CEE 465 class notes Abrams - CEE 465-C DESIGN OF STRUCTURAL SYSTEMS Instructor Dr Daniel P Abrams Willett Professor of Civil Engineering PhD PE 2118

CEE 465 class notes Abrams - CEE 465-C DESIGN OF STRUCTURAL...

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Unformatted text preview: CEE 465-C DESIGN OF STRUCTURAL SYSTEMS Instructor: Dr. Daniel P. Abrams, Willett Professor of Civil Engineering, PhD, PE 2118 Newmark Laboratory office phone: (217) 333-0565 cell phone: (217) 649-0334 email: [email protected] Grader: Jessica Reifschneider email: [email protected] Fall 2015 Class Location and Time: Room 2311 Newmark Civil Engineering Laboratory, 10:00-11:50am MW Prerequisite: CEE 360; and CEE 460 or CEE 461 with concurrent registration in the other Credit: 3 undergraduate hours, no graduate credit Internet Access: Information on the course can be viewed and/or downloaded from a class website located on the Illinois Compass system under . The website should be visited frequently to obtain latest versions of classnotes, homework assignments and their solutions, exam solutions, project information, reference materials and spreadsheets. Synopsis: The goal of the course is to develop skills and knowledge of how structural systems are designed and constructed. Course material encompasses the entire structural design process including definition of functional requirements, selection of structural scheme, formulation of design criteria, preliminary and computer-aided proportioning, and analysis of performance, cost, and value. The course is heavily dependent on concepts and technical information presented in previous courses on structural analysis and design of concrete and steel structures. Design examples, homework and exam problems and a comprehensive semester project help to strengthen the students’ aptitude and confidence for designing structural systems. Presentation of course material is given in a seminar context with students participating in a studio environment. An actual building is used as a sample structural system with teams of students completing and presenting its design for the semester project. Students are guided through design methods, codes and documents reflecting an actual design office experience. The course is also intended to encourage the student’s progress in the development of engineering judgment and philosophy. Required Texts: 1. Classnotes for CEE 465: Design of Structural Systems, D.P. Abrams. Available from CEE Copy Shop, 1st Floor, Newmark CE Laboratory 2. Recommended references on reserve in the Grainger Library and on the Compass site. Homework Problems: Homework problems will be assigned every week based on lecture material. Most of the problems will be referenced to elements of the semester project and will be in the form of staged submittals done by individuals and teams. Semester Project: A multistory building will be designed for gravity and lateral wind and earthquake loadings. The project will consist of formulation of design criteria, development of specifications and design drawings and supporting calculations. The project will include coverage of all course topics and will be done as a team effort. Teams will submit their project, make a verbal presentation to the class and be assigned a common grade. Midterm and Final Exams: The midterm exam will be given on Wednesday, October 7 and will be given for the full duration of the class meeting time. A final exam will be given on Monday, December 14 from 8:00am to 11:00am. Exams will be closed book, however, a single sheet of handwritten notes can be brought to the midterm exam, and two sheets of notes can be brought to the final exam. Grading: problem assignments: 15%; project: 25%; midterm exam: 25%; final exam: 35% 
 CEE 465 DESIGN OF STRUCTURAL SYSTEMS Fall 2015 Class Date Topics 1. 8-24-15 SAP Modeling 2. 8-26-15 3. 8-31-15 Introduction/The Design Process 1-2 4. 9-2-15 Gravity Loads 3 9-7-15 Labor Day 5. 9-9-15 Simple Column Design 3 6. 9-14-15 Structural Layout 4 7. 9-16-15 Concrete Slab Design 5 8. 9-21-15 Metal Deck Design 5 9. 9-23-15 Beam Loadings 6 10. 9-28-15 Concrete Beam Design 6 11. 9-30-15 Composite Beam Design 6 12. 10-5-15 Frame Design for Gravity Loads 6 13. 10-7-15 Midterm Exam 14. 10-12-15 Steel Column Base Plates 7 15. 10-14-15 Lateral Loads: Wind/Seismic 8/9 16. 10-19-15 “ “ “ 17. 10-21-15 “ “ “ 18. 10-26-15 19. 10-28-15 “ “ “ “ 20. 11-2-15 “ “ “ “ 21. 11-4-15 “ “ “ “ 22. 11-9-15 23. 11-11-15 24. 11-16-15 25. 11-18-15 “ Module 14 “ 9 Design of Lateral Systems Lateral Drift of Systems “ 10 11 “ Foundations 12 “ Thanksgiving Break 26. 11-30-15 Building Information Modeling 27. 12-2-15 Review and Team Meetings 28. 12-7-15 Team Project Presentations 29. 12-9-15 12-14-15 “ “ “ Final Exam, 8:00am – 11:00am 13 
 CEE 465 Design of Structural Systems (1) Introduction Structural Engineering Philosophy Engineering can be simple with a knowledge of basic concepts*, a mastering of skills through experience, an intellectual curiosity and a creative mind. D.P. Abrams *This course provides this. 1-2 CEE 465 Design of Structural Systems Course Outline 1. 2. Introduction The Design Process 3.  4.  Gravity Loads – Simple Column Design Structural Layout 4. Concrete Slabs & Metal Deck 5. 6. Concrete Beam Design Composite Beam Design 7. 8. Steel Column Base Plates Lateral Forces 9. Lateral Systems: Frames, Walls, Bracing 10. 11.  Lateral Deflections Foundations 12.  BIM 1-3 Course Ideals •  Capstone design course. •  •  •  •  •  •  •  •  Integrate knowledge from prior courses. Multistory building design. Project emphasis. Systems vs. Components Team coordination. Studio vs. classroom settings. Skill development vs. information transfer. Hand calculations vs. computational methods. 1-4 CEE 465 Design of Structural Systems Parts vs. Systems Design of individual beams, columns or walls is only as good as the distribution of forces to them. Structural response and integrity is more dependent on system configuration than on strength or stiffness of individual members. System concepts are the most important. 1-5 Course References 1. International Building Code, International Code Council. 2. Chicago Building Code. 3. Minimum Design Loads for Buildings and Other Structures, ASCE 7, American Society of Civil Engineers. 4. Building Code Requirements for Structural Concrete, American Concrete Institute (ACI-318), Farmington-Hills, MI. 5. Manual of Steel Construction, American Institute of Steel Construction, Inc., ASD/LRFD, AISC, Chicago, IL. 6. Building Code Requirements and Specification for Masonry Structures, The Masonry Society (TMS-402, ACI 530, ASCE 5). 7. Steel Roof and Floor Deck Catalog, Vulcraft Nucor Corporation. 8. Textbooks used in your previous design and analysis classes. 1-6 
 Design of Structural Systems (2) Design Process/Design Criteria Structural Engineering Philosophy Structures should be designed based on human intuition, not on computational prescriptions. 2-2 Design of Structural Systems Building Design Objectives •  •  To create a structure that safely and economically accomplishes its function. To communicate the design to the appropriate parties. 2-3 Building Design Objectives To create a structure that safely and economically accomplishes its function. In collaboration with: •  Owner •  Architects •  Mech./Elect./Plumbing Consultants •  Acoustical Consultants •  Vertical Transportation •  Interior Designers •  Geotechnical •  Fire Consultants •  Blast Consultants 2-4 Design of Structural Systems Building Design Process Objective Responsibilities of the Structural Engineer: Respect for the knowledge and opinions of all other members of the Project Team. Technical Knowledge •  •  •  •  Design Analysis Material Properties Construction Methods Engineering Judgment •  Experience •  Observation •  Thought Communication Ability •  Written •  Oral •  Drawing 2-5 Building Design Process Steps •  Schematic (Concept) Design •  Design Development •  Construction Documents •  Construction Administration 2-6 Design of Structural Systems Schematic Design Develop Several Possible Structural Schemes •  •  •  •  •  Construction Materials Column Spacing Lateral Force Resisting System Floor Framing Layout Connections Minimal Drawings Material Quantity Estimate for each Scheme Outline Specification (Design Criteria) •  •  •  •  General Project Description Structural System Description Design Loads Material Grades 2-7 Design Development •  Select a structural system. •  Refine the design of critical elements. •  Verify coordination with other building systems. •  Refine material quantity estimate. •  Further develop design drawings – begin construction drawings. 2-8 Design of Structural Systems Construction Documents •  Complete design of all structural components. •  Develop all construction drawings as required to illustrate design. •  Develop detailed project specifications. •  Building permit process. 2-9 Construction Administration •  Review shop drawings. •  Periodic site visits. •  Attend construction coordination meetings. •  Develop and implement quality control program including testing and inspection. 2 - 10 Design of Structural Systems Structural Design Criteria •  System description. •  Municipal building codes. •  Design standards. •  Material properties. •  Consultant reports. •  Serviceability criteria. •  Other. 2 - 11 Structural System Description •  •  •  •  •  •  •  Intended use of building. Building location. Number of stories. General plan layout and dimensions. Gravity load resisting system. Lateral load resisting system. Foundation system. 2 - 12 Design of Structural Systems Municipal Building Codes •  •  •  •  •  International Building Code (IBC) Uniform Building Code (UBC) Southern Building Code (SBC) Building Officials Code Admin. (BOCA) Specific Local Codes •  Chicago Building Code •  New York City Code, etc. 2 - 13 Approximate Code Usage Prior to 2001 UBC (Uniform Bldg. Code) BOCA (Basic Bldg. Code) SBC (Standard Bldg. Code) 2 - 14 Design of Structural Systems Code Usage after 2007 IBC (International Bldg. Code) 2 - 15 Municipal Building Codes Structural Engineering Considerations •  Provide design load criteria. •  Reference design standards. •  Some design standards within municipal codes. 2 - 16 Design of Structural Systems Design Standards •  •  •  •  •  AISC ACI 318 (concrete) TMS 402 (masonry) ASCE 7 – Minimum Design Loads National Design Spec. for Wood Construction •  AWS 2 - 17 Material Properties Structural Engineering Considerations •  Types of material available. •  Quality of materials. •  Cost of local materials. •  Availability and cost of qualified work force. 2 - 18 Design of Structural Systems Consultant Reports •  •  •  •  •  •  •  Geotechnical Acoustical Environmental Blast Wind Fire Landscape 2 - 19 Serviceability Criteria •  •  •  •  •  Floor deflection. Floor vibration. Lateral displacement. Lateral acceleration. Building vibration. 2 - 20 Design of Structural Systems Other Considerations •  Owner specified loadings. •  Construction constraints. •  Availability of quality work force. •  Availability of testing and inspection laboratory services. 2 - 21 Structural Computer Software •  Analysis •  Design •  Drafting (CAD) •  Building Information Modeling (BIM) 2 - 22 
 Design of Structural Systems (3) Gravity Loads 3-1 Structural Engineering Philosophy A common misconception is that results of structural analysis must be correct. Few structural engineering calculations are precise or exact, yet few structures fall down. 3-2 Design of Structural Systems Design Load Criteria Floor load criteria should be determined for each different use area in the building and recorded as demonstrated on this slide. 3-3 Gravity Load Combinations ASCE 7: Chapter 2 3-4 Design of Structural Systems Gravity Load Combinations per ASCE 7: i. U = 1.4D ii. U = 1.2D + 1.6L + 0.5(Lr or S or R) iii. U = 1.2 D +1.6(Lr or S or R) + φ1L D = DL + SDL DL = self weight of structure SDL = superimposed dead load L Lr S R φ1 φ1 = = = = = = Live Load Roof Live Load Snow Load Rain Load 1.0 when L>100 psf 0.5 for other L 3-5 Tributary Area C B 1 A B1 A2 B2 3 2 A1 3-6 Design of Structural Systems 100w 100w 100w 100w 30’ 10’ 10’ 50 ft2 20’ 50 ft2 100 ft2 10’ 100 ft2 100w + 50w = 150w 3-7 30’ 150w 10’ 10’ 10’ 20’ tributary area = 150 ft2 3-8 Design of Structural Systems 100w 50w 66.7w 83.3w 30’ 10’ 20’ 83.3w + 50w = 133.3w 10’ 50 ft2 100 ft2 10’ 50 ft2 66.7w opening 3-9 1 ( 200w ) = 66.7w 3 2 ( 200w ) = 133.3w 3 30’ 10’ 10’ 10’ 20’ tributary area = 200 ft2 opening 3 - 10 Design of Structural Systems Dead Loads ASCE 7: Chapter 3 γ = 150 lbs for concrete ft 3 γ = 490 lbs for steel ft 3 3 - 11 Dead Loads Dead Load, DL – Self weight of the structure Superimposed Dead Load, SDL – Weights of all material of construction incorporated into the building other than the self weight of the structure including: l  l  l  l  l  l  Fixed Partitions Floor Finishes Ceilings Cladding M/E/P Equipment Roofing Note: Typical values for dead loads can be found in references. 3 - 12 Design of Structural Systems Occupancy Live Load …group of 40 students in a box 6’x6’ inside dimensions. These men averaged 163 lbs. each in weight giving an average load of 181 psf on the 36 sq. ft. loaded. The men were carefully selected with the view to producing as large a load as possible… Transactions, Am. Soc. C.E., Vol. 54, p. 441 3 - 13 Live Load, LL Loads resulting from the use and occupancy of the building. See ASCE-7 Chapter 4 for specific loading requirements. 3 - 14 Design of Structural Systems Live Loads: Partition Loads ASCE 7 – Section 4.2.2: 3 - 15 Live Load Reduction ASCE 7: Section 4.8: ! 15 $ L = Lo # 0.25 + & K LL AT % " L = Lo = KLL= AT = Reduced Design Live Load (psf) Unreduced Design Live Load (psf) Live Load Element Factor Tributary Area (ft2) Note: L shall not be less than 0.50Lo for members supporting one floor. L shall not be less than 0.40Lo for members supporting 2 or more floors. 3 - 16 Design of Structural Systems Live Load Reduction Columns (per ASCE-7, Section 4.8) Element KLL 4 interior columns exterior columns without cantilever slabs 4 edge columns with cantilever slabs 3 corner columns with cantilever slabs 2 3 - 17 KLL = 4 100 1.00 0.90 0.80 0.70 900 0.60 2500 Live Load Reduction Factor Live Load Reduction 0.50 0.40 0.30 0 1000 2000 3000 4000 5000 Tributary Area, ft 3 - 18 Design of Structural Systems ASCE 7 Commentary Chapter 4 ⎡ L = Lo ⎢0.25 + ⎣ 15 ⎤ ⎥ K LL AT ⎦ influence area = K LL AT 3 - 19 Live Load Reduction Columns (per Chicago Building Code): for live loads of 100 psf or less: less than greater than Tributary Area (ft2) Influence Area (ft2) Percentage of Live Load 200 800 100 300 1200 68 400 1600 63 600 2400 56 800 3200 52 900 3600 50 3 - 20 Design of Structural Systems Live Load Reduction Columns (per Chicago Building Code): Notes: 11. Linear interpolation between tabulated percentage of live load is permitted. 2. No reduction is allowed for areas to be occupied as places of public assembly or for roofs. For garages and parking facilities see note 3. 3. For live loads that exceed 100 psf, and in garages and parking facilities for passenger vehicles only, members supporting more than one floor may be designed to carry not less than 80% of the live load. 3 - 21 Roof Live Load Reduction ASCE-7, Section 4.9: Lr = Lo R1 R2 where 12 ≤ Lr ≤ 20 psf R1 = 1 for At ≤ 200 ft 2 R1 = 1.2 − 0.001At for 200ft 2 < At < 600 ft 2 R1 = 0.6 for At ≥ 600 ft 2 R2 = 1 for F ≤ 4 in R2 = 1.2 − 0.05F for 4 < F < 12 R2 = 0.6 for F ≥ 12in in 1’-0” in F = rise(inches ) 3 - 22 Design of Structural Systems Snow Loads ASCE 7: Chapter 7 3 - 23 Snow Loads 60 psf pf = 0.7CeCtIspg pg = ground snow load Ce = exposure factor Ct = thermal factor Is = importance factor 50 psf 25 psf 20 psf Figure 7-1, pg values 3 - 24 Design of Structural Systems Snow Drift Loads In addition to the basic snow load Section 7 of ASCE 7 also has provisions for snow drift. That is the build-up of snow against vertical projections. Snow drift loads can be significantly larger than the basic snow load. Projection Drift Surcharge Load Basic Snow Load Roof 3 - 25 Design of Concrete Columns P Pu ≤ φPn = φ [ 0.85 f 'c Ac + f y Ast ] 0.8 φ = 0.65 for tied column ρg = Ast Ag 3% ≤ ρ g ≤ 8% Ast = ρ g Ag = 0.03Ag Ac = Ag − Ast = 0.97Ag Pu = 0.65[ 0.85 f 'c (0.97Ag ) + f y (0.03Ag )] 0.8 Pu = 0.52[ 0.82 f 'c + 0.03 f y ] Ag P Ag = Pu 0.52[ 0.82 f 'c + 0.03 f y ] 3 - 26 Design of Structural Systems Design of Concrete Columns P Ag = Pu 0.52[ 0.82 f 'c + 0.03 f y ] for f’c = 4000 psi and Grade 60 reinforcement Ag = Pu (kips, inch) 2.64 b=h= P Pu 2.64 Ast = ρ g Ag = 0.03bh 3 - 27 Design of Concrete Columns Minimum Ties h #3 ties for #10 longitudinal bars #4 ties for #11, #14 and #18 bars b maximum tie spacing = 16 db of longitudinal bar = 48 db of ties = least dimension of column ( b or h) max. of 6” from unsupported bar every corner and alternate bar must be tied 3 - 28 Design of Structural Systems Design of Concrete Columns Tied Column ϕ = 0.65 3 - 29 Column Schedules Reinforced Concrete A3 B3 8 - #11 12 - #11 12 - #14 12 - #14 12 - #11 8 - #11 STORY 3 8 - #11 12 - #11 12 - #14 12 - #14 12 - #11 8 - #11 STORY 2 16 - #11 22 - #11 20 - #14 20 - #14 22 - #11 16 - #11 BASEMENT 16 - #11 22 - #11 20 - #14 22 - #14 22 - #11 16 - #11 SIZE 24 X 24 24 X 28 30 X 30 30 X 30 28 X 24 24 X 24 LEVEL STORY 5 A4 B4 A5 B5 STORY 4 STORY 1 3 - 30 Design of Structural Systems Design of Steel Columns φ c Pn ≥ Pu φ c = 0.9 KL E for ≤ 4.71 or Fe ≥ 0.44QFy r QFy for KL E > 4.71 or Fe < 0.44QFy r QFy Pn = Fcr Ag QFy ⎡ ⎤ Fcr = ⎢ 0.658 Fe ⎥ QFy ⎢⎣ ⎥⎦ Fcr = 0.877Fe Fe = Q = 1 for most rolled H - shaped sections π 2E ⎛ KL ⎞ 2 ⎜ ⎟ ⎝ r ⎠ 3 - 31 Design of Steel Columns Fcr KL/r 3 - 32 Design of Structural Systems Design of Steel Columns 3 - 33 Column Schedules Structural Steel A3 B3 A4 B4 A5 B5 3 - 34 
 Design of Structural Systems (4) Structural Layout Structural Engineering Philosophy Structural analysis is good for confirming notions of structural behavior and design, but little else. 4-2 Design of Structural Systems Components of the Structure •  Floor system •  Vertical supporting members •  Lateral load resisting system •  Foundation •  Other structural members 4-3 Floor Systems •  The floor system consists of the structural members that comprise the floor of a story in a building. •  The floor system includes the girders, beams, and joists (if used), and the slab that spans between them, or the slab, when it is directly supported on columns, as in slab-column systems. 4-4 Design of Structural Systems Floor Systems (low to mid-rise construction) The floor framing is usually the largest component of the overall cost of the structure. 4-5 Floor Systems slab columns Reinforced Concrete Flat Plate Floor System 4-6 Design of Structural Systems Floor Systems slab column girders Reinforced Concrete Two-Way Slab Floor System 4-7 Floor Systems beams slab columns girders Reinforced Concrete One-Way Slab and Beam Floor System 4-8 Design of Structural Systems Floor Systems girders slab beams columns shear studs Structural Steel Floor Framing 4-9 Floor Systems – Load Path Structural Steel Floor Framing – Gravity Load Path 4 - 10 Design of Structural Systems Floor Systems Structural Steel Floor Framing – Gravity Load Path 4 - 11 Floor Systems Structural Steel Floor Framing – Gravity Load Path 4 - 12 Design of Structural Systems Floor Systems Structural Steel Floor Framing – Gravity Load Path 4 - 13 Floor Systems Framing Type Typ. Span Length Concrete • Reinforced Concrete Beams and Girders 20 - 40 ft. • Post-Tensioned Concrete Beams and Girders 50-100 ft. • Prestressed/Precast Concrete 20 – 50 ft. Structural Steel • Wide Flange Steel Beams and Girders 20 - 50 ft. • Steel Plate Girders 50-200 ft. • Steel/Concrete Composite Beams and Girders 20 - 60 ft. • Steel Trusses 60-150 ft. • Bar Joists 12 - 50 ft. 4 - 14 Design of Structural Systems Vertical Supporting Members •  The vertical supporting members hold up the floor system at each story, and carry the accumulated gravity loads all the way down to the foundation of the structure. •  They usually are either columns or reinforced concrete walls. 4 - 15 Foundat...
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