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

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

Design and Detailing for SDC B Columns Shear strength requirements for columns in ordinary moment frames (ACI 18.3.3) 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 18.3.3(a) and 18.3.3(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

Design and Detailing for SDC C Beams of Intermediate Moment Frames Summary of requirements (ACI 18.4.2) Flexure Confinement Shear

Design and Detailing for SDC C Beams of Intermediate Moment Frames Flexural requirements

Design and Detailing for SDC C Beams of Intermediate Moment Frames Confinement requirements

Hoops

Design and Detailing for SDC C 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

Design and Detailing for SDC C 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

Design and Detailing for SDC C Two-way slabs without beams (ACI 18.4.5) May be considered part of the seismic-force- resisting system in buildings assigned to SDC B and C

Design and Detailing for SDC C Two-way slabs without beams Two-way shear Shear caused by factored gravity loads limited to

Design and Detailing for SDC C Columns of Intermediate Moment Frames Summary of requirements (ACI 18.4.3) Transverse reinforcement Shear strength

Design and Detailing for SDC C Columns of Intermediate Moment Frames Transverse reinforcement

Design and Detailing for SDC C Columns of Intermediate Moment Frames Transverse reinforcement requirements for columns supporting discontinued stiff members

Design and Detailing for SDC C 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

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

Design and Detailing for SDCs D, E, and F Beams of Special Moment Frames General requirements Factored axial force Geometric requirements

Design and Detailing for SDCs D, E, and F Beams of Special Moment Frames Flexural requirements

Design and Detailing for SDCs D, E, and F Beams of Special Moment Frames Lap splice requirements

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F Beams of Special Moment Frames Shear requirements

Design and Detailing for SDCs D, E, and F Columns of Special Moment Frames Summary of requirements (ACI 18.7) General Flexure Longitudinal reinforcement Transverse reinforcement Shear

Design and Detailing for SDCs D, E, and F Columns of Special Moment Frames General requirements Geometric constraints

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F Columns of Special Moment Frames Longitudinal reinforcement requirements

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F Joints of Special Moment Frames Summary of requirements (ACI 18.8) General Transverse reinforcement Shear Development length of bars in tension

Design and Detailing for SDCs D, E, and F 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)

Design and Detailing for SDCs D, E, and F 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.

Design and Detailing for SDCs D, E, and F Joints of Special Moment Frames Transverse reinforcement For less than full joint confinement Provide column transverse reinforcement through joint

Design and Detailing for SDCs D, E, and F 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……

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F Joints of Special Moment Frames Development length of bars in tension Straight bars

Design and Detailing for SDCs D, E, and F Special Structural Walls Summary of requirements (ACI 18.10) Reinforcement Shear strength Flexure and axial loads Boundary elements

Design and Detailing for SDCs D, E, and F Special Structural Walls Reinforcement requirements Minimum reinforcement per ACI 11.6 Maximum spacing = 18 in.

Design and Detailing for SDCs D, E, and F Special Structural Walls Reinforcement requirements Two curtains of reinforcement must be provided

Design and Detailing for SDCs D, E, and F Special Structural Walls Shear strength ≤8 𝐴 𝑐𝑣 𝑓 𝑐 ′

Design and Detailing for SDCs D, E, and F Special Structural Walls Flexure and axial loads Design in accordance with ACI 22.4

Design and Detailing for SDCs D, E, and F Special Structural Walls Wall segments

Design and Detailing for SDCs D, E, and F Special Structural Walls Boundary elements Two design approaches ACI 18.10.6.2 (displacement-based) ACI 18.10.6.3

Design and Detailing for SDCs D, E, and F Special Structural Walls ACI 18.10.6.2 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

Design and Detailing for SDCs D, E, and F Special Structural Walls ACI 18.10.6.3 Applicable to essentially all walls

Design and Detailing for SDCs D, E, and F Special Structural Walls Boundary elements Detailing requirements where boundary elements are required (ACI 18.10.6.4)

Design and Detailing for SDCs D, E, and F Special Structural Walls Boundary elements Detailing requirements where boundary elements are not required (ACI 18.10.6.5)

Design and Detailing for SDCs D, E, and F Coupling Beams ACI 18.10.7

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F Wall Piers ACI 18.10.8 Must satisfy the special moment frame requirements for columns ACI 18.7.4, 18.7.5 and 18.7.6 Alternatively, where ℓ 𝑤 𝑏 𝑤 ≥2.5 Must satisfy (a) through (f) of ACI 18.10.8.1

Design and Detailing for SDCs D, E, and F Structural Diaphragms Summary of requirements (ACI 18.12) Minimum thickness Reinforcement Flexural strength Shear strength

Design and Detailing for SDCs D, E, and F Foundations Summary of requirements (ACI 18.13) Footings, foundation mats, and pile caps Grade beams and slabs-on-ground Piles, piers, and caissons

Design and Detailing for SDCs D, E, and F Foundations Footings, foundation mats, and pile caps

Design and Detailing for SDCs D, E, and F Foundations Grade beams

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F 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 18.12 for diaphragms

Design and Detailing for SDCs D, E, and F Foundations Piles, piers, and caissons

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F 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

Design and Detailing for SDCs D, E, and F Members not Designated as Part of the SFRS Two-way slabs without beams Where Δ 𝑥 ℎ 𝑠𝑥 ≥ 0.035− 1 20 𝑣 𝑢𝑔 𝜙 𝑣 𝑐 or Δ 𝑥 ℎ 𝑠𝑥 >0.005 Provide slab shear reinforcement conforming to ACI 8.7.6 (stirrups) or ACI 8.7.7 (headed studs) supplying a nominal shear strength 𝑣 𝑠 ≥3.5 𝑓 𝑐 ′

Design and Detailing for SDCs D, E, and F Members not Designated as Part of the SFRS Wall Piers Must satisfy the requirements of ACI 18.10.8