CRSI Detailing

8/8/2019 CRSI Detailing

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Engineers Responsibility

for Detailing ReinforcedConcrete Structures

Neal S. Anderson, PE, SE, FACI Vice President of Engineering

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Dilbert !!

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What is Rebar Detailing?

The art of placing reinforcing in aconcrete member to follow the

design intent

Thou shall follow the design &placing rules of ACI ,AASHTO, and CRSI . . . .

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Why is Detailing Important?

It is how the project gets builtNot everything gets caught

When problems occur . . . Delays in the project Cost implications Possible finger pointing

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U.S. Detailing Practice

Structural Design A/EStructural Design A/E

BuildinBuildin Brid eBrid e

Drawings / Specs

Drawings / Specs

PlacingDrawingsPlacing

Drawings

Structural Placing

Drawings

Structural Placing

Drawings

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Detailing of Rebar in Concrete

BuildingsBridges

Two Case StudiesWhat can we (SEs) do?

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Buildings

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Building Deliverables

Drawings Structural Architectural

Project Specifications Section 03200 - Reinforcing

General Notes

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ACI 318 Building Code

Dawn of timeCurrent version is2008

Governs buildingdesignContains info onreinforcing

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ACI 318, Section 1.2.1 Drawings, Details & Specs

Specified strength / grade ofreinforcementSize and location of all Structural elements Reinforcement Anchors

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Reinforcement anchorage lengthsLap splices Location

ACI 318, Section 1.2.1 Drawings, Details & Specs

Length

Mechanical & welded splices Type Location

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Building Drawings

Beams / girdersColumns

FoundationsPlans, sections, & details

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Building Drawings

Beam / irder table

Many elements are shown TYPICAL

Column schedule

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Typical Beam Detail

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m n

D e t a i

l s

T y p

i c a l

C o l

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Building Drawings

Structural (& arch) drawingsMany typical details chedules tables Bar size & spacing (#5 @ 12 o.c.)

Detailers role Placing plans development Bill of material for fabrication

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Bridges

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Bridge Deliverables

Drawings Structural rebar placing

Rebar schedules Civil

General / structural notesProject special provisions Rebar covered in Std Specs.

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Plans Bar Schedule

A. Bar ID (unique)

B. Quantity (or #)C. Rebar size

. o a eng(includingbends)

E. Depiction ofshape

A B C D E

(E) = Epoxy coated 19

Plans Bend DiagramsStirrups

L-bars

Straight with180 hook

Bar ID fromschedule 20

Rebar Markings for Deck

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Plans splices

Bridge deck plan

Contact lapsplice length

Splice locations &length

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Bridge Drawings

Structural & placing drawingsVery prescriptive by DOT a E b E bars ~ deck h(E) & v(E) bars ~ wall

Detailers role Check engineers layout Bill of materials

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Buildings vs. Bridges

Buildings - Private

Bidding package Lump sum

Bridges - Public

Bidding package Unit prices Itemized

Rebar lumped inChange ordersRFIs

Unique nature - notcookie cutter

Rebar Weight ~ plain & (E) Placing unit

Not many COs / RFIs

Bridges are moretypical

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Detailing Practice The Roles

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Detailing Responsibilities

Admittedly, this is more focusedon the building sideWhat are the issues / concerns?Why worry? Costs Project delays Structural issues

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Meet Mr. Detailer . . .

Detailer Technically trained individual Interprets contract

documents

Responsible for Placing plans development Bill of material for fabrication

They are not design professionals

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Meet Mr. SE . . .

Structural Engineer BSCE, MSCE, or PhD FE (EIT), PE, or SE

Responsible for Design of concrete Preparing design plans &

specifications Placing / shop drawing review Anything else to ensure our

designs get built properly

We are licensed design professionals 28

What are the perceived normalrelationships between SE anddetailer?

SE Point of View . . . .

How can this relationship beimproved?How do we solve the problems?Who takes the lead to avoidproblems?

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SE Relationship Perception

Detailer prepares placing drawings SE and architectural drawings CRSI Manual of Standard Practice

SE rovides back round drawin s to Detailer to assist in starting plans Detailer verifies their scale & redraws if

necessary

SE expectations: Detailer to be properly trained or Working under the supervision of an

experienced detailer 30


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SE expects interpretation questions

during the preparation stage & priorto reviewing placing drawings

questions Placing drawings to be completewith unanswered issues cloudedSE will review promptly and clearlymark comments

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SE will not transmit designchanges during the placingdrawing preparation During mark-ups

Detailer addresses mark-ups priorto fabricating & issuing finaldrawings

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How Can SEs Get Better?

Recognize the tools available Publications

Get familiar with rebar detailing

Part 1

Make buildable designs Aids in placing drawing review

Field issues cannot always besolved with a BFH

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CRSI Manual of Std. Practice

First published byCRSI in 1927Industry StandardPractices for allactivities related tosteel reinforcing barsEssential referencefor the A / E

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ACI Committee 315 Report

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ACI Detailing Manual

Current Edition ~ 2004Contains ACI 315 reportIllustrative standards

Exam le drawin s Slabs Walls Footings Bridges Etc.

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a r B e n

d s

T y p

i c a l

B

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a r B e n

d s

T y p

i c a l

B

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Typical Stirrups

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Typical Column Ties

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End Hook Dimensions

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Stirrups and Ties

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Two What Went Wrongs

Continuous beamsSlab folds

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Continuous Beam

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SE Typical Screw Ups

Conflicting reinforcing over support Different sizes called on adj. beams

Too many bars for beam width

No direction on rebar location atintersecting beamsFull length bars not taken into accountCongestion over columns Take column reinforcing into consideration

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Slab Folds

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Slab Folds Again

Two Way SlabsDifficult fordetailersSlab elevationdifferences andthe complexity ofa two-way slab

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SE Typical Screw Ups

Detail is not cut on planExtent of fold not clearly shownFold not coordinated with architectural

depth exceeds maximum fold allowedFold location many bar lengths Framing bars Fill bars spliced to longer bars

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Typ. Detailer Screw-Ups

Slab reinforcing is replaced byfold reinforcing Two-way reinf. not considered

Other structural components invicinity are effectedIncorrect laps Location , length

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Problem Resolution

Identify issues ASAP & communicateto all partiesShare possible solutions

ocumen , u o no po n ngersImplement best solution ASAP Keeps job moving

Learn from problems & dont repeat At least not on the same job

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Improving the Relationship

Allow communication between parties

Provide Detailer with latest set of

contract documents Including architectural drawings

Encourage detailer to contact SEduring placing drawing preparation

Share lesson learned experiencefrom previous projects

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Improving the Relationship

Identify potential problemsahead of timeSim lif and standardize detailsFollow latest codes & practicesKeep Detailers trained andcurrent

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Meetings !!

If needed, call early project meeting Detailer, Subs, & GC Discuss project misunderstandings

Sub / Detailer may request meeting Details confusing or not clear He/she proposes alternate detail Without changing intent, if these have

worked previously 53

Stretch Time . . . .

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How Can SEs Get Better?

Take the lead !!Identify potential issues indesi n hase

Part 2

Draw details to scale to visualize Detail / think out the tuffys Go beyond dots & lines Recognize congestion issues

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SE Takes the Lead . . .

Design process begins with EOR / SEIn-house training of young engineers Starts ASAP upon hiring from college Mentorin from ex erienced en ineers In-house seminars, site visits, lessons

learned Clarify intent at pre-constr. meetingContact detailer early Initial placing drawings indicate a lack of

understanding of design intent 56

U.S. Bar Sizes

Diameterapprox.Based on

weight

Bar Size[metric]

#

Nominal Weight,lb/ft[Nominal Mass,kg/m ]

Diameter, in.[ mm ]

CrossSectionalArea, in. 2[mm 2]

3 [10] 0.3 76 [0. 560] 0. 375 [9 .5] 0 .11 [ 71]

4 [13] 0 .6 68 [0 .9 94 ] 0 .5 00 [1 2. 7] 0 .2 0 [ 12 9]

. . . . .

6 [19] 1 .5 02 [2 .2 35 ] 0 .7 50 [1 9. 1] 0 .4 4 [ 28 4]

7 [22] 2 .0 44 [3 .0 42 ] 0 .8 75 [2 2. 2] 0 .6 0 [ 38 7]

8 [25] 2 .6 70 [3 .9 73 ] 1 .0 00 [2 5. 4] 0 .7 9 [ 51 0]

9 [29] 3 .4 00 [5 .0 60 ] 1 .1 28 [2 8. 7] 1 .0 0 [ 64 5]

10 [32] 4 .3 03 [6 .4 04 ] 1 .2 70 [3 2. 3] 1 .2 7 [ 81 9]

11 [36] 5 .313 [7.907] 1 .410 [35 .8 ] 1 .56 [1006]

14 [43] 7 .650 [11 .38] 1 .693 [43 .0 ] 2 .25 [1452]

18 [57] 13.60 [20 .24] 2 .257 [57 .3 ] 4 .00 [2581] 57


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U.S. Bar Sizes

Figure 6-1 fromCRSIs Manual of Standard Practice

BarSize

NominalDiameter( in. )

OutsideDiameter( in. )

3 3/8 7/16

4 1/2 9/16

6 3/4 7/8

7 7/8 1

8 1 1-1/89 1.128 1-1/4

10 1 270 1-7/16

11 1.410 1-5/8

14 1 693 1-7/8

18 2 257 2-1/2 58

Common Problem Areas

Beam column jointsBrackets / haunches / ledges

T-JointsTop of columns

59 Avoid Congestion

Beam-Column Joints

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Beam-Column Joints

Perimeter ofColumn Reinf.

Think curtains orplanes of steelreinforcing

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Beam-Column Joints

Congestion is a givenConsider making beams wider B 4 in 2 in each side Corner beam bars dont interfere

Consider beams Different depths or elevations Top & bottom bar interferences

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Beam-Column Joint

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Column Brackets

Where located oncolumn?What is the size?Bar s acin ?How does thiseffect the strut-and-tie model?

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Bottom Integrity Rebar

Lap outside column to avoidcongestion

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Retaining Wall T-Joints

Easier for contractor

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Retaining Wall T-Joints

Performs better

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Coupling Beams

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Scale Drawing of Rebar

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f i g u r a

t i o n

F i n a l

C o

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Shear Wall Ends L to M

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Shear Wall Ends L to M

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Shear Wall Ends Special

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Column Ends Headed Bars

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Punching Shear Studs

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SE Need to Knows - Rebar

Standard rebar stock length (40 to) 60 ft

S ecial len ths ossible coordinate with mill or fabricator)

Try to use same steel gradethroughout project#14 & #18 may require lead time

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Use largest bar size possibleRepeat bar sizes & lengthsProvide minimum 4 - 6 in. a

SE Need to Knows - Rebar

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between top barsFollow ACI 315 for bending detailsMinimize bar bends & hooksKeep bars in one plane

SE Need to Knows - Columns

Multi-story construction, usualpractice Limit column bar lengths to one story

For larger bars & couplers Two and three story heights possible Bar sizes of #9 & > have sufficient

stiffness to use free standing two

story heights.80

SE Need to Knows - Columns

Use same column size, vary Bar size

Concrete strength Lap splices permitted up to #11#14 & #18 bars have to bemechanically spliced or welded,if tension splice

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Rebar Splicing - Coupler

Couplers are: Grouted Threaded Screw type

Manufacturers literature

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Rebar Splicing - Couplers

Couplers take up space Greater diameter than rebar

Sta er cou lersCan they be installed? Grouting Set screws

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Better SEs - Review

Identify potential issues Draw details to scale to visualize

Detail / think out the tuffys Go beyond dots & lines Recognize congestion issues

Get familiar with rebar detailing

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What Can Mr. CRSI Do?

Manuals of Standard Practice

Keep current / up to date Reflect latest Code changes

Promote field experience importance Young engineers

Work with college professors Discuss importance of detailing Properly expressing design in contract docs

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Questions?

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CRSI Detailing

Documents

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