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CE72.52 - Lecture1 - Introduction

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CE72.52 - Advanced Concrete Structures - Lecture1 - Introduction

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CE72.52 - Lecture1 - Introduction

  1. 1. 1 CE 72.52 Advanced Concrete Lecture 1: Introduction Naveed Anwar Executive Director, AIT Consulting Director, ACECOMS Affiliate Faculty, Structural Engineering, AIT August - 2015
  2. 2. The Role of Structural Engineers • To help in the creation of the safe built environment • Nothing can function, if structural engineers do not do their job well • Every other professional “Depends” on the role of structural engineers 2
  3. 3. All systems absolutely need Structures • Transportation systems • Telecommunication systems • Electricity and power systems • Water supply, waste water systems • Irrigation and agricultural systems • Mining, oil, gas, offshore platforms • Industrial plants, piping and process • Housing, commercial Businesses • Public Buildings 3
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  17. 17. 17 A MUST read for structural Engineers
  18. 18. Structural Engineering Spectrum 18 Activity Conception – Analysis – Design – Detailing ... Structure Buildings – Bridges – Trusses – Shells – Towers ... Code American – British – European – Japanese ... Material Concrete – PSC – Steel – Timber ... Model 2D Frame/Truss – 3D Frame/Truss – Full 3D FEM .... Analysis Linear Static – NL Static – Linear Dynamic – Large Disp. .... Solution Equation Solution – Finite Elements – Programming ... Advanced Concrete l Dr. Naveed Anwar
  19. 19. Structural Design Office: Activities 19 Design Management Structural Designer Office Management Coordination Client Dealing Principle Conception Detailing Design Analysis Costing Advanced Concrete l Dr. Naveed Anwar
  20. 20. CAD in Structural Engineering 20 Conception Analysis Design Detailing Integrated Expert Systems Others Advanced Concrete l Dr. Naveed Anwar
  21. 21. Reinforced Concrete Building Elements 21 Advanced Concrete l Dr. Naveed Anwar
  22. 22. Reinforced Concrete Building Elements 22 Advanced Concrete l Dr. Naveed Anwar Reference: James G. Macgregor Reinforced Concrete: Mechanics and Design, 3rd Edition.
  23. 23. Advanced Concepts and Topics • Go before and beyond the “Code” • Integrated, Unified and Generalized approaches • Main Topics 1. Material Behavior (Stress-strain, creep, shrinkage etc.) 2. Section Behavior and Design (flexure, shear, torsion) 3. Member Behavior and Design (Slabs, Beams, Columns) 4. Deep and Special Members (Strut and Tie, Deep beams, shear walls) 5. Joints and Connections 6. Material, Section and Member Ductility 7. Seismic Detailing 8. Pre-stressed Concrete 23Advanced Concrete l Dr. Naveed Anwar
  24. 24. Assignment – 1 (Previous year) • Create a map between structural engineers role and as many other disciplines and humanity needs as possible • (Hint : Use Mind Maps) 24
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  33. 33. Assignment – 1 (This year) • List Top Ten Structural Engineers of All times • Picture, name, year, country • Main projects, achievements 33
  34. 34. The Hierarchy of Structures and its Components • Physical Structures • When applied to the physical and the built environment, the term Structure means an assemblage of physical components and elements, each of which could further be a structure itself, signifying the complexity of the system 34
  35. 35. Basic Member Types and Forms 35
  36. 36. Characterization of Structures • Based on the member types, the structures can be broadly categorized as • Cable structures • Skeletal structural • Spatial structures • Solid structures and • A combination of these 36
  37. 37. The Structural System 37 pv Advanced Concrete l Dr. Naveed Anwar EXCITATION Loads Vibrations Settlements Thermal Changes RESPONSES Displacements Strains Stress Stress Resultants STRUCTURE
  38. 38. The Structural Elements 38Advanced Concrete l Dr. Naveed Anwar
  39. 39. Member Cross-sections Advanced Concrete l Dr. Naveed Anwar 39 • Cross-sections are generally associated with line type or beam type members, where the length is much longer than the other dimensions • The design of a line type member often means the design of its cross-section, which means the selection of appropriate dimensions, proportions and materials used at the cross- section level.
  40. 40. The Structural Materials • Concrete • Reinforcing Steel • Pre-stressing Steel • Hot Rolled Structural Steel • Cold Formed Structural Steel • Aluminum other metals • Structural Timber Advanced Concrete l Dr. Naveed Anwar 40
  41. 41. The Need for Analysis • We need to determine the Response of the Structure to Excitations so that: • We can ensure that the structure can sustain the excitation with an acceptable level of response 41 Advanced Concrete l Dr. Naveed Anwar Analysis Design
  42. 42. Analysis of Structure 42 0 vx zzyyxx p zyx       pv Real Structure is governed by “Partial Differential Equations” of various order Advanced Concrete l Dr. Naveed Anwar Direct Solution is only Possible for: • Simple Geometry • Simple Boundary • Simple Loading
  43. 43. Need for Structural Model 43 pv EXCITATION Loads Vibrations Settlements Thermal Changes RESPONSES Displacements Strains Stress Stress Resultants STRUCTURE STRUCTURAL MODEL Advanced Concrete l Dr. Naveed Anwar
  44. 44. Proportioning for Safety • Prime Concern: “Balance External Actions with Internal Stress Resultants with adequate margin for safety” Sd > = FOS * Fa • And Check for • Deflections, Deformations, Vibrations, Crack Width • Fire Protections, Permeability, Chemical Attacks • Ductility and Other special considerations 44Advanced Concrete l Dr. Naveed Anwar
  45. 45. Proportioning for Safety 45 S > A S FOS A Working Strength Design S FOS A FOS s L  •Ultimate Strength Design •Limit State Design •Partial FOS Design S A FOS  Load Factor Design • A = Actions due to loads • S = Strength of member • FOS = Factor of safety Advanced Concrete l Dr. Naveed Anwar
  46. 46. 46 Various Types of Structures: Special Design Procedures and Concepts for each type and material
  47. 47. Structural Design Process and Concept 47
  48. 48. Design Philosophy and Process “Structural Design is the process of proportioning the structure to safely resist the applied forces in the most cost effective and friendly manner” 48Advanced Concrete l Dr. Naveed Anwar
  49. 49. Overall Design Process • Conception • Modeling • Analysis • Design • Detailing • Drafting • Costing 49 “Integrated Design Process” Advanced Concrete l Dr. Naveed Anwar
  50. 50. Structural Design Process 50Advanced Concrete l Dr. Naveed Anwar
  51. 51. The Response and Design 51Advanced Concrete l Dr. Naveed Anwar
  52. 52. From “Loads” to “Design Actions” 52Advanced Concrete l Dr. Naveed Anwar
  53. 53. Structural Analysis vs Design Structural Analysis • Fairly General, Unified (FEM, BEM ...) • Output: Element/ Member Actions, Displacements ... Structural Design • Structural Material (RC, PSC, HRS, CFS, timber ... ) • Design Code (ACI, BS Codes, EuroCode, JIS ... ) • Design Approach (working stress, ultimate strength, limit state ... ) • Structural Members (beams, columns, slabs, footings ... ) • Local Construction Techniques and Practices • Output: Element/ Member Cross- section, Reinforcement ... 53Advanced Concrete l Dr. Naveed Anwar
  54. 54. Structural Analysis vs Design Advanced Concrete l Dr. Naveed Anwar 54
  55. 55. Loads and Stress Resultants 55Advanced Concrete l Dr. Naveed Anwar
  56. 56. Various Methods of Structural Designs 56Advanced Concrete l Dr. Naveed Anwar
  57. 57. Various Methods of Structural Design • Working Stress Design • Allowable Stress Design (ASD) • Working Stress Design (WSD) • Load Factor Design • Ultimate Strength Design • Ultimate Strength Design (USD) • Strength Design (SD) • Load and Resistance Factor Design (LRFD) • Performance Based Design • Pushover Analysis • Capacity Based Design 57Advanced Concrete l Dr. Naveed Anwar
  58. 58. From Serviceability to Performance 58  Allowable material  Control on deformation limits for design loads  Material failure criteria  Section capacity for factored loads  Ductility considerations  Deformation capacity  Load Capacity at large deformations  Extraordinary load considerations Serviceability Ability Strength Design Performance Design Advanced Concrete l Dr. Naveed Anwar
  59. 59. From Serviceability to Performance • Satisfying one design level does not ensure that other design levels will be satisfied • Serviceability design only ensures that deflections and vibrations etc. for service loads are within limits but says nothing about strength • Strength design ensures that a certain factor of safety against overload is available within a member or a cross- section but says nothing about what happens if load exceeds design level • Performance design ensures that structure as a whole reaches a specified demand level. Performance design can include, both service and strength design levels 59Advanced Concrete l Dr. Naveed Anwar
  60. 60. Design Philosophies and Methods 60Advanced Concrete l Dr. Naveed Anwar
  61. 61. Limit State Design Concept 61 Types of Limit State Description Ultimate Limit states • Loss of equilibrium • Rupture • Progressive Collapse • Formation of plastic mechanism • Instability • Fatigue Serviceability limit states • Excessive deflections • Excessive crack width • Undesirable Vibration Special limit states Due to abnormal conditions and abnormal loading such as • Damage or collapse in extreme earthquakes • Structural effects of fire, explosion • Corrosion or deterioration Advanced Concrete l Dr. Naveed Anwar
  62. 62. Limit State Design Concept • Limit state design involves • Identification of all potential modes of failure (i.e. identify significant limit states • Determination of acceptable levels of safety against occurrence of each limit state • Consideration by the designer of significant limit states 62
  63. 63. Limit State Design Concept Safety Factors • Material safety Factor γm • Member Factor γb • Load Factor γf • Structural Analysis Factor γa • Structure Factor γi 63
  64. 64. Section Design Process 64 Characteristic value of material basic strength Design Strength Design member capacity Characteristic value of Load Design load Design member capacity Ym Yb Yf Ya Verification Yi Advanced Concrete l Dr. Naveed Anwar
  65. 65. Limit State Design Concept 65 Material/Stress Type γm Reinforcement 1.15 Concrete in flexure or axial load 1.50 Concrete shear strength without shear reinforcement 1.25 Concrete bond strength 1.40 Concrete other >1.50 Values of γm (BS 8110) Advanced Concrete l Dr. Naveed Anwar
  66. 66. Limit State Design Concept 66 Load Combination Load Type Dead Load Imposed Load Wind Adverse Beneficial Adverse Beneficial Dead and Imposed 1.4 1 1.6 0 - Dead and wind 1.4 1 - - 1.4 Dead , wind and imposed 1.2 1.2 1.2 1.2 1.2 Design Load = γf x Characteristic Load Values of γm (BS 8110) Advanced Concrete l Dr. Naveed Anwar
  67. 67. What is Advanced in this course? 67Advanced Concrete l Dr. Naveed Anwar
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