Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

intro• what is RING?

• >5000 downloads from www.shef.ac.uk/ring

• recent & current developments sponsored by Network Rail & UIC

developments to the RING masonry arch bridge analysis software

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

the presentation…

developments to RING:

(i) recent

(ii) current

(iii) future...

1992

2003/4

2004/5

2005+

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

(i) recent developments• speedup for multi-ring

problems (in RING 1.5)– obtained by switching to a

joint equilibrium formulation

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

(i) recent developments [cont.]

• RING originally treated friction as associative; i.e. dilatancy accompanies sliding

• new version will provide option to model non-associative friction (more conservative)

Normal force, n

Shear force, s

Normal force, n

= tan

Shear force, s

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

• essence of non-associative friction algorithm:

– involves solving a series of LP sub-problems with successively

modified failure surfaces

– sub-problem governed by a Mohr-Coulomb failure surface with an effective cohesion intercept

– a negative angle of friction is also initially specified

– parameters are updated at each iteration by referring to the

real problem, with the angle of friction also being successively

relaxed towards zero

Normal force

Shear force

Algorithm failure surface

Problem failure surface

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

– new algorithm applicable to large problems

– cpu time 20 that for associative friction

problems

– often larger reductions in load factor for walls

than arches…

• non-associative example

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

(ii) current developments:• complete rewrite of program

underway…

• better documentation– incl. manual focussed on railway

bridges (for UIC)

• better user-interface:– possible to change local, block

level, properties– no limits on numbers of spans,

blocks etc.

– greater interactivity

• provision of load library

• gross displacement analysis feature

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

(iii) future developments:• key priorities:

(a) soil-structure interaction

(b) reinforcement synthesis

(c) presence of RC slabs

(d) full 3D modelling

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

(a) soil-structure interaction

• currently influence of backfill (if present) modelled indirectly:

• the form of the passive pressure distribution is specified in advance of an analysis

Passive fill pressures

Dispersion of applied load

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

(a) soil-structure interaction [cont.]

• but RING quite often identifies non-

standard failure modes…

• …here soil pressures may not be as

initially specified [in practice likely to be greater resistance]

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

• another non-standard failure mode (Konjic bridge, Bosnia)

Load

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

(b) reinforcement synthesis

• what if bridge found to be under-strength?

• limit analysis & limit design synthesis problems

are closely linked

• design synthesis could perhaps be used to

automatically identify:– soil reinforcement

– even truss reinforcement

e.g. ‘arch’ at Seville Expo(!)

Matthew Gilbert & Husham AhmedUniversity of Sheffield

Arch ’04, Barcelona18/11/04

conclusions

• RING has recently been enhanced, making it

much faster for some problems

• RING is now being rewritten & will be

enhanced & extended in the future

• downloadable from: www.shef.ac.uk/ring

developments to the RING masonry arch bridge analysis software