STRUCTURAL CROSS-SECTIONS STRUCTURAL CROSS-SECTIONS Analysis and Design NAVEED ANWAR Asian Institute of Technology Thailand FAWAD AHMED NAJAM Asian Institute of Technology Thailand AMSTERDAM(cid:129)BOSTON(cid:129)HEIDELBERG(cid:129)LONDON NEWYORK(cid:129)OXFORD(cid:129)PARIS(cid:129)SANDIEGO SANFRANCISCO(cid:129)SINGAPORE(cid:129)SYDNEY(cid:129)TOKYO Butterworth-HeinemannisanimprintofElsevier Butterworth-HeinemannisanimprintofElsevier TheBoulevard,LangfordLane,Kidlington,OxfordOX51GB,UnitedKingdom 50HampshireStreet,5thFloor,Cambridge,MA02139,UnitedStates Copyrightr2017ElsevierInc.Allrightsreserved. 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BritishLibraryCataloguing-in-PublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary LibraryofCongressCataloging-in-PublicationData AcatalogrecordforthisbookisavailablefromtheLibraryofCongress ISBN:978-0-12-804443-8 ForInformationonallButterworth-Heinemannpublications visitourwebsiteathttps://www.elsevier.com Publisher:JoeHayton AcquisitionEditor:KenMcCombs EditorialProjectManager:PeterJardim ProductionProjectManager:MohanaNatarajan Designer:VictoriaPearson TypesetbyMPSLimited,Chennai,India DEDICATION This book is dedicated to our desire for understanding the physical world around us. ABOUT THE AUTHORS Naveed Anwar is Executive Director/CEO of AIT Solutions (AITS), Director of Asian Center for Engineering Computations and Software (ACECOMS), and an affiliated member of the Structural Engineering Faculty at the Asian Institute of Technology (AIT), Thailand. Dr. Anwar received his BSc degree in Civil Engineering from the University of Engineering & Technology, Lahore, Pakistan, and both masters and PhD degrees in Structural Engineering from Asian Institute of Technology, Bangkok, Thailand. He teaches academic courses and supervises research for masters and PhD students at AIT related to reinforced concrete mechanics, design of tall buildings, and bridge structures. Dr. Anwar has an experience of over 35 years while completing hun- dreds of projects related to structural modeling, analysis and design of buildings and bridges, construction project management, structural health assessment, and other related areas. His main area of expertise is the per- formance-based design and evaluation of new and existing structures, especially high-rise buildings. He has also conducted hundreds of profes- sional trainings, workshops, and seminars, attended by thousands of pro- fessionals in more than 15 countries. He is also proficient in the development of computer software for structural engineering applications, including general structural analysis, earthquake resistant design, structural detailing, and is the author of several software and computing tools. Fawad A. Najam received his BS degree in Civil Engineering from the University of Engineering and Technology (UET, Taxila), Pakistan, and MS degree in Structural Engineering from the National University of Sciences and Technology (NUST), Islamabad, Pakistan. Currently, he is associated with Department of Structural Engineering at the Asian Institute of Technology (AIT) and AIT Solutions (AITS) in Thailand, and has received PhD in Structural Engineering. He is also a member of the Structural Engineering Faculty at the National University of Sciences and Technology (NUST), Islamabad, Pakistan. His areas of interest include structural dynamics, seismic performance evaluation of high-rise buildings, and structural engineering software development. His research encompasses various practical issues related to seismic design and analysis procedures used in current structural xi xii AbouttheAuthors engineering practice. He has also participated actively in various research and academic projects, while working at various appointments including faculty positions, civil/structural engineering consultant, and research associate at various organizations in Pakistan and Thailand. PREFACE The cross-sections and their properties are a basic component in almost all aspects of analysis and design of structures. In fact, the primary objec- tive of an efficient design process is to proportion the cross-sections of structural elements to resist the applied load effects and actions. Also, the preliminary dimensions and properties of cross-sections are required to start the modeling and analysis process for the structural system, to pre- pare initial cost estimates and even to refine the basic space planning and utilization schemes. It is the key role cross-sections play in overall struc- tural behavior, analysis, and design, which motivated authors to write a book focusing on their basic understanding and behavior, with an empha- sis on computer applications. The main objective of this book is to provide a consolidated and con- sistent information, insight and explanation of various aspects of cross- section behavior and design, irrespective of, but with due consideration to different materials. It discusses theoretical formulations, practical analy- sis, design computations, and computer applications for determination of cross-sectional response. The main areas of focus and distribution of chap- ters is as follows: 1. The overall view of cross-section behavior with respect to various aspect of structural mechanics and computing is covered in the Chapter 1, Structures and Structural Design. It discusses the basic con- cepts and procedures for structural analysis and design, including a dis- cussion of the development of structural design philosophy and progression of design approaches, terminating with a discussion of performance-based design. The chapter also discusses the basic con- cepts of stiffness, nonlinearity of relationships between deformations and corresponding actions, etc., and lays the foundation for the remaining chapters in the book. 2. The meaning and computation of cross-section properties, from A(cid:1)Z (areatoplasticsectionmodulus)arecoveredinChapter2,Understanding Cross-Sections. It provides the basis for the study and understanding of the structural cross-sections. The anatomy and hierarchy of the cross- section shapes, types, and the materials they are made up, is extensively covered. Several methods for defining the cross-sections, including parametric and general procedures are discussed. The main focus is on computing the geometric properties of various section shapes, using xiii xiv Preface closed-form solutions as well as more general polygon and mesh-based procedures are discussed. In addition to the formulae to compute the properties, a discussion on the significance of various properties helps to improve the cross-section behavior computer-based methods and several solved examples are included followed by problem for readers to try and explore.Thechapter makesuseofextensiveillustrationsanddiagrams. 3. The meaning and calculation of stress-resultants using a unified and integratedapproacharecoveredinChapter3,Axial-FlexuralResponse of Cross-Sections. This treatment of cross-sectional behavior is unique and not covered in most of the books on this subject. A set of general equation as well as computation procedure is presented to determine the capacity interaction surface of generalized cross-section made up of anynumberandconfigurationofmaterials.Severalsolvedexamplesare presented, together with flow charts to demonstrate the code-based proceduresfordesignofbeam-columnsections. 4. The shear and torsion stress distribution and design calculations for rein- forced concrete sections are covered in Chapter 4, Response and Design for Shear and Torsion. Several detailed flow charts are included to dem- onstrate the procedures used in ACI, BS, and Euro codes for design of cross-sectionsubjectedtoshearandtorsion,followedbysolvedexamples. 5. Thedesignofcolumncross-sections,slendernesseffects,buckling,andrel- evant behavioral aspects of columns are covered in Chapter 5, Response andDesignofColumnCross-Sections.Italsodiscussestheroleofbound- ary conditions on slenderness and provides guidelines about when and howsecond-ordereffectscanbeconsideredindesignprocessforcolumns. ItprovidesanoverviewofcolumndesignapproachesasprescribedinACI and BS codes and various practical design considerations and guidelines forproportioninganddetailingofRCcolumnsarealsoincluded. 6. The ductility considerations, confinement of reinforced concrete sections, and related issues for cross-section analysis and design are covered in Chapter 6, Ductility of Cross-Sections. The definition and development of action-deformation curves especially moment(cid:1)curvature ðM2φÞ curve is discussed extensively. The pro- cedure to generate the moment(cid:1)curvature curve, using the general formulation of axial(cid:1)flexural response developed in Chapter 3, is demonstrated. Various factors such as confinement, rebar distribution and axial load effect on the ductility are also shown through examples. 7. Thereviewofvarioustechniquesandtechnologiestoretrofitthecross- sections are covered in Chapter 7, Retrofitting of Cross-Sections. The Preface xv methods to calculate the capacity of retrofitted cross-sections using the formulations presented in Chapter 2, Chapter 3, and Chapter 4, are presented. Evaluation of sections subjected to high temperatures is also discussedindetail. 8. The discussion about various latest software and applications for computer-aided analysis of cross-sections are covered in Chapter 8, Software Development and Application for the Analysis of Cross- Sections. A brief introduction of CSiCOL (a comprehensive software package for the analysis and design of reinforced and composite col- umn sections) is also included. This chapter also introduces various new ideas and scopes related to development of mobile applications for structural analysis on both Android and iOS platforms. Various applications of cloud computing and component-based software engineering in analysis and design of structures, are also introduced. Over last two decades, the senior author has had the opportunity to work with and contribute entirelyor partially to the development of soft- ware tools dealing with the behavior and design of cross-sections and can be used in conjunction with the material presented in this book for prac- tical applications. Some of these include: 1. Structural Design Library, SDL-1, by Technosoft Computer Applications, Lahore, Pakistan, (1993). 2. Structural Designers Library, SDL-2, by Asian Center for Engineering Computations and Software ACECOMS, Asian Institute of Technology, Thailand, (1996). 3. General Engineering Assistant and Reference, GEAR, by Asian Center for Engineering Computations and Software, ACECOMS, Asian Institute of Technology, Thailand, (1997). 4. RISA Section, by RISATechnologies, California, USA (2000). 5. CSI Section Builder, by Computers and Structures, Inc. (CSi), Berkeley, California, USA, (2001). 6. CSiCOL, by Computers and Structures, Inc. (CSi), California, USA, (2008). The information presented in this book is derived and based on the development of these software, and the senior author gratefully acknowl- edges the contribution of the organizations who released these software for their support, encouragement, and permission to use some of the material. The readers of this book can be the senior undergraduate stu- dents in civil engineering, graduate students in structural engineering, and practicing structural engineers, interested in developing the basic xvi Preface understanding of the behavior of cross-sections. It can also be a reference for those desiring to develop or understand the software tools for cross- section analysis. This book is not intended to cover the conventional lit- erature review, or duplication of information readilyavailable in textbooks or reference books. It will also not cover the derivation and proofs of equations and formulae, instead, adequate references have been included for readers interested in these aspects. The readers of this book are encouraged to visit the web site www. structuralengineering.info to get additional and updated information related to the material presented in this book. The readers are also wel- come to contact the authors directly for their comments and queries regarding the behavior of cross-sections, their modeling, analysis, and design. Naveed Anwar [email protected] [email protected] Fawad A. Najam [email protected] [email protected] November 2016