bs 6349 part 1.2 assessment of actions moving into ...€¦ · bs 6349 part 1.2 – assessment of...

BS 6349: “Maritime Works”

Advancing on Firm Foundations 13th February 2017

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BS 6349 Part 1.2 – Assessment of

actions

Moving into Practice

1

Steve Osborn

Atkins Fellow



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Prologue

Why is BS 6349: Part 1.2 “Faulty”?

16 February 2017 2



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Prologue

During public

comment, someone

said “The equations

for wind and current

area both have 10-4

multipliers, which

converts the

Newtons to tonnes.”

3

Erroneous

power?



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Prologue

If we assume that CTW

and similar constants

are dimensionless this

is true. So we

changed the formula

to this:-

4



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Prologue

Except that CTW is not

dimensionless, so our

original formulae were

right.

5



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Prologue

So BSI withdrew the standard

The moral of this story:-

• Perhaps we should trust our judgement more

• Scrutinise the comments very carefully

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Prologue

The consequences:-

• An important contribution to the industry has been

withdrawn for several months

• Confidence has been disturbed

• Quite a few people (including in China, Africa and

France!) suddenly lost a document they were relying

on

7



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Prologue

Revised text has been approved and will

be available very shortly

8



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Contents

• Layout of the standard

• Part 1.2’s function as the “controlling document”

• Sea state and waves

• How the earthquake section was finalised

• Some interesting additions

• Summarising

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Contents






• Summarising

10



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Layout of the standard

11

Combinations of actions and structural design

Wave and water level conditions

Actions loads and hydraulic responses



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The main sections of Part 1.2 are:-

• Combinations of actions and structural design

– Which is discussed later in this presentation

• Wave and water level conditions

– Also discussed later in this section

• Actions loads and hydraulic responses

• Annexes A to I

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Actions loads and hydraulic responses:-

• In itself is a major section

• Covers hydraulic actions, currents and waves

• Ship induced actions such as berthing and mooring (generally referring to Part 4), but also actions such as propeller wash

• Earthquakes

• Cargo loadings

• Cargo handling equipment loadings

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Contents






• Summarising

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The “Controlling Document”

Part 1.2 has a major role as the

“controlling document” for all structural

design in the BS 6349 series

• It provides the “rules” connecting the codes

describing maritime works facilties to the Eurocodes

that permit the structural design.

• Much as BS 5400 Part 2 used to for Bridges.

15



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16

“Actions” and “Controlling”

Code in one.

The revised BS 6349:Part

1.2

“Material”

Eurocode

e.g. EC3-2



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Contains the tables of partial factors

17



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Contains the tables of partial factors

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Contains the combination formulae

19

In Eurocode 0, the

combination formulae

are in 5 separate

tables on different

pages (see following –

actually 10, that’s 5 for

buildings and 5 for

bridges, all on different

pages!!)



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Compare that with finding your way round Eurocode 0

20

Showing you only the

building set -

Combination formulae

for the EQU set



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Partial factors are in

an obscure corner of

the tables

Combination

formulae for

the STR/GEO

set B



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Combination

formulae for

the STR/GEO

set C



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Combination

formulae for

seismic and

accidental

actions



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Combination

formulae for

SLS cases



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And just to remind you, all 5 tables are here……

25

Persistent and

transient

Accidental

Seismic

Construction

SLS



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And here!

26

Partial factors for

the EQU set A Partial factors for

the STR/GEO set

B

Partial factors for

the STR/GEO set

C



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Contains the tables of

combination factors

• (More about those when

discussing seismic issues)

27



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Selection of partial factors now rationalised

• For most variable actions, partial factors have been set at 1.50.

• For elastomeric fenders, typical partial factor has been set at 1.35 – a reduction

– Because the latest version of Part 4 requires additional load to allow for tolerances in rubber.

– Not reasonable increase load factors since loads are highly predictable and more factors are taken into account

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Contents






• Summarising

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Sea state and waves

This is a very large section:-

• Not possible to highlight everything

• However it brings some new approaches

16 February 2017 30



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Sea state and waves

The change in

the

introduction is

indicative

This is from

Part 1:2000

16 February 2017 31



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Sea state and waves

This is from Part 1.2,

2016

Includes an immediate

review of the purpose of

obtaining the wave

information

16 February 2017 32



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Sea state and waves

Different information for different

purposes, e.g.

33

Open piled structures Breakwaters Mooring analysis



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Sea state and waves

Immediately kicks off with reminder to choose your method to suit the requirement:-.

34

• Method of

simplification to suit

what is required

• Is it for near shore or

deeper seas?



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Sea state and waves

• Climate change – completely new

• Wave characteristics – now more focus on

spectral and non-linear theories (previous heavily

based in linear theory)

• Offshore wave climate – new/ updated to focus

more on use of global numerical hindcast

sources rather than empirical hindcasts or

visually observed data

• New sections on joint (dependent) probability

35



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Sea state and waves

Much information is now in

the Annexes:-

• e.g. formulae for linear wave

analysis

• Wave prediction curves

36



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Sea state and waves


the Annexes:-


analysis


37



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Sea state and waves


the Annexes:-


analysis


• Shallow water wave transformation

information

38



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Sea state and waves

Much information is now in the Annexes:-

• e.g. formulae for linear wave analysis


• Shallow water wave transformation information

• Information on wave breaking processes

39



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Sea state and waves

Includes new recommendations for

physical model testing

40



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Sea state and waves

The assessment of hydraulic

actions:-

• Complexity means it is wise to refer to

detailed documentation, e.g. by CIRIA et al

• Information on wave formulae are given in

Annex E

• Information on flow induced vibrations etc

also there.

41



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Sea state and waves

The assessment of hydraulic actions:-

• Certain formulae for vertical walls now not explicitly quoted.

• e.g. Sainflou formula not displayed, but accessible via references (e.g. McConnell, Allsop and Flohr)

• Propeller wash scour issues highlighted and references available via PIANC

42



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Contents






• Summarising

43



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The earthquake section

• The plans for finalising this

section were presented last year.

• The approach of pointing to both

Eurocode 8 and AISC 61-14 were

endorsed

• Part 1.2 only goes as far as

defining seismic accelerations

44



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Eurocode 8 criteria for “Damage Limitation”

Taken as the Level 1 earthquake

45



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Eurocode 8 criteria for “No collapse”


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Eurocode 8 criteria for “No collapse”


47

What is “residual load bearing

capacity”?



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AISC 61-14 has three

requirements

48

More or less equivalent to

“No collapse”

More or less equivalent to

“Damage limitation”

An additional but useful

criterion (relates to PIANC)



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AISC 61-14 is the most

advanced code dealing with

seismic maritime issues

49

Very good for quays and

suspended jetties

Doesn’t cover retaining

wall type quays



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The key items in

BS6349 Part 1.2 are:-

50

Defines the Level 1 and Level 2

earthquake



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The key items in

BS6349 Part 1.2

are:-

51

Provides the means to carry out

the controlled and repairable

damage assessment using the

“Performance factor” and

reference to AISC 61-14 where

needed

Invokes the Eurocode 8

importance classes and

factors



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By this means we can invoke both:-

• Eurocode 8

• AISC 61-14

52



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A word about combination factors

53

Factor for quasi-permanent

value of a variable action



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Magnitude of seismic action

Magnitude of building personnel loading

Characteristic value

Quasi permanent value



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Magnitude of building personnel loading





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In the Eurocode that explains this:-

56

One assumes that those that designed the Eurocodes chose

these for seismic combinations to provide a suitable joint

probability ------ if only to allow for people not loading the area at

night!



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Cargo storage areas

57


Magnitude of cargo storage loading



Load can be expected to have less variation

So need to move the quasi permanent factor up



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This is what the Eurocode did for storage

loadings:

58



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This is what the BS6349 has done for

cargo areas:-

59



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Contents






• Summarising

60



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Some interesting additions

Since last year another “tweak” has been

introduced.

Guidance on bollard/mooring hook

loadings with multiple wires

61



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Table 8 gives useful

guidance and definition of

scenarios

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Guidance on reach

stacker loadings

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Guidance on rubber tyred

gantries

64



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Contents






• Summarising

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Summarising

• BS 6349 Part 1.2 now completes the update of

Part 1:2000.

• It improves our connection to the Eurocodes

• It opens the way to new areas (particularly

seismic and scour)

• It is already making an international impact

– Even though it is presently suspended!!

66



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Summarising

• Completing the update of Part 1 has been a

gargantuan task.

• Even Part 1.2 on its own has been an heroic

undertaking.

• Please show your appreciation for the

contributors listed in the next slide

67



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Summarising

68

Initial thinking:

William Allsop

Jan De Waal

Terry Hedges

Dick Thomas

Simon Burchett

Partial factors:

Steve Osborn

Adrian Douglas

David Smith

Graeme Walker

Sea-state:

Jo Evans

Simon Burchett

John Fenton

Mark Calverley

Dominic Hames

Peter Hunter

Peter Hawkes

Hydraulic/ environmental actions:

Simon Burchett

Simon Everitt

Giovanni Cuomo

Ian Cruickshank

Gareth Evans

Operational actions:

Chris Boysons

David Veale

Mark McBride

Roger Allen

Andy Cook

Peter Stebbings

Peter Beamish

Seismic actions:

Steve Osborn

David Smith

Jack Pappin

Ziggy Lubkowski

Edmund Booth

Ian Smith

Helge Frandsen

Iain Tromans

Dimitrios Pachakis



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Summarising

69

Corporate support • Aecom

• Arup

• Atkins

• CH2M

• Edmund Booth

• HR Wallingford

• Mott MacDonald

• Ramboll

• Royal HaskoningDHV

• WSP/Parsons Brinkerhoff



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THANK YOU

70

bs 6349 part 1.2 assessment of actions moving into ...€¦ · bs 6349 part 1.2 – assessment of...

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