751.11 Bearings - Revision history

Hoskir: /* 751.11.2.1 Elastomeric Bearings */ updated per RR4033

2025-04-14T15:58:05Z

751.11.2.1 Elastomeric Bearings: updated per RR4033

← Older revision		Revision as of 10:58, 14 April 2025
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	Horizontal factored shear force, <math>{F_H} = \sqrt{(F_T)^2 + (F_L)^2}</math> in kips per girder		Horizontal factored shear force, <math>{F_H} = \sqrt{(F_T)^2 + (F_L)^2}</math> in kips per girder

	For expansion bearings, transverse F<sub>T</sub> = 0.25(DL) per girder & longitudinal F<sub>L</sub> = 0.		For expansion bearings, transverse F<sub>T</sub> = max (A<sub>s</sub>, 0.25)(DL) per girder & longitudinal F<sub>L</sub> = 0.

	Where DL = unfactored dead load reaction at the bent, kips		Where DL = unfactored dead load reaction at the bent, kips

	For fixed bearings, transverse F<sub>T</sub> = 0.25(DL) per girder and Longitudinal F<sub>L</sub> = (0.25)(segment weight)/(# of girders)		::A<sub>s</sub> = Acceleration Coefficient (effective peak ground acceleration coefficient)

			For fixed bearings, transverse F<sub>T</sub> = max (A<sub>s</sub>, 0.25)(DL) per girder and Longitudinal F<sub>L</sub> = max (A<sub>s</sub>, 0.25)(segment weight)/(# of girders)

	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.

Hoskir: /* 751.11.3.5 Anchor Bolts */ updated per RR3983

2025-01-28T20:22:31Z

751.11.3.5 Anchor Bolts: updated per RR3983

← Older revision		Revision as of 15:22, 28 January 2025
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	! colspan="8" \| TABLE OF ANCHOR BOLT WELLS		! colspan="8" \| TABLE OF ANCHOR BOLT WELLS
	\|-		\|-
	\| Anchor Bolt Diameter \|\| Well Diameter X \|\| Well Depth Y \|\| Spiral Depth B \|\| Spiral Diameter C\|\|W5 Nominal Length \|\| W5 Actual Length\|\|Bolt Extension into Concrete		\| Anchor Bolt Diameter<sup>1</sup> \|\| Well Diameter X \|\| Well Depth Y \|\| Spiral Depth B \|\| Spiral Diameter C\|\|W5 Nominal Length \|\| W5 Actual Length\|\|Bolt Extension into Concrete
	\|-		\|-
	\| 1" \|\| 3" \|\| 12" \|\| 9" \|\| 8" \|\| 14'-10" \|\| 14-'6" \|\| 9"		\| 1" \|\| 3" \|\| 12" \|\| 9" \|\| 8" \|\| 14'-10" \|\| 14-'6" \|\| 9"

Hoskir: /* 751.11.3.5 Anchor Bolts */ updated per RR3983

2025-01-28T19:36:11Z

751.11.3.5 Anchor Bolts: updated per RR3983

← Older revision		Revision as of 14:36, 28 January 2025
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	====751.11.3.5 Anchor Bolts====		====751.11.3.5 Anchor Bolts====

	Show anchor bolt well locations and details on the plans.		Show anchor bolt well locations and details on the plans.

	Only removable forming material is required for forming anchor bolt wells in accordance with [~~http~~://www.modot.org/~~business/standards_and_specs/SpecbookEPG.pdf#page=11~~ Sec 712] and as determined by the contractor which could include PVC, styrofoam, carboard, etc. In lieu of anchor bolts wells, anchor bolts holes may be drilled when permitted in the field as a contractor option, or where required which shall be noted on the plans.		Only removable forming material is required for forming anchor bolt wells in accordance with [https://www.modot.org/missouri-standard-specifications-highway-construction Sec 712] and as determined by the contractor which could include PVC, styrofoam, carboard, etc. In lieu of anchor bolts wells, anchor bolts holes may be drilled when permitted in the field as a contractor option, or where required which shall be noted on the plans.

	Drilling anchor bolt holes should not be permitted in the field or made required on the plans unless reinforcement is detailed on plans to clear anchor bolt wells. An example of drilling needing to be required on the plans would be rehabilitations involving existing bent caps.		Drilling anchor bolt holes should not be permitted in the field or made required on the plans unless reinforcement is detailed on plans to clear anchor bolt wells. An example of drilling needing to be required on the plans would be rehabilitations involving existing bent caps.
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	'''Clearance for reinforcement:'''		'''Clearance for reinforcement:'''

	<center>		<center>
	{\|		{\|
	\|-		\|-
	\|colspan="4"\|[[Image:751.11.3.5-PartPlan.png\|center]]		\| colspan="4" \| [[Image:751.11.3.5-PartPlan.png\|center]]
	\|-
	~~!SQUARE\|\| \|\|style="text-align:center"\|SKEWED\|\| ~~
	\|-		\|-
			\| style="text-align:center" \| '''SQUARE''' \|\| \|\| style="text-align:center" \| '''SKEWED''' \|\|
	\|}		\|}

	'''PART PLAN OF BEAM TOPS'''<br/>		'''PART PLAN OF BEAM TOPS'''<br/>
	'''(INT. BENTS SHOWN)''' </center>		'''(INT. BENTS SHOWN)'''
			</center>


	'''*''' Use even number of bars in beam tops for square bridges when possible.		'''*''' Use even number of bars in beam tops for square bridges when possible.


	Note: Details shown above are for information only. Place the following note on the plans, preferably with "General Notes."		Note: Details shown above are for information only. Place the following note on the plans, preferably with "General Notes."

	"All reinforcing bars in the tops of substructure beams or caps shall be spaced to clear anchor bolt wells for bearings by at least 1/2"."		"All reinforcing bars in the tops of substructure beams or caps shall be spaced to clear anchor bolt wells for bearings by at least 1/2"."



	<center>		<center>
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	{\| border="1" cellspacing="1" cellpadding="3" style="text-align:center"		{\| border="1" cellspacing="1" cellpadding="3" style="text-align:center"
	\|-		\|-
	!colspan="8"\|TABLE OF ANCHOR BOLT WELLS		! colspan="8" \| TABLE OF ANCHOR BOLT WELLS
	\|-		\|-
	\|Anchor Bolt Diameter\|\|Well Diameter X\|\|Well Depth Y\|\|Spiral Depth B\|\|Spiral Diameter C\|\|W5 Nominal Length\|\|W5 Actual Length\|\|Bolt Extension into Concrete		\| Anchor Bolt Diameter \|\| Well Diameter X \|\| Well Depth Y \|\| Spiral Depth B \|\| Spiral Diameter C\|\|W5 Nominal Length \|\| W5 Actual Length\|\|Bolt Extension into Concrete
	\|-		\|-
	\|1"\|\|3"\|\|12"\|\|9"\|\|8"\|\|14'-10"\|\|14-'6"\|\|9"		\| 1" \|\| 3" \|\| 12" \|\| 9" \|\| 8" \|\| 14'-10" \|\| 14-'6" \|\| 9"
	\|-		\|-
	\|1 1/4"\|\|4"\|\|15"\|\|12"\|\|9"\|\|19’-7"\|\|19'-1"\|\|12"		\| 1 1/4" \|\| 4" \|\| 15" \|\| 12" \|\| 9" \|\| 19’-7" \|\| 19'-1" \|\| 12"
	\|-		\|-
	\|1 1/2"\|\|4"\|\|18"\|\|15"\|\|9"\|\|22'-8"\|\|22'-2"\|\|15"		\| 1 1/2" \|\| 4" \|\| 18" \|\| 15" \|\| 9" \|\| 22'-8" \|\| 22'-2" \|\| 15"
	\|-		\|-
	\|2"\|\|4"\|\|21"\|\|18"\|\|9"\|\|25'-9"\|\|25'-2"\|\|18"		\| 2" \|\| 4" \|\| 21" \|\| 18" \|\| 9" \|\| 25'-9" \|\| 25'-2" \|\| 18"
	\|-		\|-
	\|2 1/2"\|\|4"\|\|28"\|\|25"\|\|9"\|\|33'-1"\|\|32'-4"\|\|25"		\| 2 1/2" \|\| 4" \|\| 28" \|\| 25" \|\| 9" \|\| 33'-1" \|\| 32'-4" \|\| 25"
	\|}		\|}
			<sup>1</sup> 1-inch bolt diameter is listed for use with Type C bearings and 1.25-inch bolt diameter is listed for use with Type D and E bearings.

	Nominal length is based on out-to-out dimension. Actual length is the measured along the centerline of the W5 wire. Both nominal length and actual length includes the length of the three side wires.		Nominal length is based on out-to-out dimension. Actual length is the measured along the centerline of the W5 wire. Both nominal length and actual length includes the length of the three side wires.

	Omit spiral on 21" WF if anchor bolt spacing is less than 6".		Omit spiral on 21" WF if anchor bolt spacing is less than 6".

			{\| border="1" cellspacing="1" cellpadding="3" style="text-align:center"

	{\| border="1" cellspacing="1" cellpadding="3"
	\|-		\|-
	!colspan="8"\|TABLE OF BOLT WEIGHTS		! colspan="8" \| TABLE OF BOLT WEIGHTS
	\|-		\|-
	\|align="left"\|Description\|\|1"\|\|1 1/4"\|\|1 1/2"\|\|2"\|\|2 1/2"		\| align="left" \| Description \|\| 1" \|\| 1 1/4" \|\| 1 1/2" \|\| 2" \|\| 2 1/2"
	\|-		\|-
	\|align="left"\|Unthreaded (#/in.)\|\|----\|\|----\|\|0.5\|\|0.89\|\|1.39		\| align="left" \| Unthreaded (#/in.) \|\| ---- \|\| ---- \|\| 0.5 \|\| 0.89 \|\| 1.39
	\|-		\|-
	\|align="left"\|Threaded (#/in.)\|\|----\|\|----\|\|0.425\|\|0.755\|\|1.20		\| align="left" \| Threaded (#/in.) \|\| ---- \|\| ---- \|\| 0.425 \|\| 0.755 \|\| 1.20
	\|-		\|-
	\|align="left"\|Nut (lbs.)\|\|----\|\|----\|\|1.31\|\|2.99\|\|5.64		\| align="left" \| Nut (lbs.) \|\| ---- \|\| ---- \|\| 1.31 \|\| 2.99 \|\| 5.64
	\|-		\|-
	\|align="left"\|Weight used for entire bearing (#/ft.)\|\|2.673\|\|4.175\|\|----\|\|----\|\|----		\| align="left" \| Weight used for entire bearing (#/ft.) \|\| 2.673 \|\| 4.175 \|\| ---- \|\| ---- \|\| ----
	\|-		\|}
	\|}</center>		</center>

	Epoxy coat anchor bolt wells at bents with expansion devices.		Epoxy coat anchor bolt wells at bents with expansion devices.


	'''SWEDGE ANCHOR BOLT DETAILS'''		'''SWEDGE ANCHOR BOLT DETAILS'''

	~~<center>~~		{\| border="1" class="wikitable" style="margin: auto; text-align:center"
	{\| border="1" class="wikitable" style="margin: ~~1em~~ auto ~~1em auto" style="~~text-align:center"
	\|+		\|+
	\| style="background:#BEBEBE" width="300" \|'''[~~http~~://www.modot.org/~~business/consultant_resources/bridgestandards.htm~~ Bridge Standard Drawings]'''		\| style="background:#BEBEBE" width="300" \|'''[https://www.modot.org/bridge-standard-drawings Bridge Standard Drawings]'''
	\|-		\|-
	\|~~align="center"\|[https://www.modot.org/bearings-brg~~ Bearings - BRG]		\| Bearings - BRG
	\|}		\|}

	~~</center>~~

	====751.11.3.6 Girder/Beam Chairs====		====751.11.3.6 Girder/Beam Chairs====

Hoskir: /* 751.11.3.3 PTFE Bearings */ updated per RR3983

2025-01-28T19:16:24Z

751.11.3.3 PTFE Bearings: updated per RR3983

← Older revision		Revision as of 14:16, 28 January 2025
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	====751.11.3.3 PTFE Bearings====		====751.11.3.3 PTFE Bearings====

	Note: The location of anchor bolts in relation to the slotted holes in the sole plate shall correspond with the temperature at the time of erection. At 60°F the slotted holes should center on the anchor bolts.		Note: The location of anchor bolts in relation to the slotted holes in the sole plate shall correspond with the temperature at the time of erection. At 60°F the slotted holes should center on the anchor bolts.

	<center>		<center>
	{\| style="text-align:~~left~~"		{\| style="text-align:center"
	\|-		\|-
	\|colspan="4"\|[[Image:751.11.3.3 Sec AA.jpg\|800px\|center]]		\| colspan="4" \| [[Image:751.11.3.3 Sec AA.jpg\|800px\|center]]
	\|-		\|-
	~~!style="text-align:center"~~\|SECTION A-A\|\| ~~ ~~\|\| ~~ ~~\|\|SIDE VIEW		\| '''SECTION A-A''' \|\| \|\| \|\| '''SIDE VIEW'''
	\|-		\|-
	\|colspan="4"\|[[Image:751.11.3.3 Part Plan.jpg\|800px\|center]]		\| colspan="4" \| [[Image:751.11.3.3 Part Plan.jpg\|800px\|center]]
	\|-		\|-
	~~!style="text-align:center"~~\|PART PLAN VIEW\|\| ~~ ~~\|\| ~~ ~~\|\| ~~ ~~		\| '''PART PLAN VIEW''' \|\| \|\| \|\|
	\|-		\|-
			\| colspan="4" \| [[Image:751.11 PTFE Bearings Notes.gif]]
	\|}		\|}
	</center>		</center>
	[[Image:751.11 PTFE Bearings Notes.gif]]		[[Image:751.11 PTFE Bearings Notes.gif\|center]]

	Notes:		Notes:

	~~For use of smaller or larger diameter anchor bolts than shown in the table “Anchor Bolt Diameter” and~~ with ~~approval of SPM or SLE, see Fabrication Operations Engineer~~.		Anchor bolt grade preferred is ASTM F1554 (Grade 55) with ASTM A563 Grade A Heavy Hex nuts. Anchor bolt grade ASTM F1554 (Grade 105) with ASTM A563 Grade DH Heavy Hex nuts may be used if required by design.

	'''*''' Slot width may be increased on wide roadways to accommodate lateral expansion. See Structural Project Manager.		'''*''' Slot width may be increased on wide roadways to accommodate lateral expansion. See Structural Project Manager.
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	If anchor bolts are believed to be insufficient in restraining pad transverse movement, straps shall be used if the maximum distance between the anchor bolt and edge of girder is not exceeded. If straps are not required, or do not fit without exceeding this distance, stopper plates shall still be used and without recessed ends.		If anchor bolts are believed to be insufficient in restraining pad transverse movement, straps shall be used if the maximum distance between the anchor bolt and edge of girder is not exceeded. If straps are not required, or do not fit without exceeding this distance, stopper plates shall still be used and without recessed ends.

			'''Details of the sole plate connection to the prestress girder.'''
	Details of the sole plate connection to the prestress girder.

	[[Image:751.11.3.3 Section thru Girder Detail.jpg\|center\|650px]]		[[Image:751.11.3.3 Section thru Girder Detail.jpg\|center\|650px]]

	[[Image:751.11.3.3 Notes Sec thru Girder.jpg\|center\|700px]]		[[Image:751.11.3.3 Notes Sec thru Girder.jpg\|center\|700px]]
			<center>'''SECTION THRU GIRDER'''</center>
	<center>
	'''SECTION THRU GIRDER'''


	[[Image:751.11.3.3 Sec End of Girder Detail.jpg\|center\|600px]]		[[Image:751.11.3.3 Sec End of Girder Detail.jpg\|center\|600px]]
			<center>'''SECTION AT END OF GIRDER'''</center>

	~~'''SECTION AT END OF GIRDER'''~~		<center>'''*''' See [[751.22 P/S Concrete I Girders#751.22.3.4 Girder Reinforcement\|EPG 751.22.3.4 Girder Reinforcement]]</center>

	'''*''' See [[751.22 P/S Concrete I Girders#751.22.3.4 Girder Reinforcement\|EPG 751.22.3.4 Girder Reinforcement]]
	</center>

	====751.11.3.4 Bearing Edge Distance====		====751.11.3.4 Bearing Edge Distance====

Hoskir: /* 751.11.3.2 Elastomeric Bearings for Steel Girders */ updated per RR3983

2025-01-28T19:05:58Z

751.11.3.2 Elastomeric Bearings for Steel Girders: updated per RR3983

← Older revision		Revision as of 14:05, 28 January 2025
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	====751.11.3.2 Elastomeric Bearings for Steel Girders====		====751.11.3.2 Elastomeric Bearings for Steel Girders====

	'''Laminated Expansion Bearings'''		'''Laminated Expansion Bearings'''

	Note: The location of anchor bolts in relation to the slotted holes in the sole plate shall correspond with the temperature at the time of erection. At 60°F the slotted holes should center on the anchor bolts.		Note: The location of anchor bolts in relation to the slotted holes in the sole plate shall correspond with the temperature at the time of erection. At 60°F the slotted holes should center on the anchor bolts.

	[[Image:751.11.3.2.1 Laminated Expansion 2021.jpg\|900px\|center]]		[[Image:751.11.3.2.1 Laminated Expansion 2021.jpg\|900px\|center]]
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	[[Image:751.11.3.2.2 Laminated Expansion 2021.jpg\|900px\|center]]		[[Image:751.11.3.2.2 Laminated Expansion 2021.jpg\|900px\|center]]

	Notes:		Notes:

	~~For use of smaller or larger diameter anchor bolts than shown in the table “Anchor Bolt Diameter” and~~ with ~~approval of SPM or SLE, see Fabrication Operations Engineer~~.		Anchor bolt grade preferred is ASTM F1554 (Grade 55) with ASTM A563 Grade A Heavy Hex nuts. Anchor bolt grade ASTM F1554 (Grade 105) with ASTM A563 Grade DH Heavy Hex nuts may be used if required by design.

	Bevel sole plate to match the slope of girder to the nearest 1/8" total difference in thickness across the plate. Minimum thickness shall be 1 1/2" at centerline bearing and 1" at the edge of bearing. (by design)		Bevel sole plate to match the slope of girder to the nearest 1/8" total difference in thickness across the plate. Minimum thickness shall be 1 1/2" at centerline bearing and 1" at the edge of bearing. (by design)

	For <math>\, \triangle </math> > 2 1/2", use PTFE bearings.		For <math>\, \triangle </math> > 2 1/2", use PTFE bearings.

	'''*''' Slot width may be increased on wide roadways to accommodate lateral expansion. See Structural Project Manager.		'''*''' Slot width may be increased on wide roadways to accommodate lateral expansion. See Structural Project Manager.

	'''**''' Designer should verify that minimum dimensions are met or neoprene will melt and flow into hole during manufacturing of bearings.		'''**''' Designer should verify that minimum dimensions are met or neoprene will melt and flow into hole during manufacturing of bearings.



	'''Laminated Fixed Bearing'''		'''Laminated Fixed Bearing'''
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	[[Image:751.11.3.2.2 Laminated Fixed 2021.jpg\|900px\|center]]		[[Image:751.11.3.2.2 Laminated Fixed 2021.jpg\|900px\|center]]

	Notes:		Notes:

	~~For use of smaller or larger diameter anchor bolts than shown in the table “Anchor Bolt Diameter” and~~ with ~~approval of SPM or SLE, see Fabrication Operations Engineer~~.		Anchor bolt grade preferred is ASTM F1554 (Grade 55) with ASTM A563 Grade A Heavy Hex nuts. Anchor bolt grade ASTM F1554 (Grade 105) with ASTM A563 Grade DH Heavy Hex nuts may be used if required by design.

	Bevel sole plate to match the slope of girder to the nearest 1/8" total difference in thickness across the plate. Minimum thickness shall be 1 1/2" at centerline bearing and 1" at the edge of bearing. (by design)		Bevel sole plate to match the slope of girder to the nearest 1/8" total difference in thickness across the plate. Minimum thickness shall be 1 1/2" at centerline bearing and 1" at the edge of bearing. (by design)

	'''*''' Slot width may be increased on wide roadways to accommodate lateral expansion. See Structural Project Manager.		'''*''' Slot width may be increased on wide roadways to accommodate lateral expansion. See Structural Project Manager.

	'''**''' Design should verify that minimum dimensions are met or neoprene will melt and flow into hole during manufacturing of bearings.		'''**''' Design should verify that minimum dimensions are met or neoprene will melt and flow into hole during manufacturing of bearings.




	'''Sole Plate Clipping Details'''		'''Sole Plate Clipping Details'''
	<br/>(for Steel Structures)		<br/>(for Steel Structures)

	~~<center>~~[[Image:751.11 SolePlateClippingDetails Steel.gif]]		[[Image:751.11 SolePlateClippingDetails Steel.gif\|center]]
			<center>'''SECTION THRU BEARING'''</center>
	'''SECTION THRU BEARING'''</center>

	Minimum edge distance shall be maintained on all holes in sole plate. Slotted holes shown are for expansion bearings.		Minimum edge distance shall be maintained on all holes in sole plate. Slotted holes shown are for expansion bearings.

	====751.11.3.3 PTFE Bearings====		====751.11.3.3 PTFE Bearings====

Hoskir: /* 751.11.3.1 Elastomeric Bearings for P/S I-Girders */ updated per RR3983

2025-01-28T18:54:23Z

751.11.3.1 Elastomeric Bearings for P/S I-Girders: updated per RR3983

← Older revision		Revision as of 13:54, 28 January 2025
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	===751.11.3 Details===		===751.11.3 Details===
	====751.11.3.1 Elastomeric Bearings for P/S I-Girders====		====751.11.3.1 Elastomeric Bearings for P/S I-Girders====

	'''Expansion Bearings'''		'''Expansion Bearings'''

	Note: The location of anchor bolts in relation to the slotted holes in the sole plate shall correspond with the temperature at the time of erection. At 60°F the slotted holes should center on the anchor bolts.		Note: The location of anchor bolts in relation to the slotted holes in the sole plate shall correspond with the temperature at the time of erection. At 60°F the slotted holes should center on the anchor bolts.

	[[Image:751.11.3.1.1 2021.jpg\|900px\|center]]		[[Image:751.11.3.1.1 2021.jpg\|900px\|center]]
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	[[Image:751.11.3.1.2 2021.jpg\|900px\|center]]		[[Image:751.11.3.1.2 2021.jpg\|900px\|center]]

	Notes:		Notes:

	~~For use of smaller or larger diameter anchor bolts than shown in the table “Anchor Bolt Diameter” and~~ with ~~approval of SPM or SLE, see Fabrication Operations Engineer~~.		Anchor bolt grade preferred is ASTM F1554 (Grade 55) with ASTM A563 Grade A Heavy Hex nuts. Anchor bolt grade ASTM F1554 (Grade 105) with ASTM A563 Grade DH Heavy Hex nuts may be used if required by design.

	Bevel sole plate to match the slope of girder to the nearest 1/8" total difference in thickness across the plate. Minimum thickness shall be 1 1/2" at centerline bearing and 1" at the edge of bearing. (By design)		Bevel sole plate to match the slope of girder to the nearest 1/8" total difference in thickness across the plate. Minimum thickness shall be 1 1/2" at centerline bearing and 1" at the edge of bearing. (By design)

	For <math>\, \triangle </math> > 2 1/2", use PTFE bearings.		For <math>\, \triangle </math> > 2 1/2", use PTFE bearings.

	'''*''' Slot width may be increased on wide roadways to accommodate lateral expansion. See Structural Project Manager.		'''*''' Slot width may be increased on wide roadways to accommodate lateral expansion. See Structural Project Manager.

	'''**''' Designer should verify that minimum dimensions are met or neoprene will melt and flow into hole during manufacturing of bearings.		'''**''' Designer should verify that minimum dimensions are met or neoprene will melt and flow into hole during manufacturing of bearings.

Hoskir: /* 751.11.2.4 PTFE (Polytetraflouroethylene) Bearings */

2024-09-11T19:38:10Z

751.11.2.4 PTFE (Polytetraflouroethylene) Bearings

← Older revision		Revision as of 14:38, 11 September 2024
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	\|}		\|}
	Note:</br>		Note:</br>
	Vertical pressure = ~~DL<sub>max</sub>~~/A, where A is the total PTFE surface area minus the dimpled area, if applicable.</br>		Vertical pressure = DLmax/A, where A is the total PTFE surface area minus the dimpled area, if applicable.</br>
	Intermediate values may be determined by interpolation. Integer values shall be used for plans reporting.</br>		Intermediate values may be determined by interpolation. Integer values shall be used for plans reporting.</br>
	Dimpled PTFE sliding surfaces are the preferred PTFE type. Flat PTFE may be used with SPM or SLE approval. The contractor is allowed to use unfilled or filled pads so the filled values should be used in design.</br>		Dimpled PTFE sliding surfaces are the preferred PTFE type. Flat PTFE may be used with SPM or SLE approval. The contractor is allowed to use unfilled or filled pads so the filled values should be used in design.</br>
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	PTFE dimensions are the same as the bearing pad dimensions.		PTFE dimensions are the same as the bearing pad dimensions.

	Service ~~DL<sub>max</sub>~~ = 50 kips</br>		Service DLmax = 50 kips</br>
	Service LL = 73 kips</br>		Service LL = 73 kips</br>
	PTFE length, L = 11 in</br>		PTFE length, L = 11 in</br>
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	Check h<sub>rt</sub> at first-slip:		Check h<sub>rt</sub> at first-slip:

	~~DL<sub>max</sub>~~ /A = 50/100.1= 0.5 ksi = 500 psi</br>		DLmax /A = 50/100.1= 0.5 ksi = 500 psi</br>
	μ = 4%</br>		μ = 4%</br>
	Deflection of bearing pad at first-slip, Δ<sub>s-slip</sub> = ~~ɣFR(μ)DL~~<sub>~~max~~</sub>(h<sub>rt</sub>)/(AG) = 1.0(4/100)50(1.0)/(100.10.2) = 0.1 in</br>		Deflection of bearing pad at first-slip, Δ<sub>s-slip</sub> = ɣ<sub>FR</sub>(μ)DLmax(h<sub>rt</sub>)/(AG) = 1.0(4/100)50(1.0)/(100.10.2) = 0.1 in</br>
	h<sub>rt</sub> ≥ 2Δ<sub>s-slip</sub> = 2*0.1= 0.2 in OK</br>		h<sub>rt</sub> ≥ 2Δ<sub>s-slip</sub> = 2*0.1= 0.2 in OK</br>
	The PTFE sliding surface accommodates the remainder of the thermal movement at the bearing.		The PTFE sliding surface accommodates the remainder of the thermal movement at the bearing.
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	This check will be met by satisfying the maximum compressive stress check for the elastomeric bearing pad.		This check will be met by satisfying the maximum compressive stress check for the elastomeric bearing pad.

	~~DL<sub>max</sub>~~/A ≤ 3.0 ksi </br>		DLmax/A ≤ 3.0 ksi </br>
	50/100.1= 0.5 ksi < 3.0 OK		50/100.1= 0.5 ksi < 3.0 OK

	(~~DL<sub>max</sub>~~ + LL)/A ≤ 4.5 ksi </br>		(DLmax + LL)/A ≤ 4.5 ksi </br>
	(50+73)/100.1= 1.23 ksi < 4.5 OK		(50+73)/100.1= 1.23 ksi < 4.5 OK

Hoskir: /* 751.11.2.4 PTFE (Polytetraflouroethylene) Bearings */ fixed text sub formatting errors

2024-09-11T19:09:51Z

751.11.2.4 PTFE (Polytetraflouroethylene) Bearings: fixed text sub formatting errors

← Older revision		Revision as of 14:09, 11 September 2024
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	'''General'''		'''General'''

	PTFE bearings shall be used if Δs > 2.5 in.		PTFE bearings shall be used if Δ<sub>s</sub> > 2.5 in.

	PTFE sliding bearing shall consist of a lower unit and an upper unit as follows:		PTFE sliding bearing shall consist of a lower unit and an upper unit as follows:
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	\|}		\|}
	Note:</br>		Note:</br>
	Vertical pressure = ~~DLmax~~/A, where A is the total PTFE surface area minus the dimpled area, if applicable.</br>		Vertical pressure = DL<sub>max</sub>/A, where A is the total PTFE surface area minus the dimpled area, if applicable.</br>
	Intermediate values may be determined by interpolation. Integer values shall be used for plans reporting.</br>		Intermediate values may be determined by interpolation. Integer values shall be used for plans reporting.</br>
	Dimpled PTFE sliding surfaces are the preferred PTFE type. Flat PTFE may be used with SPM or SLE approval. The contractor is allowed to use unfilled or filled pads so the filled values should be used in design.</br>		Dimpled PTFE sliding surfaces are the preferred PTFE type. Flat PTFE may be used with SPM or SLE approval. The contractor is allowed to use unfilled or filled pads so the filled values should be used in design.</br>
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	PTFE dimensions are the same as the bearing pad dimensions.		PTFE dimensions are the same as the bearing pad dimensions.

	Service ~~DLmax~~ = 50 kips</br>		Service DL<sub>max</sub> = 50 kips</br>
	Service LL = 73 kips</br>		Service LL = 73 kips</br>
	PTFE length, L = 11 in</br>		PTFE length, L = 11 in</br>
	PTFE width, W = 13 in</br>		PTFE width, W = 13 in</br>
	PTFE surface area, A = 143 - (30/100)143 = 100.1 ~~in2~~, assume dimpled area is 30% of total PTFE surface area</br>		PTFE surface area, A = 143 - (30/100)143 = 100.1 in<sup>2</sup>, assume dimpled area is 30% of total PTFE surface area</br>
	Total elastomer thickness, ~~hrt~~ = 1.0 in</br>		Total elastomer thickness, h<sub>rt</sub> = 1.0 in</br>
	Elastomer shear modulus, G = 0.2 ksi		Elastomer shear modulus, G = 0.2 ksi

	Check ~~hrt~~ at first-slip:		Check h<sub>rt</sub> at first-slip:

	~~DLmax~~ /A = 50/100.1= 0.5 ksi = 500 psi</br>		DL<sub>max</sub> /A = 50/100.1= 0.5 ksi = 500 psi</br>
	μ = 4%</br>		μ = 4%</br>
	Deflection of bearing pad at first-slip, Δs-slip = ɣFR(μ)~~DLmax~~(~~hrt~~)/(AG) = 1.0(4/100)50(1.0)/(100.10.2) = 0.1 in</br>		Deflection of bearing pad at first-slip, Δ<sub>s-slip</sub> = ɣFR(μ)DL<sub>max</sub>(h<sub>rt</sub>)/(AG) = 1.0(4/100)50(1.0)/(100.10.2) = 0.1 in</br>
	~~hrt~~ ≥ ~~2Δs~~-slip = 2*0.1= 0.2 in OK</br>		h<sub>rt</sub> ≥ 2Δ<sub>s-slip</sub> = 2*0.1= 0.2 in OK</br>
	The PTFE sliding surface accommodates the remainder of the thermal movement at the bearing.		The PTFE sliding surface accommodates the remainder of the thermal movement at the bearing.

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	This check will be met by satisfying the maximum compressive stress check for the elastomeric bearing pad.		This check will be met by satisfying the maximum compressive stress check for the elastomeric bearing pad.

	~~DLmax~~/A ≤ 3.0 ksi </br>		DL<sub>max</sub>/A ≤ 3.0 ksi </br>
	50/100.1= 0.5 ksi < 3.0 OK		50/100.1= 0.5 ksi < 3.0 OK

	(~~DLmax~~ + LL)/A ≤ 4.5 ksi </br>		(DL<sub>max</sub> + LL)/A ≤ 4.5 ksi </br>
	(50+73)/100.1= 1.23 ksi < 4.5 OK		(50+73)/100.1= 1.23 ksi < 4.5 OK

Hoskir: /* 751.11.2.4 PTFE (Polytetraflouroethylene) Bearings */ updated per RR3932

2024-09-10T15:42:29Z

751.11.2.4 PTFE (Polytetraflouroethylene) Bearings: updated per RR3932

@@ Line 920: / Line 920: @@
 '''General'''
 PTFE sliding bearing shall consist of a lower unit and an upper unit as follows:
-The lower unit shall be PTFE bonded to a 1/8” stainless steel plate which is vulcanized to a neoprene pad.
+The lower unit shall be PTFE bonded to a 1/8” stainless steel plate which is vulcanized to a laminated neoprene pad.
 The upper unit shall be a 1/8” highly polished stainless steel plate welded to a steel sole plate.
-Durometer hardness is to be used for sliding bearings.
+Durometer hardness and shear modulus G = 0.2 ksi is to be used for sliding bearings.
-Design:
+The following table represents the coefficients of friction for the design of PTFE sliding surfaces and are to be used instead of LRFD Table 14.7.2.5-1.
-Neoprene Elastomeric Pad
+{| class="wikitable" style="text-align: center;"
-{|
+|+ Design Coefficients of Friction at Various Vertical Pressures
-|Maximum (DL +LL) Compressive Stress ||= 1000 psi
+! rowspan=2 | PTFE Types !! colspan="5" | Coefficient of Friction, μ
 |-
-|Minimum (DL) Compressive Stress|| = 200 psi
+| style="text-align: left" | Filled - Dimpled || 5% || 4% || 4% || 4% || 4%
 |}
 ====751.11.2.5 Multi-Rotational High Load Bearings====

Hoskir: /* 751.11.3.3 PTFE Bearings */ updated per RR3932

2024-09-10T15:39:46Z

751.11.3.3 PTFE Bearings: updated per RR3932

← Older revision		Revision as of 10:39, 10 September 2024
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	'''****''' Designer should verify that minimum dimensions are met or neoprene will melt and flow into the hole during manufacturing of bearing.		'''****''' Designer should verify that minimum dimensions are met or neoprene will melt and flow into the hole during manufacturing of bearing.

			Either stopper plates, or both stopper plates and straps shall be used to restrain potential longitudinal, or longitudinal and transverse pad movement, respectively.

			If anchor bolts are believed to be insufficient in restraining pad transverse movement, straps shall be used if the maximum distance between the anchor bolt and edge of girder is not exceeded. If straps are not required, or do not fit without exceeding this distance, stopper plates shall still be used and without recessed ends.