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20/05/2008 LimitState:GEO launch & technology briefing - ICE London 12/01/2015geo1.0 LimitState:GEO Eurocode 7 Colin Smith MA(Cantab) PhD Director & LimitState:GEO.

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Presentation on theme: "20/05/2008 LimitState:GEO launch & technology briefing - ICE London 12/01/2015geo1.0 LimitState:GEO Eurocode 7 Colin Smith MA(Cantab) PhD Director & LimitState:GEO."— Presentation transcript:

1 20/05/2008 LimitState:GEO launch & technology briefing - ICE London 12/01/2015geo1.0 LimitState:GEO Eurocode 7 Colin Smith MA(Cantab) PhD Director & LimitState:GEO Product Manager, LimitState Ltd

2 20/05/2008 LimitState:GEO launch & technology briefing - ICE London Contents Eurocode 7 a.Introduction b.LimitState:GEO functionality c.Examples

3 12/01/2015 geo1.0 Eurocode 7 Introduction

4 20/05/2008 LimitState:GEO launch & technology briefing - ICE London Eurocode 7 has been under development since Use of Eurocode 7 will be mandatory in the UK in Eurocode 7

5 20/05/2008 LimitState:GEO launch & technology briefing - ICE London Eurocode 7 moves away from: working stresses, overall factors of safety, to: limit state design approach, partial factors, unified approach. Eurocode 7

6 It introduces a range of separate checks: Ultimate Limit States (ULS) Serviceability Limit States (SLS) Eurocode 7 EQU : loss of equilibrium STR : failure of the structure GEO : failure of the ground UPL : failure by uplift HYD : hydraulic heave 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

7 In the UK the checks against failure in the ground (GEO) and in the structure (STR) must be checked using ‘Design Approach 1’ which specifies 2 calculations :  Design combination 1  Design combination 2 Eurocode 7 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

8 Different factors are applied if loads are: Permanent Variable Accidental Different factors are applied if loads are: Favourable Unfavourable i.e assist or resist collapse (this may not be clear at outset) Loads 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

9 Partial Factors EC7 DC1EC7 DC2Conventional bearing capacity BS8002 (Retaining walls) Permanent unfavourable load Variable unfavourable load Permanent favourable load 1.0 c'c' tan  ' cucu Overall F.O.S N/A 2.5 – 3.0N/A 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

10 Soil properties: c u = 70 kN/m 2,  = 20 kN/m 3 Example – footing design G D B Geometry: D = 0.75m, B = 1 m 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

11 Soil properties: c u = 70,  = 20 kN/m 3 Example – footing design G D B Geometry: D = 0.75m, B = 1 m G fail /B = 5.14 c u +  D = 375 kN/m (unfactored) 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

12 Design Combination 1 Factors are primarily placed on the loads and the soil properties are unfactored. Factor on: Permanent load = 1.35 Variable load = 1.5 Usually controls failure in the structure Design Combination 1 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

13 Factor on load = 1.35 Design Combination 1 G D B Factor on c u = /05/2008 LimitState:GEO launch & technology briefing - ICE London G fail = 278 kN/m = (5.14 x x 20) / 1.35

14 Design Combination 2 Factors are primarily placed on the soil properties and loads are unfactored. Factor on: c = 1.25 tan  = 1.25 c u = 1.4 Usually controls failure in the ground. Design Combination 2 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

15 Factor on load = 1.00 Design Combination 2 G D B Factor on c u = 1.4 c.f. G fail = 278 kN/m for Combination 1 20/05/2008 LimitState:GEO launch & technology briefing - ICE London G fail = 272 kN/m = 5.14 x (70/1.4) x 20

16 Different factors are applied for different ULS cases The purpose of the partial factors is to ensure the probability of failure is sufficiently low. Partial Factors 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

17 Multiple ULS cases (e.g. GEO, STR, UPL) each with own set of partial factors Use of multiple load types (Permanent, Variable, Accidental) Favourable/unfavourable to be defined and… EC7 Challenges Different failure modes to be checked (e.g. local/global, sliding/bearing etc) Drained / undrained cases to be checked 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

18 12/01/2015 geo1.0 LimitState:GEO functionality

19 Load type specification 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

20 Multiple scenarios Choose to solve one or many scenarios in one go Select partial factor sets Set long term / short term (drained/undrained) solution mode 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

21 Scenario solutions 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

22 12/01/2015 geo1.0 Examples

23 Analysis 20/05/2008 LimitState:GEO launch & technology briefing - ICE London Analysis At this stage, LimitState:GEO was used to analyse the problem as described in the previous slides (Hands on demo of software)

24 Conclusions LimitState:GEO has been designed to maximise ease of use with Eurocode 7:  Permanent, variable and accidental load specification  Unfavourable/favourable load specification  User can specify any partial factor set  Multiple scenarios can be solved together The new unified approach in Eurocode 7 makes use of generic ULS analysis software such as LimitState:GEO directly applicable to all geotechnical problem types. Flexible approach makes it easy to utilise partial factors from other design codes. 20/05/2008 LimitState:GEO launch & technology briefing - ICE London

25 12/01/2015 geo1.0 Thank you for listening


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