Practical Design of PT Buildings

Name: Practical Design of PT Buildings
Uploaded: 2017-06-28T13:12:38+00:00
Duration: PTM23S31
Channel: Sybil Wilcox
Description: Practical Design of PT Buildings

Practical Design of PT Buildings
PCA Education Foundation 2015 Professors’ Workshop July 21, 2015 _________________________________________________________ Seismic Details for Reinforced Concrete Buildings David A. Fanella, Ph.D., S.E., P.E. TGRWA, LLC Practical Design of PT Buildings May 18, 2010 SEAOI - Continuing Education Seminar

Resources

Permitted Building Systems for Different SDC
Not Permitted

ACI Table R18.2 Sections of Chapter 18 to be satisfied according to SDC 4

Design and Detailing for SDC B

Beams of Ordinary Moment Frames (ACI 18.3) Minimum 2 continuous longitudinal bars at both top and bottom faces Area of continuous bottom bars at least 25% of total area of bottom bars Bars anchored to develop fy in tension at the face of support 7

Columns Shear strength requirements for columns in ordinary moment frames (ACI ) If clear height is less than or equal to 5 times the column dimension in the direction of analysis, column must be designed for the lesser of the shear forces in ACI (a) and (b) Shear associated with development of 𝑀 𝑛 at each end due to reverse curvature bending Maximum shear obtained from design load combinations that include 𝐸 with Ω 𝑜 𝐸 substituted for 𝐸

Design and Detailing for SDC C

Beams of Intermediate Moment Frames Summary of requirements (ACI ) Flexure Confinement Shear

Beams of Intermediate Moment Frames Flexural requirements

Beams of Intermediate Moment Frames Confinement requirements

Beams of Intermediate Moment Frames Shear requirements Two methods Method 1 Factored shear force is determined based on factored gravity loads and the development of the nominal moment strength of the section at both ends of the member

Beams of Intermediate Moment Frames Shear requirements Two methods Method 2 Factored shear force is obtained from the design load combinations that include E where E is assumed to be twice that prescribed by the building code

Two-way slabs without beams (ACI ) May be considered part of the seismic-force- resisting system in buildings assigned to SDC B and C

Two-way slabs without beams Two-way shear Shear caused by factored gravity loads limited to

Columns of Intermediate Moment Frames Summary of requirements (ACI ) Transverse reinforcement Shear strength

Columns of Intermediate Moment Frames Transverse reinforcement

Columns of Intermediate Moment Frames Transverse reinforcement requirements for columns supporting discontinued stiff members

Columns of Intermediate Moment Frames Shear strength Same two methods required for beams except instead of 2E in Method 2, E is to be increased by Wo

Design and Detailing for SDCs D, E, and F

Beams of Special Moment Frames Summary of requirements (ACI 18.6) General Flexure Splices Transverse reinforcement Shear

Beams of Special Moment Frames General requirements Factored axial force Geometric requirements

Beams of Special Moment Frames Flexural requirements

Beams of Special Moment Frames Lap splice requirements

Beams of Special Moment Frames Transverse reinforcement requirements Vc = 0 when both of the following occur: Earthquake-induced shear force ≥ Vu/2 Pu < Agf’c/20

Beams of Special Moment Frames Shear requirements

Columns of Special Moment Frames Summary of requirements (ACI 18.7) General Flexure Longitudinal reinforcement Transverse reinforcement Shear

Columns of Special Moment Frames General requirements Geometric constraints

Columns of Special Moment Frames Minimum flexural strength Columns must have sufficient strength so that they will not yield prior to the beams at the beam-column joints

Columns of Special Moment Frames Minimum flexural strength If minimum flexural strength is not satisfied Lateral strength and stiffness of the columns framing into the joint are to be ignored when determining the strength and stiffness of the structure Columns must satisfy the provisions of ACI 18.14

Columns of Special Moment Frames Longitudinal reinforcement requirements

Columns of Special Moment Frames Transverse reinforcement requirements

𝑷 𝒖 ≤𝟎.𝟑 𝑨 𝒈 𝒇′ 𝒄 𝒇′ 𝒄 ≤𝟏𝟎 𝐤𝐬𝐢

𝑷 𝒖 >𝟎.𝟑 𝑨 𝒈 𝒇′ 𝒄 𝒇′ 𝒄 >𝟏𝟎 𝐤𝐬𝐢

Columns of Special Moment Frames Shear requirements Shear forces associated with development of Mpr acting at the ends of the member associated with the range of Pu Maximum shear force may be limited by the probable flexural strengths of the beams framing into the joint

First Floor Column

Joints of Special Moment Frames Summary of requirements (ACI 18.8) General Transverse reinforcement Shear Development length of bars in tension

Joints of Special Moment Frames General requirements Joint forces are calculated using a stress of 1.25fy in the beam longitudinal reinforcement passing through the joint Column dimension parallel to the beam reinforcement must be greater than or equal to 20 times the diameter of the largest longitudinal bar in the beam for normal weight concrete (26 times for lightweight concrete)

Joints of Special Moment Frames Transverse reinforcement For members framing into all 4 sides of a joint Transverse reinforcement may be taken as 50% of that required for the column Spacing is permitted to be increased to 6 in.

Joints of Special Moment Frames Transverse reinforcement For less than full joint confinement Provide column transverse reinforcement through joint

Joints of Special Moment Frames Shear strength Vn For joints confined on all four faces…… For joints confined on three faces or on two opposite faces…… For all other joints……

Joints of Special Moment Frames Shear force Shear force in joint = column shear force – (sum of the tensile force in the top beam reinforcement and the compressive force at the top of the beam on the opposite face of the column) Stress in reinforcement = 1.25fy

𝑉 𝑐𝑜𝑙 = 𝑀 𝑝𝑟 + + 𝑀 𝑝𝑟 − ℓ 𝑐 + 𝑉 𝑒,1 + 𝑉 𝑒,2 × 𝑐 1 2 ℓ 𝑐

Joints of Special Moment Frames Development length of bars in tension Straight bars

Special Structural Walls Summary of requirements (ACI 18.10) Reinforcement Shear strength Flexure and axial loads Boundary elements

Special Structural Walls Reinforcement requirements Minimum reinforcement per ACI 11.6 Maximum spacing = 18 in.

Special Structural Walls Reinforcement requirements Two curtains of reinforcement must be provided

Special Structural Walls Shear strength ≤8 𝐴 𝑐𝑣 𝑓 𝑐 ′

Special Structural Walls Flexure and axial loads Design in accordance with ACI 22.4

Special Structural Walls Wall segments

Special Structural Walls Boundary elements Two design approaches ACI (displacement-based) ACI

Special Structural Walls ACI Applicable to Walls or wall piers that are effectively continuous in cross-section over the entire height Walls with one critical section for flexure and axial loads

Special Structural Walls ACI Applicable to essentially all walls

Special Structural Walls Boundary elements Detailing requirements where boundary elements are required (ACI )

Special Structural Walls Boundary elements Detailing requirements where boundary elements are not required (ACI )

Coupling Beams ACI

Coupling Beams ℓ 𝑛 ℎ ≥4 Satisfy requirements of ACI 18.6 for beams of special moment frames ℓ 𝑛 ℎ <2 and 𝑉 𝑢 ≥2𝜆 𝑓 𝑐 ′ 𝐴 𝑐𝑤 Two intersecting groups of diagonally placed bars symmetrical about the midspan of the coupling beam 𝑉 𝑛 =2 𝐴 𝑣𝑑 𝑓 𝑦 sin 𝛼≤ 10 𝑓 𝑐 ′ 𝐴 𝑐𝑤

Wall Piers Vertical wall segment within a structural wall Bounded horizontally by two openings or by an opening and an edge Length to wall thickness ℓ 𝑤 / 𝑏 𝑤 ≤6 Clear height to horizontal length ℎ 𝑤 / ℓ 𝑤 ≥2

Wall Piers ACI Must satisfy the special moment frame requirements for columns ACI , and Alternatively, where ℓ 𝑤 𝑏 𝑤 ≥2.5 Must satisfy (a) through (f) of ACI

Structural Diaphragms Summary of requirements (ACI 18.12) Minimum thickness Reinforcement Flexural strength Shear strength

Foundations Summary of requirements (ACI 18.13) Footings, foundation mats, and pile caps Grade beams and slabs-on-ground Piles, piers, and caissons

Foundations Footings, foundation mats, and pile caps

Foundations Grade beams

Foundations Grade beams Grade beams that are part of a mat foundation that resists flexural stresses from columns that are part of the SFRS must conform to the provisions of ACI 18.6 for flexural members of special moment frames

Foundations Slab-on-ground For slabs-on-ground that are part of the SFRS (acts as a diaphragm that holds the structure together at the ground level and minimizes the effects of out-of-phase ground motion) Design and detail per ACI for diaphragms

Foundations Piles, piers, and caissons

Members not Designated as Part of the SFRS Summary of requirements (ACI 18.14) Members where combined bending moments and shear forces due to factored gravity loads and design displacements are less than or equal to the design moment and shear strengths Members where combined bending moments and shear forces due to factored gravity loads and design displacements exceed the design moment and shear strengths, or if induced moments are not calculated Slab-column connections of two-way slabs without beams and wall piers

Members not Designated as Part of the SFRS Beams Induced bending moments and shear forces are less than or equal to the design moment and shear strengths

Members not Designated as Part of the SFRS Beams Induced bending moments and shear forces exceed the design moment and shear strengths Induced bending moments and shear forces are not calculated

Members not Designated as Part of the SFRS Columns Induced bending moments and shear forces are less than or equal to the design moment and shear strengths

Members not Designated as Part of the SFRS Columns Induced bending moments and shear forces exceed the design moment and shear strengths Induced bending moments and shear forces are not calculated Detailing requirements are essentially the same as those for columns in special moment frames

Members not Designated as Part of the SFRS Two-way slabs without beams Where Δ 𝑥 ℎ 𝑠𝑥 ≥ 0.035− 𝑣 𝑢𝑔 𝜙 𝑣 𝑐 or Δ 𝑥 ℎ 𝑠𝑥 >0.005 Provide slab shear reinforcement conforming to ACI (stirrups) or ACI (headed studs) supplying a nominal shear strength 𝑣 𝑠 ≥3.5 𝑓 𝑐 ′

Members not Designated as Part of the SFRS Wall Piers Must satisfy the requirements of ACI

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