751.23 Prestressed Concrete Double Tee Girders - Revision history

Smithk: Smithk moved page 751.23 P/S Concrete Double Tee to 751.23 Prestressed Concrete Double Tee Girders: Per BR, article renamed

2021-04-02T14:59:31Z

Smithk moved page 751.23 P/S Concrete Double Tee to 751.23 Prestressed Concrete Double Tee Girders: Per BR, article renamed

← Older revision	Revision as of 09:59, 2 April 2021
(No difference)

Smithk: /* 751.23.1.2 Girder and Slab Design */ Per BR, numerous minor clarifications related to barrier pay items

2020-08-05T18:12:57Z

751.23.1.2 Girder and Slab Design: Per BR, numerous minor clarifications related to barrier pay items

← Older revision		Revision as of 13:12, 5 August 2020
Line 105:		Line 105:
	=== 751.23.1.2 Girder and Slab Design ===		=== 751.23.1.2 Girder and Slab Design ===

	The cast-in-place slab is designed to carry only the live		The cast-in-place slab is designed to carry only the live load of the bridge. One layer of steel is used in each direction of the cast-in-place slab with one-inch clearance from bottom of slab. A one-inch integral wearing surface is deducted from effective slab depth for design.
	load of the bridge. One layer of steel is used in each
	direction of the cast-in-place slab with 1" clearance from		The double tee girder flange is designed to carry the load of the cast-in-place slab, the flange weight and a construction dead load of 50 pounds per square foot (or a 300-pound concentrated construction load per OSHA).
	bottom of slab. A 1" integral wearing surface is deducted
	from effective slab depth for design.

	The double tee girder flange is designed to carry the load
	of the cast-in-place slab, the flange weight and a ~~50 lb./sq.~~
	~~ft.~~ construction dead load. (or a 300 ~~lb.~~ concentrated
	construction load per OSHA).

	When determining the section properties of the double tee		When determining the section properties of the double tee girder the center of gravity is based upon the total area (excluding corner fillets) of the entire exterior or interior girder and not on the individual stems. Moment of inertia and dead loads to each stem are figured to the center of the flange between the stems. The non-composite dead load of the external double tee girder is divided according to the following sketch.
	girder the center of gravity is based upon the total area
	(excluding corner fillets) of the entire exterior or interior
	girder and not on the individual stems. Moment of inertia
	and dead loads to each stem are figured to the center of the
	flange between the stems. The non-composite dead load of
	the external double tee girder is divided according to the
	following sketch.


Line 129:		Line 115:


	The ~~non~~-~~composite dead~~ load of the ~~interior double tee girder~~		The cast-in-place slab is designed to carry only the live load of the bridge. One layer of steel is used in each direction of the cast-in-place slab with one-inch clearance from bottom of slab. A one-inch integral wearing surface is deducted from effective slab depth for design.
	is ~~divided evenly to~~ each ~~stem. A 9 lb./lin ft. dead load is~~
	~~added to~~ the ~~non~~-~~composite dead load~~ of ~~each stem for~~		The double tee girder flange is designed to carry the load of the cast-in-place slab, the flange weight and a construction dead load of 50 pounds per square foot (or a 300-pound concentrated construction load per OSHA).
	~~haunching~~. ~~The non~~-~~composite dead load of C.I.P.~~ slab~~, girder~~
	~~and haunch are based on simple spans from Ë to Ë Bearings~~.

	The ~~composite dead load of the safety barrier~~ is ~~divided 75%~~
	to the ~~exterior stem~~ of the ~~exterior girder~~ and ~~25% to the~~
	~~interior stem of the exterior girder. No~~ dead load ~~due to~~
	~~the barrier curb is added to the interior girder. The~~
	~~composite dead load for future wearing surface is 35 lb./sq.~~
	~~ft.~~ or ~~3" of material. The composite dead~~ load ~~of safety~~
	~~barrier curb, and future wearing surface are based on~~
	~~continuous, composite spans from Ë to Ë Bearings~~.

	The live load design is based on HL93. The live load		The live load design is based on HL93. The live load distribution factors are figured separate for exterior and interior Double Tee Girders. The assumption, that if the bridge is widened in the future the exterior girder then becomes an interior girder should be investigated.
	distribution factors are figured separate for exterior and
	interior Double Tee Girders. The assumption, that if the
	bridge is widened in the future the exterior girder then
	becomes an interior girder should be investigated.

	Composite sections are adjusted for the difference in		Composite sections are adjusted for the difference in

EPGsysop: /* 751.23.1.1 Material Properties */

2017-10-16T19:57:34Z

751.23.1.1 Material Properties

← Older revision		Revision as of 14:57, 16 October 2017
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	\|-		\|-
	\| \|\|colspan="2"\|Maximum allowed initial prestress force per strand <br/>		\| \|\|colspan="2"\|Maximum allowed initial prestress force per strand <br/>
	= ''A<sub>ps</sub>xf<sub>pbt</sub>'' kips		= ''A<sub>ps</sub> x f<sub>pbt</sub>'' kips
	\|-		\|-
	\| \|\|colspan="2"\|Maximum allowed initial force = '''30.98''' kips for '''0.5''' inch diameter strand<br/>		\| \|\|colspan="2"\|Maximum allowed initial force = '''30.98''' kips for '''0.5''' inch diameter strand<br/>

EPGsysop: /* 751.23.1.1 Material Properties */Per BR, report on the girder plans the required number of strands by design and the total initial prestress force using EPG 751.50 Standard Detailing Notes H2c1.3.

2017-10-13T13:48:08Z

751.23.1.1 Material Properties: Per BR, report on the girder plans the required number of strands by design and the total initial prestress force using EPG 751.50 Standard Detailing Notes H2c1.3.

@@ Line 76: / Line 76: @@
 |Strand area,
 |align="right"|<math>\, A_{ps} = 0.217 in^2</math>
 |-
 |colspan="3"|&nbsp;

Smithk: /* 751.23.1.1 Material Properties */ Per Bridge, corrected Optional concrete strand area (to 0.217 sq.in.)

2013-02-11T14:25:02Z

751.23.1.1 Material Properties: Per Bridge, corrected Optional concrete strand area (to 0.217 sq.in.)

← Older revision		Revision as of 09:25, 11 February 2013
Line 75:		Line 75:
	\|		\|
	\|Strand area,		\|Strand area,
	\|align="right"\|<math>\, A_{ps} = 0.~~153~~ in^2</math>		\|align="right"\|<math>\, A_{ps} = 0.217 in^2</math>
	\|-		\|-
	\|colspan="3"\|		\|colspan="3"\|

Smithk: /* 751.23.1 General */

2012-02-15T19:02:04Z

751.23.1 General

← Older revision		Revision as of 14:02, 15 February 2012
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	\|colspan="2"\|		\|colspan="2"\|
	\|align="right"\|<math>\, f'_c = 7.0 ksi</math>		\|align="right"\|<math>\, f'_c = 7.0 ksi</math>
	\|}		\|-
			\|colspan="2"\|Modulus of Elasticity,
	~~::::::::::~~Modulus of Elasticity, <math>\, E_c = 33,000\ K_1 \ (w_c^{1.5}) \sqrt{f^'_c}</math>		\|align="right"\|<math>E_c = 33,000\ K_1 \ (w_c^{1.5}) \sqrt{f^'_c}</math>
			\|-
	~~::::::::::~~f'<sub>c</sub> in ksi		\|
			\|Where,
	~~::::::::::~~K<sub>1</sub> = correction factor for source of aggregate		\|
	~~:::::::::::~~= 1.0 unless determined by physical testing		\|-
			\|
	~~::::::::::~~<math>w_c = 0.145 kcf\ \mbox{for}\ f'_c\le 5.0 ksi</math>		\|f'<sub>c</sub> in ksi
			\|-
	~~::::::::::~~'''<math>w_c = 0.140 + 0.001 f'_c\ \mbox{for}\ f'_c>5.0 ksi </math>'''		\|
			\|colspan="2"\|K<sub>1</sub> = correction factor for source of aggregate<br> <font color = "white">aa</font color="white"> = 1.0 unless determined by physical testing
	~~{\| border="0" cellpadding="4" cellspacing="0" align="center" style="textalign:left" width="418"~~		\|-
			\|
			\|colspan="2"\|<math>w_c = 0.145 kcf\ \mbox{for}\ f'_c\le 5.0 ksi</math>
			\|-
			\|
			\|colspan="2"\|'''<math>w_c = 0.140 + 0.001 f'_c\ \mbox{for}\ f'_c>5.0 ksi </math>'''
	\|-		\|-
	\|		\|

Smithk: /* 751.23.1.1 Material Properties */ Per Bridge, clarification of modulus of elasticity formula

2012-02-10T19:49:03Z

751.23.1.1 Material Properties: Per Bridge, clarification of modulus of elasticity formula

← Older revision		Revision as of 14:49, 10 February 2012
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	\|colspan="2"\|		\|colspan="2"\|
	\|align="right"\|<math>\, f'_c = 7.0 ksi</math>		\|align="right"\|<math>\, f'_c = 7.0 ksi</math>
	\|-		\|}
	~~\|colspan="3"\|~~Modulus of Elasticity, <math>\, E_c = ~~33000~~ K_1 w_c~~\sqrt[~~1.5]{f'_c}</math>
	\|-		::::::::::Modulus of Elasticity, <math>\, E_c = 33,000\ K_1 \ (w_c^{1.5}) \sqrt{f^'_c}</math>
	~~\|colspan~~=~~"3"\|For~~ <math>\, f'_c\le 5 ksi~~, w_c = 0.145 kcf~~</math>
	\|-		::::::::::f'<sub>c</sub> in ksi
	~~\|colspan="3"\|For~~ <math>~~\, f'_c>5 ksi,~~ w_c = 0.140 + 0.001 f'_c</math>
	\|-		::::::::::K<sub>1</sub> = correction factor for source of aggregate
	\|~~colspan~~="3"~~\|<math>\, K_1</math>~~ = ~~correction factor for source of aggregate~~		:::::::::::= 1.0 unless determined by physical testing
	\|-
	~~\| ~~		::::::::::<math>w_c = 0.145 kcf\ \mbox{for}\ f'_c\le 5.0 ksi</math>
	~~\|colspan~~="2"\|=~~1.0 unless determined by physical testing~~
			::::::::::'''<math>w_c = 0.140 + 0.001 f'_c\ \mbox{for}\ f'_c>5.0 ksi </math>'''

			{\| border="0" cellpadding="4" cellspacing="0" align="center" style="textalign:left" width="418"
	\|-		\|-
	\|		\|

Smithk: attached article to new EPG 751

2010-04-15T15:09:41Z

attached article to new EPG 751

← Older revision		Revision as of 10:09, 15 April 2010
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	[[Category:751 LRFD ~~Manual General~~]]		[[Category:751 LRFD Bridge Design Guidelines]]

EPG-Admin at 18:49, 28 September 2007

2007-09-28T18:49:44Z

New page

== 751.23.1 General ==

=== 751.23.1.1 Material Properties ===

{| border="0" cellpadding="4" cellspacing="0" align="center" style="textalign:left"

!colspan="3" align="left"|Concrete
|-
|colspan="2" width="300pt"|Standard compressive strength for P/S Double Tee Girder shall be:
|align="right"|<math>\, f'_{ci} = 4.5 ksi</math>
|-
|colspan="2"| 
|align="right"|<math>\, f'_c = 6.0 ksi</math>
|-
|colspan="2"|Optional concrete strength shall be:
|align="right"|<math>\, f'_{ci} = 5.0 ksi</math>
|-
|colspan="2"| 
|align="right"|<math>\, f'_c = 7.0 ksi</math>
|-
|colspan="3"|Modulus of Elasticity, <math>\, E_c = 33000 K_1 w_c\sqrt[1.5]{f'_c}</math>
|-
|colspan="3"|For <math>\, f'_c\le 5 ksi, w_c = 0.145 kcf</math>
|-
|colspan="3"|For <math>\, f'_c>5 ksi, w_c = 0.140 + 0.001 f'_c</math>
|-
|colspan="3"|<math>\, K_1</math> = correction factor for source of aggregate
|-
| 
|colspan="2"|=1.0 unless determined by physical testing
|-
| 
|-
!colspan="3" align="left"|Prestressing strand
|-
|colspan="3"|Type of strand:
|-
|colspan="3"|AASHTO M203 (ASTM A416) Grade 270
|-
|colspan="3"|Uncoated, seven-wire, low-relaxation strand
|-
|colspan="2"|Ultimate tensile strength,
|align="right"|<math>\, f_{pu} = 270 ksi</math>
|-
|colspan="2"|Yield strength,
|align="right"|<math>\, f_{py} = 0.9 f_{pu} ksi</math>
|-
|colspan="2"|Strand modulus of elasticity,
|align="right"|<math>\, E_p = 28500 ksi</math>
|-
|colspan="3"|For standard concrete:
|-
| 
|Strand diameter,
|align="right"|<math>\, d_{ps} = 0.5 in</math>
|-
| 
|Strand area,
|align="right"|<math>\, A_{ps} = 0.153 in^2</math>
|-
|colspan="3"|For optional concrete:
|-
| 
|Strand diameter,
|align="right"|<math>\, d_{ps} = 0.6 in</math>
|-
| 
|Strand area,
|align="right"|<math>\, A_{ps} = 0.153 in^2</math>
|-
|colspan="3"| 
|-
!colspan="3" align="left"|Mild reinforcing steel
|-
|colspan="2"|Minimum yield strength,
|align="right"|<math>\, f_y = 60.0 ksi</math>
|-
|colspan="2"|Steel modulus of elasticity,
|align="right"|<math>\, E_s = 29000 ksi</math>
|}

=== 751.23.1.2 Girder and Slab Design ===

The cast-in-place slab is designed to carry only the live
load of the bridge. One layer of steel is used in each
direction of the cast-in-place slab with 1" clearance from
bottom of slab. A 1" integral wearing surface is deducted
from effective slab depth for design.

The double tee girder flange is designed to carry the load
of the cast-in-place slab, the flange weight and a 50 lb./sq.
ft. construction dead load. (or a 300 lb. concentrated
construction load per OSHA).

When determining the section properties of the double tee
girder the center of gravity is based upon the total area
(excluding corner fillets) of the entire exterior or interior
girder and not on the individual stems. Moment of inertia
and dead loads to each stem are figured to the center of the
flange between the stems. The non-composite dead load of
the external double tee girder is divided according to the
following sketch.

<center>[[Image:751.23 section thru double tee.gif]]</center>

The non-composite dead load of the interior double tee girder
is divided evenly to each stem. A 9 lb./lin ft. dead load is
added to the non-composite dead load of each stem for
haunching. The non-composite dead load of C.I.P. slab, girder
and haunch are based on simple spans from Ë to Ë Bearings.

The composite dead load of the safety barrier is divided 75%
to the exterior stem of the exterior girder and 25% to the
interior stem of the exterior girder. No dead load due to
the barrier curb is added to the interior girder. The
composite dead load for future wearing surface is 35 lb./sq.
ft. or 3" of material. The composite dead load of safety
barrier curb, and future wearing surface are based on
continuous, composite spans from Ë to Ë Bearings.

The live load design is based on HL93. The live load
distribution factors are figured separate for exterior and
interior Double Tee Girders. The assumption, that if the
bridge is widened in the future the exterior girder then
becomes an interior girder should be investigated.

Composite sections are adjusted for the difference in
modulus of elasticity of slab and girder by multiplying by
the factor (Eslab/Egirder). A 1" integral wearing surface is
deducted for effective slab design.

Negative moment reinforcement is based on the amount
required for the entire roadway width and not the amount
required for each stem. The continuous span lengths are
based on the distance from the Ë Bearing at End Bents to the
Ë Interior Bent. The area of reinforcing bars is provided
by adding bars between the normal longitudinal bars.

Continuity is obtained at intermediate supports by extending
and bending all strands to form interlocking right angle
hooks and pouring a concrete diaphragm monolithic with deck
slab encasing the prestressed girders with the flange cut
back at diaphragm.

Camber is based on simple spans. A transformed moment of
inertia is figured for the total exterior or interior double
tee girder since the total girder is cambered at the same
rate.

Maximum horizontal curvature for Double-Tee structures is 3^.
Outside flange edge of exterior girders on curved bridges is
to be curved.

== 751.23.2 Details ==

=== 751.23.2.1 Girder Dimensions ===

<center>[[Image:751.23 part plan of ps conc dbl tee girder.gif]]</center>
<center>'''Part Plan of P/S Conc. Dbl. Tee Girder'''</center>

<center>[[Image:751.23 section thru ps conc dble tee girder.gif]]</center>
<center>'''Section Thru P/S Conc. Dbl. Tee Girder'''</center>

<center>[[Image:751.23 section thru ps conc dble tee girder detail a.gif]]</center>
<center>'''Detail "A"'''</center>

=== 751.23.2.2 Vent Holes ===

<center>Note: Use vent holes only on all stream crossing structures.</center>

<center>[[Image:751.23 double tee vent hole details.gif]]</center>
{| border="0" align="center"
|colspan="3" width="215" align="right"|'''Part Elevation of Girder Stem'''
|width="50pt"| 
|<center>'''Part Section Near Vent Hole'''</center>
|}

=== 751.23.2.3 Diaphragm Reinforcement ===

<center>[[Image:751.23 double tee diaphragm reinf. for end bent int bent.gif]]</center>
{| border="0" align="center"
|colspan="3" width="300" align="center"|'''End Bent'''
|width="50pt"| 
|width="75" align="right"|'''Int. Bent'''
|}

<center>[[Image:751.23 double tee diaphragm reinf. for skew thru 30 deg skew over 30 deg.gif]]</center>
{| border="0" align="center"
|colspan="3" width="200" align="center"|'''Skew Thru 30 ø'''
|width="175pt"| 
|width="175" align="left"|'''Skew Over 30 ø'''
|}

<center>[[Image:751.23 double tee diaphragm reinf. for skew thru 30 deg skew over 30 deg notes.gif]]</center>

=== 751.23.2.4 Detail of Optional Construction Joint ===

<center>[[Image:751.23 double tee optional constr joint.gif]]</center>

<center>'''Optional Const. Joint'''</center>

<center>[[Image:751.23 double tee optional constr joint sec aa.gif]]</center>

<center>'''Section A-A'''</center>

<math>*</math> Place Const. Joint 6" from negative reinforcement in slab.

Note: Const. Joint placement will be determined by direction of slab pour.

=== 751.23.2.5 Details for Curved Structures ===

<center>[[Image:751.23 double tee curved structure detail.gif]]</center>

[[Category:751 LRFD Manual General]]