DESIGN AND DETAILING OF LOW-RISE REINFORCED

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DESIGN AND DETAILING OF LOW-RISEREINFORCED CONCRETE BUILDINGSDIAPHRAGMSJune 12, 2018

ObjectivesAnalysis methodsDesign and detailing requirements forshear, chord, and shear transferreinforcementDesign and detailing of collectors

References Design and Detailing of Low-Rise ReinforcedConcrete Buildings, CRSI, 2017

Chapters1. Introduction2. Reinforced Concrete Building Systems3. Design and Detailing Requirements for SDC Aand B4. Design and Detailing Requirements for SDC C5. Design and Detailing Requirements for SDC D, E,and F

Chapters1. Introduction2. Reinforced Concrete Building Systems3. Design and Detailing Requirements for SDC Aand B4. Design and Detailing Requirements for SDC C5. Design and Detailing Requirements for SDC D, E,and F

AppendicesA. Reinforcing Bar DataB. Design Aids for TorsionC. Cross-sectional Constant 𝐢𝐢 for Two-way Slab Systemsand Edge BeamsD. Critical Section Properties for Square ColumnsE. Design Strength Interaction Diagrams for SquareColumnsF. Design Strength Interaction Diagrams for ReinforcedConcrete Walls

References Design Guide for Economical Reinforced ConcreteStructures, CRSI, 2016www.crsi.org

References Building Code Requirements for StructuralConcrete, ACI 318-14, 2014

Definition of Low-Rise Building No more than 6 stories above grade Height no more than 72 ft Fundamental period less than or equal to 0.5 sec

AnalysisMethods

Diaphragms Diaphragm in-plane forces Diaphragm transfer forces Connection forcesbetween diaphragm andvertical elements of theLFRS Forces from bracingvertical or sloped buildingelements Diaphragm out-of-planeforcesACI Figure R12.1.1

Diaphragms ACI 12.3 Thickness Must satisfy all applicable strength and serviceabilityrequirements

Design Forces Wind ASCE/SEI Chapters 26 – 30

Design Forces Seismic ASCE/SEI 12.10.1.1𝑛𝑛𝑛𝑛𝑖𝑖 π‘₯π‘₯𝑖𝑖 π‘₯π‘₯𝐹𝐹𝑝𝑝𝑝𝑝 𝐹𝐹𝑖𝑖 𝑀𝑀𝑖𝑖 𝑀𝑀𝑝𝑝𝑝𝑝 0.2𝑆𝑆𝐷𝐷𝐷𝐷 𝐼𝐼𝑒𝑒 𝑀𝑀𝑝𝑝𝑝𝑝 0.4𝑆𝑆𝐷𝐷𝐷𝐷 𝐼𝐼𝑒𝑒 𝑀𝑀𝑝𝑝𝑝𝑝

Design Forces Transfer

Design Forces Connection

Design Forces Soil Flood and tsunami Column bracing

Analysis Methods ACI 12.4.2.4 Rigid diaphragm model Flexible diaphragm model Bounding analysis FEM Strut-and-tie model

Classifications Rigid Flexible Semi-rigid (-flexible)

Classifications

Diaphragm Rigidity Rigid diaphragms Wind loads ASCE/SEI 26.2 Concrete slabs with span/depth 2 Earthquake loads ASCE/SEI 12.3.1.2 Concrete slabs with span/depth 3 and no horizontalirregularities in accordance with ASCE/SEI 12.3.2.1

Diaphragm Rigidity Flexible diaphragms

Diaphragm Rigidity Reinforced concrete roof and floor systems Rigid diaphragms Lateral forces are transferred to the elements of the LFRSbased on the stiffness of those elements

Force DistributionChord force (typ.)𝑉𝑉1CollectorelementStructural wallCollectorelement𝑻𝑻𝒖𝒖Uniform sheardistributionπ‘ͺπ‘ͺ𝒖𝒖Lateral force, 𝑉𝑉𝑉𝑉2Structural wall(collector elementsnot required)

Rigid Diaphragm ModelSpringsπ‘…π‘…π‘–π‘–π‘˜π‘˜π‘–π‘– 𝛿𝛿𝑖𝑖

Rigid Diaphragm Model Reactions in Walls A, B,and C determined fromanalysis𝛿𝛿𝑖𝑖 𝛿𝛿𝐹𝐹𝐹𝐹 𝛿𝛿𝑉𝑉𝑉𝑉

Rigid Diaphragm Model Equivalent distributedload𝑀𝑀1 𝑀𝑀22𝑀𝑀1 𝑀𝑀2 β„“1 β„“2 β„“3 𝑅𝑅𝐴𝐴 𝑅𝑅𝐡𝐡 𝑅𝑅𝐢𝐢 𝑉𝑉2β„“1 β„“2 β„“332 𝑅𝑅𝐴𝐴 β„“1 𝑅𝑅𝐡𝐡 β„“1 β„“2 𝑅𝑅𝐢𝐢 β„“1 β„“2 β„“3

Rigid Diaphragm Model Shear and momentdiagrams

Rigid Diaphragm Model Design shear strength of the diaphragm Shear diagram Connections of the diaphragm to the verticalelements of the LFRS Axial compressive and tensile forces in the collectors,if any

Chord force (typ.)Rigid Diaphragm Model𝑻𝑻𝒖𝒖𝐿𝐿 Moment diagramπ‘ͺπ‘ͺ𝒖𝒖Lateral force, 𝑉𝑉π‘ͺπ‘ͺ𝒖𝒖 𝑻𝑻𝒖𝒖 𝑴𝑴𝒖𝒖,π’Žπ’Žπ’Žπ’Žπ’Žπ’ŽπŸŽπŸŽ. πŸ—πŸ—πŸ—πŸ—πŸ—πŸ—

Rigid Diaphragm Model

Large Openings

Large Openings

𝑅𝑅𝑑𝑑,𝐿𝐿Large Openings Seismic forces𝑅𝑅𝑑𝑑,𝑅𝑅 𝑀𝑀𝑒𝑒,𝑑𝑑,𝐿𝐿 𝑀𝑀𝑒𝑒,𝑑𝑑,𝑅𝑅 𝑀𝑀𝑒𝑒,𝑑𝑑 𝑀𝑀𝑒𝑒,𝑑𝑑,𝐿𝐿Top segmentπ‘ͺπ‘ͺ𝒖𝒖,𝟏𝟏 𝑻𝑻𝒖𝒖,πŸπŸπ‘΄π‘΄ 𝒖𝒖,𝒕𝒕 𝟎𝟎. πŸ—πŸ—πŸ—πŸ—π‘³π‘³πŸπŸ 𝑀𝑀𝑒𝑒,𝑑𝑑,𝑅𝑅

𝑅𝑅𝑏𝑏,𝐿𝐿Large Openings Seismic forces𝑅𝑅𝑏𝑏,𝑅𝑅 𝑀𝑀𝑒𝑒,𝑏𝑏,𝐿𝐿 οΏ½1 𝐴𝐴2𝐴𝐴2𝐴𝐴1 𝐴𝐴2 𝑀𝑀𝑒𝑒,𝑏𝑏 𝑀𝑀𝑒𝑒,𝑏𝑏,𝐿𝐿Bottom segmentπ‘ͺπ‘ͺ𝒖𝒖,𝟐𝟐 𝑻𝑻𝒖𝒖,πŸπŸπ‘΄π‘΄ 𝒖𝒖,𝒃𝒃 𝟎𝟎. πŸ—πŸ—πŸ—πŸ—π‘³π‘³πŸπŸ 𝑀𝑀𝑒𝑒,𝑏𝑏,𝑅𝑅

𝑅𝑅𝑑𝑑,𝐿𝐿Large Openings Wind ��𝑅 𝑀𝑀𝑒𝑒,𝑑𝑑,𝐿𝐿 𝑀𝑀𝑒𝑒,𝑑𝑑,𝑅𝑅𝐿𝐿31 3𝑀𝑀𝐿𝐿𝐿𝐿1 𝐿𝐿32 𝑀𝑀𝑒𝑒,𝑑𝑑 𝑀𝑀𝑒𝑒,𝑑𝑑,𝐿𝐿Top segmentπ‘ͺπ‘ͺ𝒖𝒖,𝟏𝟏 𝑻𝑻𝒖𝒖,πŸπŸπ‘΄π‘΄ 𝒖𝒖,𝒕𝒕 𝟎𝟎. ���𝑅 𝑀𝑀𝑒𝑒,𝑑𝑑,𝑅𝑅𝐿𝐿31 3𝑀𝑀𝑅𝑅𝐿𝐿1 𝐿𝐿32

𝑅𝑅𝑏𝑏,𝐿𝐿Large Openings Wind ��𝑅 𝑀𝑀𝑒𝑒,𝑏𝑏,𝐿𝐿 𝑀𝑀𝑒𝑒,𝑏𝑏,𝑅𝑅𝐿𝐿32 3𝑀𝑀𝐿𝐿𝐿𝐿1 𝐿𝐿32 𝑀𝑀𝑒𝑒,𝑏𝑏 𝑀𝑀𝑒𝑒,𝑏𝑏,𝐿𝐿Bottom segmentπ‘ͺπ‘ͺ𝒖𝒖,𝟐𝟐 𝑻𝑻𝒖𝒖,πŸπŸπ‘΄π‘΄ 𝒖𝒖,𝒃𝒃 𝟎𝟎. ���𝑅 𝑀𝑀𝑒𝑒,𝑏𝑏,𝑅𝑅𝐿𝐿32 3𝑀𝑀𝑅𝑅𝐿𝐿1 𝐿𝐿32

Large Openings Total tensile chord forcealong edge of diaphragm Total tensile chord force is obtained by adding thesecondary tensile chord force to the primary tensilechord force Primary tensile chord force at location of opening:𝑇𝑇𝑒𝑒 𝑀𝑀𝑒𝑒 𝑑𝑑 𝑀𝑀𝑒𝑒 0.95𝐿𝐿 Secondary tensile chord force: 𝑇𝑇𝑒𝑒,1 𝑀𝑀𝑒𝑒,𝑑𝑑𝑑𝑑 𝑀𝑀𝑒𝑒,𝑑𝑑0.95𝐿𝐿1

Large Openings Total tensile chord forcealong edge of diaphragm 𝑻𝑻𝒖𝒖,𝟏𝟏 𝑴𝑴𝒖𝒖,π’•π’•πŸŽπŸŽ. πŸ—πŸ—πŸ—πŸ—π‘³π‘³πŸπŸπ‘»π‘»π’–π’– 𝑴𝑴𝒖𝒖 𝟎𝟎. πŸ—πŸ—πŸ—πŸ—πŸ—πŸ—

Large Openings Tensile chordreinforcement Tensile chord reinforcement is to be provided basedon the larger of the following: Primary tensile chord force obtained from the maximumoverall moment:𝑇𝑇𝑒𝑒 𝑀𝑀𝑒𝑒,π‘šπ‘šπ‘šπ‘šπ‘šπ‘š 0.95𝐿𝐿 Summation of the primary tensile chord force at the locationof the opening plus the secondary tensile chord force at theopening: 𝑇𝑇𝑒𝑒 𝑇𝑇𝑒𝑒,1 𝑀𝑀𝑒𝑒 0.95𝐿𝐿 𝑀𝑀𝑒𝑒,𝑑𝑑0.95𝐿𝐿1

Large Openings Tensile chordreinforcement For openings that are not centered in the diaphragm Conservative to provide tensile chord reinforcement over theentire length of the diaphragm edge based on a total tensilechord force equal to the following: 𝑀𝑀𝑒𝑒,π‘šπ‘šπ‘šπ‘šπ‘šπ‘š 0.95𝐿𝐿 𝑀𝑀𝑒𝑒,𝑑𝑑0.95𝐿𝐿1

Large Openings Tensile chordreinforcement 𝑻𝑻𝒖𝒖,𝟏𝟏 𝑴𝑴𝒖𝒖,π’•π’•πŸŽπŸŽ. πŸ—πŸ—πŸ—πŸ—π‘³π‘³πŸπŸπ‘»π‘»π’–π’– 𝑴𝑴𝒖𝒖,π’Žπ’Žπ’Žπ’Žπ’Žπ’Ž 𝟎𝟎. πŸ—πŸ—πŸ—πŸ—πŸ—πŸ—

Large Openings Secondary tensile chordforces at corners ofopenings𝑻𝑻𝒖𝒖,𝟐𝟐 𝑴𝑴 𝒖𝒖,𝒃𝒃,𝑹𝑹 𝟎𝟎. πŸ—πŸ—πŸ—πŸ—π‘³π‘³πŸπŸBottom segment

Analysis Requirements Analysis must be performed for forces acting in theopposite direction as shown Larger area of reinforcement determined from both analysesis provided along the edges of the diaphragm and openings,if any, for simpler detailing Analyses required for forces acting in theperpendicular direction of analysis

Shear, Chord,and ShearTransferReinforcement

Shear οΏ½οΏ½οΏ½π‘šπ‘š 𝑉𝑉𝑒𝑒,π‘šπ‘šπ‘šπ‘šπ‘šπ‘š 𝐿𝐿

Shear StrengthRequirementsπœ™πœ™π‘‰π‘‰π‘›π‘› πœ™πœ™π΄π΄π‘π‘π‘π‘ 2πœ†πœ† 𝑓𝑓𝑐𝑐′ πœŒπœŒπ‘‘π‘‘ 𝑓𝑓𝑦𝑦𝐴𝐴𝑐𝑐𝑐𝑐 gross area of diaphragmπœŒπœŒπ‘‘π‘‘ distributed reinforcement oriented in the directionof analysisπœ™πœ™ 0.75 for buildings assigned to SDC A, B, or C that donot utilize special moment frames or specialstructural walls

Shear οΏ½οΏ½οΏ½π’Žπ’Ž ��𝑛 πœ™πœ™πœ™π΄π΄π‘π‘π‘π‘ 𝑓𝑓𝑐𝑐′𝑉𝑉𝑒𝑒 πœ™πœ™ 2𝐴𝐴𝑐𝑐𝑐𝑐 πœ†πœ† π‘“π‘“π‘π‘β€²πœŒπœŒπ‘‘π‘‘ 𝑓𝑓𝑦𝑦

Chord Reinforcement𝑇𝑇𝑒𝑒 πœ™πœ™π‘‡π‘‡π‘›π‘› πœ™πœ™π΄π΄π‘ π‘  π‘“π‘“π‘¦π‘¦πœ™πœ™ 0.9𝑻𝑻𝒖𝒖𝑨𝑨𝒔𝒔 π“π“π’‡π’‡π’šπ’š

Chord Reinforcement Placed perpendicular to the lateral force Provided in addition to any other requiredreinforcement In slabs without perimeter beams, typicallyconcentrated near the edge of the slab and tied toeither the top or bottom flexural reinforcement In slabs with perimeter beams, can be located withinthe slab outside of the beam cross-section

Chord ReinforcementChord reinforcement

Shear TransferReinforcement Between the diaphragm and the vertical elements ofthe LFRS Between the diaphragm and the collector elements

Shear TransferReinforcement Shear-friction at joints

Shear TransferReinforcement Along Wall Bπœ™πœ™π‘‰π‘‰π‘›π‘› πœ™πœ™πœ™πœ™π΄π΄π‘£π‘£π‘£π‘£ 𝑓𝑓𝑦𝑦 𝑉𝑉𝑒𝑒 𝑅𝑅𝐡𝐡 𝐿𝐿

Shear TransferReinforcement Along Wall B Required area of dowel bars ��𝑹𝑩𝑩 𝑳𝑳 π“π“π’‡π’‡π’šπ’š πππœ‡πœ‡ 0.6πœ™πœ™ 0.75

Shear TransferReinforcement Coefficient of friction πœ‡πœ‡

Shear TransferReinforcement Along Wall AShear transfer depends on width of collector

Shear TransferReinforcement Where width of collector thickness of wall All tension and compression forces from collector aretransferred directly into the wall boundary Along Wall A𝑨𝑨𝒗𝒗𝒗𝒗𝑹𝑹𝑨𝑨 π‘³π‘³πŸπŸ π“π“π’‡π’‡π’šπ’š πππœ‡πœ‡ 0.6πœ™πœ™ 0.75

Shear TransferReinforcement Along Wall A Where width of collector thickness of wall 𝐴𝐴𝑣𝑣𝑣𝑣 must be determined using the uniform shear along thewall length plus a portion of the total collector force

Shear TransferReinforcement Width of collector thickness of wall

Shear TransferReinforcement Width of collector thickness of wall

Shear TransferReinforcement Width of collector thickness of wall

Shear TransferReinforcement Along collectors Required area of dowel bars ��𝑹𝑨𝑨 𝑳𝑳 π“π“π’‡π’‡π’šπ’š πππœ‡πœ‡ 1.4πœ™πœ™ 0.75

Tension Reinforcement Width of collector thickness of wall

Shear TransferReinforcement Alternate shear transfer Reinforcement in slab

Shear TransferReinforcement Alternate shear transfer Reinforcement in slab

Dowel Bars Dowel bars must also be designed for any out-ofplane wind and seismic forces that act on the wall

Design andDetailing ofCollectors

Collectors Must be provided whereelements of the LFRS donot extend the full depthof the diaphragm

Collectors Portion of the slab or areinforced concretebeam Slab or beam has thesame width as themember of the LFRSFigure 3.104

Collectors

Collectors Design and detailingrequirements Collectors must be designed for the combinedfactored load effects due to Axial tension forces due to lateral loads and flexure andshear forces due to gravity loads Axial compression forces due to lateral loads and flexure andshear forces due to gravity loads Design strength interaction diagram Must include both axial compression and tensile segments

Collectors Design and detailingrequirements

Design Procedure Figure 3.106 Examples Section 3.8.7

Design andDetailingRequirementsSDC C

SDC C Design and detailing requirements of ACI Chapter 12are applicable

Collector Design Maximum of the three forces in ASCE/SEI 12.10.2.1 Forces calculated using seismic load effects includingoverstrength factor Ξ©π‘œπ‘œ with seismic forces determined bythe Equivalent Lateral Force Procedure of ASCE/SEI 12.8 orthe Modal Response Spectrum Analysis of ASCE/SEI 12.9 Forces calculated using seismic load effects includingoverstrength factor Ξ©π‘œπ‘œ with seismic forces determined byASCE/SEI Equation 12.10-1 Forces calculated using the load combinations ofASCE/SEI 12.4.2.3 with seismic forces determined byASCE/SEI Equation 12.10-2

Design andDetailingRequirementsSDC D, E, AND F

SDC D, E, and F ACI 18.12

Analysis Model Rigid diaphragm model can be used to determine inplane design bending moments, shear forces, andaxial forces Chord reinforcement and shear transferreinforcement can be determined using methodsoutlined previously

Diaphragm Forces Connections ofdiaphragms to verticalelements of the SFRSand to collectors Collectors and theirconnections to thevertical elements of theLFRS Design forces determined in accordance withASCE/SEI 12.10.1.1 must be increased by 25% forstructures with the following irregularities Horizontal structural irregularities Type 1a, 1b, 2, 3, or 4 Vertical structural irregularity Type 4

Horizontal StructuralIrregularities Types 1a and 1b

Horizontal StructuralIrregularities Type 2

Horizontal StructuralIrregularities Type 3

Horizontal StructuralIrregularities Type 4

Vertical StructuralIrregularity Type 4

Minimum Reinforcement ACI 18.12.7.1 ACI 24.4 𝐴𝐴𝑠𝑠,π‘šπ‘šπ‘šπ‘šπ‘šπ‘š 0.0018𝐴𝐴𝑔𝑔 Maximum spacing 18 in.

Shear StrengthRequirementsπœ™πœ™π‘‰π‘‰π‘›π‘› πœ™πœ™π΄π΄π‘π‘π‘π‘ 2πœ†πœ† 𝑓𝑓𝑐𝑐′ πœŒπœŒπ‘‘π‘‘ 𝑓𝑓𝑦𝑦𝐴𝐴𝑐𝑐𝑐𝑐 gross area of diaphragmπœŒπœŒπ‘‘π‘‘ distributed reinforcement oriented in the directionof analysisπœ™πœ™ must not exceed the least value of πœ™πœ™ for shear used forthe vertical elements of the SFRS

Collector Design Maximum of the three forces in ASCE/SEI 12.10.2.1 Forces calculated using seismic load effects includingoverstrength factor Ξ©π‘œπ‘œ with seismic forces determined bythe Equivalent Lateral Force Procedure of ASCE/SEI 12.8 orthe Modal Response Spectrum Analysis of ASCE/SEI 12.9 Forces calculated using seismic load effects includingoverstrength factor Ξ©π‘œπ‘œ with seismic forces determined byASCE/SEI Equation 12.10-1 Forces calculated using the load combinations ofASCE/SEI 12.4.2.3 with seismic forces determined byASCE/SEI Equation 12.10-2

Collectors Design and detailingrequirements At sections where combined compressive stress 0.2𝑓𝑓𝑐𝑐′ Provide transverse reinforcement conforming to ACI 18.7.5.2(a)through (e) and ACI 18.7.5.3 for columns of special moment frames Transverse reinforcement conforming to aboverequirements need not be provided at sections wherecombined compressive stress 0.15𝑓𝑓𝑐𝑐′ Limits of 0.2𝑓𝑓𝑐𝑐′ and 0.15𝑓𝑓𝑐𝑐′ are to be increased to 0.5𝑓𝑓𝑐𝑐′and 0.4𝑓𝑓𝑐𝑐′ , respectively, in cases where forces have beenamplified by the overstrength factor Ξ©π‘œπ‘œ

Collectors Design and detailingrequirements For collectors that are part of the slab Required longitudinal reinforcement must be in addition toany of the other required reinforcement for flexure Longitudinal reinforcement should be located near the middepth of the slab Maximum bar spacing 18 in.

Collectors Design and detailingrequirements For collectors that are reinforced concrete beams All applicable design and detailing requirements for beamsmust be satisfied Longitudinal reinforcement in the beam is determined forcombined flexure and axial tension and combined flexureand axial compression Transverse reinforcement is determined for shear and/ortorsion

Collectors Design and detailingrequirements Longitudinal reinforcement must extend into theattached element of the LFRS a distance equal to atleast ℓ𝑑𝑑 It is recommended to extend the longitudinal bars throughthe entire length of the member of the LFRS that is in-planewith the collector Provide tension splices in accordance with ACI 25.5where required

Detailing RequirementsFigure 5.60

Detailing RequirementsFigure 5.60

Example

Example 5.19 SDC D 𝑆𝑆𝐷𝐷𝐷𝐷 1.00 SIDL 10 psf πΏπΏπ‘Ÿπ‘Ÿ 20 psf 𝑓𝑓𝑐𝑐′ 4,000 psi Grade 60 reinforcement Design roof diaphragm forseismic forces in N-Sdirection4-story building

Example 5.19𝑛𝑛𝑛𝑛𝑖𝑖 π‘₯π‘₯𝑖𝑖 π‘₯π‘₯𝐹𝐹𝑝𝑝𝑝𝑝 𝐹𝐹𝑖𝑖 𝑀𝑀𝑖𝑖 𝑀𝑀𝑝𝑝𝑝𝑝 0.2𝑆𝑆𝐷𝐷𝐷𝐷 𝐼𝐼𝑒𝑒 𝑀𝑀𝑝𝑝𝑝𝑝 0.2 1.00 1.0 𝑀𝑀𝑝𝑝𝑝𝑝 0.200𝑀𝑀𝑝𝑝𝑝𝑝 0.4𝑆𝑆𝐷𝐷𝐷𝐷 𝐼𝐼𝑒𝑒 𝑀𝑀𝑝𝑝𝑝𝑝 0.4 1.00 1.0 𝑀𝑀𝑝𝑝𝑝𝑝 0.400𝑀𝑀𝑝𝑝𝑝𝑝

Example 5.19 Redundancy factor 𝜌𝜌 1.0 Example 5.16

Example 5.19 CM and CRFigure 5.66𝑒𝑒 0.05 102.33 5.1β€²

40’Example 5.1920’𝑀𝑀1𝑀𝑀2100’ 𝑀𝑀1 100 𝑀𝑀1 10022 12𝑀𝑀2 𝑀𝑀1 100 33312𝑀𝑀2 𝑀𝑀1 100 𝑀𝑀1 3.13 kips ft and 𝑀𝑀2 3.53 kips ft2 3100 150 40 183 60

Example 5.19Figure 5.66

Example 5.19 Chord π‘š2,778𝐢𝐢𝑒𝑒 𝑇𝑇𝑒𝑒 36.6 kips𝑑𝑑0.95 80𝑇𝑇𝑒𝑒36.6𝐴𝐴𝑠𝑠 0.68 in.2πœ™πœ™π‘“π‘“π‘¦π‘¦ 0.9 60Provide 2-#6 chord bars along the north and side edges ofthe slab

Example 5.19Maximum shear force in diaphragm: Shear strength138.0 1.7 Conservatively assuming πœŒπœŒπ‘‘π‘‘ 0:πœ™πœ™π‘‰π‘‰π‘›π‘› πœ™πœ™π΄π΄π‘π‘π‘π‘ 2πœ†πœ† 𝑓𝑓𝑐𝑐′ 0.6 8.0 12 4,000 1,000 7.3 kips ft 1.7 kips ft

Example 5.19 Shear transferreinforcement – East walland diaphragm9.2𝑅𝑅𝐸𝐸 𝐿𝐿 𝐴𝐴𝑣𝑣𝑣𝑣 πœ™πœ™π‘“π‘“π‘¦π‘¦ πœ‡πœ‡ 0.6 60 0.6 0.42 in.2 ftUse #5 dowel bars spaced at8 in. on center

Example 5.19 Shear transferreinforcement –Diaphragm and collectorsShear force in diaphragm 2.5 1.7 0.6 5.8 kips/ft𝛀𝛀𝒐𝒐Figure 5.67

Example 5.19 Shear transferreinforcement –Diaphragm and collectors𝐴𝐴𝑣𝑣𝑣𝑣𝑅𝑅𝐸𝐸 𝐿𝐿5.8 0.12 in.2 ftπœ™πœ™π‘“π‘“π‘¦π‘¦ πœ‡πœ‡ 0.6 60 1.4Provide #4 bars spaced at 14 in. on center

Example 5.19 Collector design Collectors and theirconnections must bedesigned for the maximumof the three forces inASCE/SEI 12.10.2.11. Forces calculated using the seismic load effectsincluding overstrength of ASCE/SEI 12.4.3 with seismicforces determined using the Equivalent Lateral ForceProcedure of ASCE/SEI 12.8 or the modal responsespectrum analysis procedure of ASCE/SEI 12.9Building frame system: Ξ©π‘œπ‘œ 2.5Diaphragm force 333 kips (see Table 5.17) Axial force in collector 2.5 92 230 kips

Example 5.19 Collector design Collectors and theirconnections must bedesigned for the maximumof the three forces inASCE/SEI 12.10.2.12. Forces calculated using the seismic load effectsincluding overstrength of ASCE/SEI 12.4.3 with seismicforces determined by ASCE/SEI Equation (12.10-1)Diaphragm force 333 kips (see Table 5.17) Axial force in collector 2.5 92 230 kips

Example 5.19 Collector design Collectors and theirconnections must bedesigned for the maximumof the three forces inASCE/SEI 12.10.2.13. Forces calculated using the load combinations ofASCE/SEI 2.3.6 with seismic forces determined byASCE/SEI Equation (12.10-2)Minimum 𝐹𝐹𝑝𝑝𝑝𝑝 0.2𝑆𝑆𝐷𝐷𝐷𝐷 𝐼𝐼𝑒𝑒 𝑀𝑀𝑝𝑝𝑝𝑝 0.2 1.00 1.0 1,222 244 kips 333 kips Axial force in collector will be less than that fromMethods 1 and 2Collector axial force 230 kips

Example 5.19 Collector design

Example 5.19 Collector design 3-#8 top bars 2-#8 side bars 3-#8 bottom bars

Example 5.19 Confinementreinforcement perACI 18.12.7.5230,000𝑓𝑓𝑐𝑐𝑐𝑐 411 psi 0.5𝑓𝑓𝑐𝑐′ 2,000 psi20 28Transverse reinforcement satisfying ACI 18.12.7.5 need notbe provided

Example 5.19 Transversereinforcement𝐴𝐴𝑣𝑣 𝑓𝑓𝑦𝑦𝑦𝑦 𝑑𝑑2 0.11 60 25.5𝑑𝑑 7.1 in. 12.8 in.𝑠𝑠 𝑉𝑉𝑒𝑒28.32 0 𝑉𝑉𝑐𝑐0.6πœ™πœ™Collector subjected to significantaxial tension 𝐴𝐴𝑣𝑣 𝑓𝑓𝑦𝑦𝑦𝑦0.75𝑓𝑓𝑐𝑐′ 𝑏𝑏𝑀𝑀 2 0.11 60,0000.75 4,000 20 13.9 in.𝐴𝐴𝑣𝑣 𝑓𝑓𝑦𝑦𝑦𝑦2 0.11 60,000 13.2 in. 50 2050𝑏𝑏𝑀𝑀Provide #3 ties spaced at 7 in. on center over the entirelength of the collectors

Example 5.19 Reinforcement details

Example 5.20 Diaphragm with largeopening

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Jun 12, 2018Β Β· Design and detailing requirements for shear, chord, and shear transfer . References Design and Detailing of Low -Rise Reinforced Concrete Buildings, CRSI, 2017. Chapters. 1. Introduction 2. Reinforced Concrete Building Systems 3. Design and Detailing Requirements for SDC A . Design Guide

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