3.7 ASCE 7 Seismic Design Criteria ASCE 7 – Chapter 11
Chapter 3 – General Provisions & Seismic Design CriteriaSDR Workbook – 2015 IBC VersionAlternative Seismic Design Category DeterminationIBC §1613.3.5.1Where S1 0.75, the Seismic Design Category is permitted to be determined from IBC Table 1613.3.5(1)alone (i.e, using SDS only) when all of the following apply: Ta 0.8 TS in each of the two orthogonal directions, and the fundamental period of the structure used to calculate the story drift - T TS in each ofthe two orthogonal directions, andS ASCE 7 (12.8-2) is used to determine the seismic response coefficient CS DS , and(R Ie ) The diaphragms are rigid (per ASCE 7 – §12.3.1) or for diaphragms that are flexible, thedistance between vertical elements of the seismic force-resisting system (SFRS) 40 feetSimplified Design ProcedureIBC §1613.3.5.2Where the alternate Simplified Design Procedure of ASCE 7 – §12.14 is used, the Seismic DesignCategory shall be determined in accordance with ASCE 7.3.7 ASCE 7 Seismic Design CriteriaASCE 7 – Chapter 11ScopeASCE 7 - §11.1.2Every structure (e.g., buildings and nonbuilding structures), and portion thereof, including nonstructuralcomponents, shall be designed and constructed to resist the effects of earthquake motions as prescribed bythe seismic requirements of ASCE 7.ApplicabilityASCE 7 - §11.1.3Structures and their nonstructural components shall be designed and constructed in accordance with therequirements of the following chapters based on the type of structure or component: Buildings: ASCE 7 – Chapter 12 Nonbuilding Structures: ASCE 7 – Chapter 15 Nonstructural Components: ASCE 7 – Chapter 13 Seismically Isolated Structures: ASCE 7 – Chapter 17 Structures with Damping Systems: ASCE 7 – Chapter 18Seismic Importance Factor, IeASCE 7 - §11.5.1Each structure shall be assigned an importance factor (Ie) in accordance with ASCE 7 – Table 1.5-2 based on the Risk Category of the building (or other structure) from IBC – Table 1604.5. Risk Category IRisk Category IIRisk Category III (high occupancy)Risk Category IV (essential facilities) Ie 1.0Ie 1.0Ie 1.25*Ie 1.5*The seismic importance factor (Ie) is used in the Seismic Response Coefficient (CS) equations with theintent to raise the yield level for important structures (e.g., hospitals, fire stations, emergency operationcenters, hazardous facilities, etc.).Use of an importance factor greater than one is intended to provide for a lower inelastic demand on astructure which should result in lower levels of structural and nonstructural damage.1-36Steven T. Hiner, MS, SE
Chapter 4 – Seismic Design Requirements for Building StructuresSDR Workbook – 2015 IBC VersionApproximate Fundamental Period, TaASCE 7 – §12.8.2.1The approximate fundamental period shall be determined by the following:Ta Ct hnxASCE 7 (12.8-7)where:Ct & x are determined from ASCE 7 – Table 12.8-2hn height in feet, from the base to the uppermost level of the structureNOTE: See Table C1 – Approximate Fundamental Period, Ta (Appendix C, p. 5-17) for tabulated valuesof ASCE 7 (12.8-7). Steel Moment-Resisting Frames (SMF, IMF & OMF) –Ta 0.028hn0.8Or alternatively (for Steel MRF structures 12 stories and average story height 10 feet):Ta 0.1NASCE 7 (12.8-8)where:N number of stories (i.e., levels) above the base Concrete Moment-Resisting Frames (SMF, IMF & OMF) –Ta 0.016hn0.9Or alternatively (for Concrete MRF structures 12 stories and average story height 10 feet):Ta 0.1N ASCE 7 (12.8-8)Steel EBF, Steel BRBF, or Dual System w/ EBF & SMF –Ta 0.03hn0.75 All Other Structural Systems – (e.g., shear walls, CBF, Dual Systems)Ta 0.02hn0.75NOTE: Refer to ASCE 7 – §12.8.2.1 and equations (12.8-9) & (12.8-10) for an alternative method ofcalculating Ta for structures with concrete or masonry shear walls.4.10Actual vs. Design Seismic ForcesThe Risk-Targeted Maximum Considered Earthquake (MCER) ground motion is the most severeearthquake effects considered by the IBC & ASCE 7.The basis for the mapped MCER ground motions in ASCE 7-10 is significantly different from that of themapped MCE ground motions in ASCE 7-05 and previous editions of ASCE 7. The MCER probabilisticground motions are based on a uniform collapse risk (e.g., 1% probability of collapse in 50 years), ratherthan a uniform hazard (e.g., 2% probability of being exceeded in 50 years). The assumption is thatbuildings designed in accordance with ASCE 7-10 have a collapse probability of not more than 10% (onaverage) if MCER ground motions were ever to occur at the building site.In regions of high seismicity (e.g., many areas of California), the seismic hazard is typically controlled bylarge magnitude events occurring on a limited number of well defined fault systems. For these regions, itis considered more appropriate to use deterministic MCER ground motions where a collapse probability of1-56Steven T. Hiner, MS, SE
Chapter 5 – Earthquake Loads and Load CombinationsSDR Workbook – 2015 IBC VersionEv effect of vertical seismic forces (i.e., due to vertical ground motions) as defined inASCE 7 – §12.4.2.2. Ev can be positive or negative due to the cyclic nature of(vertical) seismic ground motions.Horizontal Seismic Load Effect with Overstrength Factor, EmhASCE 7 – §12.4.3.1The horizontal seismic load effect with overstrength factor (Emh) shall be determined in accordance withthe following: Emh 0QEASCE 7 (12.4-7)where:QE effects of horizontal seismic forces from the seismic base shear V (per ASCE 7 –§12.8.1) or the seismic lateral force Fp (per ASCE 7 – §13.3.1). See ASCE 7 – §12.5.3& ASCE 7 – §12.5.4 for consideration of orthogonal effects) 0 overstrength factor per ASCE 7 – Table 12.2-1Exception: Emh need not exceed the maximum force that can develop in the element asdetermined by see ASCE 7 – §12.4.3.15.2 Load CombinationsGeneralIBC §1605IBC §1605.1Buildings (and other structures) and portions thereof shall be designed to resist the load combinationsspecified in: IBC §1605.2 (Strength Design or Load & Resistance Factor Design – SD/LRFD) orIBC §1605.3 (Allowable Stress Design – ASD), andIBC Chapters 18 through 23, andThe seismic load effects including overstrength factor ( 0) in accordance with ASCE 7 – §12.4.3where required by ASCE 7 – §12.2.5.2, §12.3.3.3, or ASCE 7 – §12.10.2.1NOTE: When using the Simplified Procedure of ASCE 7 – §12.14, the seismic load effects includingoverstrength factor of ASCE 7 – §12.14.3.2 shall be used (i.e., 0 2.5 assumed).Load combinations are a way of considering the maximum (or minimum) forces on a structural elementusing principles of superposition.The load combinations consider combined effects of gravity loads (e.g., dead load, floor live load, rooflive load, rain load, snow load) and other load effects as a result of earthquake, wind, flood, earthpressure, fluid pressure, etc.Notations –D Dead loadE Combined effect of horizontal and vertical earthquake induced forces as defined inASCE 7 – §12.4.2F Load due to fluids with well-defined pressures and maximum heightsFa Flood load in accordance with ASCE 7 – Chapter 5H Load due to earth pressure, ground water pressure, or pressure of bulk materialsL Floor live load, and roof live load 20 psf1-74Steven T. Hiner, MS, SE
SDR Workbook – 2015 IBC VersionChapter 8 – Diaphragm Design & Wall RigidityChapter 8Diaphragm Design & Wall Rigidity8.1 Diaphragm DesignASCE 7 – §12.10.1Diaphragms shall be designed for both the shear and bending stresses resulting from design forces.Diaphragm Design Force, FpxStrength Design force levelFloor and roof diaphragms shall be designed to resist design seismic forces from the structural analysis,but shall not be less than that determined in accordance with the following:nFpx Fi xni wi xw pxASCE 7 (12.10-1)iThe diaphragm design force shall not be less than:Fpx 0.2 S DS I e w px minimumASCE 7 (12.10-2)The diaphragm design force need not exceed:Fpx 0.4 S DS I e w px maximumwhere:ASCE 7 (12.10-3)wpx weight of the diaphragm and the elements tributary thereto at Level x includingapplicable portions of other loads from ASCE 7 – §12.7.2 (e.g., 25% of floor live load forstorage/warehouse, 10 psf minimum for partitions, total operating weight of permanentequipment, 20% of design snow load where Pf 30 psf, etc.).Figure 8.1 – Diaphragm Design Force F F3 F4 F5 w p 2Fp 2 2 w2 w3 w4 w5 Steven T. Hiner, MS, SE1-105
SDR Workbook – 2015 IBC VersionChapter 9 – IBC Chapter 23 – WoodThe weight of the wall (WW) can be considered a dead load effect (D). While the weight of the wall mightbe considered in the determination of the total seismic force on the shear wall (i.e., V1 CS WW), it willnot be used to determine Ev because the dead load effect (D) does not contribute to the determination ofthe calculated unit wall shear.NOTE: The Redundancy factor ( ) shall be considered in the design of the shear walls.Therefore, E E h QE V1 So the ASD calculated unit wall shear:ASD calculated wall (0.7)(total wall shear) shear wall width (0.7 V1 ) b(units of plf)sNOTE: The equation above is used to determine the drag force, and may be used for shear wall designwhen the wall weight (Ww) is not significant, not given in a problem statement, or when the diaphragmdesign force (e.g., ws fpx Fpx / L) includes all perimeter walls of the building essentially when thebase shear (V ) is used to design the diaphragm.Otherwise, the weight of the shear wall (Ww) can be included in the ASD calculated unit wall shear:ASD calculated wall (0.7)(V1 CSWW ) b(units of plf)sUsing the ASD calculated wall and SDPWS Table 4.3A (see Table 9.5), choose the appropriate: WSP panel gradeWSP nominal panel thicknessFastener (nail) sizeFastener (nail) spacingSuch that the ASD allowable wall ASD calculated wall Shear Walls in a LineSDPWS §4.3.3.4The shear distribution to individual shear walls in a shear wall line shall provide the same calculateddeflection (δsw) in each shear wall (i.e., the shear force shall be distributed based on the relative stiffnessesof the individual shear walls).Alternatively, where nominal shear capacities of all WSP shear walls with aspect ratios h/bs 2:1 aremultiplied by 2bs/h for design, shear distribution to individual full-height (shear) wall segments shall bepermitted to be taken as proportional to the shear capacities of the individual full height wall segmentsused in design, and the nominal shear capacities need not be reduced by the ARFWSP in SDPWS §4.3.4.2. h/bs 2:1 use nominal unit shear capacities from SDPWS Table 4.3A with no reduction 2:1 h/bs 3.5:1 use nominal unit shear capacities from SDPWS Table 4.3A multiplied by 2bs/hExample - given two WSP shear walls on same wall line. Wall A: h 12′ & bs 7′ and Wall B: h 12′& bs 4′. Determine the percent shear in each shear wall with an applied total shear of V1 assumingboth shear walls use the same WSP and nailing with a nominal capacity of 520 plf: Wall A: h/bs (12′ / 7′) 1.71 2:1 no unit shear capacity reduction necessaryCapacity of Wall A 520 plf (bs) 520 plf (7′) 3,640 lbsSteven T. Hiner, MS, SE1-139
Chapter 10 – Other Material ChaptersSDR Workbook – 2015 IBC VersionHoop - closed tie reinforcement that provides strength for shear and confinement for the concretecore.Confinement - provides for the ductile performance of members and increases the compressivestrength of the confined concrete which helps to compensate for strength loss due to the "spalled"outer concrete shell.Strong Column - Weak Beam DesignACI 318-14 – §18.7.3.2Intent is to confine flexural yielding (inelastic) to the beams while the columns remain elastic throughouttheir seismic response.At any beam/column joint: Mnc (6/5) MnborACI 318 (18.7.3.2) nominal flexural strength of 6 nominal flexural strength of columns framing into the joint 5 beams framing into the joint Intermediate Moment Frames (IMF)(Not permitted in Seismic Design Category D, E & F) ACI 318-14 – §18.4R 5 for reinforced concrete IMFLimited special detailing of beam-column joint, therefore limited ductility (i.e., lower R).Ordinary Moment Frames (OMF)(Not permitted in Seismic Design Category C, D, E & F) ACI 318-14 – §18.3R 3 for reinforced concrete OMFNo special detailing of beam-column joint, therefore very limited ductility (i.e., very low R).Special Reinforced Concrete Shear Walls(Typically required in Seismic Design Category D, E & F)ACI 318-14 – §18.10Special reinforced concrete structural walls (i.e., shear walls) need to comply with the requirements ofACI 318 – §18.2.3 through §18.2.8 and §18.10. R 5 for special reinforced concrete shear walls - Bearing Wall SystemR 6 for special reinforced concrete shear walls - Building Frame SystemFigure 10.4 – Special Reinforced Concrete Shear Wall1-160Steven T. Hiner, MS, SE
SDR Workbook – 2015 IBC VersionIntermediate Reinforced Masonry Shear Walls(Not permitted in Seismic Design Category D, E & F) ACI 530-13 – §7.3.2.5R 3½ for intermediate reinforced masonry shear walls - Bearing Wall SystemR 4 for intermediate reinforced masonry shear walls - Building Frame SystemOrdinary Reinforced Masonry Shear Walls(Not permitted in Seismic Design Category D, E & F) Chapter 10 – Other Material ChaptersACI 530-13 – §7.3.2.4R 2 for ordinary reinforced masonry shear walls - Bearing Wall SystemR 2 for ordinary reinforced masonry shear walls - Building Frame SystemFigure 10.6 – 8 x 8 x 16 Concrete Masonry Units (CMU)10.4 IBC Chapter 22 – SteelGeneralIBC §2205.1The design, fabrication and erection of structural steel elements of buildings, structures and portionsthereof shall be in accordance with AISC 360-10 – Specification for Structural Steel Buildings (includedin the AISC Steel Construction Manual).Structural Steel Seismic Force-Resisting SystemsIBC §2205.2.1The design, detailing, fabrication and erection of structural steel s
Chapter 3 – General Provisions & Seismic Design Criteria SDR Workbook – 2015 IBC Version 1-36 Steven T. Hiner, MS, SE Alternative Seismic Design Category Determination IBC §1613.3.5.1 Where S1 0.75, the Seismic Design Category is permitted to be determined from IBC Table 1613.3.5(1) alone (i.e, using SDS only) when all of the following apply: Ta 0.8 TS in each of the two orthogonal .
Briefing on the Effort to Update ASCE 31 and 41 Slide 1 Proposed Updates to ASCE 31 and 41 A Mid -cycle Snapshot Update for the BSSC PUC December 7, 2010 Washington, DC Bob Pekelnicky Vice - Chair and Secretariat Slide 2 ASCE 31 -03 Seismic Evaluation of Existing Buildings ASCE 41 - 06 Supplement No. 1 Seismic Rehabiliation of Existing Buildings
NCS eNewsletter Archives: go to www.asce-ncs.org and view along the sidebar. Address Changes: Call 1-800-548-ASCE, e-mail member@asce.org, visit www.asce.org, or write: ASCE - Membership, 1801 Alexander Bell Drive, Reston, VA 20191. Include your membership number. Newsletter Officers (2020-2021) Mike Venezia, President
BACKGROUND ON ASCE 41 ASCE 41-13 is an update and combination of the ASCE 41-06 and ASCE 31-03 stan-dards, which are intended for the seismic evaluation and retrofit of existing buildings. ASCE 41-13 establishes tables of accepta
of ASCE 7-10 for mid-period buildings at Site Class D sites. Overview of ASCE 7-16 Seismic Design Methods and Parameters . 11.4-1, ASCE 7-The American Society of Civil Engineers (ASCE), Standard, Minimum Design Loads for Buildings and Other Structures, ASCE 7-16, inc
Building Code Requirements for Masonry Structures (ACI 530-02/ASCE 5-02/TMS 402-02) and Specifi cations for Masonry Structures (ACI 530.1-02/ASCE 6-02/TMS . ASCE/EWRI 40-03 Regulated Riparian Model Water Code ASCE/SEI 41-06 Seismic Rehabilitation of Existing Buildings ASCE/EWRI 42-04 Standard Practice for the Design and Opera-
This document, also available on the ASCE Student Conferences page of the ASCE Website, defines the 2022 ASCE Innovation Contest and the rules for both the student symposium and Society-wide finals competition levels. Requests for Information (RFI) should be sent to student@asce.org with the subject line "ASCE Innovation Contest RFI."
Jan 31, 2020 · The 2018 International Building Code (IBC 2018), and by extension referenced provisions of ASCE 7-16, was adopted July 2019 by the State of Utah. ASCE 7-16 introduces significant changes to prescribed seismic forces for the design of structures when compared to IBC 2015 and ASCE 7-10. These changes include updated mapped B/C boundary seismic .
Chapter 5 of ASCE 7 and ASCE 24. FEMA deems ASCE 24 to meet or exceed the minimum National Flood Insurance Program (NFIP) requirements for buildings and structures. The 2015 I-Codes reference ASCE 24 -14, while the 2006 through 2012 I-Codes reference ASCE 24 -05. A summary of significant technical revisions from
