751.24 Retaining Walls - Revision history

Hoskir: /* 751.24.2.1 Design */ updated link

2026-10-29T20:37:48Z

751.24.2.1 Design: updated link

← Older revision		Revision as of 14:37, 29 October 2026
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	Global stability (i.e., overall and compound stability) of the wall shall be performed in accordance with FHWA GEC 011, and LRFD BDS 11.6.3.7 and 11.10.5.6. For additional information, See [[321.1_Design_of_Earth_Slopes#321.1.2_Slope_Stability_Analyses_for_Special_Foundation_Investigations\|EPG 321.1.2 Slope Stability Analyses for Special Foundation Investigations]].		Global stability (i.e., overall and compound stability) of the wall shall be performed in accordance with FHWA GEC 011, and LRFD BDS 11.6.3.7 and 11.10.5.6. For additional information, See [[321.1_Design_of_Earth_Slopes#321.1.2_Slope_Stability_Analyses_for_Special_Foundation_Investigations\|EPG 321.1.2 Slope Stability Analyses for Special Foundation Investigations]].

	For MSE walls settlement limit, see [[321.2_Geotechnical_Guidelines#321.2.4.2_Walls\|EPG 321.2.4.2 Walls]].		For MSE walls settlement limit, see [[321.2_Geotechnical_Guidelines#321.2.2.2_Walls\|EPG 321.2.2.2 Walls]].

Hoskir: /* 751.24.3.2 Design */ fixed minor text error

2026-10-29T20:34:51Z

751.24.3.2 Design: fixed minor text error

← Older revision		Revision as of 14:34, 29 October 2026
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	: Extreme Event I and II Limit State:		: Extreme Event I and II Limit State:
	: Factored bearing resistance = Nominal bearing resistance from the Geotechnical report X Resistance factor		: Factored bearing resistance = Nominal bearing resistance from the Geotechnical report * Resistance factor
	: Resistance factor = 0.8      LRFD BDS 11.5.8		: Resistance factor = 0.8      LRFD BDS 11.5.8

Hoskir: /* 751.24.3.2 Design */

2026-10-29T16:13:00Z

751.24.3.2 Design

← Older revision		Revision as of 10:13, 29 October 2026
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	: Extreme Event I and II Limit State:		: Extreme Event I and II Limit State:
	: Factored bearing resistance = Nominal bearing resistance from ~~Geotech~~ report X Resistance factor		: Factored bearing resistance = Nominal bearing resistance from the Geotechnical report X Resistance factor
	: Resistance factor = 0.8      LRFD BDS 11.5.8		: Resistance factor = 0.8      LRFD BDS 11.5.8

Hoskir: /* 751.24.2.1 Design */

2026-10-29T16:11:00Z

751.24.2.1 Design

← Older revision		Revision as of 10:11, 29 October 2026
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	:: Extreme Event I Limit State:		:: Extreme Event I Limit State:
	:: Factored bearing resistance = Nominal bearing resistance from Geotechnical report * Resistance factor.		:: Factored bearing resistance = Nominal bearing resistance from the Geotechnical report * Resistance factor.
	:: Resistance factor = 0.9 in accordance with LRFD BDS 11.5.8		:: Resistance factor = 0.9 in accordance with LRFD BDS 11.5.8

Hoskir: /* 751.24.2.1 Design */ fixed error due to update

2026-10-29T16:09:14Z

751.24.2.1 Design: fixed error due to update

← Older revision		Revision as of 10:09, 29 October 2026
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	Designs of Mechanically Stabilized Earth (MSE) walls shall be completed by consultants or contractors in accordance with Section 11.10 of LRFD specifications, FHWA-NHI-10-024 and FHWA-NHI-10-025 for LRFD. [https://www.modot.org/bridge-pre-qualified-products-list Bridge Pre-qualified Products List (BPPL)] provided on MoDOT's web page and in Sharepoint contains a listing of facing unit manufacturers, soil reinforcement suppliers, and wall system suppliers which have been approved for use. See [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=11 Sec 720] and [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=14 Sec 1010] for additional information. The Geotechnical Section is responsible for checking global stability of permanent MSE wall systems, which should be reported in the Foundation Investigation Geotechnical Report. For MSE wall preliminary information, see [[751.1_Preliminary_Design#751.1.4.3_MSE_Walls\|EPG 751.1.4.3 MSE Walls]]. For design requirements of MSE wall systems and temporary shoring (including temporary MSE walls), see [[:Category:720_Mechanically_Stabilized_Earth_Wall_Systems#720.2_Design_Requirements\|EPG 720 Mechanically Stabilized Earth Wall Systems]]. For staged bridge construction, see [[751.1_Preliminary_Design#751.1.2.11_Staged_Construction\|EPG 751.1.2.11 Staged Construction]].		Designs of Mechanically Stabilized Earth (MSE) walls shall be completed by consultants or contractors in accordance with Section 11.10 of LRFD specifications, FHWA-NHI-10-024 and FHWA-NHI-10-025 for LRFD. [https://www.modot.org/bridge-pre-qualified-products-list Bridge Pre-qualified Products List (BPPL)] provided on MoDOT's web page and in Sharepoint contains a listing of facing unit manufacturers, soil reinforcement suppliers, and wall system suppliers which have been approved for use. See [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=11 Sec 720] and [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=14 Sec 1010] for additional information. The Geotechnical Section is responsible for checking global stability of permanent MSE wall systems, which should be reported in the Foundation Investigation Geotechnical Report. For MSE wall preliminary information, see [[751.1_Preliminary_Design#751.1.4.3_MSE_Walls\|EPG 751.1.4.3 MSE Walls]]. For design requirements of MSE wall systems and temporary shoring (including temporary MSE walls), see [[:Category:720_Mechanically_Stabilized_Earth_Wall_Systems#720.2_Design_Requirements\|EPG 720 Mechanically Stabilized Earth Wall Systems]]. For staged bridge construction, see [[751.1_Preliminary_Design#751.1.2.11_Staged_Construction\|EPG 751.1.2.11 Staged Construction]].

	Global (overall) stability of a permanent MSE wall shall be performed by the Geotechnical Section or their agent and the global stability of a temporary MSE wall shall be performed by the contractor/wall designer. The ~~cCompound~~ stability of a permanent MSE wall and temporary MSE wall shall be performed by the contractor/wall designer.		Global (overall) stability of a permanent MSE wall shall be performed by the Geotechnical Section or their agent and the global stability of a temporary MSE wall shall be performed by the contractor/wall designer. The compound stability of a permanent MSE wall and temporary MSE wall shall be performed by the contractor/wall designer.

	Global stability (i.e., overall and compound stability) of the wall shall be performed in accordance with FHWA GEC 011, and LRFD BDS 11.6.3.7 and 11.10.5.6. For additional information, See [[321.1_Design_of_Earth_Slopes#321.1.2_Slope_Stability_Analyses_for_Special_Foundation_Investigations\|EPG 321.1.2 Slope Stability Analyses for Special Foundation Investigations]].		Global stability (i.e., overall and compound stability) of the wall shall be performed in accordance with FHWA GEC 011, and LRFD BDS 11.6.3.7 and 11.10.5.6. For additional information, See [[321.1_Design_of_Earth_Slopes#321.1.2_Slope_Stability_Analyses_for_Special_Foundation_Investigations\|EPG 321.1.2 Slope Stability Analyses for Special Foundation Investigations]].

Hoskir: /* 751.24.3.2 Design */ updated per RR4244

2026-10-26T15:35:46Z

751.24.3.2 Design: updated per RR4244

Show changes

Hoskir: /* 751.24.2.1 Design */ updated per RR4244

2026-10-26T15:31:53Z

751.24.2.1 Design: updated per RR4244

Show changes

Hoskir: /* 751.24.2.1 Design */ updated per RR4023

2025-07-11T15:04:30Z

751.24.2.1 Design: updated per RR4023

← Older revision		Revision as of 09:04, 11 July 2025
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	:::For foundations supported on soil or rock, the location of the resultant of the reaction forces shall be within the middle two-thirds of the base width, L or (e ≤ 0.33L) for γ<sub>EQ</sub> = 0.0 and middle eight-tenths of the base width, L or (e ≤ 0.40L) for γ<sub>EQ</sub> = 1.0. For γ<sub>EQ</sub> between 0.0 and 1.0, interpolate e value linearly between 0.33L and 0.40L. For γ<sub>EQ</sub> refer to LRFD 3.4.		:::For foundations supported on soil or rock, the location of the resultant of the reaction forces shall be within the middle two-thirds of the base width, L or (e ≤ 0.33L) for γ<sub>EQ</sub> = 0.0 and middle eight-tenths of the base width, L or (e ≤ 0.40L) for γ<sub>EQ</sub> = 1.0. For γ<sub>EQ</sub> between 0.0 and 1.0, interpolate e value linearly between 0.33L and 0.40L. For γ<sub>EQ</sub> refer to LRFD 3.4.

	:::Note: Seismic design shall be performed for γ<sub>EQ</sub> = 0.5~~. If live loads act to reduce the eccentricity, then γ<sub>EQ</sub> shall be taken as 0.0.~~		:::Note: Seismic design shall be performed for γ<sub>EQ</sub> = 0.5

	::Eccentricity, (e) Limit for Extreme Event II:		::Eccentricity, (e) Limit for Extreme Event II:
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	When rock is anticipated within the 5 feet zone below the MSE wall leveling pad, prebore into rock and prebore holes shall be sufficiently wide to allow for a minimum 10 feet embedment of pile and pipe pile spacer. When top of rock is anticipated within the 5 to 10 feet zone below the MSE wall leveling pad, prebore into rock to achieve a minimum embedment (pile only) of 10 feet below the bottom of leveling pad. Otherwise, the pipe pile spacer requires a minimum 5 feet embedment below the levelling pad. Consideration shall also be given to oversizing the prebore holes in rock to allow for temperature movements at integral end bents.		When rock is anticipated within the 5 feet zone below the MSE wall leveling pad, prebore into rock and prebore holes shall be sufficiently wide to allow for a minimum 10 feet embedment of pile and pipe pile spacer. When top of rock is anticipated within the 5 to 10 feet zone below the MSE wall leveling pad, prebore into rock to achieve a minimum embedment (pile only) of 10 feet below the bottom of leveling pad. Otherwise, the pipe pile spacer requires a minimum 5 feet embedment below the levelling pad. Consideration shall also be given to oversizing the prebore holes in rock to allow for temperature movements at integral end bents.

	For bridges not longer than 200 feet, the minimum clearance from the back face of MSE walls to the front face of the end bent beam, also referred to as setback, shall be 4 ft. 6 in. (typ.) unless larger than 18-inch pipe pile spacer required. The 4 ft. 6 in. dimension is ~~based on the use of~~ 18-inch inside diameter pipe pile spacers & FHWA-NHI-10-24, Figure 5-17C, ~~which will help ensure~~ that ~~soil reinforcement is~~ not ~~skewed more than 15°~~ for ~~nut~~ and ~~bolt reinforcement connections~~. ~~Similarly,~~ the minimum setback shall be ~~determined~~ when larger diameter pile spacers are required. For bridges longer than 200 feet, the minimum setback shall be 5 ft. 6 in. based on the use of 24-inch inside diameter of pipe pile spacers. ~~Other types of connections may require different methods~~ for ~~splaying. In the event that the minimum setback cannot be used~~, the following guidance for pipe pile spacers clearance shall be used: pipe pile spacers shall be placed 18 in. clear min. from the back face of MSE wall panels; 12 in. minimum clearance is required between pipe pile spacers and leveling pad and 18 in. minimum clearance is required between leveling pad and pile.		For bridges not longer than 200 feet, the minimum clearance from the back face of MSE walls to the front face of the end bent beam, also referred to as setback, shall be 4 ft. 6 in. (typ.) unless larger than 18-inch pipe pile spacer required. The 4 ft. 6 in. dimension serves a dual purpose:
			:1) the setback ensures that soil reinforcement is not skewed more than 15° for nut and bolt reinforcement connections to clear an 18-inch inside diameter pipe pile spacers by 6 inches per FHWA-NHI-10-24, Figure 5-17C, while considering vertical and horizontal pile placement tolerances
			:2) the setback helps to reduce the forces imparted on the MSE wall from bridge movements that typically are not accounted for in the wall design and cannot be completely isolated using a pipe pile spacer. Increasing the minimum setback shall be considered when larger diameter pile spacers are required or when other types of soil reinforcement connections are anticipated

			For bridges longer than 200 feet, the minimum setback shall be 5 ft. 6 in. based on the use of 24-inch inside diameter of pipe pile spacers.

			If interference with soil reinforcement is not a concern and the wall is designed for forces from bridge movement, the following guidance for pipe pile spacers clearance shall be used: pipe pile spacers shall be placed 36 in. clear min. from the back face of MSE wall panels to allow for proper compaction; 12 in. minimum clearance is required between pipe pile spacers and leveling pad and 18 in. minimum clearance is required between leveling pad and pile. For isolated pile (e.g, walls skewed from the bent orientation), the pipe pile spacer may be placed 18 in. clear min. from the back face of MSE wall panels.

	'''MSE Wall Plan and Geometrics'''		'''MSE Wall Plan and Geometrics'''

Hoskir: /* 751.24.3.2 Design */ minor update to fix equation

2025-03-24T18:33:37Z

751.24.3.2 Design: minor update to fix equation

← Older revision		Revision as of 12:33, 24 March 2025
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	:* For foundations supported on soil or rock, the location of the resultant of the reaction forces shall be within the middle two-thirds of the base width, B or (e ≤ 0.33B) for γ<sub>EQ</sub> = 0.0 and middle eight-tenths of the base width, B or (e ≤ 0.40B) for γ<sub>EQ</sub> = 1.0. For γ<sub>EQ</sub> between 0.0 and 1.0, interpolate e value linearly between 0.33B and 0.40B. For γ<sub>EQ</sub> refer to LRFD 3.4.		:* For foundations supported on soil or rock, the location of the resultant of the reaction forces shall be within the middle two-thirds of the base width, B or (e ≤ 0.33B) for γ<sub>EQ</sub> = 0.0 and middle eight-tenths of the base width, B or (e ≤ 0.40B) for γ<sub>EQ</sub> = 1.0. For γ<sub>EQ</sub> between 0.0 and 1.0, interpolate e value linearly between 0.33B and 0.40B. For γ<sub>EQ</sub> refer to LRFD 3.4.

	:Note: Seismic design shall be performed for γ<sub>EQ</sub> = 0.5. If live loads act to reduce the eccentricity, then ~~γEQ~~ shall be taken as 0.0.		:Note: Seismic design shall be performed for γ<sub>EQ</sub> = 0.5. If live loads act to reduce the eccentricity, then γ<sub>EQ</sub> shall be taken as 0.0.

	Eccentricity, (e) Limit for Extreme Event II:		Eccentricity, (e) Limit for Extreme Event II:

Hoskir: /* 751.24.3.2 Design */ updated per RR4024

2025-03-18T18:06:53Z

751.24.3.2 Design: updated per RR4024

← Older revision		Revision as of 12:06, 18 March 2025
Line 470:		Line 470:
	:* For foundations supported on soil or rock, the location of the resultant of the reaction forces shall be within the middle two-thirds of the base width, B or (e ≤ 0.33B) for γ<sub>EQ</sub> = 0.0 and middle eight-tenths of the base width, B or (e ≤ 0.40B) for γ<sub>EQ</sub> = 1.0. For γ<sub>EQ</sub> between 0.0 and 1.0, interpolate e value linearly between 0.33B and 0.40B. For γ<sub>EQ</sub> refer to LRFD 3.4.		:* For foundations supported on soil or rock, the location of the resultant of the reaction forces shall be within the middle two-thirds of the base width, B or (e ≤ 0.33B) for γ<sub>EQ</sub> = 0.0 and middle eight-tenths of the base width, B or (e ≤ 0.40B) for γ<sub>EQ</sub> = 1.0. For γ<sub>EQ</sub> between 0.0 and 1.0, interpolate e value linearly between 0.33B and 0.40B. For γ<sub>EQ</sub> refer to LRFD 3.4.

	:Note: Seismic design shall be performed for γ<sub>EQ</sub> = 0.5		:Note: Seismic design shall be performed for γ<sub>EQ</sub> = 0.5. If live loads act to reduce the eccentricity, then γEQ shall be taken as 0.0.

	Eccentricity, (e) Limit for Extreme Event II:		Eccentricity, (e) Limit for Extreme Event II: