Newsletter - Winter 2011/12Welcome to the latest edition of the LimitState newsletter, where you will find topical information on LimitState software and its practical application. This edition includes information on using LimitState:RING 3.0 to assess arch bridges containing 'saddles', and an article on working platform design using LimitState:GEO. Also included is news on our 'recommend a colleague' scheme, where you can potentially obtain free renewals for life. |
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News - LimitState:RING 3.0c ReleasedA new maintenance release of our masonry arch analysis software LimitState:RING is now available. LimitState:RING 3.0b adds pointed arch profiles and allows user-defined extrados definition for interpolated arch profiles. This release also fixes a number of other bugs. Full details of this and all previous releases are available here.
Users of previous versions are advised to upgrade. The software is available to download immediately from www.limitstate.com/try-buy/download-ring and all customers with current support and maintenance contracts can use this version with their existing license
A new maintenance release of our masonry arch analysis software LimitState:RING is now available. LimitState:RING 3.0c adds Italian, Czech and Spanish language support, and incorporates a number of minor fixes. Full details of this and all previous releases are available in the release history. Users of previous versions are advised to upgrade as soon as possible. The software is available to download immediately:
All customers with current support and maintenance contracts can use this version with their existing license. |
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News - Concrete Saddle Modelling Capability
The new reinforcement option in LimitState:RING 3.0 opens up many new possibilities, including the capability to model the effects of a reinforced concrete 'saddle', cast over the arch barrel to increase load carrying capacity.
To demonstrate the capability, the predicted failure mechanisms for multi-ring brickwork arch bridges tested by the Transport Research Laboratory (TRL) in the UK which were (a) unstrengthened, and (b) reinforced with a saddle are shown below:
Critical failure mechanisms for unstrengthened (a) and saddle reinforced (b) TRL arch bridges, as modelled by LimitState:RING (click to enlarge) It was found that the corresponding predicted load carrying capacities matched the experimental capacities reasonably well, as indicated in the table below (which also lists a bridge containing near-surface reinforcement for comparative purposes):
Single and multi-span bridges containing reinforced concrete saddles can be modelled, obviating the need to resort to highly simplistic 'rules of thumb' to model the anticipated effects of saddles on load carrying capacity. |
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News - LimitState Customer Referral Programme Announced
The scheme offers you a 50% discount voucher each time you introduce our software to colleagues working in other offices or organizations. Any colleagues that you recommend will also benefit by receiving a voucher which reduces their first support and maintenance renewal fee by 50%. By introducing enough colleagues you may never need to pay support and maintenance fees again! To learn more, visit the Customer Referral Programme page or download the PDF below:
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News - ADAMA Engineering are new North American Distributor
ADAMA President Dov Leshchinsky said,
LimitState Director Dr Matthew Gilbert spoke at a three-day course arranged by ADAMA Engineering in Newark, New Jersey on October 26-28, 2011. Details of courses are available from the ADAMA website. |
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News - LimitState Director joins Eurocode 7 ‘Numerical Models’ Group
In response to a European Commission (EC) mandate for further evolution of the Structural Eurocodes, the sub-committee for Eurocode 7 (TC250/SC7) has established Evolution Groups to prepare background papers concerning any technical problems with the current version of Eurocode 7; and to suggest possible solutions to these problems. The aim of Evolution Group 4 ‘Numerical Models’ is to identify where issues exist in the implementation of designs in accordance with Eurocode 7 using numerical methods, and to propose solutions. |
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News - LimitState:GEO featured in 'Soil Dynamics and Earthquake Engineering'LimitState:GEO was used extensively in a recent paper in the international journal, Soil Dynamics and Earthquake Engineering. Entitled "Pseudo-static limit analysis by discontinuity layout optimization The paper then goes on to verify the DLO analysis against the work of Mononobe-Okabe and Richard and Elms, examining the effects of wall inertia and combined retaining wall failure modes. A framework for modelling water pressures during seismic loading within a computational limit analysis framework is then proposed, and discussed in the context of two quay wall failures from the Kobe earthquake. Further details of the paper may be found at: http://dx.doi.org/10.1016/j.soildyn.2011.03.014 |
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LimitState:GEO Feature - The Benefits of Using Computational Limit Analysis SoftwareIntroduction
LimitState:GEO featured in an article that appeared in the September 2011 edition of theGeotechnica magazine, illustrating its use in working platform design. A summary of the key points is reproduced below. To read the full article, visit theGeotechnica online. Working platform designCurrent industry guidance for working platforms is available, for example in the good practice guide ‘Working platforms for tracked plant’, BR470 (Skinner, 2004, BRE). This provides a straightforward semi-empirical design method for determining platform strength and thickness. As illustrated in Figure 1, computational limit analysis (CLA) software, such as LimitState:GEO, allows a quick check of any design to be performed. LimitState:GEO shows the extent of the failure mechanism and also frees users from many of the restrictions of semi-empirical methods, for example allowing the following to be considered:
as well as providing scope for straightforward sensitivity studies. Comparison with widely-used examplesFigure 2 compares the results of LimitState:GEO analysis with the examples given in the widely-used guidance document BR470 for clay subgrade. It can be seen that a good match (typically less than 4% difference) is obtained between the two approaches for plane strain (2D) analysis. Obtaining the results using LimitState:GEO requires only a few minutes to set up the model. Analyses typically solve in seconds or minutes.
Figure 2: Comparison of BR470 and CLA plane strain results for a range of subgrade undrained shear strength (cu) values. However, LimitState:GEO really comes into its own when non-standard design situations are involved, e.g. when considering stability on a sloped platform (Figure 3a), a multi-layered subgrade (3b), or when checking how close plant can be taken to a platform edge (3c). In this latter case, the available bearing capacity was reduced by 26% (the same strength of platform material was assumed throughout. In practice reduced strength may be found at the edges, a situation which is easily modelled in LimitState:GEO).
Figure 3: Different working platform configurations, analysed using LimitState:GEO. a) Sloped platform; b) Multi-layered subgrade and c) Collapse mechanism at platform edge |
LimitState are pleased to announce the launch of their Customer Referral Programme, which allows customers to save money on their support and maintenance fees by introducing their colleagues to LimitState software.
LimitState Director and LimitState:GEO Product Manager Dr Colin Smith has accepted an invitation to join the TC250/SC7 Eurocode 7 Evolution Group 4 ‘Numerical Models’.
: Application to seismic analysis of retaining walls", the article describes how discontinuity layout optimization (DLO), the powerful analysis technique used in LimitState:GEO, can handle pseudo-static seismic analysis problems.
