+ +

Terms & Conditions


Go to -> Company Details

Go to -> Licensing of Oasys software – Licensing Documentation PDF

Go to -> Help with ordering

Privacy and Cookies

Data Security

Website Terms and Conditions

Software Licensing Terms

Privacy and Cookies

We may change this privacy notice from time to time by updating this page.

What information do we collect?

When you use this website, we may collect the following information:

  • the areas of the website that you visit
  • information about your computer, such as which browser you are using, your network location, the type of connection you are using (e.g. broadband, ADSL etc) and your IP address

We do this by using cookies, which are small files that help us track how our visitors use the website and enable us to understand where we can improve your experience. If you would like to find out which cookies we use and the information they track see our Cookies Policy.

Once you submit or register information through our website we will know who you are and your activities on this website and information about you and/or your company may be recorded on our systems. For example, we may ask for personal information when you download our software including:

  • your name
  • company name
  • email address
  • postal address
  • telephone number
  • country where you are based
  • Social media ID
  • your comments/questions
  • services/markets you are interested in

We may also collect personal information from telephone calls and/or other correspondence with you.

What do we do with the information we collect?

The information we capture is used for various purposes. The main purpose is to provide you with our services (whether available via the website or offline). We also use the information for:

  • website development
  • understanding how our visitors interact on the website
  • understanding what our clients are interested in
  • understanding what potential clients are interested in
  • dealing with enquiries/concerns
  • marketing our services and people to you
  • market research
  • service development
  • internal record keeping


We would like to provide you with information about our services and other information which we think you may find interesting. We may send you such information by post, email and/or telephone, unless you have asked us not to do so.

We will not provide your personal information to other organisations for marketing purposes without your explicit consent.

If at any time you do not want your information used for direct marketing purposes, please contact us or follow the unsubscribe link in our marketing email messages.

Who do we share this information with?

We may share your personal information with companies acting on our behalf who will only use the information to provide that service. However, we will retain control of your data and any third party service provider that we use must act in accordance with our instructions. We may also share your personal information with a purchaser or potential purchaser of our business.

In some circumstances, we may have to disclose your personal information by law, because a court or the police or other law enforcement agency has asked us for it.

How to get copies of or amend the information we have collected

You may request details of the personal information that we hold about you under data protection laws. If you would like a copy of the information held about you please write to us at oasys@arup.com or at: Data Protection Officer, 13 Fitzroy Street, London, UK, W1T 4BQ. Please note that we may charge a small £10 administration fee for information requests.

If you think any information we have about you is incorrect or incomplete, please email us as soon as possible. We will correct or update any information as soon as we can.

top ]

Data Security

We are committed to ensuring that your information is secure. In order to prevent unauthorised access or disclosure we have put in place suitable physical, electronic and managerial procedures to safeguard and secure the information we collect, including locked cabinets, electronic password protection and pass card access to buildings.

If at any point you suspect or receive a suspicious communication from someone suggesting they work for Oasys or a website claiming to be affiliated with Oasys, please forward the communication to us or report the incident by email to oasys@arup.com or in writing to Oasys, 13 Fitzroy Street, London, UK, W1T 4BQ as soon as possible.

top ]

Website Terms and Conditions

The contents of this web site are protected by copyright and other intellectual property rights under international conventions. No copying of any words, images, graphic representations or other information contained in this web site is permitted without the prior written permission of the webmaster for this site.

Oasys accepts no responsibility for the content of any external site that links to or from this site.

top ]

Software Licensing Terms

Terms and Conditions of Purchase

The full conditions of purchase and maintenance for all Oasys software are set out in the Oasys Software Licence and Support Agreement. All prices are subject to TAX at the current rate.

Prices and specifications are subject to change without notice – please ask for a written quotation.

Although every care has been taken to ensure the accuracy of all information contained herein, the contents do not form or constitute a representation, warranty, or part of any contract.

Superseded Versions of Terms and Conditions

Oasys keeps copies of all superseded versions of its terms and conditions.

Maintenance & Support Services

Twelve months support and maintenance is included with most products. Thereafter maintenance is typically 20% of the current sales price.

An annual maintenance service is available for most programs after the first year.

This service includes:

  • telephone/fax/email/web based support
  • free software updates available via internet download
  • personalised output header for many products

Form-finding asymmetric bridges

Authored by Peter Debney

I am often asked about form finding tension structures but the other day I was asked how to do one that I have not done before: an asymmetric bridge.

Form-finding is a method that determines the geometrically optimal structure to resist a set of tension forces. This may be a fabric surface or a net of cables, but the end result is a structure that has the minimum inherent energy yet has all the forces in balance.

Compression structures are different though. The minimum energy form for an arch, for example, is a pile of rubble. While tension forces stiffen, compression buckles. This means that to form-find an arch you need to cheat. Thankfully engineers of the past realised that ideal arches are mirror images of ideal catenaries: to form find an arch you simply need to turn it upside down. This means that to form find a compression structure you need to reverse the loads and put it all into tension.

So, to the bridge. I wasn’t initially given a form to work to, so I decided to make a tied arch bridge with a deck that snakes like an S in plan. Constructing the deck’s form was a simple matter of using the flex command from within GSA; likewise I flexed the arch (coincident bar and spacer elements) into a parabolic arch of a suitable rise.   Manually added ties completed the basic geometry.

As discussed above, to form find the arch I need to put it into tension, but I could not reverse the load on the ties as that would put them into compression, and neither could I simply apply point loads for the hangers as the force direction must change as the arch moves. I decided I needed to make mirror image copies of the ties above the arch to pull it into shape.

While GSA can mirror elements and nodes through a plane, I needed to mirror about a parabola. The easiest way I could think of was to copy the node coordinates into Excel and use the functions there to create the new locations, having first reordered the node numbers along a vector using the Manage Data command. I then copied the new nodes back into GSA and added the extra ties.

The last step before form finding was to ensure that the deck and real hangers would not interfere, so I created a Stage containing just the arch and upper hangers. I also created a similar one for the “real” geometry for the subsequent static analyses.

Having set the form finding soap film target prestresses, I could then form find the analysis stage to determine the arch geometry and prestress.

That completed, I just needed to reverse the arch prestress loads in the loads table using the function command, copy the tie prestress into the “real” hangers, and change the arch Bars into Beams to produce the result you can download below.

Is this the final form? Well, no. For one thing such a form find tends to be an iterative process and so some elements of the above exercise will need repeating; for another I didn’t include all the necessary forces.

What have I left out and how should you deal with it? I look forward to hearing your suggestions.

Here is the GSA arch model. Note that it is in 8.7 format, so you will need that version or higher to open it.

Require more information?

  • This field is for validation purposes and should be left unchanged.

Newsletter Sign up

Please fill out your details below to receive the latest oasys news.
  • This field is for validation purposes and should be left unchanged.