction to the basis of the finite element method, covering fundamental theory and worked examples in the detail required for readers to apply the knowledge to their own engineering problems and understand more advanced applications.

This edition sees a significant rearrangement of the book s content to enable clearer development of the finite element method, with major new chapters and sections added to cover:

Weak forms

Variational forms

Multi-dimensional field problems

Automatic mesh generation

Plate bending and shells

Developments in meshless techniques

Focusing on the core knowledge, mathematical and analytical tools needed for successful application, "The Finite Element Method: Its Basis and Fundamentals" is the authoritative resource of choice for graduate level students, researchers and professional engineers involved in finite element-based engineering analysis.
A proven keystone reference in the library of any engineer needing to understand and apply the finite element method in design and development. Founded by an influential pioneer in the field and updated in this seventh edition by an author team incorporating academic authority and industrial simulation experience. Features reworked and reordered contents for clearer development of the theory, plus new chapters and sections on mesh generation, plate bending, shells, weak forms and variational forms."

This book is the fifth volume of the proceedings of the 4th GeoShanghai International Conference that was held on May 27 - 30, 2018. This volume, entitled "Tunneling and Underground Construction", covers the recent advances and technologies in tunneling and underground structure engineering. It presents the state-of-the-art planning philosophy, theories, experiments, methodologies and findings in the related areas. The importance of underground space utilization to the development of human society is also addressed. The challenges and future directions of underground engineering are highlighted. The topics include but are not limited to the tunneling and underground construction induced ground deformation, mechanical behaviors of segmental lining systems, tunneling in challenging situations, maintenance tactic and emergency counter-measures. The book may benefit researchers and scientists from the academic fields of tunneling and underground structure engineering as well as practical engineers from the industry. Each of the papers included in this book received at least two positive peer reviews. The editors would like to express their sincerest appreciation to all of the anonymous reviewers all over the world, for their diligent work.

Curing is one of those activities that every civil engineer and construction worker has heard of, but in reality does not worry about much. In practice, curing is often low on the list of priorities on the construction site, particularly when budgets and timelines are under pressure. Yet the increasing demands being placed on concrete mixtures also mean that they are less forgiving than in the past. Therefore, any activity that will help improve hydration and so performance, while reducing the risk of cracking, is becoming more important. Curing Concrete explains exactly why curing is so important and shows you how to best do it. The book covers: The fundamentals behind hydration How curing affects the properties of concrete, improving its long-term performance What curing technologies and techniques you can use for different applications How to effectively specify, provide, and measure curing in a project The author also gives numerous examples of how curing-or a lack of it-has affected concrete performance in real-world situations. These include examples from hot and cold climates, as well as examples related to high-performance concrete, performance parameters, and specifications and testing. Written for construction professionals who want to ensure the quality and longevity of their concrete structures, this book demonstrates that curing is well worth the effort and cost.

Bridges over Water places the study of transboundary water conflicts, negotiation, and cooperation in the context of various disciplines, such as international relations, international law, international negotiations, and economics. It demonstrates their application, using various quantitative approaches, such as river basin modeling, quantitative negotiation theory, and game theory. Case-studies of particular transboundary river basins, lakes, and aquifers are also considered.This second edition updates the literature on international water and in-depth analyses on political developments and cooperation between riparian states. With an appended chapter on principles and practices of negotiation, and a new case study on the La Plata Basin, this edition is a timely update to the field of transboundary water studies.

Identifying the age of a property is a fundamental step in understanding its form of construction and in being prepared to differentiate between the characteristic defects of that age of property and defects which are more unusual and may warrant particular care in investigation and assessment. This second edition of Inspections and Reports on Dwellings: Assessing Age updates the market context within which surveyors and valuers are now operating. In particular it has a new section on post-2000 properties, reflecting the profound impact of Government policies and environmental concerns on the modern urban landscape. The book is divided into thirteen age bands with over seventy color photographs of dwellings for each period. A commentary on each age band outlines the social, environmental and technical influences on properties being built at the time, helping to explain why they look as they do. A broad range of dwellings is covered: large and small, private and public sector, old and new, and particular features which help to place a dwelling within one of the defined periods are highlighted in comments on the photographs. This book is intended for all those engaged in inspecting dwellings, whether experienced, newly qualified or studying for appropriate qualifications to become members of professional institutions.

Modeling in Geomechanics Edited by Musharraf Zaman The University of Oklahoma, USA Giancarlo Gioda Politecnico di Milano, Italy John Booker University of Sydney, Australia Geomechanics is an interdisciplinary field involving the study of natural and man-made systems with emphasis on the mechanics of various interacting phenomena. It comprises numerous aspects of engineering and scientific disciplines, which share common bases in mathematics, mechanics and physics. In recent years, with the extraordinary growth of computing power and resources, progress in the generation of new theories and techniques for the analysis of geomechanics problems has far surpassed their actual use by practitioners. This has led to a gap between our ability to deal with complex, inter-disciplinary problems in geomechanics and the actual impact of these advances on engineering practice. This book contains contributions from an international group of accomplished researchers and practitioners from various branches of soil and rock engineering, and presents the latest theoretical developments and practical applications of modeling in geomechanics. Chapters are grouped into four main sections:
* Computational procedures
* Constitutive modeling and testing
* Modeling and simulation
* Applications
Efforts have been made to include recent developments and provide suggestions and examples as to how these can be applied in modeling actual engineering problems. Researchers, practitioners and students in geomechanics, mechanics of solids, soil and rock engineering will find this book an invaluable reference.

Essentials of Offshore Structures: Framed and Gravity Platforms examines the engineering ideas and offshore drilling platforms for exploration and production. This book offers a clear and acceptable demonstration of both the theory and application of the relevant procedures of structural, fluid, and geotechnical mechanics to offshore structures. It makes available a multitude of "solved problems" and "sample problems to solve" which give readers a strong understanding of the analysis and design of steel-framed and base-supported concrete gravity offshore structures. The book highlights sensible engineering applications for offshore structural design, research, and development; it can also be useful to those working in the design industry.

• The user will have a detailed overview of the various structures used in the offshore environment and the preliminary costing factors that will influence their choice for the site.
• Analytical principles emphasized in the book will help the user to clearly comprehend the various issues that need to be taken into account in the analysis and design of an offshore structure, using the API code.
• The book includes extensive worked-out problems and sample problems for use by the students and instructors, with a Solution Manual.
• The seabed pile/gravity foundation analyses and design are clearly outlined with their embedment characteristics and problems worked out.
• A global description of environmental forces has been given that includes those due to wave, wind, current, tides, earthquakes, ice floe/sheet action, and limit ice-load on Arctic structures.
• The book outlines the various factors that influence the material choice for offshore structures including fatigue and corrosion of the platforms in the ocean environment.

Separate chapters detail the factors that influence the pile embedment and concrete gravity foundation characteristics, material choice including fatigue and corrosion, estimation of ocean environmental forces that will be exerted on the offshore structures, and the analysis fundamentals that the reader needs to possess. The last two chapters give detailed insights into the analysis and design of framed and concrete gravity platform offshore structures using API code procedures. Overall, this book is a comprehensive presentation of the analysis and design of steel and concrete offshore structures.

Construction Economics provides students with the principles underlying the relationship between economic theory and the construction industry. Its new approach specifically examines the problems of securing sustainable construction and this fifth edition broadens the message to address the immediacy of the problems relating to the carbon-based world that we have constructed. Embracing the whole process of the construction life cycle, the new edition discusses the economic impact of the Covid pandemic on the industry and the broader implications of the promise to build back better. It also includes new coverage of the opportunities offered by technology, the establishment of higher standards to achieve greater energy efficiency and wellbeing, the adoption of the principles of a circular economy, the retrofit of existing buildings and the recycling of materials. New sections also highlight the methodology of the subject to identify the boundaries of construction economics and clarify what to expect and what can be achieved. As with previous editions, it retains a tried and tested format including: a clear and user-friendly style use of colour for emphasis regular summaries of key points a glossary of key terms extensive use of tables, figures and data readings from Construction Management and Economics tutorial questions to review each section research guidance reviews of useful websites. This invaluable textbook is essential reading across a wide range of disciplines. It provides the economic context to the relevance of sustainability and debates about climate change, highlighting the vital contributions that surveyors, contractors, project managers, engineers, architects and developers can offer to take it forward.

Developed to comply with the fifth edition of the AASHTO LFRD Bridge Design Specifications [2010]--Simplified LRFD Bridge Design is "How To" use the Specifications book. Most engineering books utilize traditional deductive practices, beginning with in-depth theories and progressing to the application of theories. The inductive method in the book uses alternative approaches, literally teaching backwards. The book introduces topics by presenting specific design examples. Theories can be understood by students because they appear in the text only after specific design examples are presented, establishing the need to know theories. The emphasis of the book is on step-by-step design procedures of highway bridges by the LRFD method, and "How to Use" the AASHTO Specifications to solve design problems. Some of the design examples and practice problems covered include: Load combinations and load factors Strength limit states for superstructure design Design Live Load HL- 93 Un-factored and Factored Design Loads Fatigue Limit State and fatigue life; Service Limit State Number of design lanes Multiple presence factor of live load Dynamic load allowance Distribution of Live Loads per Lane Wind Loads, Earthquake Loads Plastic moment capacity of composite steel-concrete beam LRFR Load Rating Simplified LRFD Bridge Design is a study guide for engineers preparing for the PE examination as well as a classroom text for civil engineering students and a reference for practicing engineers. Eight design examples and three practice problems describe and introduce the use of articles, tables, and figures from the AASHTO LFRD Bridge Design Specifications. Whenever articles, tables, and figures in examples appear throughout the text, AASHTO LRFD specification numbers are also cited, so that users can cross-reference the material.

- Presents a new geometric method of structural analysis - Offers new, geometric and visually engaging Muller-Breslau Method tools - An essential resource for architecture and engineering students and instructors that is novel and geometric - Includes over 300 black and white illustrations - Includes open-ended, three dimensional student exercises throughout

Up-to-date coverage of fundamental seepage principles, closed-form solutions, and applications

Seepage in Soils combines a broad range of applications with rigorous quantitative skills to give insight into the fundamental principles and mathematical solutions of seepage. A wealth of closed-form analytical solutions are provided to solve a variety of problems, minimizing the use of computer software and numerical models.

Completely up to date with coverage of new developments in separators, filters, and geosynthetics, this textbook includes exercises in seepage quantification, seepage forces, and dewatering. Complete coverage is useful in all subdivisions of civil engineering. Material is divided into three modules:

• Principles and mathematical solutions
• Filters and drainage layers
• Applications

Only a nominal background in mathematics and soil mechanics is required for Seepage in Soils to serve as an invaluable resource for civil engineering students across many subdisciplines. In addition, it serves as a useful reference for geotechnical, environmental, and structural engineers, hydrologists, geologists, agronomists, and soil scientists.

Channelized Rivers Perspectives for Environmental Management Andrew Brookes Environmental Consultant, Reading, UK For centuries engineers have modified river channels in order to control floods, drain land, prevent erosion and improve navigation. The natural shape of many rivers has been dramatically changed, often with dire environmental consequences. This book demonstrates the role fluvial geomorphology can play in the design of river channels, both to lessen environmental impact and to enhance the success of channelization schemes. It considers the physical and biological impacts of channelization, the repercussions downstream and in the adjacent floodplain. Revised procedures and designs are proposed which minimize harsh environmental impacts. The interdisciplinary approach of the book offers river managers the opportunity to make more environmentally sensitive decisions in the course of their work. The book will be of great interest to geomorphologists, biologists and civil engineers working in the water industry.

When finding another location, redesigning a structure, or removing troublesome ground at a project site are not practical options, prevailing ground conditions must be addressed. Improving the ground-modifying its existing physical properties to enable effective, economic, and safe construction-to achieve appropriate engineering performance is an increasingly successful approach. This third edition of Ground Improvement provides a comprehensive overview of the major ground improvement techniques in use worldwide today. Written by recognized experts who bring a wealth of knowledge and experience to bear on their contributions, the chapters are fully updated with recent developments including advancements in equipment and methods since the last edition. The text provides an overview of the processes and the key geotechnical and design considerations as well as equipment needed for successful execution. The methods described are well illustrated with relevant case histories and include the following approaches: Densification using deep vibro techniques or dynamic compaction Consolidation employing deep fabricated drains and associated methods Injection techniques, such as permeation and jet grouting, soil fracture grouting, and compaction grouting New in-situ soil mixing processes, including trench-mixing TRD and panel-mixing CSM approaches The introductory chapter touches on the historical development, health and safety, greenhouse gas emissions, and two less common techniques: blasting and the only reversible process, ground freezing. This practical and established guide provides readers with a solid basis for understanding and further study of the most widely used processes for ground improvement. It is particularly relevant for civil and geotechnical engineers as well as contractors involved in piling and ground engineering of any kind. It would also be useful for advanced graduate and postgraduate civil engineering and geotechnical students.

Pile Foundations are an essential basis for many structures. It is vital that they be designed with the utmost reliability, because the cost of failure is potentially huge. Covering a whole range of design issues relating to pile design, this book presents economical and efficient design solutions and demonstrates them using real world examples. Coverage includes nonlinear response of single piles to vertical or torsional loading and to cyclic lateral loading, as well as prediction of nonlinear response of lateral pile groups, vertically loaded pile groups and the design of slope stabilising piles. Most solutions are provided as closed-form expressions.

Theory and Practice of Pile Foundations is:

• illustrated with case studies
• accompanied by practical applications in Excel and MathCad
• the first book to incorporate nonlinear interaction into pile design.

A valuable resource for students of geotechnical engineering taking courses in foundations and a vital tool for engineers designing pile foundations.

Why is knowledge of soil stress and deformation state important for off-road locomotion? How do you measure soil stress and deformation under wheel loads? What are the actual values of stresses and deformation in soil or snow under a passing wheel? Providing answers to these questions and more, Dynamics of Wheel-Soil Systems: A Soil Stress and Deformation-Based Approach is a practical reference for anyone who works with experiment design and data analysis of soil stress and deformation measurements under vehicle load. Based on the author's 15 years of experience in field experimentation on wheel-soil dynamics, the book describes methods and devices for soil stress and deformation measurements and presents numerical data from full-scale field experiments. These methods offer practical solutions to methodological problems that may arise during the design and preparation of field experiments. Provides technical information on measuring, modeling, and optimizing off-road vehicle traction-including a novel method for describing off-road traction Provides rare experimental data on soil stress and deformation under a variety of wheeled and tracked vehicles Supplies solutions for designing, building, and using soil or snow pressure transducers and sensors Compiles original experimental data on soil degradation due to agricultural machinery traffic and soil compaction Explains how to create dynamic models of wheel-soil systems based on experimental data A valuable reference on an important area of terramechanics, this book shows how to analyze and model wheel-soil interactions to create more effective designs for a range of vehicle types.

This book is an introduction to numerical analysis in geomechanics and is intended for advanced undergraduate and beginning graduate study of the mechanics of porous, jointed rocks and soils. Although familiarity with the concepts of stress, strain and so on is assumed, a review of the fundamentals of solid mechanics including concepts of physical laws, kinematics and material laws is presented in an appendix. Emphasis is on the popular finite element method but brief explanations of the boundary element method, the distinct element method (also known as the discrete element method) and discontinuous deformation analysis are included. Familiarity with a computer programming language such as Fortran, C++ or Python is not required, although programming excerpts in Fortran are presented at the end of some chapters. This work begins with an intuitive approach to interpolation over a triangular element and thus avoids making the simple complex by not doing energy minimization via a calculus of variations approach so often found in reference books on the finite element method. The presentation then proceeds to a principal of virtual work via the well-known divergence theorem to obtain element equilibrium and then global equilibrium, both expressed as stiffness equations relating force to displacement. Solution methods for the finite element approach including elimination and iteration methods are discussed. Hydro-mechanical coupling is described and extension of the finite element method to accommodate fluid flow in porous geological media is made. Example problems illustrate important concepts throughout the text. Additional problems for a 15-week course of study are presented in an appendix; solutions are given in another appendix.

Major events-notably the Broadgate fire in London, New York's World Trade Center collapse, and the Windsor Tower fire in Madrid-as well as the enlightening studies at the Cardington fire research project have given international prominence to performance-based structural fire engineering. As a result, structural fire engineering has increasingly attracted the interest not only of fire and structural engineers but also of researchers and students. And studies in recent years have generated a vast number of findings. Performance-Based Fire Engineering of Structures summarizes the latest knowledge on performance-based approaches to structural fire engineering, enabling readers to critically assess research in the field. Whereas most recent books have been mainly concerned with dissemination of principles encapsulated in established codes of practice such as the Eurocodes, this work addresses in depth: Global structural behaviour and modelling Progressive collapse of structures in fire and the importance of connection robustness The integrity of compartmentation in fire Structural fire engineering under realistic fire conditions and its implications for material properties The limitations of research results and design methods The unexploited potential for advanced fire engineering design This authoritative book draws on the work of internationally active researchers who were core members of the European Network project's COST C26 working group on fire resistance. It helps readers develop a thorough understanding of how to use advanced fire engineering design to improve structural safety and reduce construction costs.