751.22 Prestressed Concrete I Girders - Revision history

Hoskir: /* 751.22.2.3 Flexure */ updated per RR4046

2025-07-11T19:22:10Z

751.22.2.3 Flexure: updated per RR4046

@@ Line 372: / Line 372: @@
 ===751.22.2.3 Flexure===
 Flexure capacity of girders shall be determined as the following.
@@ Line 421: / Line 420: @@
 Required steel area is equal to:
 <math>\,A1=\frac{T_t}{f_s}</math>
 Where:
 {|
@@ Line 450: / Line 447: @@
 |M<sub>u</sub> ||=||Total factored moment from Strength I load combination,  (kip-in.)
 |}
 ===751.22.2.4 Shear===

Hoskir: /* 751.22.2.7 Dowel Bars */ updated per RR4033

2025-04-18T18:05:53Z

751.22.2.7 Dowel Bars: updated per RR4033

← Older revision		Revision as of 13:05, 18 April 2025
Line 1,019:		Line 1,019:

	\|}		\|}
	::::\|Note: Minimum reinforcement shown. Dowel bar size, spacing and length by design.		:::::Note: Minimum reinforcement shown. Dowel bar size, spacing and length by design.

	::::Dowel bars shall be used for all fixed intermediate bents under prestressed superstructures. Generally, for typical bridges that require seismic details only (strength limit states), shear resistance from shear key is not considered.		::::Dowel bars shall be used for all fixed intermediate bents under prestressed superstructures. Generally, for typical bridges that require seismic details only (strength limit states), shear resistance from shear key is not considered.


	Dowel bars connect standard concrete diaphragms and beams on concrete girder bridges (standard fixed diaphragms are those with beam stirrups NOT extending up into the diaphragm). If the dowel bars are not exposed to net tension a 15-inch embedment shall be used regardless of bar size. Dowel bars size and spacing shall be determined by shear design of the bars. (Minimum #6 Bars @ 12" cts.). Dowel bars should be designed for a minimum horizontal force equal to 25% of the maximum dead load applied to the bearing. Live load is ignored in horizontal force computation. For seismic design category SDC B, C and D, dowel bars shall develop minimum L<sub>d</sub> into diaphragm but shall not extend into slab and develop minimum L<sub>d</sub> into beam but 3” minimum clear from bottom face of the beam. Dowel bars shall not be hooked to meet development requirements.		Dowel bars connect standard concrete diaphragms and beams on concrete girder bridges (standard fixed diaphragms are those with beam stirrups NOT extending up into the diaphragm). If the dowel bars are not exposed to net tension a 15-inch embedment shall be used regardless of bar size. Dowel bars size and spacing shall be determined by shear design of the bars. (Minimum #6 Bars @ 12" cts.). Dowel bars should be designed for a minimum horizontal force equal to 25% of the maximum dead load applied to the bearing. Live load is ignored in horizontal force computation.

			For seismic design category SDC B, C and D, dowel bars shall develop minimum L<sub>d</sub> into diaphragm but shall not extend into slab and develop minimum L<sub>d</sub> into beam but 3” minimum clear from bottom face of the beam. Dowel bars shall not be hooked to meet development requirements.

	:The number of dowels must also fit into the space available on the key:		:The number of dowels must also fit into the space available on the key:

Hoskir: /* 751.22.2.7 Dowel Bars */ updated per RR4033

2025-04-18T17:51:54Z

751.22.2.7 Dowel Bars: updated per RR4033

← Older revision		Revision as of 12:51, 18 April 2025
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	===751.22.2.7 Dowel Bars===		===751.22.2.7 Dowel Bars===

	[[Image:751.22.3.15.~~jpg~~\|center\|650px]]		[[Image:751.22.2.7_01-2025.png\|center\|650px]]


Line 1,019:		Line 1,019:

	\|}		\|}
			::::\|Note: Minimum reinforcement shown. Dowel bar size, spacing and length by design.

	::::Dowel bars shall be used for all fixed intermediate bents under prestressed superstructures. Generally, for typical bridges that require seismic details only (strength limit states), shear resistance from shear key is not considered.		::::Dowel bars shall be used for all fixed intermediate bents under prestressed superstructures. Generally, for typical bridges that require seismic details only (strength limit states), shear resistance from shear key is not considered.


	Dowel bars connect standard concrete diaphragms and beams on concrete girder bridges (standard fixed diaphragms are those with beam stirrups NOT extending up into the diaphragm). For a calculated seismic vertical reaction or an anticipated foundation settlement resulting in a net tensile reaction, use the development length of dowel bars into beam and into diaphragm based on dowel bar size. If the dowel bars are not exposed to net tension a 15-inch embedment shall be used regardless of bar size. Dowel bars size and spacing shall be determined by shear design of the bars. (Minimum #6 Bars @ 12" cts.). Dowel bars should be designed for a minimum horizontal force equal to 25% of the maximum dead load applied to the bearing. Live load is ignored in horizontal force computation. For seismic design category SDC B, C and D, dowel bars shall develop minimum L<sub>d</sub> into diaphragm but shall not extend into slab and develop minimum L<sub>d</sub> into beam but 3” minimum clear from bottom face of the beam. Dowel bars shall not be hooked to meet development requirements.		Dowel bars connect standard concrete diaphragms and beams on concrete girder bridges (standard fixed diaphragms are those with beam stirrups NOT extending up into the diaphragm). If the dowel bars are not exposed to net tension a 15-inch embedment shall be used regardless of bar size. Dowel bars size and spacing shall be determined by shear design of the bars. (Minimum #6 Bars @ 12" cts.). Dowel bars should be designed for a minimum horizontal force equal to 25% of the maximum dead load applied to the bearing. Live load is ignored in horizontal force computation. For seismic design category SDC B, C and D, dowel bars shall develop minimum L<sub>d</sub> into diaphragm but shall not extend into slab and develop minimum L<sub>d</sub> into beam but 3” minimum clear from bottom face of the beam. Dowel bars shall not be hooked to meet development requirements.

	:The number of dowels must also fit into the space available on the key:		:The number of dowels must also fit into the space available on the key:

Hoskir: /* 751.22.2.7 Dowel Bars */ updated per RR4033

2025-04-14T15:59:43Z

751.22.2.7 Dowel Bars: updated per RR4033

← Older revision		Revision as of 10:59, 14 April 2025
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	===751.22.2.7 Dowel Bars===		===751.22.2.7 Dowel Bars===


	[[Image:751.22.3.15.jpg\|center\|650px]]		[[Image:751.22.3.15.jpg\|center\|650px]]
Line 1,025:		Line 1,024:


	Dowel bars connect standard concrete diaphragms and beams on concrete girder bridges (standard fixed diaphragms are those with beam stirrups NOT extending up into the diaphragm). For a calculated seismic vertical reaction or an anticipated foundation settlement resulting in a net tensile reaction, use the development length of dowel bars into beam and into diaphragm based on dowel bar size. If the dowel bars are not exposed to net tension a 15-inch embedment shall be used regardless of bar size. Dowel bars size and spacing shall be determined by shear design of the bars. (Minimum #6 Bars @ 12" cts.). Dowel bars should be designed for a minimum horizontal force equal to 25% of the maximum dead load applied to the bearing. Live load is ignored in horizontal force computation.		Dowel bars connect standard concrete diaphragms and beams on concrete girder bridges (standard fixed diaphragms are those with beam stirrups NOT extending up into the diaphragm). For a calculated seismic vertical reaction or an anticipated foundation settlement resulting in a net tensile reaction, use the development length of dowel bars into beam and into diaphragm based on dowel bar size. If the dowel bars are not exposed to net tension a 15-inch embedment shall be used regardless of bar size. Dowel bars size and spacing shall be determined by shear design of the bars. (Minimum #6 Bars @ 12" cts.). Dowel bars should be designed for a minimum horizontal force equal to 25% of the maximum dead load applied to the bearing. Live load is ignored in horizontal force computation. For seismic design category SDC B, C and D, dowel bars shall develop minimum L<sub>d</sub> into diaphragm but shall not extend into slab and develop minimum L<sub>d</sub> into beam but 3” minimum clear from bottom face of the beam. Dowel bars shall not be hooked to meet development requirements.

	:The number of dowels must also fit into the space available on the key:		:The number of dowels must also fit into the space available on the key:
Line 1,036:		Line 1,035:
	Horizontal factored shear force, <math>F_H = \sqrt {(F_T)^2 + (F_L)^2}</math> in kips		Horizontal factored shear force, <math>F_H = \sqrt {(F_T)^2 + (F_L)^2}</math> in kips

	For expansion bearings, transverse F<sub>T</sub> = 0.25(DL) & longitudinal F<sub>L</sub> = 0.		For expansion bearings, transverse F<sub>T</sub> = max (A<sub>s</sub>, 0.25)(DL) & longitudinal F<sub>L</sub> = 0 per girder.
	:Where DL = unfactored dead load reaction at the bent, kips		:Where DL = unfactored dead load reaction at the bent, kips
			::A<sub>s</sub> = Acceleration Coefficient (effective peak ground acceleration coefficient)

	For fixed bearings, Transverse F<sub>T</sub> = 0.25(DL) and Longitudinal F<sub>L</sub> = (0.25)(segment weight) at bent.		For fixed bearings, Transverse F<sub>T</sub> = max (A<sub>s</sub>, 0.25)(DL) and Longitudinal F<sub>L</sub> = max (A<sub>s</sub>, 0.25)(segment weight) at bent.
	:Segment weight includes the full width of superstructure and should be distributed appropriately among fixed bents.		:Segment weight includes the full width of superstructure and should be distributed appropriately among fixed bents.

Line 1,110:		Line 1,110:
	::Otherwise		::Otherwise
	:::<math>T_n = A_b F_{ub} \Big[ 1- \Big(\frac{p_u}{\empty_s R_n} \Big)^2 \Big]^{0.5}</math>		:::<math>T_n = A_b F_{ub} \Big[ 1- \Big(\frac{p_u}{\empty_s R_n} \Big)^2 \Big]^{0.5}</math>


	==751.22.3 Details==		==751.22.3 Details==

Hoskir: /* 751.22.3.9.3 Closed Diaphragm */ updated per RR4028

2025-04-14T13:08:28Z

751.22.3.9.3 Closed Diaphragm: updated per RR4028

← Older revision		Revision as of 08:08, 14 April 2025
Line 2,127:		Line 2,127:

	The simplified detail below is for I girders. The actual details required on the plans can be developed for all girder types by substituting the dimensions and reinforcement of the corresponding section near the diaphragm detail of [[#751.22.3.7 Closed Concrete Intermediate Diaphragms\|EPG 751.22.3.7]] and the dimensions from the corresponding Section A-A of [[#751.22.3.9.1 Dimensions\|EPG 751.22.3.9.1 Dimensions]].		The simplified detail below is for I girders. The actual details required on the plans can be developed for all girder types by substituting the dimensions and reinforcement of the corresponding section near the diaphragm detail of [[#751.22.3.7 Closed Concrete Intermediate Diaphragms\|EPG 751.22.3.7]] and the dimensions from the corresponding Section A-A of [[#751.22.3.9.1 Dimensions\|EPG 751.22.3.9.1 Dimensions]].
			{\| cellpadding="10" style="text-align:center; margin:auto"
	[[image:751.22.3.9.~~3_2022~~.~~jpg~~\|center\|~~650px~~]]		\|-
			\| [[image:751.22.3.9.3_01-2025.png\|center\|470px]] \|\| [[image:751.22.3.9.3_02-2025.png\|center\|225px]]
			\|-
			\| '''SECTION THRU CLOSED END DIAPHRAGM''' \|\|
			\|}

	===751.22.3.10 Coil Inserts and Tie Rods===		===751.22.3.10 Coil Inserts and Tie Rods===

Hoskir: /* 751.22.3.9.2 Reinforcement */ updated per RR4028

2025-04-14T13:07:05Z

751.22.3.9.2 Reinforcement: updated per RR4028

@@ Line 2,021: / Line 2,021: @@
 ====751.22.3.9.2 Reinforcement====
 The reinforcement shall be detailed on the plan sheets for concrete end diaphragms as shown below except:
-:* Bar marks revised as required.
+* Bar marks revised as required.
-:* Abbreviations used as required.
+* Abbreviations used as required.
-:* Add "(Typ.)" to dimensions and leader notes as appropriate.
+* Add "(Typ.)" to dimensions and leader notes as appropriate.
 All U bar reinforcement shall use stirrup bends.
@@ Line 2,032: / Line 2,032: @@
 '''I Girders Type 2, 3, 4 and 6'''
+{| cellpadding="10" style="text-align:center; margin:auto"
-[[image:751.22.3.9.2_IGirders1.jpg|center|750px]]
+|-
-[[image:751.22.3.9.2_IGirders2.jpg|center|700px]]
+| colspan="3" | [[image:751.22.3.9.2_01-2025.png|center|650px]]
 '''Bulb-Tee Girders Type 7 and 8'''
+{| cellpadding="10" style="text-align:center; margin:auto"
-[[image:751.22.3.9.2_BulbTee1.jpg|center|750px]]
+|-
-[[image:751.22.3.9.2_BulbTee2.jpg|center|700px]]
+| colspan="3" | [[image:751.22.3.9.2_06-2025.png|center|750px]]
 '''NU Girders'''
 NU 53 girders are shown in the following details. The details for other NU girder types are similar.
+{| cellpadding="10" style="text-align:center; margin:auto"
-[[image:751.22.3.9.2_NU1.jpg|center|750px]]
+|-
-[[image:751.22.3.9.2_NU2.jpg|center|700px]]
+| colspan="3" | [[image:751.22.3.9.2_10-2025.png|center|775px]]
 ====751.22.3.9.3 Closed Diaphragm====

Hoskir: /* 751.22.3.8.2 Reinforcement */ updated per RR4028

2025-04-14T13:05:54Z

751.22.3.8.2 Reinforcement: updated per RR4028

@@ Line 1,901: / Line 1,901: @@
 ====751.22.3.8.2 Reinforcement====
 The reinforcement shall be detailed on the plan sheets for open concrete intermediate diaphragms as shown below except:
-:* Bar marks revised as required.
+* Bar marks revised as required.
-:* Abbreviations used as required.
+* Abbreviations used as required.
-:* Add "(Typ.)" to dimensions and leader notes as appropriate.
+* Add "(Typ.)" to dimensions and leader notes as appropriate.
 All U bar reinforcement shall use stirrup bends.
@@ Line 1,912: / Line 1,912: @@
 '''I Girders Type 2, 3, 4 and 6'''
 '''Bulb-Tee Girders Type 7 and 8'''
 '''NU Girders'''
 NU 53 girders are shown in the following details. The details for other NU girder types are similar.
-[[image:751.22.3.8.2_NU1.jpg|750px|center]]
+{| cellpadding="10" style="text-align:center; margin:auto"
-[[image:751.22.3.8.2_NU2.jpg|700px|center]]
+|-
 ===751.22.3.9 Concrete End Diaphragms===

Hoskir: /* 751.22.3.7.2 Reinforcement */ updated per RR4028

2025-04-14T13:03:54Z

751.22.3.7.2 Reinforcement: updated per RR4028

Show changes

Hoskir: /* 751.22.2.3 Flexure */ updated per RR4028

2025-04-14T13:01:37Z

751.22.2.3 Flexure: updated per RR4028

← Older revision		Revision as of 08:01, 14 April 2025
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	For NU girders, A1 reinforcement shall consist of the four 3/8-inch diameter reinforcement support strands with deformed bars added only as needed. The WWR in the top flange shall not be used for A1 reinforcement because there is insufficient clearance to splice the WWR.		For NU girders, A1 reinforcement shall consist of the four 3/8-inch diameter reinforcement support strands with deformed bars added only as needed. The WWR in the top flange shall not be used for A1 reinforcement because there is insufficient clearance to splice the WWR.

	~~Reinforcement shall be designed and spliced using f’<sub>ci<~~/~~sub> in accordance with [[751~~.~~5 Structural Detailing Guidelines#751~~.~~5.9.2.8 Development and Lap Splices\|EPG 751.5.9.2.8 Development and Lap Splices]~~].		See guidance on [https://www.modot.org/bridge-standard-drawings Bridge Standard Drawings (Prestressed I-Girders - PSI)] for required lap lengths, if required.

Hoskir: /* 751.22.3.7.4 Bent Details */ minor edit added , on note d

2024-08-02T16:14:09Z

751.22.3.7.4 Bent Details: minor edit added , on note d

← Older revision		Revision as of 11:14, 2 August 2024
Line 1,782:		Line 1,782:
	:<span style="color:green; font-weight:bold;">(c)</span> W" is width of bearing and is equal to width of bottom flange minus 1½ inches. Bearing length and thickness is by design.		:<span style="color:green; font-weight:bold;">(c)</span> W" is width of bearing and is equal to width of bottom flange minus 1½ inches. Bearing length and thickness is by design.

	:<span style="color:green; font-weight:bold;">(d)</span> 3¾" minimum. With the approval of the SPM the diaphragm may be made flush with substructure beams not greater than three feet wide.		:<span style="color:green; font-weight:bold;">(d)</span> 3¾" minimum. With the approval of the SPM, the diaphragm may be made flush with substructure beams not greater than three feet wide.

	:<span style="color:green; font-weight:bold;">(e)</span> Remove thickness for tapered bearings.		:<span style="color:green; font-weight:bold;">(e)</span> Remove thickness for tapered bearings.