321.1 Design of Earth Slopes - Revision history

Hoskir: /* 321.1.3.3 Settlement Limits */ updated link

2026-10-29T20:40:13Z

321.1.3.3 Settlement Limits: updated link

← Older revision		Revision as of 14:40, 29 October 2026
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	A bridge approach slab should be utilized at bridge abutments if the total settlement approaches 3 inches.		A bridge approach slab should be utilized at bridge abutments if the total settlement approaches 3 inches.

	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]].

	==321.1.4 References==		==321.1.4 References==

Hoskir: /* 321.1.2.3 Load Factors */ fixed error when updating

2026-10-29T16:02:47Z

321.1.2.3 Load Factors: fixed error when updating

← Older revision		Revision as of 10:02, 29 October 2026
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	Live Loads: LL and PL		Live Loads: LL and PL
	* LL in LRFD BDS is equated to a live load surcharge where LL (or q)=γ<sub>q</sub>*h<sub>eq</sub>, γ<sub>q</sub> is the unit weight of ~~live~~ (125pcf), and h<sub>eq</sub> is the equivalent height of soil (ft) for vehicular load. The variable h<sub>eq</sub> is dependent on height, orientation and proximity to traffic; refer to LRFD BDS Tables 3.11.6.4.1-1 and 3.11.6.4.1-2 for h<sub>eq</sub> and FHWA GEC 011, Appendix C for an example application.		* LL in LRFD BDS is equated to a live load surcharge where LL (or q)=γ<sub>q</sub>*h<sub>eq</sub>, γ<sub>q</sub> is the unit weight of soil (125pcf), and h<sub>eq</sub> is the equivalent height of soil (ft) for vehicular load. The variable h<sub>eq</sub> is dependent on height, orientation and proximity to traffic; refer to LRFD BDS Tables 3.11.6.4.1-1 and 3.11.6.4.1-2 for h<sub>eq</sub> and FHWA GEC 011, Appendix C for an example application.

	Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads.		Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads.

Hoskir: /* 321.1.1.2 Rock Slopes */ fixed a couple errors due to update

2026-10-29T15:58:37Z

321.1.1.2 Rock Slopes: fixed a couple errors due to update

← Older revision		Revision as of 09:58, 29 October 2026
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	\|For grade separations, consideration should be given to selective grading of fill materials so that better materials are placed in fill spill slopes (i.e. beneath bridge abutments) so that the spill slopes can be steepened. While such handling will likely increase costs for fill placement, some additional handling can be justified if it results in reducing bridge length. Selective fill placement is not generally practical on stream crossings -- only on grade separations.		\|For grade separations, consideration should be given to selective grading of fill materials so that better materials are placed in fill spill slopes (i.e. beneath bridge abutments) so that the spill slopes can be steepened. While such handling will likely increase costs for fill placement, some additional handling can be justified if it results in reducing bridge length. Selective fill placement is not generally practical on stream crossings -- only on grade separations.
	\|-		\|-
	\|[[#321.1.1.1_Soil_Slopes\|Table 321.1]] permits spill slopes to be 0.5:1V steeper than side slopes for several soil types, but no steeper than 2H:1V, where the elevation differential between the toe of slope and grade at the bridge end is less than 20 feet. This recognizes the fact that the effective height of the spill slope will be reduced by at least 6 to 8 ft. because of the abutment headwall. This concept becomes more complicated at stream channel crossings where it is necessary to consider the depth and condition of the stream channel and their effect on bridge end location. For example, one might have CL glacial soils and a height differential between grade and toe of slope of some 15 feet. [[#321.1.1.1_Soil_Slopes\|Table 321.1]] requires 2.5H:1V side slopes and 2H:1V spill slopes for CL fill soils. However, if the stream channel is entrenched in CL soil another 15 feet deep so that the total height differential is greater than 20 feet, the bridge ends should be stepped back to or beyond a point determined by projecting a 2.5H:1V upward from the toe of the channel slope to intersection with grade. For typically steep channel banks, this will generally leave a substantial bench at natural ground level, which provides some room for bank sloughing without affecting the integrity of the spill slope. The spill slope would remain at 2H:1V but the bridge end would be located as if it were at least 2.5H:1V.		\|[[#321.1.1.1_Soil_Slopes\|Table 321.1]] permits spill slopes to be 0.5H:1V steeper than side slopes for several soil types, but no steeper than 2H:1V, where the elevation differential between the toe of slope and grade at the bridge end is less than 20 feet. This recognizes the fact that the effective height of the spill slope will be reduced by at least 6 to 8 ft. because of the abutment headwall. This concept becomes more complicated at stream channel crossings where it is necessary to consider the depth and condition of the stream channel and their effect on bridge end location. For example, one might have CL glacial soils and a height differential between grade and toe of slope of some 15 feet. [[#321.1.1.1_Soil_Slopes\|Table 321.1]] requires 2.5H:1V side slopes and 2H:1V spill slopes for CL fill soils. However, if the stream channel is entrenched in CL soil another 15 feet deep so that the total height differential is greater than 20 feet, the bridge ends should be stepped back to or beyond a point determined by projecting a 2.5H:1V upward from the toe of the channel slope to intersection with grade. For typically steep channel banks, this will generally leave a substantial bench at natural ground level, which provides some room for bank sloughing without affecting the integrity of the spill slope. The spill slope would remain at 2H:1V but the bridge end would be located as if it were at least 2.5H:1V.
	\|-		\|-
	\|Now things get even more complicated. To this point, we have not really considered some of the possible complications to the stability of stream and channel slopes. There is a caution in the text beneath the slope selection chart that, "Factors such as foundations, seepage, susceptibility to inundation, etc. may dictate flatter slopes." Even ignoring foundations, which call for a special investigation, there is no simple way of considering the effects of water that will fit every case. Determining proper slopes in such circumstances involves consideration of a complex intermingling of factors such as flooding rate, height and duration, rate of recession, water velocity, scour potential, soil strength, weight, permeability, swell potential, and seepage rates, all further complicated by considerations of costs and the risks and consequences of failure.		\|Now things get even more complicated. To this point, we have not really considered some of the possible complications to the stability of stream and channel slopes. There is a caution in the text beneath the slope selection chart that, "Factors such as foundations, seepage, susceptibility to inundation, etc. may dictate flatter slopes." Even ignoring foundations, which call for a special investigation, there is no simple way of considering the effects of water that will fit every case. Determining proper slopes in such circumstances involves consideration of a complex intermingling of factors such as flooding rate, height and duration, rate of recession, water velocity, scour potential, soil strength, weight, permeability, swell potential, and seepage rates, all further complicated by considerations of costs and the risks and consequences of failure.
	\|-		\|-
	\|The following general comments and guidelines are offered, however, to supplement the [[~~320~~.~~1 Preliminary Geotechnical Report~~#~~320~~.1.4.~~5 Guide for Slope Recommendations~~\|Guide for Slope Recommendations]]. First, use the chart to determine the slope (spill or side) you would use if water were not a factor. This is the slope to which you will make adjustments based on the following considerations.		\|The following general comments and guidelines are offered, however, to supplement the [[321.1_Design_of_Earth_Slopes#321.1.1.1_Soil_Slopes\|Table 321.1 Guide for Slope Recommendations]]. First, use the chart to determine the slope (spill or side) you would use if water were not a factor. This is the slope to which you will make adjustments based on the following considerations.
	\|-		\|-
	\|For moderate stream flows of average flood duration, about 0.5H:1V flatter may suffice. For prolonged flooding followed by drawdown, 1:1 flatter may be appropriate. For intermittent or low-flow streams subject only to flash flooding, no flattening may be needed. <u>Always</u> inspect stream slopes for evidence of slides and sloughs and inspect the condition of adjacent structures over the same stream. Consider the <u>width</u> of the embankment; a 4-lane roadway is more likely to fail into a stream channel than a narrow county road or railroad fill. Consider also the consequences of failure; be more conservative for heavily traveled arterial roadways than for minor or rural supplemental roads for example.		\|For moderate stream flows of average flood duration, about 0.5H:1V flatter may suffice. For prolonged flooding followed by drawdown, 1:1 flatter may be appropriate. For intermittent or low-flow streams subject only to flash flooding, no flattening may be needed. <u>Always</u> inspect stream slopes for evidence of slides and sloughs and inspect the condition of adjacent structures over the same stream. Consider the <u>width</u> of the embankment; a 4-lane roadway is more likely to fail into a stream channel than a narrow county road or railroad fill. Consider also the consequences of failure; be more conservative for heavily traveled arterial roadways than for minor or rural supplemental roads for example.

Hoskir: updated per RR4244

2026-10-26T15:00:16Z

updated per RR4244

Show changes

Smithk: /* 321.1.2.2 General Procedure for Slope Stability Analysis Using LRFD Approach */

2019-06-18T17:53:46Z

321.1.2.2 General Procedure for Slope Stability Analysis Using LRFD Approach

← Older revision		Revision as of 11:53, 18 June 2019
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	===321.1.2.2 General Procedure for Slope Stability Analysis Using LRFD Approach===		===321.1.2.2 General Procedure for Slope Stability Analysis Using LRFD Approach===
	{\|style="padding: 0.3em; margin-left:10px; border:1px solid #ff0000; text-align:left; font-size: 95%; background:#f5f5f5" width="~~470px~~" align="right"		{\|style="padding: 0.3em; margin-left:10px; border:1px solid #ff0000; text-align:left; font-size: 95%; background:#f5f5f5" width="570px" align="right"
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	\|The procedure for design of earth slopes following LRFD is quite similar to procedures for conventional ASD analysis, with two important differences. The first difference occurs in No. 4, where factored parameters are used as input for the slope stability analyses for LRFD analyses whereas unfactored parameters are used for the traditional ASD analyses. The second difference occurs in No. 5, where instead of comparing the computed factor of safety to some required or target factor of safety as is done in ASD, the computed factor of safety is compared to a limit value (= 1.0) indicating stability or instability. In this respect, the LRFD procedure is indeed more straightforward than current procedures in that the analysis target or limit is consistent for all stability cases for the LRFD procedure whereas the analysis target for conventional ASD procedures varies from one application to another. The result of these differences is simply that, for LRFD procedures, uncertainties in the analyses are accounted for through factoring of the input parameters whereas for ASD procedures the uncertainty is accounted for through a single factor of safety. By factoring individual input parameters, it is possible to more appropriately apply conservatism to the individual parameters involved in the analysis, and therefore to effect more consistent levels of safety across a broad range of cases. Both load and resistance factors in LRFD and factors of safety in ASD are intended to account for uncertainties involved in the respective analyses. They are simply different methods for accounting for these uncertainties.		\|The procedure for design of earth slopes following LRFD is quite similar to procedures for conventional ASD analysis, with two important differences. The first difference occurs in No. 4, where factored parameters are used as input for the slope stability analyses for LRFD analyses whereas unfactored parameters are used for the traditional ASD analyses. The second difference occurs in No. 5, where instead of comparing the computed factor of safety to some required or target factor of safety as is done in ASD, the computed factor of safety is compared to a limit value (= 1.0) indicating stability or instability. In this respect, the LRFD procedure is indeed more straightforward than current procedures in that the analysis target or limit is consistent for all stability cases for the LRFD procedure whereas the analysis target for conventional ASD procedures varies from one application to another. The result of these differences is simply that, for LRFD procedures, uncertainties in the analyses are accounted for through factoring of the input parameters whereas for ASD procedures the uncertainty is accounted for through a single factor of safety. By factoring individual input parameters, it is possible to more appropriately apply conservatism to the individual parameters involved in the analysis, and therefore to effect more consistent levels of safety across a broad range of cases. Both load and resistance factors in LRFD and factors of safety in ASD are intended to account for uncertainties involved in the respective analyses. They are simply different methods for accounting for these uncertainties.
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	::c) If the factor of safety is less than 1.0, the designer must consider alternative measures to increase the factor of safety and repeat the procedure until a factor of safety approximately equal to 1.0 is achieved.		::c) If the factor of safety is less than 1.0, the designer must consider alternative measures to increase the factor of safety and repeat the procedure until a factor of safety approximately equal to 1.0 is achieved.

	Current procedures will factor the undrained shear strength, ''s<sub>u</sub>'', or the Mohr-Coulomb shear strength parameters, ''c'' and ''ϕ'' (or <math>\overline{c}</math> and <math> \overline{\phi}</math>). Resistance factors for factoring of these parameters are provided in EPG 321.1.2.4.		Current procedures will factor the undrained shear strength, ''s<sub>u</sub>'', or the Mohr-Coulomb shear strength parameters, ''c'' and ''ϕ'' (or <math>\overline{c}</math> and <math> \overline{\phi}</math>). Resistance factors for factoring of these parameters are provided in EPG 321.1.2.4.

	===321.1.2.3 Load Factors===		===321.1.2.3 Load Factors===

Smithk at 14:20, 9 January 2019

2019-01-09T14:20:16Z

← Older revision		Revision as of 08:20, 9 January 2019
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	\|[[media:321.1 MCHRP 75-1.pdf\|MCHRP 75-1, Strength and Drainage of a Rocky Residual Soil]]		\|[[media:321.1 MCHRP 75-1.pdf\|MCHRP 75-1, Strength and Drainage of a Rocky Residual Soil]]
	\|-		\|-
	\|[[media:203 MCHRP 76-1.pdf\|MCHRP 76-1, Evaluation of a One-Point Compaction Test for Missouri Soils]]		\|[[media:203 MCHRP 76-1a.pdf\|MCHRP 76-1, Evaluation of a One-Point Compaction Test for Missouri Soils]]
	\|-		\|-
	\|[[media:321.1 MCHRP 79-1.pdf\|MCHRP 79-1, Engineering Properties of Three Problem Earth Materials]]		\|[[media:321.1 MCHRP 79-1.pdf\|MCHRP 79-1, Engineering Properties of Three Problem Earth Materials]]
	\|-		\|-
	\|[[media:203 Physical Studies of Pennsylvanian Shale in a High ~~Fill~~.pdf\|Physical Studies of Pennsylvanian Shale in a High Fill]]		\|[[media:203 Physical Studies of Pennsylvanian Shale in a High Filla.pdf\|Physical Studies of Pennsylvanian Shale in a High Fill]]
	\|-		\|-
	\|[[media:321.1 Procedures for Design of Earth Slopes.pdf\|Procedures for Design of Earth Slopes Using LRFD]]		\|[[media:321.1 Procedures for Design of Earth Slopes.pdf\|Procedures for Design of Earth Slopes Using LRFD]]

EPGsysop at 18:43, 7 April 2017

2017-04-07T18:43:25Z

← Older revision		Revision as of 12:43, 7 April 2017
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	\|These boxes will provide supplemental information or commentary on application of specific provisions, supporting documentation for the provisions, or explanations for how the provisions should be applied.		\|These boxes will provide supplemental information or commentary on application of specific provisions, supporting documentation for the provisions, or explanations for how the provisions should be applied.
	\|}		\|}
	This article provides requirements for design of earth slopes commonly encountered in transportation rights of way. Such slopes commonly include embankment slopes for fills and bridge approaches and excavated slopes in cut sections of roadway. Earth slopes should be designed to maintain stability for conditions and loads that can reasonably be expected to be encountered throughout the life of the slope based on available information regarding site conditions and anticipated loadings. Earth slopes should also be designed ~~such~~ that excessive deformations are not experienced throughout the life of the structure or so that deformations that do occur do not adversely affect the travel way.		This article provides requirements for design of earth slopes commonly encountered in transportation rights of way. Such slopes commonly include embankment slopes for fills and bridge approaches and excavated slopes in cut sections of roadway. Earth slopes should be designed to maintain stability for conditions and loads that can reasonably be expected to be encountered throughout the life of the slope based on available information regarding site conditions and anticipated loadings. Earth slopes should also be designed so that excessive deformations are not experienced throughout the life of the structure or so that deformations that do occur do not adversely affect the travel way.
	{\|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="385px" align="right"		{\|style="padding: 0.3em; margin-left:7px; border:2px solid #a9a9a9; text-align:left; font-size: 95%; background:#f5f5f5" width="385px" align="right"
	\|-		\|-
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	\|It should be emphasized that this chart is a guide. It is based on some theory and it is tempered by experience. It fits most situations, but there are exceptions. Some of the exceptions have been addressed in research reports. For the most part, this chart is based on stability considerations, but in one area it is been shaded a bit for erosion control purposes. This is for the ML loesses. When dealing with a very tight right of way situation, it may be practical to steepen slopes in this material to 1V:2H (2:1) at the expense of some increased erosion problems or erosion control measures. If in doubt, shear tests can be done. To repeat, this chart is a guide - it is not carved in stone.		\|It should be emphasized that this chart is a guide. It is based on some theory and it is tempered by experience. It fits most situations, but there are exceptions. Some of the exceptions have been addressed in research reports. For the most part, this chart is based on stability considerations, but in one area it is been shaded a bit for erosion control purposes. This is for the ML loesses. When dealing with a very tight right of way situation, it may be practical to steepen slopes in this material to 1V:2H (2:1) at the expense of some increased erosion problems or erosion control measures. If in doubt, shear tests can be done. To repeat, this chart is a guide - it is not carved in stone.
	\|-		\|-
	\|For grade separations, consideration should be given to selective grading of fill materials ~~such~~ that better materials are placed in fill spill slopes (i.e. beneath bridge abutments) so that the spill slopes can be steepened. While such handling will likely increase costs for fill placement, some additional handling can be justified if it results in reducing bridge length. Selective fill placement is not generally practical on stream crossings -- only on grade separations.		\|For grade separations, consideration should be given to selective grading of fill materials so that better materials are placed in fill spill slopes (i.e. beneath bridge abutments) so that the spill slopes can be steepened. While such handling will likely increase costs for fill placement, some additional handling can be justified if it results in reducing bridge length. Selective fill placement is not generally practical on stream crossings -- only on grade separations.
	\|-		\|-
	\|Table 321.1 permits spill slopes to be 1V:0.5H (0.5:1) steeper than side slopes for several soil types, but no steeper than 1V:2H (2:1), where the elevation differential between the toe of slope and grade at the bridge end is less than 20 feet. This recognizes the fact that the effective height of the spill slope will be reduced by at least 6 to 8 ft. because of the abutment headwall. This concept becomes more complicated at stream channel crossings where it is necessary to consider the depth and condition of the stream channel and their effect on bridge end location. For example, one might have CL glacial soils and a height differential between grade and toe of slope of some 15 feet. Table 321.1 requries 1V:2.5H (2.5:1) side slopes and 1V:2H (2:1) spill slopes for CL fill soils. However, if the stream channel is entrenched in CL soil another 15 feet deep ~~such~~ that the total height differential is greater than 20 feet, the bridge ends should be stepped back to or beyond a point determined by projecting a 1V:2.5H (2.5:1) upward from the toe of the channel slope to intersection with grade. For typically steep channel banks, this will generally leave a substantial bench at natural ground level, which provides some room for bank sloughing without affecting the integrity of the spill slope. The spill slope would remain at 1V:2H (2:1) but the bridge end would be located as if it were at least 1V:2.5H (2.5:1).		\|Table 321.1 permits spill slopes to be 1V:0.5H (0.5:1) steeper than side slopes for several soil types, but no steeper than 1V:2H (2:1), where the elevation differential between the toe of slope and grade at the bridge end is less than 20 feet. This recognizes the fact that the effective height of the spill slope will be reduced by at least 6 to 8 ft. because of the abutment headwall. This concept becomes more complicated at stream channel crossings where it is necessary to consider the depth and condition of the stream channel and their effect on bridge end location. For example, one might have CL glacial soils and a height differential between grade and toe of slope of some 15 feet. Table 321.1 requries 1V:2.5H (2.5:1) side slopes and 1V:2H (2:1) spill slopes for CL fill soils. However, if the stream channel is entrenched in CL soil another 15 feet deep so that the total height differential is greater than 20 feet, the bridge ends should be stepped back to or beyond a point determined by projecting a 1V:2.5H (2.5:1) upward from the toe of the channel slope to intersection with grade. For typically steep channel banks, this will generally leave a substantial bench at natural ground level, which provides some room for bank sloughing without affecting the integrity of the spill slope. The spill slope would remain at 1V:2H (2:1) but the bridge end would be located as if it were at least 1V:2.5H (2.5:1).
	\|-		\|-
	\|Now things get even more complicated. To this point, we have not really considered some of the possible complications to the stability of stream and channel slopes. There is a caution in the text beneath the slope selection chart that, "Factors such as foundations, seepage, susceptibility to inundation, etc. may dictate flatter slopes." Even ignoring foundations, which call for a special investigation, there is no simple way of considering the effects of water that will fit every case. Determining proper slopes in such circumstances involves consideration of a complex intermingling of factors such as flooding rate, height and duration, rate of recession, water velocity, scour potential, soil strength, weight, permeability, swell potential, and seepage rates, all further complicated by considerations of costs and the risks and consequences of failure.		\|Now things get even more complicated. To this point, we have not really considered some of the possible complications to the stability of stream and channel slopes. There is a caution in the text beneath the slope selection chart that, "Factors such as foundations, seepage, susceptibility to inundation, etc. may dictate flatter slopes." Even ignoring foundations, which call for a special investigation, there is no simple way of considering the effects of water that will fit every case. Determining proper slopes in such circumstances involves consideration of a complex intermingling of factors such as flooding rate, height and duration, rate of recession, water velocity, scour potential, soil strength, weight, permeability, swell potential, and seepage rates, all further complicated by considerations of costs and the risks and consequences of failure.

Smithk: /* 321.1.2.3 Load Factors */

2013-09-05T19:52:09Z

321.1.2.3 Load Factors

← Older revision		Revision as of 13:52, 5 September 2013
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	\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.		\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.
	\|}		\|}
	Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a load factor of 1.0.		Loads to be used for stability evaluations shall be factored according to the Service I limit state.
	~~<div id="321.1.2.4 Resistance factors"></div>~~		<div id="Accordingly, a load factor of 1.0"></div>
			Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a load factor of 1.0.

	===321.1.2.4 Resistance factors for short-term, undrained conditions===		===321.1.2.4 Resistance factors for short-term, undrained conditions===

Smithk: /* 321.1.2.3 Load Factors */

2013-09-05T19:51:05Z

321.1.2.3 Load Factors

← Older revision		Revision as of 13:51, 5 September 2013
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	\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.		\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.
	\|}		\|}
	Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a<div id="~~load factor of~~ 1.0"></div> ~~load factor of 1.0.~~		Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a load factor of 1.0.
			<div id="321.1.2.4 Resistance factors"></div>

	===321.1.2.4 Resistance factors for short-term, undrained conditions===		===321.1.2.4 Resistance factors for short-term, undrained conditions===

Smithk: /* 321.1.2.3 Load Factors */

2013-09-05T19:47:23Z

321.1.2.3 Load Factors

← Older revision		Revision as of 13:47, 5 September 2013
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	\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.		\|Despite the fact that stability is really a strength limit state, load factors associated with the Service I limit state are used for all loads by convention with current AASHTO LRFD procedures. This position makes some sense when considering earth loads that often have little variability and uncertainty, but may not make sense when stability is dominated by loading from bridge or other structures.
	\|}		\|}
	Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a ~~load factor of 1.0.~~		Loads to be used for stability evaluations shall be factored according to the Service I limit state. Accordingly, a load factor of 1.0 shall be used for all applied loads, including “surcharge” loads associated with foundations or other surface loads. The soil unit weight shall also be factored using a<div id="load factor of 1.0"></div> load factor of 1.0.
	<div id="~~321.~~1.~~2.4 Resistance factors for short-term, undrained~~"></div>

	===321.1.2.4 Resistance factors for short-term, undrained conditions===		===321.1.2.4 Resistance factors for short-term, undrained conditions===