construction loading example for steel beam bridge - indot

8/10/2019 Construction Loading Example for Steel Beam Bridge - InDOT

http://slidepdf.com/reader/full/construction-loading-example-for-steel-beam-bridge-indot 1/33

Construction Loading ExampleConstruction Loading Example

Presented By: Michael L. McCool, Jr., PE 1

Construction Loading ExampleConstruction Loading ExampleINDOT Design Pol icy

2

July 24, 2012 Construction Loading Example for Steel Beam Bridge




IDM – Part 4, Chapter 403, Load Analysis & Application

403-4.0 CONSTRUCTION LOADINGS

403-4.01 General Requirements

403-4.02 Application of Construction Loading

1. Component Loads, DC

2. Construction Dead Loads, CDL

3. Construction Live Loads, CLL

4. Wind Load, WS

3

Construction Loading ExampleConstruction Loading ExampleIDM – Part 4, Chapter 403, Load Analysis & Application

4





Construction Loads

Loads during construction are:

DC = Dead Lo ad from B ridg eMembers, Formw ork, Deck, etc.

DC1 – Concrete = 150 lbs/ft 3

DC2 – Stay-in-place Formwork = 15 psf

DW = N/A for Non-Composite Construction

CDL = Construction Equipment loads such as screed rails,

overhang forms, temp railing, walkway

CDL1 – Removable Coping Deck Forms = 15 psf

CDL2 – Temporary Walkway = 15 psf – applied over a 2’-0” wideplatform on outside of coping 5

Construction Loading ExampleConstruction Loading ExampleConstruction Loads


CLL = Construction Live Load suchas Screed Machin e and Workers

CLL1 – Construction Li ve Load = 20 psf extended the entire bridgewidth pl us two feet outside of bridge copin g over 30 feetlongi tudinal l ength centered on Screed Machine Load

– = applied 6 in outside of bridge coping.

CLL3 – Vertical Railing and Walkway Load = 75 plf applied 6 inoutside of bri dge coping over 30 feet longitudi nal length centeredon Screed Machine Load

6





Construction Loads


WS = Wind Lo ad on exposed h eight of the Structure (negligiblefor interior girders)

WS - Calcul ated per AASHTO 3.8.1.1 (use 70 mph per AASHTOTemporary wor ks manual Fig 2.1)

WCEL = Wind Lo ad on scr eed machine (negligib le)

7

Construction Loading ExampleConstruction Loading ExampleIDM – Part 4, Chapter 403, Load Analysis & Application

8





IDM – Part 4, Chapter 403, Load Analysis & Application

9

Construction Loading ExampleConstruction Loading ExampleLoad Factors

[AASHTO 3.4.2.1 and 3.4.2.2] - Load Combinations

STRENGTH I - 1.25*(DC + DW) + 1.5*(CDL + CLL )

STRENGTH III - 1.25*(DC + DW) + 1.5*(CDL) + 1.25(WS)

STRENGTH IV - 1.5*(DC + DW) + 1.5*(CDL)

STRENGTH V - 1.25*(DC+DW)+1.5*(CDL)+1.35*(CLL)+0.4*(WS)

SERVICE I - 1.0*(DC+DW)+1.0*(CDL)+1.0*(CLL) +0.3*(WS)

SERVICE II - 1.0*(DC+DW)+1.0*(CDL)+1.3*(CLL)

10





IDM – Part 4, Chapter 407, Structural Steel

407-6.0 I-SECTIONS IN FLEXURE

407-6.07 Constru ctabili ty

LRFD 6.10.3 and its commentary provide additional informationregarding constructability of a steel I-girder bridg e.

See Chapter 403 for additional guidance for constructio nloading.

11

Construction Loading ExampleConstruction Loading ExampleIDM – Part 4, Chapter 407, Structural Steel

407-8.0 CONNECTIONS AND SPLICES

407-8.01 Bolted Con nection s

2. Design. A bolted connection should be designed as slip-critical at the Service II Limit state and for con structionloading, except for secondary bracing

407-8.03 Splic es

7. Design. A bolted splice shall be slip-critical under Service IIand construction loads and shall be designed in accordancewith LRFD 6.13.2.2 for the Streng th L imit state.

12





Limit States

Seven Limit State Checks

1 - Yielding Limit State Check (6.10.3.2.1-1)

2 - Lateral Torsional Buckling (6.10.3.2.1-2)and Flange Local Buckling Check

3 - Web Bend Buck ling Check (6.10.3.2.1-3)

4 - Flange Lateral Bending Check (6.10.1.6-1)

5 - Discretely Braced Flange in Tension Check (6.10.3.2.2-1)

13

Construction Loading ExampleConstruction Loading ExampleLimit States

6 - Lateral Girder Rotation Check (Service I)

14





Limit States

7 - Slip Critical Bolt Check (Service II)

15

Construction Loading ExampleConstruction Loading ExampleDesign Example - Steel Beam Bridge

Bridge GeometryThree Spans @ 66’ – 86’ – 66’Skew = 10 degr ees

Bridge Typical SectionClear Roadway = 28’-0”Beam Spacing = 3 @ 8’-3”Slab = 8”Overhang = 1’-10 ½”

16

Beam DetailsW 36x135 (Positi ve Moment Regions )W 36x194 (Negative Moment Region s)Grade 50W Steel





Bridge Typical Section

17

Construction Loading ExampleConstruction Loading ExampleBridge Framing Plan

18





Bridge Beam Elevation

19

Construction Loading ExampleConstruction Loading ExampleDeck Pour Sequencing

20





Final Design Computations

21


Determine Controlling Strength Limit State

Construction Load Code Checks, Interior Beams

Run Continuous Beam Analysis Program

Investigate all 5 Pours

Run for Strengt h I and IV

By Inspection Strength III and V will not control, No wi nd oninterior

Determine which Pour and Strength Combination Controls

22





AASHTO Code Checks


Follow AASHTO FigureC 6.4.1-1 flo w c hart

Utilize Merlin-DashProgram for Code Checks

Merlin-Dash Performsmost code checks for

reng on y

Modify Input Loads forcode checks for StrengthIV

23


Input - Construction Loading


24





Appl ied Const ruct ion Loading


25

Construction Loading ExampleConstruction Loading ExampleConstruction Load Code Checks, Interior Beams


26







27


Dead Load Deflections


AASHTO 6.10.3.5

AASHTO Gui de Spec if ication s for Temporary Works

Section 2.3.5 - Deflection for Falsework Members

Deflection <= L / 240 for Conc rete DL only

se er n- as o c ec e ec on or eac our -

Verify No Uplif t

28





Dead Load Deflections


29


Deck – Slab Tension Check


AASHTO 6.10.3.2.4

Use Continuous Beam Analysis to determine max negativemoments

Strength IV Constructi on Loading contr ols

Modify Merlin-Dash l oads, program outputs service stresses

30





Deck – Slab Tension Check


31


Service II Loading f or Slip Critical Checks


32





Determine Controlling Strength Limit State

Construction Load Code Checks, Exterior Beams

Run Continuous Beam Analysis Program

Investigate all 5 Pours to determine controlling loads

Run all load cases with modi fied loads in Merlin-Dash to getmoments

Pour 2 and 5 control

Example calculations shown for Pour 2 Strength V loading

33


Input for Construction Loading


34





Deck Pour Sequencing

35

Construction Loading ExampleConstruction Loading ExampleBridge Framing Plan

36





Steel Beam Elevation

37




38






Appl ied Construct ion Loading – Streng th V

39


Input Properties


40





Input from Merlin-Dash


41


Beam Properties


42





Flange Compressive Stress – f bu


43


First-order versus Second-order analysis


44







45

Construction Loading ExampleConstruction Loading ExampleConstruction Load Code Checks, Exterior Beams


46







47




Ampli ficat io n Fac tor

48







Ampli ficat io n Fac tor

49


Flange Lateral Bending Stress – f


50







51



52







53



54







55



56







57


[6.10.3.2.1] Check Flange Nominal Yielding


58






[6.10.3.2.1] Check Flexural Resistance

59


[6.10.3.2.1] Check Flexural Resistance

60






[6.10.3.2.1] Check Web Bend Bucklin g

61


[6.10.3.2.2] Check Tension Flang e Nominal Yieldin g

62






Addi tional Chec ks Required

[6.10.1.8] Check secti ons w ith hol es intension flanges

[6.10.3.2.4] Check longi tudin al stresses i nconcrete deck

(6.10.3.3-1) Check shear in beams

63

Construction Loading ExampleConstruction Loading ExampleServiceability for Rotation Checks, Exterior Beams

Lateral Girder Rotation Check (Service I)

Check ensures wh ile the deck is being s equentially pou red,the exterior beam does not r otate, resulting in excessiveoverhang deflections.

The eccentric lo ads should be applied to the exterior beam todetermine the amount of torsion each l oad causes.

Using the torsion, the horizontal forces i n the top flange

caus ng e ec on ou war an o om ange caus ngdeflection inward) should be calculated.

Each flange is analyzed as a continuous beam over supports,where the supports are the diaphragms.

64





Serviceability for Rotation Checks, Exterior Beams

Lateral Girder Rotation Check (Service I)

The loads are applied to match the deck pour sequence, mostlikely with th e concrete and screed machine starting on oneend, with the other end virtually u nloaded.

After t he analysi s, the inw ard d eflect io n of th e bo ttom flangeand outward deflection of the top flange should be used todetermine the rotation of the beam.

65

the rotation of the coping as shownin IDM Figu re 403-4D.

BLN limits the maximum delta of thecoping to 0.20 inches.


ANY QUESTIONS?

Presented By: Michael L. McCool, Jr., PE 66


construction loading example for steel beam bridge - indot

Documents