751.21 Prestressed Concrete Slab and Box Beams - Revision history

Hoskir: /* 751.21.3.6.1 Dimensions */ updated per RR3915

2024-07-31T18:58:03Z

751.21.3.6.1 Dimensions: updated per RR3915

← Older revision		Revision as of 13:58, 31 July 2024
Line 389:		Line 389:
	Bearing length and thickness is by design. Bearings may vary on each side of bent.		Bearing length and thickness is by design. Bearings may vary on each side of bent.

	'''<font color="green">(e)</font color="green">''' 3¾" minimum ~~for #4 stirrups in substructure beam and 5¼" minimum for #5 or #6 stirrups in substructure beam~~, ~~except~~ diaphragm ~~width shall not~~ be ~~less than 2’-6”. Make diaphragm~~ flush with substructure beams ~~less~~ than three feet wide.		'''<font color="green">(e)</font color="green">''' 3¾" minimum. With the approval of the SPM, the diaphragm may be made flush with substructure beams not greater than three feet wide.

	'''<font color="green">(f)</font color="green">''' Remove thickness for tapered bearings or when bearings vary on each side of bent.		'''<font color="green">(f)</font color="green">''' Remove thickness for tapered bearings or when bearings vary on each side of bent.

Hoskir: /* 751.21.3.6.1 Dimensions */ updated per RR3762

2023-08-22T16:19:56Z

751.21.3.6.1 Dimensions: updated per RR3762

← Older revision		Revision as of 11:19, 22 August 2023
Line 389:		Line 389:
	Bearing length and thickness is by design. Bearings may vary on each side of bent.		Bearing length and thickness is by design. Bearings may vary on each side of bent.

	'''<font color="green">(e)</font color="green">''' 3¾" minimum. Make diaphragm flush with substructure beams less than three feet wide.		'''<font color="green">(e)</font color="green">''' 3¾" minimum for #4 stirrups in substructure beam and 5¼" minimum for #5 or #6 stirrups in substructure beam, except diaphragm width shall not be less than 2’-6”. Make diaphragm flush with substructure beams less than three feet wide.

	'''<font color="green">(f)</font color="green">''' Remove thickness for tapered bearings or when bearings vary on each side of bent.		'''<font color="green">(f)</font color="green">''' Remove thickness for tapered bearings or when bearings vary on each side of bent.

Hoskir: /* 751.21.1.4 Span and Structure Lengths */ updated per RR3737

2023-07-26T20:11:50Z

751.21.1.4 Span and Structure Lengths: updated per RR3737

← Older revision		Revision as of 15:11, 26 July 2023
Line 110:		Line 110:
	The span and structure lengths for prestressed beams shall be in accordance with [[751.22_Prestressed_Concrete_I_Girders#751.22.1.4_Span_and_Structure_Lengths\|EPG 751.22.1.4 Span and Structure Lengths]], except that skewed ends of prestressed beams shall be in accordance with [[751.21_Prestressed_Concrete_Slab_and_Box_Beams#751.21.3.2.1_Skewed_Ends\|EPG 751.21.3.2.1 Skewed Ends]] instead of the coping requirements used for the I-Girders.		The span and structure lengths for prestressed beams shall be in accordance with [[751.22_Prestressed_Concrete_I_Girders#751.22.1.4_Span_and_Structure_Lengths\|EPG 751.22.1.4 Span and Structure Lengths]], except that skewed ends of prestressed beams shall be in accordance with [[751.21_Prestressed_Concrete_Slab_and_Box_Beams#751.21.3.2.1_Skewed_Ends\|EPG 751.21.3.2.1 Skewed Ends]] instead of the coping requirements used for the I-Girders.

	The following ~~charts provide potential~~ span ~~ranges (limits) for~~ prestressed spread box beams based ~~on bridges that were designed between 2010 and 2023~~. ~~Because~~ the ~~span limit charts were~~ developed using ~~previously designed bridges with~~ standard materials and shapes~~, increased~~ span lengths are possible with modification. See Increasing Girder Capacity section above for more information. ~~These charts~~ shall be used for preliminary design only.		The following chart provides a general baseline for the maximum span lengths of prestressed spread box beams based off single span designs in accordance with LRFD, 9th Edition. The designs used for this chart use the maximum practical girder spacing (approximately 11’-6”). The chart was developed using designs that used standard materials and shapes. Increased span lengths are possible with modification to the materials, shapes, and/or girder spacings used. Increased span lengths are also likely for continuous span bridges. See Increasing Girder Capacity section above for more information. This chart shall be used for preliminary design only.

	'''Limitations of the ~~Charts~~:'''		'''Limitations of the Chart:'''

	~~All charts contain~~ only ~~standard materials~~. ~~Referenced bridges contained both single and continuous span bridges~~. ~~Shapes are not modified in any way~~.		This chart only contains data on designs with a concrete compressive strength equal to 8.0ksi, this is due to a lack of sufficient data for designs using a concrete compressive strength of 6.0ksi or 7.0ksi.

	<center><b><big>Prestressed Spread Box Beam Span Ranges</big></b></center>		<center><b><big>Prestressed Spread Box Beam Single Span Ranges</big></b></center>
	[[image:751.22.1.~~4_PS_Box_6ksi_06~~-23.png\|700px\|center]]		[[image:751.22.1.4_PS_Box_8ksi_07-23.png\|700px\|center]]
	~~[[image:751.22.1.4_PS_Box_7ksi_06-23.png\|700px\|center]]~~
	~~[[image:751.22.1.4_PS_Box_8ksi_06-23.png\|700px\|center]]~~
	~~{\| style="margin: auto; vertical-align:top;"~~
	~~\|- style="vertical-align:top;"~~
	~~\| <b>Note: </b> \|\| 27in, 33in, 39in, and 42in Spread Box Beams were excluded from some graphs due to there being</br>insufficient data to produce an accurate range of span lengths.</center>~~
	\|-
	~~\| \|\| A green bar denotes that the particular type of spread box beam has three or fewer entries and should</br>not be relied on as heavily as others.</center>~~
	\|}

	===751.21.1.5 Constant and Varied Joint Filler Loads===		===751.21.1.5 Constant and Varied Joint Filler Loads===

Hoskir: /* 751.21.1.4 Span and Structure Lengths */ updated per RR3719

2023-06-30T13:52:52Z

751.21.1.4 Span and Structure Lengths: updated per RR3719

@@ Line 108: / Line 108: @@
 ===751.21.1.4 Span and Structure Lengths===
-The span and structure lengths for prestressed beams shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.1.4 Span and Structure Lengths|EPG 751.22.1.4 Span and Structure Lengths]], except that skewed ends of prestressed beams shall be in accordance with [[#751.21.3.2.1 Skewed Ends|EPG 751.21.3.2.1 Skewed Ends]] instead of the coping requirements used for the I-Girders.
+The span and structure lengths for prestressed beams shall be in accordance with [[751.22_Prestressed_Concrete_I_Girders#751.22.1.4_Span_and_Structure_Lengths|EPG 751.22.1.4 Span and Structure Lengths]], except that skewed ends of prestressed beams shall be in accordance with [[751.21_Prestressed_Concrete_Slab_and_Box_Beams#751.21.3.2.1_Skewed_Ends|EPG 751.21.3.2.1 Skewed Ends]] instead of the coping requirements used for the I-Girders.
 ===751.21.1.5 Constant and Varied Joint Filler Loads===

Hoskir: /* 751.21.3.4 Prestressing Strands */ updated per RR3684

2023-05-01T17:40:53Z

751.21.3.4 Prestressing Strands: updated per RR3684

← Older revision		Revision as of 12:40, 1 May 2023
Line 282:		Line 282:
	Lower strands may be debonded at ends to reduce compressive stresses at the beam ends.		Lower strands may be debonded at ends to reduce compressive stresses at the beam ends.

	~~The support strands may be replaced by fully stressed ½ or 0.6 inch strands when required to control temporary stresses or camber.~~

	'''Adjacent Beams Only'''		'''Adjacent Beams Only'''
Line 300:		Line 299:
	'''Box Beams'''		'''Box Beams'''

	[[image:751.21.3.4.1 box ~~2021~~.jpg\|center\|800px]]		[[image:751.21.3.4.1 box 2023.jpg\|center\|800px]]
	<center>~~+ Indicates prestressing strand~~		<center>'''<big>STRAND ARRANGEMENT</big>'''</center>
	:'''<~~font color="green"~~>~~(ɑ)~~</~~font color="green"~~>''' ~~Use 2½ inches for 24-inch beams and smaller (shape 52 bars required) when 0.6-inch strands are required at the top.~~</center>		<center>+ Indicates prestressing strand</center>


	'''Voided Slab Beams'''		'''Voided Slab Beams'''

	[[image:751.21.3.4.1 voided.jpg\|center\|~~750px~~]]		[[image:751.21.3.4.1 voided 2023.jpg\|center\|800px]]
			<center>'''<big>STRAND ARRANGEMENT</big>'''</center>

	====751.21.3.4.2 Instructions====		====751.21.3.4.2 Instructions====
Line 313:		Line 312:
	Strand instructions shall be indicated in the strand arrangement detail.		Strand instructions shall be indicated in the strand arrangement detail.

	[[image:751.21.3.4.2.jpg\|center\|650px]]		[[image:751.21.3.4.2 2023.jpg\|center\|650px]]

	:'''<font color="green">(b)</font color="green">''' Use 2'-0" for 27-inch box beams and smaller. Use 2'-6" for 33-inch box beams and larger.		<center>'''<font color="green">(b)</font color="green">''' Use 2'-0" for 27-inch box beams and smaller. Use 2'-6" for 33-inch box beams and larger.</center>
	<center>		<center>
	{\| border="1" class="wikitable" style="margin: 1em auto 1em auto; text-align:center"		{\| border="1" class="wikitable" style="margin: 1em auto 1em auto; text-align:center"

Smithk: /* 751.21.3.11 Dowel Bars and Concrete Shear Blocks */ updated a link

2022-06-01T17:23:17Z

751.21.3.11 Dowel Bars and Concrete Shear Blocks: updated a link

← Older revision		Revision as of 12:23, 1 June 2022
Line 449:		Line 449:

	====751.21.3.11 Dowel Bars and Concrete Shear Blocks====		====751.21.3.11 Dowel Bars and Concrete Shear Blocks====
	Dowel bars for fixed intermediate bents shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.2.7 ~~Dowel Bars~~\|EPG 751.22.2.7 ~~Dowel Bars~~]].		Dowel bars for fixed intermediate bents shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.7.4 Bent Details\|EPG 751.22.3.7.4 Bent Details]].

	Concrete shear blocks for open diaphragm bent caps and closed diaphragm bent caps shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.13 Concrete Shear Blocks\|EPG 751.22.3.13 Concrete Shear Blocks]].		Concrete shear blocks for open diaphragm bent caps and closed diaphragm bent caps shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.13 Concrete Shear Blocks\|EPG 751.22.3.13 Concrete Shear Blocks]].

Smithk: updated links

2022-06-01T16:23:53Z

updated links

← Older revision		Revision as of 11:23, 1 June 2022
Line 451:		Line 451:
	Dowel bars for fixed intermediate bents shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.2.7 Dowel Bars\|EPG 751.22.2.7 Dowel Bars]].		Dowel bars for fixed intermediate bents shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.2.7 Dowel Bars\|EPG 751.22.2.7 Dowel Bars]].

	Concrete shear blocks for open diaphragm bent caps and closed diaphragm bent caps shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.14 Concrete Shear Blocks\|EPG 751.22.3.14 Concrete Shear Blocks]].		Concrete shear blocks for open diaphragm bent caps and closed diaphragm bent caps shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.13 Concrete Shear Blocks\|EPG 751.22.3.13 Concrete Shear Blocks]].

	====751.21.3.12 Miscellaneous====		====751.21.3.12 Miscellaneous====
Line 475:		Line 475:
	'''Other Miscellaneous'''		'''Other Miscellaneous'''

	Other miscellaneous details shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.16 Miscellaneous\|EPG 751.22.3.16 Miscellaneous]].		Other miscellaneous details shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.14 Miscellaneous\|EPG 751.22.3.14 Miscellaneous]].

	[[Category:751 LRFD Bridge Design Guidelines]]		[[Category:751 LRFD Bridge Design Guidelines]]

Smithk: /* 751.21.3.11 Dowel Bars and Shear Blocks */ Per BR

2022-05-10T18:45:46Z

751.21.3.11 Dowel Bars and Shear Blocks: Per BR

← Older revision		Revision as of 13:45, 10 May 2022
Line 448:		Line 448:
	Detail 3/8” beveled edges to run continuously across diaphragms that are flush with outside face of exterior beams at intermediate bents. Terminate bevel at diaphragms that extend past the outside face of beam.		Detail 3/8” beveled edges to run continuously across diaphragms that are flush with outside face of exterior beams at intermediate bents. Terminate bevel at diaphragms that extend past the outside face of beam.

	====751.21.3.11 Dowel Bars and Shear Blocks====		====751.21.3.11 Dowel Bars and Concrete Shear Blocks====
	Dowel bars for fixed intermediate bents shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.13 Dowel Bars\|EPG 751.22.3.13 Dowel Bars]].		Dowel bars for fixed intermediate bents shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.2.7 Dowel Bars\|EPG 751.22.2.7 Dowel Bars]].

	~~Shear~~ blocks for open diaphragm bent caps shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.15 Shear Blocks\|EPG 751.22.3.15 Shear Blocks]].		Concrete shear blocks for open diaphragm bent caps and closed diaphragm bent caps shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.14 Concrete Shear Blocks\|EPG 751.22.3.14 Concrete Shear Blocks]].

	====751.21.3.12 Miscellaneous====		====751.21.3.12 Miscellaneous====

Smithk: /* 751.21.3.5 Camber, Haunching and Girder Steps */ updated link

2022-03-29T12:14:56Z

751.21.3.5 Camber, Haunching and Girder Steps: updated link

← Older revision		Revision as of 07:14, 29 March 2022
Line 353:		Line 353:
	====751.21.3.5 Camber, Haunching and Girder Steps====		====751.21.3.5 Camber, Haunching and Girder Steps====

	For spread beams the camber, haunch, and stepping and sloping of top flange shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.8 Camber, Haunching, and Stepping and Sloping of Top Flange\|EPG 751.22.3.8 Camber, Haunching, and Stepping and Sloping of Top Flange]].		For spread beams the camber, haunch, and stepping and sloping of top flange shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.6 Camber, Haunching, and Stepping and Sloping of Top Flange\|EPG 751.22.3.6 Camber, Haunching, and Stepping and Sloping of Top Flange]].

	For adjacent beams a camber diagram is replaced with a slab thickness diagram.		For adjacent beams a camber diagram is replaced with a slab thickness diagram.

Smithk: /* 751.21.3 Details */ Per BR, updated broken links

2022-01-11T18:19:18Z

751.21.3 Details: Per BR, updated broken links

← Older revision		Revision as of 13:19, 11 January 2022
Line 449:		Line 449:

	====751.21.3.11 Dowel Bars and Shear Blocks====		====751.21.3.11 Dowel Bars and Shear Blocks====
	Dowel bars for fixed intermediate bents shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.15 Dowel Bars\|EPG 751.22.3.15 Dowel Bars]].		Dowel bars for fixed intermediate bents shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.13 Dowel Bars\|EPG 751.22.3.13 Dowel Bars]].

	Shear blocks for open diaphragm bent caps shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.17 Shear Blocks\|EPG 751.22.3.17 Shear Blocks]].		Shear blocks for open diaphragm bent caps shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.15 Shear Blocks\|EPG 751.22.3.15 Shear Blocks]].

	====751.21.3.12 Miscellaneous====		====751.21.3.12 Miscellaneous====
Line 475:		Line 475:
	'''Other Miscellaneous'''		'''Other Miscellaneous'''

	Other miscellaneous details shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.18 Miscellaneous\|EPG 751.22.3.18 Miscellaneous]].		Other miscellaneous details shall be in accordance with [[751.22 Prestressed Concrete I Girders#751.22.3.16 Miscellaneous\|EPG 751.22.3.16 Miscellaneous]].

	[[Category:751 LRFD Bridge Design Guidelines]]		[[Category:751 LRFD Bridge Design Guidelines]]