3. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural System SelectionCIE 619 Chapter 5 – Seismic Design413. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural System SelectionCIE 619 Chapter 5 – Seismic Design423. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural System SelectionCIE 619 Chapter 5 – Seismic Design433. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural System SelectionCombinations of Framing Systems in Different–Combinations of Framing Systems in Different Directions•Different seismic force–resisting systems permitted resistDifferent seismic forceresisting systems permitted resist seismic forces along each of two orthogonal axes of the structure. • Respective R, Cd, and 0coefficients shall apply to each systemR (E-W), Cd(E-W) , and 0(E-W)R (N-S), Cd(N-S) , and 0(N-S)CIE 619 Chapter 5 – Seismic Design443. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural System SelectionCIE 619 Chapter 5 – Seismic Design453. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural System SelectionCombinations of Framing Systems in the Same–Combinations of Framing Systems in the Same Direction•Where different seismic force–resisting systems used inWhere different seismic forceresisting systems used in combination to resist seismic forces in the same direction, other than those combinations considered as d al s stems more stringent s stem limitation containeddual systems, more stringent system limitation contained in Table 12.2-1 appliesR1R2R<RRappliesCIE 619 Chapter 5 – Seismic Design46R2< R1—R2applies3. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural System Selection–R, Cd,andΩ0Values for Vertical CombinationsR, Cd, and Ω0 Values for Vertical Combinations• Value of response modification coefficient, R, used for design at any story shall not exceed lowest value of R used in the same direction at any story above that story.at any story above that story. • Deflection amplification factor, Cd, and system over strength factor, 0, used at any story shall not be less than largest value of 0used in the same direction at any story above that story.in the same direction at any story above that story.• Exceptions:– Rooftop structures not exceeding two stories in height and 10 percent of the total structure weight.of the total structure weight.– Other supported structural systems with a weight equal to or less than 10 percent of the weight of the structure.–Detached one- and two-family dwellings of light-frame construction.CIE 619 Chapter 5 – Seismic Design47ygg3. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural System SelectionRCand ΩValues for Vertical Combinations–R, Cd, and Ω0 Values for Vertical CombinationsResulting DesignValuesR = 7, Cd = 3.0 , 0 = 5.5R = 8, Cd = 2.0 , 0 = 4.0R = 7, Cd= 3.0 , 0= 5.5R = 7, Cd= 3.0 , 0= 5.5R = 6, Cd = 2.5 , 0 = 5.0R = 5, Cd = 3.0 , 0 = 5.5R = 5, Cd= 3.0 , 0= 5.5R = 6, Cd= 3.0 , 0= 5.5R = 8, Cd = 3.0 , 0 = 5.5R = 7, Cd = 3.0 , 0 = 5.5R = 5, Cd= 3.0 , 0= 5.5R = 5, Cd= 3.0 , 0= 5.5CIE 619 Chapter 5 – Seismic Design483. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural System Selection–R, Cd,andΩ0Values for Vertical CombinationsR, Cd, and Ω0 Values for Vertical Combinations• Two-stage equivalent lateral force procedure permitted for structures having flexible upper portion above a rigid lower portion, provided: –Stiffness of lower portion at least 10 times the stiffness of upperStiffness of lower portion at least 10 times the stiffness of upper portion– Period of entire structure not greater than 1.1 times period of upper portion considered as a separate structure fixed at the base– Flexible upper portion designed as a separate structure using appropriate values of R and ρ– Rigid lower portion designed as a separate structure using appropriate values of R and ρ – Reactions from upper portion determined from analysis of upper portion amplified by ratio of the R/ρ of the upper portion over R/ρ of the lower portion This ratio shall not be less than 1 0CIE 619 Chapter 5 – Seismic Design49the lower portion. This ratio shall not be less than 1.0.3. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Diaphragm FlexibilityRi id di h T i l l i i d•Rigid diaphragm: Torsional analysis required• Flexible diaphragm: Design forces proportional to tributary areasCIE 619 Chapter 5 – Seismic Design50tributary areas3. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Diaphragm FlexibilityCIE 619 Chapter 5 – Seismic Design513. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural IrregularitiesHorizontal Irregularities–Horizontal IrregularitiesCIE 619 Chapter 5 – Seismic Design523. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural IrregularitiesHorizontal Irregularities–Horizontal IrregularitiesCIE 619 Chapter 5 – Seismic Design533. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural IrregularitiesHorizontal Irregularities–Horizontal IrregularitiesCIE 619 Chapter 5 – Seismic Design543. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural IrregularitiesHorizontal Irregularities–Horizontal IrregularitiesCIE 619 Chapter 5 – Seismic Design553. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural IrregularitiesHorizontal Irregularities–Horizontal IrregularitiesCIE 619 Chapter 5 – Seismic Design563. Seismic Design Requirements of ASCE 7-05 for Building StructuresASCE 7-05 for Building Structures• Structural IrregularitiesHorizontal Irregularities–Horizontal IrregularitiesCIE 619 Chapter 5