3D MODELING FOR STRUCTURES - dot.state.pa.us · MODELING FOR STRUCTURES . DAVID MIRAGLIA, P.E. ... arches. more complex . Add spandrel ... face, but the bottom is at a

CASE STUDY: SR 228 OVER

BREAKNECK CREEK

MODELING FOR STRUCTURES

DAVID MIRAGLIA, P.E. ROBERT GUYER, E.I.T.

NTM ENGINEERING, INC.

1. Project Introduction 2. Project Evolution & Alternates 3. Constructability & Design-ability 4. Identified Removal Limits 5. Identified Construction Sequence 6. Complex Reinforcement Layout 7. Detailing Examples

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CASE STUDY AGENDA

Topic 1

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PROJECT INTRODUCTION


SR 228 Corridor Improvement PennDOT District 10-0 Adams Township in Butler County Project to widen corridor Replace structurally deficient bridge

over CSX Railroad Extend existing concrete arch under

approach to bridge 4


Arch is to the lef t s ide of the sur vey. Br idge is to the r ight s ide of the sur vey. S tat ion ahead to the r ight . Breakneck Creek f lows general ly nor th . Ent i re arch extens ion and hal f o f br idge constructed in Phase 1 .

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Existing survEy

STA. AHD.

• Cast- in-Place Concrete Arch

• 55° Skew

• 75’-0” Out-Out Length

• Multi -Centered Arch

• 26’-9” Opening at Springl ine

• 6’-8” of Fi l l over Crown

• Arch 9” Thick at Crown

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Existing arch Plan

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Existing arch sEction

• Cast- in-Place Concrete Arch

• 55° Skew

• 75’-0” Out-Out Length

• Multi -Centered Arch

• 26’-9” Opening at Springl ine

• 6’-8” of Fi l l over Crown

• Arch 9” Thick at Crown

Topic 2

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PROJECT EVOLUTION & ALTERNATES


Extension in Kind Cast-in-Place Match Opening 75’-0” Upstream Friction Loss Doubles

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PROJECT EVOLUTION

Increases Water Surface Elevation

The original extension-in-kind concept causes increases to the 100-year flood water sur face elevation upstream. No water sur face increases were tolerable. To reduce the fr ict ion loss, arch opening had to be increased.

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PROJECT EVOLUTION

ExtEnsion in kind

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Extension in Kind

All Precast Arch Culvert

Combination of Precast & Cast- in-Place

All Cast- in-Place Arch

ALTERNATES

A

PROS: Faster Construction Familiar Method Potential Cost Saver CONS: Skews are Limited Transition to Existing Without Good Tie-In, Must Replace Entire Arch

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Extension in Kind




ALTERNATES

A

PROS: Precast Part Built Quickly C.I.P. Transition to Existing Fewer Skew Limitations CONS: Transition End Shapes Set Potential Debris Catcher Two Construction Methods More Costly

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PRECAST C.I.P. COMBINATION

altErnatE 2

Star t w i th ex ist ing arch end. Remove ex is t ing spandrel wal l . Cast foot ings and pedesta ls . Cast “overarch” to square end. Tapered sect ion to t rans i t ion between openings. Cover ent i re length wi th 30’ precast arches . Add spandre l wal l .

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ALTERNATE 2 Shor tcomings : Excavate to expose top of arch. Remove ex is t ing spandrel & counter for ts . Long st retch of cost ly precast . Tapered sect ion and overarch d i f f icult to cast . Tapered sect ion does not fu l ly remove b lunt end.

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Star t w i th ex ist ing arch end. Remove ex is t ing spandrel wal l . Cast foot ings and pedesta ls . Cast “overarch” to square end. Tapered sect ion to t rans i t ion between openings. Ex tend length wi th 30’ precast arches . Add spandre l wal l .

ALTERNATE 3 Shor tcomings : Excavate to expose top of arch. Remove ex is t ing spandrel & counter for ts . Shor t s t retch of cost ly precast . Tapered sect ion and overarch d i f f icult to cast . B lunt end removed by even more complex cast ings .

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DESIGN CHANGE!

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Star t w i th ex ist ing arch end. Remove ex is t ing spandrel wal l . Cast foot ings . Cast “overarch” to square end. Tapered sect ion to t rans i t ion between openings. Ex tend length wi th 36’ precast arches . Add spandre l wal l .

ALTERNATE 4 Shor tcomings : Excavate to expose top of arch. Remove ex is t ing spandrel & counter for ts . Shor t s t retch of cost ly precast . Tapered sect ion and overarch d i f f icult to cast . Tapered sect ion does not fu l ly remove b lunt end.

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Star t w i th ex ist ing arch end. Remove ex is t ing spandrel wal l . Cast foot ings and pedesta ls . Cast “overarch” to square end. Tapered sect ion to t rans i t ion between openings. Ex tend length wi th 36’ precast arches . Add spandre l wal l .

ALTERNATE 5 Shor tcomings : Excavate to expose top of arch. Remove ex is t ing spandrel & counter for ts . Shor t s t retch of cost ly precast . Tapered sect ion and overarch d i f f icult to cast . B lunt end removed by even more complex cast ings .

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DESIGN CHANGE!

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Extension in Kind




ALTERNATES

A

PROS: Few Design Limitations Can Skew to 55° Single Construction Method Minimal Removal of Existing CONS: Slower Construction Unfamiliar Techniques Standard Arch

Reinforcement Orientation

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Star t w i th ex ist ing arch end. Use ex is t ing spandrel wal l as shor ing. Cast foot ings . Cast wedge arch to square end. Tapered sect ion to t rans i t ion between openings. Ex tend length wi th 36’ C . I .P. arch. Add spandre l wal l .

ALTERNATE 6 Shor tcomings : Wedge arch and tapered sect ion d i f f icult to cast . Each bar in wedge arch would be a d i f ferent length . Min imum f i l l over arch’s near r ight corner requi res more ROW, c reates unbalanced loading, and i t i s ug ly.

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Use ex is t ing spandrel wal l as shor ing. Remove o ld wings & foot ings . Cast foot ings . Cast co l lar and tapered arch, w i th skewed end. Ex tend length wi th 36’ C . I .P arch wi th skewed ends . Add counter for ts & spandrel wal l . Add wingwal ls .

SELECTED ALTERNATIVE Advantages : S ingle method of construct ion. A large c rane is not requi red. End of arch matches roadway skew. Trans i t ion geometr y s impli f ied by bas ing proposed arch sect ion on ex ist ing arch sect ion. Water eased through taper.

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SELECTED ALTERNATIVE Advantages : S ingle method of construct ion. A large c rane is not requi red. End of arch matches roadway skew. Trans i t ion geometr y s impli f ied by bas ing proposed arch sect ion on ex ist ing arch sect ion. Water eased through taper.

Arch or Barrel

Spandrel Wall or

Headwall

Wingwall

Footing

Counterfort

arch tErMs 101

Topic 3

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CONSTRUCTABILITY & DESIGN-ABILITY


Skews are hard to bui ld on, and in many cases harder to des ign. But a l igning the bars normal to the arch’s center -l ine c reates many issues. The “Typica l” bars are only typical for a th i rd of the arch length .

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CONSTRUCTION & DESIGN

BARS VARY IN RADIUS, LENGTH,

AND BEND UP INTO COLLAR

BARS VARY IN RADIUS

AND LENGTH “TYPICAL”

BARS

BARS VARY IN LENGTH,

AND BEND UP INTO

SPANDREL WALL

36’-0

”

BARS VARY IN RADIUS, LENGTH,

AND BEND UP INTO COLLAR

BARS VARY IN RADIUS

AND LENGTH “TYPICAL”

BARS

BARS VARY IN LENGTH,

AND BEND UP INTO

SPANDREL WALL

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CONSTRUCTION & DESIGN

BARS VARY IN RADIUS

AND LENGTH

TYPICAL BARS

3D Draf t ing Rule #1 I f i t i s a pain to draw i t w i l l be a pain to bui ld . To a l low the pr imar y bars to fo l low the skew, the arch was des igned a long the skew. So instead of des igning a 36’ -0” opening, a 43 ’ -11½” span was used.

BARS VARY IN RADIUS

AND LENGTH

TYPICAL BARS

Topic 4

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IDENTIFIED LIMITS OF REMOVAL


Construct Temporary Shoring

Construct Cof ferdam

Excavate & Expose Wings

Remove Wings & Footings

Construct Proposed Footings

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LIMITS OF REMOVAL

Topic 5

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IDENTIFIED SEQUENCE OF

CONSTRUCTION


Arch foot ings bui l t f i r s t . Segment C was bui l t next so construct ion could move in both d i rect ions . Segment B and the Spandrel Wal l could now be formed and poured against Segment C . Segment A was cast af ter so formwork could br idge between ex ist ing arch and hardened Segment B .

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IDENTIFY SEQUENCE OF CONSTRUCTION

The wing stems could be cast at the same t ime as the tapered arch (Segment A) . FY I : Cont ractor chose to pour Segment B wi th Segment C , then pour Segment A , then the spandrel and wings .

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The bar re l ’s c i rcumference is over 55 ’ , therefore the BC standards requi re at least one opt ional longi tudinal construct ion jo ints . Two jo ints keep a construct ion jo int away f rom the arch c rown. Cut the arch approx imately in th i rds , then add a jo int in the headwal l at that e levat ion.

Topic 6

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SIMPLIFY LAYOUT OF THE COMPLEX REINFORCEMENT


Reinforc ing the arch was never go ing to be easy. 3D model ing a l lowed us to s impli fy bar layout as much as poss ible . Des igners tested schemes to f ind the best ar rangement . Deta i led bar cur ve rad i i and arc lengths . When deta i l ing was done, bar schedule was complete .

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REBAR LAYOUT

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Typica l rebar in constant arch . Lower arch bars at 6” spac ing are lapped to the foot ing bars and extend past the opt ional constr. jo int . Upper arch bars at 12” spacing lap to lower bars . Upper arch bars osc i l late s ide - to -s ide to provide s tagger between sp l ices .

REBAR LAYOUT

BD-633M requi res latera l #4 t ies at 12” max spac ing for shear and to t ie the two mats together. Because the arch th ickness var ies rad ial ly, the t ie lengths var y, and in the taper segment they var y both rad ial ly and longi tudinal ly. And that i s a lot o f t ies .

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REBAR LAYOUT

latEral shEar tiEs not shoWn For clarity …and BEcausE that’s an aWFul lot oF tiEs to draW… What Was that #1 rulE oF 3d draFting again?

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REBAR LAYOUT

Opt ion A : Provide a deta i led shear t ie matr ix that would show bar marks as they var y rad ia l ly & longi tudinal ly. Opt ion B : Use #3 t ies at 6” rad ial ly, pre -bent w i th a J -hook on one end, and f ie ld bent to 90° at the other. We chose B… Cont ractor went w i th A .

9576 tiEs in 4 diFFErEnt lEngths

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Spandrel wall reinforced ver t ical ly with #5 U-Bars @ 9” top & bottom. The top of the wall is normal to the front face, but the bottom is at a 55° skew through the arch. The skew of fset through this wall happens to be about 9”.

REBAR LAYOUT

sPandrEl Wall - Plan viEW

sPandrEl Wall - ElEvation viEW

9” Typ.

9” Typ.

sPandrEl Wall - Plan viEW

sPandrEl Wall - ElEvation viEW

9” Typ.

9” Typ.

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The top U-bars could have been normal to the top of the wal l , the bottom U-bars skewed, and a spi ra l would have been created for the whole wal l . However, an ef fect ive way to present th is on 2D drawings wasn’t found. So a l l of the bars were skewed except four U-bars in the top corners.

Intrados Falsework

Concrete Arch

Spandrel Wall Reinforcement

REBAR LAYOUT

The photos used throughout the presentat ion were taken by : Tom Knier iem

D - 1 0 S t r uc t u ra l C o n t r o l E n g i n e e r

Joe Roman

K C I P r o j . M a n a g e r

John

Yamashita N T M E n g i n e e r

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ADDITIONAL CONSTRUCTION PHOTOS

Topic 7

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DETAILING EXAMPLES


The “co l lar” g ives the tapered sect ion a f lat sur face. The co l lar ’s per imeter i s 90° to the spandrel wal l . The co l lar i s a constant 18” th ick f rom the wal l . The taper enters the co l lar at an ang le f rom 45°28’00” to 113°11’17” . 42

COLLAR DETAIL

Counter for ts suppor t the spandrel wal l against latera l ear th pressure. Smal l counter -for ts can be atop the arch, but wi l l create upl i f t on the arch. PennDOT’s ARCH sof tware cannot analyze these discreet loads.

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COUNTERFORT PEDESTALS

Tal ler counter -for ts can be anchored to the foot ings, removing the upl i f t issue. To receive the counter for t , a pedestal was created. The pedestal extends beyond the counter for t to contain the s loped rebar.

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COUNTERFORT PEDESTALS

Counter for t ends at wal l , c reat ing an acute corner which is hard to form & easy to spal l . Reinforcement ex tends above and beyond headwal l . Could square the top, but i ssue re locates to the bot tom. A lso , the counter for t ’s top and s ides are no longer at 90°.

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COUNTERFORT CONNECTION TO SPANDREL

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Top of counter for t c l ipped to e l iminate form & spal l issue. Reinforcement bent to enter the headwal l hor izontal ly. Front of headwal l bumped out to prov ide development length of counter for t hooks.

COUNTERFORT CONNECTION TO SPANDREL

Waterproofing membrane should be p laced across co ld jo ints under f i l l . In th is “ t rough” between the arch r ing and the counter for t , we have two co ld jo ints that need to be protected. That ’s 6” w ide at the base… How wide is the carpenter?

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TROUGH DETAIL

Waterproofing Membrane

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Whi le the o ld deta i l looked s imple in sect ion v iew, i t i s ver y d i f f icult when v iewed in 3D. The bet ter deta i l f i l ls the bot tom of the t rough to the weephole inver t . Not only i s the “bottom” wider, but i t prevents water pool ing below the weephole .

TROUGH DETAIL

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The 3D l imits of backfi l l can be used to locate the requi red l imits of the spandrel wal l . C l ipping the corners reduces excess wal l , prevents the eros ion concerns of the future inspectors, and is better aesthet ical ly.

Theoretical Toe of Slope

Practical Toe of Slope

SPANDREL WALL CLIPS

sPandrEl Wall – FroM aBovE thE roadWay

Spandrel Wall

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The 3D l imits of backfi l l can be used to locate the requi red l imits of the spandrel wal l . C l ipping the corners reduces excess wal l , prevents the eros ion concerns of the inspectors in the future , and is better aesthet ical ly.

SPANDREL WALL CLIPS

sPandrEl Wall – FroM strEaM lEvEl

Almost Done… CONCLUSION


Where’s lunch?

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1. Introduction to Project 2. Alternate Study 3. Constructability & Design-ability 4. Limits of Removal 5. Sequence of Construction 6. Layout of Reinforcement 7. Examples of Detailing

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CASE STUDY SUMMARY

Documents

3D MODELING FOR STRUCTURES - dot.state.pa.us · MODELING FOR STRUCTURES . DAVID MIRAGLIA, P.E. ... arches. more complex . Add spandrel ... face, but the bottom is at a