REVISION OF BSS 8002, 8004, AND 8081 · 2019-10-29 · REVISION OF BSS 8002, 8004, AND 8081 Dr Andrew Bond (Geocentrix) Dr Caesar Merrifield (Coffey) Dr Devon Mothersille (Geoserve

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Burnham Green,

Hertfordshire, AL6 ONL.

Tel: +44 (0)800 093 1453

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GEOSERVE GLOBAL LTD

Bridging the gap

REVISION OF BSS 8002, 8004, AND 8081

Dr Andrew Bond (Geocentrix)

Dr Caesar Merrifield (Coffey)

Dr Devon Mothersille (Geoserve Global)

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Outline of talk

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15 mins

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15 mins

5 mins

Andrew

Purpose/structure of the revised British

standards

BS 8004 – Foundations and BS 8002 – Earth retaining structures

Summary of key points

Caesar

BS 8081 – Grouted anchors

Devon


Eurocode 7 Workshop on NCCI ©2015 Geocentrix Ltd, Coffey, and Geoserve Global. All rights reserved

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Revival of withdrawn/obsolete geotechnical standards Several important geotechnical ‘codes of practice’ were withdrawn in March 2010 on the introduction of the Structural Eurocodes, including:

• BS 8004:1986, Code of practice for foundations

• BS 8002:1994, Code of practice for earth retaining structures

The following standard remained but was largely incompatible with Eurocode 7:

• BS 8081:1989, Code of practice for ground anchorages (renamed ‘grouted anchors’)

The ‘revival’ of these standards was sponsored by HS2 because they want to put them out with contracts for enabling work starting in June 2015.

Additional (related) work sponsored by HS2 includes:

• Revision of CIRIA C580 (2003), Embedded retaining walls – guidance for economic design

• Creation of PAS 8812, Guide to the application of European Standards in temporary works design (co-sponsored by the Temporary Works Forum, TWf)

Other relevant (related) work includes:

• Revision of BS 5930:1999+A2:2010, Code of practice for site investigations (renamed ‘ground investigations’)


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Relationship between British Standards and Eurocode 7


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S Presentational conventions for the ‘new’ geotechnical BSs

“The provisions of this standard are presented in roman (i.e. upright) type. Its recommendations are expressed in sentences in which the principal auxiliary verb is

“should”. Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element.”

Foreword to BSs 8002, 8004, and 8081

• “should” expresses recommendations of these standard

• “may” expresses permissibility (e.g. as an alternative to the primary recommendation)

• “can” expresses possibility (e.g. a consequence of an action or an event)

Notes and commentaries are provided throughout the text of this standard. Notes give references and additional information that are important but do not form part of the recommendations. Commentaries give background information.

Note that the word “shall” is NOT used in BSs 8002, 8004, or 8081

“shall” is used in Eurocode 7 (BS EN 1997-1 and -2)


Eurocode 7 timeline 2010-2020


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Proposed structure of EN 1997-1: 202x and EN 1997-2: 202x

EN 1997: 202x

1. General rules

2. Ground investigation

3. Geotechnical constructions

Part 1 – General rules

1. General

2. Basis of geotechnical design

3. Materials

4. Durability

5. Geotechnical analysis

6. Ultimate limit states

7. Serviceability limit states

8. Execution

9. Testing

10. Reporting

Part 2 – Ground investigation

1. General

2. Principles of ground investigation

3. Planning of ground investigations

4. Sampling and groundwater measurements

5. Field tests

6. Laboratory tests

7. Reporting


NEW

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Proposed EN 1997-3:202x – Geotechnical constructions

EN 1997: 202x

1. General rules

2. Ground investigation

3. Geotechnical constructions

Part 3 – Geotechnical constructions

1. General

2. Slopes, cuttings, and embankments

3. Spread foundations

4. Pile foundations

5. Retaining structures

6. Anchors

7. Ground improvement

8. Reinforced soil structures

Annexes (calculation models for each type of construction)

Part 3’s common sub-sections

1. General

2. Actions and design situations

3. Design considerations

4. Design methods/calculation models

5. Ultimate limit state design

6. Serviceability limit state design

7. Structural design

8. Execution (supervision, monitoring, and maintenance)

9. Testing

10. Reporting


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Changing contents of BS 8004 for foundations BS 8004:1986 (186 pp) Foreword (1 pp) 1. General (7 pp) 2. Design of foundations (27 pp) 3. Shallow foundations (5 pp) 4. Deep and subaqueous foundations (13

pp) 5. Cofferdams and caissons (17 pp) 6. Geotechnical processes: groundwater

lowering, grouting and other methods of changing the ground characteristics in situ (38 pp)

7. Pile foundations (32 pp) 8. Tide work, underwater concreting and

diving (6 pp) 9. Site preparation for foundation work

(6 pp) 10. Durability of timber, metal and

concrete structures (9 pp) 11. Safety precautions (10 pp) Appendices (10 pp)

DPC BS 8004:2015 (101 pp)

Foreword (1 pp)

1. Scope (1 pp)

2. Normative references (4 pp)

3. Terms and definitions (1 pp)

4. General rules (25 pp)

5. Spread foundations (11 pp)

6. Pile foundations (42 pp)

Annexes (*normative)

A. *Underpinning (4 pp)

B. *Helical pile foundations (4 pp)

C. Specific formations (2 pp)

Bibliography (5 pp)


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Changing contents of BS 8002 for earth retaining structures

BS 8002:1994 (134 pp)

Foreword (2 pp)

1. Introduction (6 pp)

2. Data for design (12 pp)

3. Design philosophy, design method and earth pressure (24 pp)

4. Design of specific earth retaining structures (71 pp)


A. *Graphs for Ka and Kp (8 pp)

B. Traditional design methods for embedded walls (3 pp)

C. Bibliography (4 pp)

DPC BS 8004:2015 (92 pp)

Foreword (1 pp)

1. Scope (1 pp)


3. Terms and definitions (1 pp)

4. General rules (31 pp)

5. Gravity retaining walls (16 pp)

6. Semi-gravity retaining walls (7 pp)

7. Embedded retaining walls (14 pp)

8. Cofferdams, basements, and strutted excavations (4 pp)


A. *Deadman anchors (5 pp)

B. Specific formations (1 pp)

C. Archeological finds (1 pp)

Bibliography (3 pp)


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Changing contents of BS 8081 for grouted anchors BS 8081:1989 (177 pp)

Foreword (1 pp)

Introduction (1 pp)

1. Scope (1 pp)

2. Definitions (6 pp)

3. Symbols (2 pp)

4. Responsibilities (1 pp)

5. Site investigation (5 pp)

6. Design (14 pp)

7. Material and components (10 pp)

8. Corrosion and corrosion protection (20 pp)

9. Stressing equipment (1 pp)

10. Construction (10 pp)

11. Testing (13 pp)

12. Maintenance (1 pp)

13. Legal aspects (2 pp)

Appendices (73 pp)

DPC BS 8081:2015 (135 pp)

Foreword (1 pp)

1. Scope (1 pp)


3. Terms, definitions and symbols (9 pp)

4. General recommendations (5 pp)

5. Limit states (1 pp)

6. Design situations (1 pp)

7. Design considerations (3 pp)

8. Ultimate limit state design (1 pp)

9. Serviceability limit state design (1 pp)

10. Structural design (1 pp)

11. Anchor design (4 pp)

12. Materials (6 pp)

13. Durability (12 pp)

14. Execution (10 pp)

15. Considerations relating to testing (1 pp)


17. Reporting (1 pp)

Annexes A-I (informative) (69 pp)

Bibliography (4 pp)


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standards



Caesar


Devon



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BS 8081:2015 Code of practice for grouted anchors

I will discuss the status of and main changes in BS 8081:2015 and then concentrate on the clauses associated with the design of the anchor.

Dr Devon Mothersille will then concentrate on durability, execution and the important area of anchor testing.


Dr Caesar Merrifield (Coffey)

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BS 8081:2015 Scope for the revision

BSI requirements as set out in 2014

1. ‘The recommendations included in the revised BS 8081 will not conflict in any way with either normative or informative clauses in the associated European standards which supersede BS 8081:1989.’

2. ‘…it is widely acknowledged amongst UK practitioners, that an extensive collection of recommendations and guidance, not covered in the Eurocodes/Euronorms, will be lost when BS8081:1989 is superseded.’

3. ‘The revised document will be compatible with the Eurocodes and effectively fill the gaps in guidance and reference material that currently exist with the new Eurocodes.’

i.e. Complying with the concept of being NCCI


BS 8

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Changing contents of BS 8081 for grouted anchors BS 8081:1989 (177 pp)

Foreword (1 pp)

Introduction (1 pp)

1. Scope (1 pp)

2. Definitions (6 pp)

3. Symbols (2 pp)

4. Responsibilities (1 pp)

5. Site investigation (5 pp)

6. Design (14 pp)

7. Material and components (10 pp)

8. Corrosion and corrosion protection (20 pp)

9. Stressing equipment (1 pp)

10. Construction (10 pp)

11. Testing (13 pp)


13. Legal aspects (2 pp)

Appendices (73 pp)

DPC BS 8081:2015 (135 pp)

Foreword (1 pp)

1. Scope (1 pp)


3. Terms, definitions and symbols (9 pp)

4. General recommendations (5 pp)

5. Limit states (1 pp)

6. Design situations (1 pp)

7. Design considerations (3 pp)

8. Ultimate limit state design (1 pp)

9. Serviceability limit state design (1 pp)

10. Structural design (1 pp)

11. Anchor design (4 pp)

12. Materials (6 pp)

13. Durability (12 pp)

14. Execution (10 pp)

15. Considerations relating to testing (1 pp)


17. Reporting (1 pp)

Annexes A-I (informative) (69 pp)

Bibliography (4 pp) Eurocode 7 Workshop on NCCI ©2015 Geocentrix Ltd, Coffey, and Geoserve Global. All rights reserved

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Annexes - BS 8081:2015 Code of practice for grouted anchors

DPC BS 8081:2015(135pp) - ANNEXES (* proposed normative)

A. Indicative Record sheets (5pp)

B. Design of anchors (29pp)

C. Water testing and pre-grouting (1pp)

D. Tendon Young’s Modulus values (1pp)

E. Corrosion (5pp)

F. Corrosion protection (2pp)

G. *Testing (22pp)

H. General considerations on monitoring (4pp)

I. Health and safety (1pp)

Bibliography (5pp)


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BS 8081:2015 - Main changes

• BS 8081:2015 is now a Code of Practice and not a Standard – i.e. provision of recommendations, possibilities and information only.

• Language in accordance with BSI Rules for the structure and drafting of UK standards; 2012.

• Appropriate EC and EN compliant e.g. with EC7 (in particular DESIGN), BS EN 1537 and (yet to be published) EN ISO 22477-5 - (more from Devon Mothersille on this)

• Terminology introduced to address new concepts of design and processes of testing.

• BS8081:2015 addresses only the design, execution and testing of anchors and not general design application of anchors. (i.e. BS 8081:1989 Appendix D; Overall stability has not been included).


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BS 8081:2015 – Focus of this section

Design of the anchor (Clause 11 and Annex B)

• Compatibility with limit state design principles

• Definition of EULS;d and Fserv;k

• Relationship between Fserv;k (EC7) and TW (BS8081:1989)

• Implementation of the efficiency factor feff.

• Process of anchor sizing (design of fixed anchor length)


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BS 8081:2015 - New Terminology – Grout/ground interface

EC7 requires the design of the anchor to consider all limit states.

New terminology;-

EULS;d = Ultimate limit state force to be resisted by the anchor (kN)

Fserv;k = Characteristic value of the maximum anchor force, including effect of lock off load, and sufficient to prevent a serviceability limit state in the supported structure (kN) ≈ TW (BS 8081:1989)

RGG;k = Characteristic ultimate ground/grout interface resistance (kN) ≈ Tf (BS8081:1989)

γGG = partial resistance factor for ultimate ground/grout interface resistance (= 3.0 - Table 2)

ξGG = ground/grout interface correlation factor ( = 1.1 – Cl 11.3.2.5) Eurocode 7 Workshop on NCCI ©2015 Geocentrix Ltd, Coffey, and Geoserve Global. All rights reserved

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BS 8081:2015 – Relationship TW and Fserv;k


BS 8081:1989 TW found from overall stability

analysis (L.E.M.) with FoS up to

1.5

i.e TW = 1.5 x T(unfactored SLS condition)

T = the derived axial force that the

anchor provides to maintain

equilibrium (unfactored)

BS 8002:2015 FD = Fserv;k = SD x F x PSLS

≈ 1.5 x PSLS

From L.E.M. analysis

Where;-

PSLS = design axial force

that the anchor provides to

prevent a SLS (i.e.

unfactored)(= T)

BS 8081:2015 Since compliant with BS 8002:2015 through

consideration of stability of supported structure

at serviceability limit state;-

TW ≈ Fserv;k

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BS 8081:2015 – Derivation of RGG;k

𝑅GG;k = 𝑚𝑖𝑛 𝑅GG;calcx feff ;𝑅GG;m

𝝃𝐆𝐆

Where;-

RGG;calc = calculated ultimate ground/grout interface

resistance

RGG;m = measured ultimate ground/grout interface

resistance


BS 8081:2015

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BS 8081:2015 – Resistance efficiency factor applied to RGG;calc


Anchor resistance

efficiency factor

implemented for

both sands and

clayey ground

RGG;k = RGG;calc x feff

For Clayey soils

feff = 1.6 x Lfixed-0.57

For sandy soils

feff = 0.91Ltan

Derived from:- BARLEY, A.D. Theory

and practice of the single bore multiple

anchor system.

Proc. International Symposium on

Anchors in Theory and Practice,

Salzburg, Austria.

1995 pp293-301

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BS 8081:2015 – Design of anchor fixed length - grout/ground

𝑅GG;k = 𝑚𝑖𝑛 𝑅GG;calcx feff ;𝑅GG;m

ξGG

𝐹Serv;k ≤𝑅GG;k

γGG

And;-

𝐹ULS;d ≤ 𝑅GG;k


𝑇𝑓 = 𝑚𝑖𝑛 𝑇f;calc; 𝑇f;measured

𝑇W ≤𝑇f3.0

This was not expressly

examined in BS 8081:1989

BS 8081:2015 BS 8081:1989

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BS 8081:2015 – Concluding remarks


Objectives achieved in revision

• Reduction in size of document

• NCCI with respect to appropriate ENs and ECs

• Maintain current practice of sizing fixed anchor

lengths by single stress reduction factor (FoS?)

• Retained and updated valuable information from

BS8081:1989 in Annexes as much as possible

• Incorporated Testing Annex to provide guidance

pending the publication of EN ISO 22477-5

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Caesar


Devon



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This part of the presentation will cover:

Brief introduction

Sections within DPC BS8081:2015;

Materials

Durability

Execution

Considerations relating to testing

Maintenance

Reporting

Annexes A-I (informative)

Closing remarks

To create a document that is compatible

with EC7

The technical authors’ essential objectives in revising BS8081:1989:

Avoid alienating the UK ground anchor

industry


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Brief introduction


Materials

Durability Execution


Maintenance

Reporting


Closing remarks

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BS8081:1989

‘Section 7: Materials and components’

‘Section 8: Corrosion and corrosion protection’

DPC BS8081:2015 retains essential recommendations with 25% reduction in word count (cross-reference made to BS EN 1537:2013 throughout)

‘Section 12: Materials’

• grouts

• tendons

• encapsulations

• anchor head

‘Section 13: Durability’

• information and figures relating to Double Corrosion Protection retained

• information on nature of corrosion moved to Annex E (Corrosion) and Annex F (Corrosion protection)

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Brief introduction


Materials

Durability

Execution Considerations relating to testing

Maintenance

Reporting


Closing remarks

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BS8081:1989

‘Section 10: Construction’

DPC BS8081:2015 retains the essential recommendations with 25% reduction in word count (cross-reference made to BS EN 1537:2013 throughout)

‘Section 14: Execution’

• drilling

• storage and handling of tendons

• installation

• grouting

• stressing – equipment (e.g. hydraulic jacks, load cells and gauges)

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Brief introduction


Materials

Durability

Execution

Considerations relating to testing Maintenance

Reporting


Closing remarks

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Extract from clause 3.2 DPC BS8081:2015 NOTE Regarding the relationship between the ‘Working load of anchorage’ Tw (BS 8081:1989, Clause 3) and the characteristic value of the maximum anchor force , FServ;k, the design and testing of grouted anchors in the UK was traditionally based on a specified ‘working load’ termed Tw. BS 8081:1989 Clause 2.21.7 defines the working load as ‘the safe load (Tw) of the anchor’ , the magnitude of which is routinely derived from limit equilibrium stability analysis of the anchored structure. In order to allow for load losses (a large component of which was historically due to relaxation of prestressing steel), it has been routine practice that anchors have been locked off at 110%Tw. This took account of the fact that relaxation in prestressing steels could account for up to approximately 9% prestress loss. In situations where the lock -off load is set at 110%Tw, and no greater load is reasonably expected during the service life of the anchor, then Tw can be taken as equivalent to FServ;k /1.1, since, by definition, FServ;k includes the effect of the lock -off load. However, as it is currently acknowledged that modern prestressing steels account for prestress losses of less than 1.5%, a lock off load of about 102%Tw might be more appropriate. In the context of this code of practice, it is therefore adopted that Tw approximates to the maximum characteristic anchor force FServ;k.

In the context of this code of practice, it is

therefore adopted that Tw approximates to

the maximum characteristic anchor force

Fserv;k

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Annex G: Testing

Salient points

• Procedures for stressing and testing moved to Annex G

• Basic structure similar to that of BS8081:1989

• The basis of the revision centres on the relationship; ‘Tw’= Fserv;k

• Proof load defined in BS EN 1997-1:2004+A1:2013

• No distinction made between temporary and permanent anchors from a resistance standpoint

• Proving tests are now called investigation tests in accordance with EC7

• All acceptance criteria for investigation, suitability and acceptance tests are referenced to UK NA to EC7 (NA+A1:2014)

• Observation times have been reduced;

• Investigation tests; load-time data – 10 days reduced to 3 days

• Suitability tests; load-time data at Fserv;k – 10 days reduced to 1 day and in the event of non-conformance, 30 days observation reduced to 3 days

• Apparent tendon free length criterion – lower bound limit relaxed from 90% to 80%

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Brief introduction


Materials

Durability

Execution


Maintenance

Reporting Annexes A-I (informative)

Closing remarks

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DPC BS8081:2015, Section 16 Maintenance

Subject to minor revision to incorporate reference to published literature covering the grading of anchors heads subject to corrosive degradation

DPC BS8081:2015, Section 17 Reporting

Subject to minor revision to incorporate the concept of the Geotechnical Feedback Report (GFR) or close-out report as per DPC BS8002:2015 and DPC BS8004:2015.

This report should include;

• a record of anchor construction and any changes to the design

• results of monitoring and testing conducted during construction

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Brief introduction


Materials

Durability

Execution


Maintenance

Reporting


Closing remarks

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DPC BS8081:2015 – Annexes

Annex A – Indicative record sheets

Annex B – Design of anchors

Annex C – Water testing and pre-grouting NOTE additional section on post-grouting of anchors to be added to Annex C

Annex D – Tendon Young’s modulus values

Annex E – Corrosion (reduced in size by 15% from original text)

Annex F – Corrosion protection (reduced in size by 41% from original text)

Annex G – Testing

Annex H – General considerations on monitoring

Annex I – Health and safety

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Brief introduction


Materials

Durability

Execution


Maintenance

Reporting


Closing remarks

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Closing remarks

• The drafting of DPC BS8081:2015 was carried out within strict guidelines and time constraints stipulated by BSI

• The overall objective was to retain the information, within the original document, considered essential to the future of ground anchor practice

• It was explicitly specified that the revised document should contain non-contradictory complimentary information

• The revised document is compatible with EC7 and associated Euronorms

• In the absence of EN ISO 22477-5, Annex G will provide the necessary guidance on testing of anchors

• The acceptance criteria for the testing of anchors are referenced in the UK NA to EC7

• The structure and layout is comparable with BS8004 and BS8002 and facilitates the structure to be adopted in the revision of EC7 in 2020

• The document is still evolving, an internal review by the technical authors has generated 99 comments/amendments

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BS 8004:2015 and BS 8002:2015, Codes of practice for …

Foundations (101pp) Earth retaining structures (92pp)

Foreword (1pp)

1. Scope (1pp)

2. Normative references (4pp)

3. Terms and definitions (1pp)

4. General rules (25/31pp)

5. Spread foundations (11pp) 5. Gravity retaining walls (16pp)

6. Pile foundations (42pp) 6. Semi-gravity retaining walls (7pp)

7. Embedded retaining walls (14pp)

8. Cofferdams, basements, and strutted excavations (4 pp)


A* Underpinning (4pp) A* Deadman anchors (5pp)

B* Helical pile foundations (4pp) B. Specific formations (1pp)

C. Specific formations (2pp) C. Archaeological finds (1pp)

Bibliography (5/3pp) Eurocode 7 Workshop on NCCI ©2015 Geocentrix Ltd, Coffey, and Geoserve Global. All rights reserved

General rules – key topics for BS 8004

Ground investigation

Minimum number and depth of ‘exploration points’ for low-rise buildings

Ground parameters

Suggested values for weight density of coarse and fine soils and fill

Updated guidance on selecting cv for coarse and fine soils

Standardizing terminology for stiffness values (secant, tangent, small-strain, large strain)

‘Default’ expressions for Gsec and G0 (‘in the absence of reliable test values’)

Partial factors

Proposes ,cv = 1.0 (to overcome ambiguity in Eurocode 7)

Reporting

Confirms Eurocode 7’s requirements for GIR and GDR

Recommends production of ‘Geotechnical Feedback Report’ (aka ‘close-out report’)


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General rules – key topics for BS 8002

General rules nearly identical to BS 8004


Spacing of ‘investigation points’ ≤ 20 m along wall ‘unless ground conditions are sufficiently uniform to justify a greater spacing’

For embedded walls, depth of investigation ≥ 2H for unsupported or ≥ H for supported structure

Actions

Simplified loading model for traffic next to bridges

Earth pressure model from compaction theory

Design of embedded walls

Clarifies application of partial factors from Design Approach 1, Combination 1 (i.e. apply 1.11 to variable actions and 1.35 to effects of actions)

Re-introduces model factor on prop/anchor loads, depending on method of analysis

Clearly maps design effects of actions from retaining wall design to design actions used for subsequent anchor design (FULS,d, FServ,d, FServ,k)


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§4.2

.1.1


Ground investigations should conform to BS EN 1997-2 and BS 5930

Number of investigation points (n)

• High-rise buildings/industrial structures, conform to B.3 of Eurocode 7 Part 2

• Low-rise buildings, should satisfy (A = plan area of foundation):

low-rise building/housing [is] a building of not more than three storeys above ground intended for domestic occupation and of traditional masonry construction (for

example: detached, semi-detached, and terraced housing or flats). Also includes certain single-storey, non-residential buildings

BS 8103-1:2011

Depth of investigation (za)

• High-rise buildings/industrial structures, conform to B.3 of Eurocode 7 Part 2, i.e.:

• Low-rise buildings, should satisfy (bF = smaller side length of foundation on plan):

2

2 2

3 for 300

100 for 300

A mn

A m A m

greater of 3 or 6a Fz b m

greater of 2 or 3a Fz b m


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FIG

UR

E 2

Suggested values for weight density of coarse and fine soils


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TA

BLE 1

Values of ang, PSD, and dil to obtain φ'pk,k and φ'cv,k


25

BO

LTON

(20

14

, PER

S. CO

MM

.) Origin of the 30 + A + B + C formulation for cv,k

“The 30 + A + B + C formulation was never properly documented; no reference was available. I think it may originally have been proposed by Sowers and Sowers, but I

cannot verify that. I believe it was drafted by an early CP2 revision committee member who later died! The committee adopted it in the final 1994 revision which

was BS 8002 … even though my 1986 paper was then in existence of course.

“Actually, the 30 + A + B formulation for critical state friction angle is quite useful; it is just a pity there is no clear science behind it!”

Bolton (2014, pers. comm.)

“I attach a paper by Santamarina, who is very reliable. His Fig 2 shows a black line

from Terzaghi et al 1996 which is the best expectation for pure clays without

inclusions, together with data of large of cv at large IP for some clays with a

profusion of faecal pellets, foraminifera, or other micro-lumpy inclusions.”

Bolton (2014, pers. comm.)


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Terminology for stiffness parameters


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BS 8

00

4:2

01

5 §4

.12

.3

Geotechnical Feedback Report

The Geotechnical Feedback Report is also known as a “close-out report”

On completion of the works, a Geotechnical Feedback Report (GFR) should be

prepared that covers the following broad classes of information:

• a record of construction and any changes to its design; and

• results of monitoring and testing conducted during construction.

The Geotechnical Feedback Report should be tailored to suit the size and

complexity of the works.

The record of construction should include, as appropriate: (list of items follows)

The results of monitoring and testing should include: (list of items follows)


Shallow foundations – key topics

Calculation models for shallow foundations

Bearing capacity formulation

Effective stress method based on Poulos, Carter, and Small (includes depth, ground inclination, and soil rigidity factors)

Total stress method based on Salgado et al.

Presumed bearing resistance values removed


27

N values compared


Pile foundations – key topics

Calculation models for pile foundations

Based on ground parameters

Coarse soils – effective stress model (Nq based on Fleming et al., depends on pile type, density index, and stress level)

Fine soils – total stress model ( linked to pile type, shear strength, and stress level)

Based on field tests

Cone penetration tests – factors for base and shaft (cb and cs)

Standard penetration tests – factors for base and shaft (nb and ns)

(where the factors depend on soil and pile type)

Guidance on downdrag

Treatment of downdrag as an additional force, not as negative resistance

Presence of downdrag in ULS and SLS verifications

Structural design of cast-in-place concrete piles without permanent casing


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BS 8

00

4:2

01

5 F

IGU

RE 5

Suggested values for Nq (based on Fleming et al. 2008)


BS 8

00

4:2

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5 T

AB

LE 12

Values of empirical coefficients cs and cb


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BS 8

00

4:2

01

5 F

IGU

RE 6

Downdrag (aka ‘negative skin friction’)


Retaining walls – key topics

Simplified load model for vehicle traffic next to bridges

Replace patch loads with blanket surcharge

Guidance on compaction earth pressures

Based on Ingold model

Model factor on prop/strut/anchor loads

Depends on calculation model for retaining wall design

Explicitly stated where the factor goes – important to avoid confusion in acnhor design


30

Imposed loads on vehicle traffic areas next to bridges


Earth pressure from compaction theory


31

Model factor for load-effects in props, struts, and anchors


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Outline of talk

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The revised British Standards – 8004, 8002, and 8081 – are intended to:

• Complement (and not contradict) the current version of Eurocode 7 and its National Annexes

• Provide clarification of Eurocode 7’s requirements, where required

• Be future-proof against significant changes to Eurocode 7 expected in 2020 or thereabouts

• Update 20-30 year old technical information contained in the withdrawn or obsolete codes

• Work together as a coherent set of modern standards


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What happens next?

24th March 2015

Review ends – comments are collated by BSI and sent to authors

14th April 2015

Steering Group meets to discuss comments on BS 8081

28th-29th April 2015

Steering Groups meet to discuss comments on BSs 8004 and 8002

End May 2015

All comments resolved – proceed to publication

End June 2015

Obtain approval of revised standards (B/526)

Publication of 2015 versions of BSs 8004, 8002, and 8081

Thanks to:

Brian Simpson (Chair of B/516)

Tony Suckling (Chair of Steering Group for BS 8004)

Paul Thurlwell (Chair of Steering Group for BS 8002)

Mick Gavins (Chair of Steering Group for BS 8081)


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HTTP://D

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DPC period is about to close …

Please visit BSI’s draft standards website to access the DPCs:

http://drafts.bsigroup.com

The deadline for comments on these drafts is:

Tuesday 24th March 2015


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Any questions?

10 mins

15 mins

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Andrew


standards



Caesar


Devon



http://drafts.bsigroup.com/

http://drafts.bsigroup.com/

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Documents

REVISION OF BSS 8002, 8004, AND 8081 · 2019-10-29 · REVISION OF BSS 8002, 8004, AND 8081 Dr Andrew Bond (Geocentrix) Dr Caesar Merrifield (Coffey) Dr Devon Mothersille (Geoserve