751.37 Drilled Shafts - Revision history

Hoskir: updated old math code

2026-01-15T18:48:57Z

updated old math code

Hoskir: /* 751.37.6.4 Transverse Reinforcement */ updated per RR4033

2025-04-14T16:26:06Z

751.37.6.4 Transverse Reinforcement: updated per RR4033

← Older revision		Revision as of 11:26, 14 April 2025
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	===751.37.6.4 Transverse Reinforcement===		===751.37.6.4 Transverse Reinforcement===

	Minimum transverse reinforcement shall be designed to resist the potential of diagonal cracking and improve ductility, and to control the stability of the reinforcement cage. Follow the four-step procedure, below:		Minimum transverse reinforcement shall be designed to resist the potential of diagonal cracking and improve ductility, and to control the stability of the reinforcement cage. Follow the four-step procedure, below for seismic design category SDC A.

			For Seismic detail requirements for seismic design category, SDC B, C and D, See [[751.9_Bridge_Seismic_Design#751.9.1.2_LRFD_Seismic_Details\|EPG 751.9.1.2 LRFD Seismic Details]].

	'''No. 1. Determine if Transverse Reinforcement is Required for Loading'''		'''No. 1. Determine if Transverse Reinforcement is Required for Loading'''

Hoskir: /* 751.37.6.2 Longitudinal Reinforcement */ updated per RR4033

2025-04-14T16:23:43Z

751.37.6.2 Longitudinal Reinforcement: updated per RR4033

← Older revision		Revision as of 11:23, 14 April 2025
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	{\| style="margin: 1em auto 1em auto" width="800"		{\| style="margin: 1em auto 1em auto" width="800"
	\|-		\|-
	\|align="left" rowspan="2"\|<math>\frac{0.135 A_g f^'_c}{f_y} \le A_{steel} \le 0.08 A_g</math>\|\|align="center"\| (~~consistent~~ units of stress)\|\|align="right"\|Equation 751.37.6.1		\| align="left" rowspan="2" \| <math>\frac{0.135 A_g f^'_c}{f_y} \le A_{steel} \le 0.04 A_g</math> \|\| align="center" \| (Consistent units of stress)\|\|align="right"\|Equation 751.37.6.1
	\|-		\|-
	\|align="center"\|''' LRFD 5.7.4.2'''\|\|		\| align="center" \| '''LRFD 5.7.4.2 and SGS 8.8.1''' \|\|
	\|}		\|}

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	:''A<sub>steel</sub>'' = cross-sectional area of longitudinal steel reinforcement (consistent units of area).		:''A<sub>steel</sub>'' = cross-sectional area of longitudinal steel reinforcement (consistent units of area).

	MoDOT prefers to follow LRFD 5.7.4.2 for drilled shafts since for typical cases, the potential exists for load transfer between the concrete and steel casing. (The minimum area of reinforcement based on LRFD is 10 percent less than ACI for f’<sub>c</sub> = 4 ksi).		MoDOT prefers to follow LRFD 5.7.4.2 for drilled shafts since for typical cases, the potential exists for load transfer between the concrete and steel casing. (The minimum area of reinforcement based on LRFD is 10 percent less than ACI for f’<sub>c</sub> = 4 ksi).

	===751.37.6.3 Factored Axial Resistance===		===751.37.6.3 Factored Axial Resistance===

Hoskir: /* 751.37.1.6 Drilled Shaft General Detail Considerations */ updated per RR4033

2025-04-14T16:18:03Z

751.37.1.6 Drilled Shaft General Detail Considerations: updated per RR4033

← Older revision		Revision as of 11:18, 14 April 2025
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	===751.37.1.6 Drilled Shaft General Detail Considerations===		===751.37.1.6 Drilled Shaft General Detail Considerations===
			For Seismic detail requirements for seismic design category, SDC B, C and D, See [[751.9_Bridge_Seismic_Design#751.9.1.2_LRFD_Seismic_Details\|EPG 751.9.1.2 LRFD Seismic Details]].

	[[image:751.37.1.6 01.png\|700px\|center]]		[[image:751.37.1.6 01.png\|700px\|center]]

	Pay items shown in above table are for example only, show actual pay items and quantities in plan details for specific project.		Pay items shown in above table are for example only, show actual pay items and quantities in plan details for specific project.

Hoskir: /* 751.37.6.1 Reinforcement Design */

2025-03-24T20:56:29Z

751.37.6.1 Reinforcement Design

← Older revision		Revision as of 15:56, 24 March 2025
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	Minimum clear spacing between longitudinal bars as well as between transverse bars shall not be less than five times the maximum aggregate size or 5 in. (LRFD 10.8.3.9.3).		Minimum clear spacing between longitudinal bars as well as between transverse bars shall not be less than five times the maximum aggregate size or 5 in. (LRFD 10.8.3.9.3).

	For minimum concrete cover for drilled shaft, see [~~http~~://www.modot.org/~~business/standards_and_specs/SpecbookEPG.pdf#page=11~~ Sec 701.4.12.1]. If drilled shaft diameter does not match Sec 701.4.12.1 then use concrete cover for the next greater diameter drilled shaft. For rock sockets use 3” min. clear cover.		For minimum concrete cover for drilled shaft, see [https://www.modot.org/missouri-standard-specifications-highway-construction Sec 701.4.12.1]. If drilled shaft diameter does not match Sec 701.4.12.1 then use concrete cover for the next greater diameter drilled shaft. For rock sockets use 3” min. clear cover.

	For longitudinal reinforcement, splicing shall be in accordance with LRFD 5.10.8.4.		For longitudinal reinforcement, splicing shall be in accordance with LRFD 5.10.8.4.

Hoskir: /* 751.37.1.6 Drilled Shaft General Detail Considerations */ updated per RR3878

2024-05-23T20:40:01Z

751.37.1.6 Drilled Shaft General Detail Considerations: updated per RR3878

← Older revision		Revision as of 15:40, 23 May 2024
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	===751.37.1.6 Drilled Shaft General Detail Considerations===		===751.37.1.6 Drilled Shaft General Detail Considerations===
	[[image:751.37.1.6.~~jpg~~\|700px\|center]]		[[image:751.37.1.6 01.png\|700px\|center]]
	Pay items shown in above table are for example only, show actual pay items and quantities in plan details ~~as per~~ specific project.		Pay items shown in above table are for example only, show actual pay items and quantities in plan details for specific project.

	''Notes:''		''Notes:''
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	::::When determining P bar diameter for barbill, assume 3/8” casing unless otherwise specified.		::::When determining P bar diameter for barbill, assume 3/8” casing unless otherwise specified.
	::::See [[751.50 Standard Detailing Notes#G8. Drilled Shaft\|EPG 751.50, G8]], for notes to include for drilled shafts and rock sockets (starting at G8.1).		::::See [[751.50 Standard Detailing Notes#G8. Drilled Shaft\|EPG 751.50, G8]], for notes to include for drilled shafts and rock sockets (starting at G8.1).
	::(2) See [[#751.37.1.1 Dimensions and Nomenclature\|EPG 751.37.1.1 Dimensions and Nomenclature]] for [~~[media~~:751.37.1.~~1 Design Aid 2021~~.~~pdf\|~~Design Aid: Minimum Rock Socket Length]].		::(2) See [[#751.37.1.1 Dimensions and Nomenclature\|EPG 751.37.1.1 Dimensions and Nomenclature]] for [https://epg.modot.org/forms/general_files/BR/751.37.1.1_Drilled_Shaft_Design_Aid.docx Design Aid: Minimum Rock Socket Length].
			::(3) When difference between drilled shaft and column diameter is 6" a single reinforcement cage is typically used for the socket and shaft and the vertical reinforcement extends into the column. A separate column steel cage is then placed around the protruding shaft reinforcement without requiring an adjustment to minimum cover for rock socket or column reinforcement. When difference between drilled shaft and column diameter is 12” either the vertical column steel or dowels will need to be extended into the shaft or the cover in the socket and shaft will need to be increased to allow the shaft reinforcement to extend into the column. In the former scenario an optional construction joint is recommended as discussed in note 4 for oversized shafts. In the latter scenario the same number of vertical bars should be used in the shaft and column to allow the shaft bars to be tied to the column cage. Any reduction in cage diameter required for fit-up shall be considered in design.
			::(4) When difference between drilled shaft and column diameter is greater than 12" (oversized shaft generally 18" to 24" larger than column), show "Optional construction joint" at bottom of column/dowel reinforcement in the drilled shaft and use [[751.50_Standard_Detailing_Notes#G8._Drilled_Shaft\|EPG 751.50 Standard Detailing Notes G8.8 and G8.9]] in plan details.

	<center>		<center>
	{\| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"		{\| border="1" class="wikitable" style="margin: 1em auto 1em auto" style="text-align:center"
	\|+		\|+
	\| style="background:#BEBEBE" width="400" \|'''[~~http~~://www.modot.org/~~business/consultant_resources/bridgestandards.htm~~ Bridge Standard Drawings]'''		\| style="background:#BEBEBE" width="400" \|'''[https://www.modot.org/bridge-standard-drawings Bridge Standard Drawings]'''</br> (Drilled Shafts - DSS → As Built Drilled Shaft Data [DSS_01])
	\|-		\|-
	\|align="center"\|[~~http~~://www.modot.org/~~business~~/~~standard_drawings2/drilled_shaft_new_title_block.htm~~ As Built Drilled Shaft Data ]		\|align="center"\|[https://www.modot.org/media/14725 As Built Drilled Shaft Data (PDF)]
	\|}		\|}

Hoskir: /* 751.37.1.1 Dimensions and Nomenclature */ updated per RR3878

2024-05-23T20:29:27Z

751.37.1.1 Dimensions and Nomenclature: updated per RR3878

← Older revision		Revision as of 15:29, 23 May 2024
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	\|colspan="5"\|<sup>'''4'''</sup> The dimensions “D<sub>s</sub>” and “L<sub>s</sub>” are not explicitly used in any of the design equations that follow in favor of generally referring to the diameter of any segment of an overall shaft as “D” which can be a rock socket segment. This is not entirely true for the dimension “L<sub>s</sub>” which is explicitly used as part of a settlement design equation that follows. Judicial use of the appropriate segment and use of the appropriate diameter and length of a segment is implicit to the correct use of the design equations that follow. (See [[#751.37.2 General Design Procedure and Limit States\|EPG 751.37.2 General Design Procedure and Limit States]].)		\|colspan="5"\|<sup>'''4'''</sup> The dimensions “D<sub>s</sub>” and “L<sub>s</sub>” are not explicitly used in any of the design equations that follow in favor of generally referring to the diameter of any segment of an overall shaft as “D” which can be a rock socket segment. This is not entirely true for the dimension “L<sub>s</sub>” which is explicitly used as part of a settlement design equation that follows. Judicial use of the appropriate segment and use of the appropriate diameter and length of a segment is implicit to the correct use of the design equations that follow. (See [[#751.37.2 General Design Procedure and Limit States\|EPG 751.37.2 General Design Procedure and Limit States]].)
	\|-		\|-
	\|colspan="5"\|<sup>'''5'''</sup> See [~~[media~~:751.37.1.~~1 Design Aid 2021~~.~~pdf\|~~Design Aid: Minimum Rock Socket Length]]		\| colspan="5" \| <sup>'''5'''</sup> See [https://epg.modot.org/forms/general_files/BR/751.37.1.1_Drilled_Shaft_Design_Aid.docx Design Aid: Minimum Rock Socket Length]
	\|}		\|}

Hoskir: /* 751.37.6.1 Reinforcement Design */ updated per RR 3680

2023-04-18T15:05:32Z

751.37.6.1 Reinforcement Design: updated per RR 3680

← Older revision		Revision as of 10:05, 18 April 2023
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	For minimum concrete cover for drilled shaft, see [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=11 Sec 701.4.12.1]. If drilled shaft diameter does not match Sec 701.4.12.1 then use concrete cover for the next greater diameter drilled shaft. For rock sockets use 3” min. clear cover.		For minimum concrete cover for drilled shaft, see [http://www.modot.org/business/standards_and_specs/SpecbookEPG.pdf#page=11 Sec 701.4.12.1]. If drilled shaft diameter does not match Sec 701.4.12.1 then use concrete cover for the next greater diameter drilled shaft. For rock sockets use 3” min. clear cover.

	For longitudinal reinforcement, splicing shall be in accordance with LRFD 5.11.5.		For longitudinal reinforcement, splicing shall be in accordance with LRFD 5.10.8.4.

	For transverse reinforcement, lap splices for closed circular stirrups/ties shall be provided and staggered in accordance with LRFD 5.10.6.3. Lap length of 1.3 '''l'''<sub>d</sub> (Class B) for closed stirrups/ties shall be provided in accordance with LRFD 5.11.2.~~6.4~~.		For transverse reinforcement, lap splices for closed circular stirrups/ties shall be provided and staggered in accordance with LRFD 5.10.4.3. Lap length of 1.3 '''l'''<sub>d</sub> (Class B) for closed stirrups/ties shall be provided in accordance with LRFD 5.10.8.2.6d.

	For lap length, see [[751.5 Structural Detailing Guidelines#751.5.9.2.8.1 Development and Lap Splice General\|EPG 751.5.9.2.8.1 Development and Lap Splice General]].		For lap length, see [[751.5 Structural Detailing Guidelines#751.5.9.2.8.1 Development and Lap Splice General\|EPG 751.5.9.2.8.1 Development and Lap Splice General]].

Smithk: /* 751.37.1.6 Drilled Shaft General Detail Considerations */

2021-11-02T17:53:44Z

751.37.1.6 Drilled Shaft General Detail Considerations

← Older revision		Revision as of 12:53, 2 November 2021
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	::::See [[#751.37.1.3 Casing\|EPG 751.37.1.3]] for casing requirements and alternatives.		::::See [[#751.37.1.3 Casing\|EPG 751.37.1.3]] for casing requirements and alternatives.
	::::When determining P bar diameter for barbill, assume 3/8” casing unless otherwise specified.		::::When determining P bar diameter for barbill, assume 3/8” casing unless otherwise specified.
	::::See [[751.50 Standard Detailing Notes#G8. Drilled Shaft\|EPG 751.50, G8]], for notes to include for drilled shafts and rock sockets (~~Starting~~ at G8.1).		::::See [[751.50 Standard Detailing Notes#G8. Drilled Shaft\|EPG 751.50, G8]], for notes to include for drilled shafts and rock sockets (starting at G8.1).
	::(2) See [[#751.37.1.1 Dimensions and Nomenclature\|EPG 751.37.1.1 Dimensions and Nomenclature]] for [[media:751.37.1.1 Design Aid 2021.pdf\|Design Aid: Minimum Rock Socket Length]].		::(2) See [[#751.37.1.1 Dimensions and Nomenclature\|EPG 751.37.1.1 Dimensions and Nomenclature]] for [[media:751.37.1.1 Design Aid 2021.pdf\|Design Aid: Minimum Rock Socket Length]].

Smithk: /* 751.37.1.6 Drilled Shaft General Detail Considerations */

2021-11-02T17:50:20Z

751.37.1.6 Drilled Shaft General Detail Considerations

← Older revision		Revision as of 12:50, 2 November 2021
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	::::See [[#751.37.1.3 Casing\|EPG 751.37.1.3]] for casing requirements and alternatives.		::::See [[#751.37.1.3 Casing\|EPG 751.37.1.3]] for casing requirements and alternatives.
	::::When determining P bar diameter for barbill, assume 3/8” casing unless otherwise specified.		::::When determining P bar diameter for barbill, assume 3/8” casing unless otherwise specified.
	::::See [[751.50 Standard Detailing Notes#G.8 Drilled Shaft\|EPG 751.50, G8]], for notes to include for drilled shafts and rock sockets (Starting at G8.1).		::::See [[751.50 Standard Detailing Notes#G8. Drilled Shaft\|EPG 751.50, G8]], for notes to include for drilled shafts and rock sockets (Starting at G8.1).
	::(2) See [[#751.37.1.1 Dimensions and Nomenclature\|EPG 751.37.1.1 Dimensions and Nomenclature]] for [[media:751.37.1.1 Design Aid 2021.pdf\|Design Aid: Minimum Rock Socket Length]].		::(2) See [[#751.37.1.1 Dimensions and Nomenclature\|EPG 751.37.1.1 Dimensions and Nomenclature]] for [[media:751.37.1.1 Design Aid 2021.pdf\|Design Aid: Minimum Rock Socket Length]].